# Street legal VW Sandrail dune buggy project. "Time will tell if it works"



## akseminole (Jan 5, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I have a similar build in the works, though I am leaning towards series or AC. I am looking forward to seeing how this works out for you


I've searched and searched and have been astounded to find next to Nothing about Stock vw engine performance. Rpm/torque bands etc. Reading about performance builds tell me nothing about a baseline to expect and extrapolate from.

I found this and I hope it helps:

http://www.thesamba.com/vw/forum/viewtopic.php?t=349827&highlight=max+rpm


"A stock non-counterweighted crank is good for only 4,500 to 5,000 rpm maximum. However, as a practical matter, you will start losing power before then. If you look through the owner's manuals available here, you will find that the 40 hp made peak power at 3,900 rpm, the 1300 at 4,000 rpm, the 1500 at 4,200 rpm, and the 1600 SP and DP at 4,400 rpm. Thus, as a practical matter, there's no need to rev much over 4,500 for any stock engine, as hp begins to drop off before then."

http://www.oocities.org/eduhachek/tech.html

https://groups.google.com/forum/m/#!topic/rec.autos.makers.vw.aircooled/3GFPdU5Q2uc

http://www.thesamba.com/vw/forum/viewtopic.php?t=229935&postdays=0&postorder=asc&start=20

It seems that 4,000 rpm is considered 55mph territory, but at what horsepower and torque I have no clue.


I guess I'm just spoiled by looking at HPEVS dyno charts for their motors.

Anyway, good luck!


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## akseminole (Jan 5, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

A thought, but idk if it will work for you. You could put taller tires on you car to compensate for your motor spinning slower than whatever the gears "think" you should be going for 4,000 rpm or whatever.

Idk, I assume that more knowledgeable people will step in soon.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

So, I will be attaching the adapter plate and coupling the motor to the drivetrain fairly soon. Will post pictures as things progress.

I do not have a speedometer. Does anyone have a recommendation about how to implement a cheap one?

I'm planning on keeping a separate 12v system from the traction motor battery pack. It will float charge via solar. My headlights are incandescent and an unnecessary drain, so I will be upgrading them to LED. I'm debating between cree XML2 and much larger brandless LEDs. The XML's have a practical limit of 1000 lumen output max driven, which should be _ok_ for travel. The other giant "100W" LEDs, which I will likely underdrive but might be too inefficient for my needs. Will experiment.

I'm not actually all that mechanically inclined, so I'm playing a lot of this by ear.


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## Duncan (Dec 8, 2008)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Hi your car is "similar" to mine 

And I will join the chorus saying - motor too small - mine is 102Kg (maybe a bit on the large side)
http://www.diyelectriccar.com/forum...-dubious-device-44370p7.html?highlight=duncan


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## Yabert (Feb 7, 2010)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Please anticipate to change your motor by a 8'' or 9'' DC motor (maybe forklift) in a close future (consider simple modification on adapter plate for other motors).
It's simple, if you drive your car like it's possible to drive it (enjoy the torque and the speed) you will destroy your tinny motor soon...
Oh! Keep in mind that a 8 or 9'' motor will give you better performance (more torque).

About speedometer, I suggest you a cheap way to know a lot of good infos: http://www.ebikes.ca/shop/ebike-parts/cycle-analysts.html

Hey, by the way, nice buggy


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## akseminole (Jan 5, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I know that not everyone has the budget for these, but I'll put it out there all the same.

I'm pretty seriously considering the 4x6 lights as they are street legal driving lights, only pull 40watts between the two of them and are already set up to just bolt on and wire in.

The 7" lights (DOT/FMVSS certified) are more likely something that I will put in my Jeep, but I know they make 7" external light mounts. Also they only pull like 20-25 watts each at 12v with a high and low beam function.


http://www.amazon.com/gp/aw/d/B00HSG2XHM/ref=mp_s_a_1_1?qid=1411047176&sr=8-1&pi=SX200_QL40

http://www.kchilites.com/catalog/pr...-pack-system-kc-711-spread-beam/category/381/

Housing to mount 7" light.
http://www.pacificcustoms.com/ac941411.html

http://www.amazon.com/gp/aw/d/B003LJ0WLE/ref=pd_aw_sbs_2?pi=SL500_SS115&simLd=1

I've actually owned the 1st gen of these trucklite LED lamps and also this generation of them as well. I much prefer the 2nd gen design over the first. The light pattern is superior. The light color is just perfect. White, no yellow tinges or blues, just white.*

There are some artifacts(a slight "x" pattern from each lamp) in the light pattern on the road caused by the optics and reflector which Can be annoying if you let that kind of thing bother you. I just ignored it and enjoyed the superior(to halogen) light.*

I like that they work on a range of voltage from 9v-33v so even if your battery is low, they can still put light out or if your system runs (for whatever reason) at 24v.*
12.8v low beam 1.8 amp
12.8v high beam 3.6 amp

Also, they are DOT/FMVSS certified, which for a street legal buggy could be a thing to consider.

http://www.amazon.com/gp/aw/d/B007K8AA7I/ref=pd_aw_sbs_7?pi=SL500_SS115&simLd=1

In a bit more affordable category, I've ordered a set similar to these and for the money, it was actually pretty decent light output.
However, Not street legal. "Off-road" only.

http://www.amazon.com/gp/aw/d/B00E0KPXN0/ref=mp_s_a_1_3?qid=1411045234&sr=8-3&pi=SY200_QL40


These seem like they would be the easiest way to get speedometer functionality in your rig as long as you don't routinely travel underground or in concrete jungles where you can't get a good gps signal. I don't know what the legality of using them as your only speedometer is, that's up to you to determine.

The first two would just "look" right at home in your buggy. The others are cheaper.

GPS speedometer selection from amazon, most expensive to cheapest:

http://www.amazon.com/gp/aw/d/B00B0Z8JE8/ref=mp_s_a_1_7?qid=1411051355&sr=8-7&pi=AC_SX110_SY165_QL70

http://www.amazon.com/gp/aw/d/B00B0ZA1LC/ref=mp_s_a_1_6?qid=1411044189&sr=8-6&pi=AC_SX110_SY165_QL70

http://www.amazon.com/gp/aw/d/B005X4QCAA/ref=mp_s_a_1_3?qid=1411044189&sr=8-3&pi=SX200_QL40

http://www.amazon.com/gp/aw/d/B00KZPN6UQ/ref=mp_s_a_1_5?qid=1411044189&sr=8-5&pi=AC_SX110_SY165_QL70


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## ga2500ev (Apr 20, 2008)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

For the speedometer I'm sure that nothing would be cheaper than an old cell phone with GPS and a speedometer app. Would'm even need cell service to use.

ga2500ev


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## akseminole (Jan 5, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

^Cheapest, most likely.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Thanks for all of the suggestions so far!

Minor update, acquired a clutchless coupler and adapter plate to mount this thing. I still have to cut out my key to size. I might also try to bolt the coupler directly to the threaded center of my motor shaft. It might require a little turning on the lathe to fit a bolt in. It might not be necessary at all, since the key and 2 set screws seems more than enough to keep it in place. I'm also highly considering doing forced air via this bilge blower in the pic that pulls ~110w.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

So, I cut out my key and it didn't quite fit into my adapter, so I had to file it down for a little while. It ended up snapping in nicely after some work.

I ordered a Cycle Analyst to have a speedometer and power consumption read-outs. Should come in within a few days.

I go to mount the motor, and the pilot shaft is keeping my adapter from sliding on all of the way. I end up having to cut it all the way to the splines, and it's still not quite flush while trying to mount it. I'll figure something out.










While dealing with the annoyance, I removed some of the old gas equipment (tank/coolers/etc). There's more room in the back now to maybe weld on a platform for batteries:









I temporarily put my motor in the front seat area while I work out the mounting issue; until then, the motor hanging out under the steering wheel here:









I still haven't removed the clutch pedal or gas, since they are sort of integrated with the brakes. I might have to cut them off.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Cycle Analyst arrived with 600A shunt.











I realized I don't have a high amp fuse yet. I went digging through my high school car stereo equipment, and I found a 400A fuse. I'm assuming it was 12v rated. If I use this on my 74v setup, does it matter? It would be awesome to reuse it for this budget build 










For the 12v electronics:

I have a 5AH 3S 11.1v LIPO pack lying around, and I have hacked a 3S2P 18650 laptop battery pack apart to add to it. I managed to get the latpop's BMS working independently so it still balances all of the cells. I already tested it on a charge. I'm going to combine the BMS of the laptop pack with the 3S LIPO since they run the same specs/voltages. This should give me 100Wh at 12v to run basic accessories (LED lights all around, horn, etc). I will add more capacity if I discover it's needed. Doing this instead of lead acid should cut weight by a good 40-50 pounds. I didn't want to do a DC-DC converter off the main pack. That thing is going to be busy enough as-is. Pics of the test setup will come soon. I finally get some days off starting tomorrow to try to possibly get that motor adapter on completely so I can literally get the wheels turning on this project


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## Yabert (Feb 7, 2010)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Jayls5 said:


> I'm assuming it was 12v rated. If I use this on my 74v setup, does it matter?


Yes. Normally a 12v fuse can't be use at 72v. By chance, ANN fuse are rated at 80 Vdc


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## Karter2 (Nov 17, 2011)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Jayls5 said:


> ....for around town travel, within a 10-15 mile range....
> ....30AH 74v nominal LIPO pack. ~2.2 KWh
> 
> We will see if it works.


 It may work, but I cannot see you making that 10 mile mark with that battery pack.!


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Karter2 said:


> It may work, but I cannot see you making that 10 mile mark with that battery pack.!


Before I even saw this last night, I was worried about range anxiety and ordered another ten 5AH 4S batteries to bring my pack capacity up to ~3 kWh. I did this to reduce required DOD per trip, and my discharge rate should now only be 5C at max (continuous) current draw with peaks of 10C for the "absolute max" acceleration I will probably never bother with. I think this is good for LiCoCO2 LIPO cells.

I think a good comparison here is the Prius plug-in hybrid that gets up to 11 miles on a 4.4 kWh pack with a curb weight of 3100 pounds. Mine is easily half the weight, no climate control/lights run off of the battery pack, and have 70% of the energy to work with. Are we in the realm of reason now?


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## crack monkey (May 30, 2011)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Why not use the vw speedometer? It is probably the easiest option. Hooks right into the drivers front wheel. 


Keep building!


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Since the adapter plate didn't go on initially, I had a few options to try. I ended up trying to seat the coupler on a little bit further. I put it in the oven for a little while then used an old book and a deadblow hammer to get the thing as far on as I could. It didn't look like it was on any further, but to my surprise, it slid in and the adapter plate was flush!

Problem #2. One of the drill holes didn't line up. I didn't have many tools on hand at our little "Maker Space" I'm building it at, so I just kind of chipped away at it with a drill for a while until I got the bolt through. 

Finally on:



















I immediately brought out my compact LIPO/controller box to give this thing a whirl. Hooking it up:










I'm only using 4 AWG for the time being. When I upgrade the pack size, I will take care of the wire as well.



















And of course, a video to go along with everything:






I had acceleration ramps turned WAYYY down, and max motor amps way down as well. 


I was so excited to test the thing, I didn't bother to check polarity. I knew it would run either way, but it's backwards in the video. *Now, I have some questions for the more seasoned people here.* I am told these motors are set for CCW rotation. What orientation does that apply to? Motor shaft facing me?

Also, you can clearly see a little vibration/roughness at higher speed in my video. How much is normal? Perhaps tires need a little balancing? You can hear the brakes lightly dragging once per RPM, but it's not significant. Also, there was a tiny bit of an odd smell, and I know nothing about transmissions. Is there a spot for transmission lube on this thing? I didn't have enough time to look things over tonight on that manual. As always, thanks for the help guys.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Minor update. I cut off the old clutch/gas pedals from the assembly, removed the lines, and a few other miscellaneous items that were no longer needed.

I brought my laptop and reprogrammed the controller for 100% acceleration and higher output. Did a quick few bursts of 10C discharge at 300A from my (soon to be upgraded) battery pack, just left the car in top gear. The higher settings certainly seem to give it more pep. 

Video: https://www.youtube.com/watch?v=5q7OQecAtmM 

Based on my tire specs, the circumference = 94.2" with Revs/Mile = 672.6. So, my wheel needs to be turning 672 RPM to hit 60 MPH. No idea how close it is at the moment, but we'll find out soon.


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## akseminole (Jan 5, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I keep wondering if you are going to remove the starter motor from the transmission and free up about 5-10lbs. 

I think there is a company(or companies) that sell a starter block off plate for it too. 
Though it seems like just any piece of sheet metal that covers the hole and bolts on would work.

Another less practical idea, if you left the starter gear teeth on (the flywheel?) and use the starter as an emergency motive power system. Dead on the side of the road and need to move the car onto a trailer, use your starter motor to move the dune buggy! I've used the starter motor to move a jeep forward, if it'll move a jeep it'll probably move your car.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



akseminole said:


> I keep wondering if you are going to remove the starter motor from the transmission and free up about 5-10lbs.
> 
> I think there is a company(or companies) that sell a starter block off plate for it too.
> Though it seems like just any piece of sheet metal that covers the hole and bolts on would work.
> ...


I was actually talking about removing that thing today. If I remember correctly, the gear no longer connects to anything since I went clutchless without a flywheel. I just don't have anything to cover the hole with after removal; I was thinking a thin plate of 6061 aluminum will do the trick, but it's definitely on my eventual to-do list. 



crack monkey said:


> Why not use the vw speedometer? It is probably the easiest option. Hooks right into the drivers front wheel.
> 
> 
> Keep building!


Forgot to respond to this earlier. I opened up the electronics box for it, and that speedometer does indeed still seem to be attached to the driver's side front wheel. Only the rear wheels are spinning on the jack-stands at the moment, so we'll find out if it works on the first test drive. If not, the cycle analyst will still cover it.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

So, I'm working the next few days, but I figured I'd show what just showed up at my door. This should make 40 of them, around ~3 kWh. They all arrived around the same voltage, around 15.4v.










I've already gone this far with everything. I'm thinking about buying enough to make it 25 miles where some of my friends/family live.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Just got back from vacation, and a few things arrived while I was gone:

Another set of batteries, and a lightweight/waterproof aluminum military case. I just ordered my last set of 10 LIPO's and they're on the way. This will make a total of sixty of them. Twenty can be seen in the picture. Total power in the end: 4.44 kWh. That's officially more than the plug-in Prius.  The prius has a range of 11 miles pure electric, so I am hoping to get 25 miles from my little buggy.











I plan to house all batteries, motor controller, shunt, main fuse, contactor, 800w charger, and resistive balancers inside. Drill/Grommet the sides of the case for external wires. There will be 1 hole for power to motor, and another out the other side for throttle, cycle analyst, and external 110v charge cord. I'm thinking about getting some ceramic insulating material to line the case for extra fire protection.


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## akseminole (Jan 5, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Wondering how the project is going?


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## epyon (Mar 20, 2008)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Any news on driving the dune ? You can't use a tube frame here in Las Vegas , our DMV is stupid .


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



akseminole said:


> Wondering how the project is going?




I replaced the transmission fluid, replaced the broken brake reservoir, bled/refilled the brake fluid, and removed the starter motor (dead weight). My friend and I also cut out fiberglass matting to size for my final aluminum box, still in the works.

Then, today I did a proof of concept of my charging system on my "tester" pack. I soldered on connectors to my 84v series charger and hooked it up while running passive resistive balancers to keep the cells behaved:










Charged up the pack to 82 volts, and did my first test run in first gear! I had to do it indoors because no lights in a silent car on Halloween = dead kids. Short runway:

http://www.youtube.com/watch?v=icPn7w4Tw_8

 I was not expecting it to perform like this


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## tylerwatts (Feb 9, 2012)

Looking great. And you have a lovely filming assistant too! Good looking project dude.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



tylerwatts said:


> Looking great. And you have a lovely filming assistant too! Good looking project dude.



Thank ya. I was surprised she stayed so still when I peeled out and backed up right to her.

So today was cold and rainy, not a good test day. So, I did a little soldering/gluing to combine a laptop battery to a 3S LIPO. Now they're both being managed automatically by the same BMS 

10AH to run the 12v electronics, I think it should be more than enough to last an entire drive after I convert all of the lights over to LED. Not pretty, but just showing the wiring chaos before I wrap it:


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## electronmonk (Oct 30, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Just my $0.02 on your headlights. If you're still thinking of building your own using LEDs, consider the Cree CXA series. All you'd need is an old computer heat sink to mount them to (I use Artic Silver thermal epoxy) and a constant current driver (I lean towards Mean Well brand). Look for the 9V rated ones which play nice with a 12V system. I get mine off of Mouser.com which has the LEDs, drivers, and different optics to go with them.

Also, what you've got running looks awesome, keep up the good work and I hope to see your great success!


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



electronmonk said:


> Just my $0.02 on your headlights. If you're still thinking of building your own using LEDs, consider the Cree CXA series. All you'd need is an old computer heat sink to mount them to (I use Artic Silver thermal epoxy) and a constant current driver (I lean towards Mean Well brand). Look for the 9V rated ones which play nice with a 12V system. I get mine off of Mouser.com which has the LEDs, drivers, and different optics to go with them.
> 
> Also, what you've got running looks awesome, keep up the good work and I hope to see your great success!


Interesting, I haven't messed around with CREE's COB LEDs, just their SMD's. I looked at the specs, and I'm not sure it's going to compete with some LEDs I already have. I was planning on running one of my 36v "100w" LEDs. I'd do 1 per headlight, under-driven at 50w for plenty of light. I've got a nice 100w CC/CV buck/boost driver to run it already as well. I have them in warm tint and cool tint:










I've already built a pretty sweet light out of one of them using a dichroic beamsplitter. You can check out the build if you're bored: http://imgur.com/a/AC97a

I still haven't taken apart the headlight housing to see if it will fit yet, but I probably have a set of cree XML's lying around if it doesn't. I'd just wire as many as I needed in series until I got my desired output, since my driver is variable voltage.


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## electronmonk (Oct 30, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I didn't know what you already had, and I'm a big fan of not spending money that I don't have to, and I like the color temperature on those


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Absolutely. Either way, I appreciate the suggestion.

The moment of truth today:

1st gear acceleration with passenger:




2nd gear acceleration with passenger:





Nothing is finalized of course, just wanted to see how it ran. There's a ton of work left to do, but this thing has _no_ problem getting up to speed.


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## tylerwatts (Feb 9, 2012)

Jay 
Looks good. Any chance next time you can do a shot of the same acceleration videoing the speedometer and rpm please? I'm keen to see how the power band of that little motor performs and holds it's own up to speed. 
Thanks


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



tylerwatts said:


> Jay
> Looks good. Any chance next time you can do a shot of the same acceleration videoing the speedometer and rpm please? I'm keen to see how the power band of that little motor performs and holds it's own up to speed.
> Thanks


I'll try. I haven't installed the cycle analyst yet, and the stock speedometer is pretty bouncy and delayed. If you want to go by sound, the peak of 1st gear in the video was bouncing around 20-22 mph.

I turned down the controller to 200A (the continuous motor rating) and cruised around in that last night. It was _ok_ on acceleration in 2nd gear. It's at least 35 mph, possibly 40 mph topping out 2nd. I just didn't have enough runway for a safe test on that one during my brief night run. I'll try to get some vids for you eventually.


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## tylerwatts (Feb 9, 2012)

Thanks. No pressure, just if you are doing it again. Looking good though and I'm pleased your motor is performing well.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I'll be working six 12 hour shifts in a row, so not much will be done until next thursday.

My friend made me a small wooden box to place inside of my aluminum case. It will push the fiberglass flush against the walls and give me some nice mounting surfaces for electrical components. I just hope everything fits, because the fireproofing and wood takes away a good amount of volume.

Also, to increase my continuous current handling, I purchased this:










I'm hoping I can keep a constant 275A-300A without overheating now. Will report back in a week!


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Think I have enough?

lol:










This is going to suck to wire up, but that's the trade-off to get cheap & power dense cells.


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## akseminole (Jan 5, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

When you say cheap, how much did they all set you back(including shipping?)?


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



akseminole said:


> When you say cheap, how much did they all set you back(including shipping?)?


First of all, I already had half of them from another project a few years ago when they were about $22 a pop after shipping.

I will be using 60 of them now. Current price is about $25 after shipping for a 5AH 14.8v 4S battery. I probably paid about $1410 for everything. In total, the pack is 60AH 74v (4.44 kWh). The impressive part is the 20C continuous rating. This means that I could have 1200A on tap if I feel like upgrading to a motor+controller with more balls. I also like that it weighs about 35 pounds less than an equivalent LiFePO4 pack.

I honestly haven't looked into how much LiFePO4 prices have gone down or where the best prices are. How much does it cost for one that's the same as mine? It would require about 23 60AH LiFePO4 batts to match it I think.


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## Karter2 (Nov 17, 2011)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Those hard case packs are excellent value $/kWhr, and $/kW
..but don't expect to get that 20c performance for more than a sec or two.
Experience suggests a continuous output of <10C is best if you don't want puffed cells or worse.
I suggest you also cycle and capacity match each pack if you have not already, to ensure you weed out any bad cells....( 5-10% dud cells are not uncommon in those packs )
Be sure never to over discharge them also (3.5v /cell minimum )


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Karter2 said:


> Those hard case packs are excellent value $/kWhr, and $/kW
> ..but don't expect to get that 20c performance for more than a sec or two.
> Experience suggests a continuous output of <10C is best if you don't want puffed cells or worse.
> I suggest you also cycle and capacity match each pack if you have not already, to ensure you weed out any bad cells....( 5-10% dud cells are not uncommon in those packs )
> Be sure never to over discharge them also (3.5v /cell minimum )


I think their quality control has improved a lot. I've only had a single battery come in DOA. I've ordered extras for other projects, probably 75 in total now. Only a few had noticeably unbalanced/mismatched cells, of which I used for stupid stuff like jumping cars. Even the "bad" ones are still alive after years.

I know LIPO heats up if you push them below certain voltages, and I'm pretty cautious. So far I've never let them get below 3.7v after running them, and I've got low voltage alarms to make sure it doesn't happen.

I'll look out for cells of varying capacity on the newest ones that just came in, but I didn't experience that issue on my first 30 of them over the course of 2 years. I do appreciate the concern/suggestions; I'm one of those nerds who reads peer reviewed journals on stuff like this, so I'm about as cautious as you can be on my budget.


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## Karter2 (Nov 17, 2011)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I'm sure you know what to do, it's just that with several (12 ?) of those 4s packs hooked up in parallel it's very easy for one weak cell to be forced down below min voltage .
Capacity and charge state equalisation is very important to prevent smoke and flames !
Do you plan to parallel at cell level also ?...it has it's pro,s and con,s !


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## toddshotrods (Feb 10, 2009)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Jayls5 said:


> ...my first 30 of them over the course of 2 years...


How many charge/discharge cycles do you think you have on them. One of the supposed drawbacks of LiPo is low cycle life, often spec'd at 500 or less, depending on how they're used. I plan to use them in the bike, so I am curious about what others have seen in real use.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Karter2 said:


> I'm sure you know what to do, it's just that with several (12 ?) of those 4s packs hooked up in parallel it's very easy for one weak cell to be forced down below min voltage .
> Capacity and charge state equalisation is very important to prevent smoke and flames !
> Do you plan to parallel at cell level also ?...it has it's pro,s and con,s !


Correct, there will be twelve hardcase batteries paralleled together.

I might cover a lot of stuff you already know in this response, but it's also being said for anyone wanting to learn. 

On my initial connecting of the batteries, I will ensure they are within 0.01v of each other so very little in-rush current will happen between them. The state of charge vs voltage isn't linear, so it's super important to be as exact as possible or you're abusing one of your batteries with excess charge current as they try to equalize.

Since I'm using batteries from 2 years ago along with new ones, I expect there to be some differences in capacity/impedence, and one (parallel pack) may charge faster than the rest. I think the best course of action is to implement an auto-off relay when any of the parallel packs reach 4.2v per cell during charging. I decided to order extra new batteries so I don't have to make any single parallel pack with mixed old + new cells, and that's why you see a few extras in the picture if you bothered to count. No regen. I just took the money saved from not buying a regen controller and put that into more batteries.

I have slow passive balancers that will be used each charge, good for continually correcting minor differences. Yes, every single cell inside each battery will also be paralleled through the "balancing leads". If any paralleled cells within the batteries read significantly lower after driving it around, I know one cell is in trouble dragging the rest down, and I will annoyingly have to find it. That's the cost of not having a legitimate BMS. On the bright side I don't have to pay for a BMS, and there will be zero parasitic drain or losses through BMS circuits/mosfets.

A weak cell won't go below min voltage if the others are keeping it afloat. My max discharge current will be a nice safe 5C at 300A now. Say I put a 300A load on my pack, and one paralleled cell is going bad. Bad cells usually have increased resistance. Electricity always goes through the path of least resistance; the healthier cells will have increased demand but still far within their safe range. If all of this is happening, it's highly likely that it will manifest as some differences in average cell voltages after a long drive. 




toddshotrods said:


> How many charge/discharge cycles do you think you have on them. One of the supposed drawbacks of LiPo is low cycle life, often spec'd at 500 or less, depending on how they're used. I plan to use them in the bike, so I am curious about what others have seen in real use.


Well, I'm using the exact same cells on another project that saw 2-4C average. I imagine a few hundred times and they seem exactly the same as when I bought them originally. That's all qualitative though, no hard numbers to back it up. I think that 500 or less is usually assuming the abuse of its high discharge rating on RC toys. I'm speculating though.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Tinkering around today:











A year ago, I bought some proprietary adjustable temperature sensing relay boards that run on 12v. Looks like I can finally put them to use! I brought out the hot plate and infrared thermometer and calibrated it for 125C temps. My roommate hooked me up with a spare piezo speaker. The plan is to hook up the temp probe to the motor. A green LED will be placed on the NC (normally closed) portion of the relay to indicate everything is good. When the high temp triggers the relay, the green LED will turn off, and a red LED will light up along with the Piezo buzzing to let me know to give my motor a break and let the fan cool it down some. This setup is _super cheap_. 

I haven't decided what I will use my second temperature board for... choices are:
1) Battery temp monitoring
2) Lower temp setting to trigger the cooling fan only when necessary, so I won't run it 100% of the time (especially while it's still cool out).


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## toddshotrods (Feb 10, 2009)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Jayls5 said:


> ...Well, I'm using the exact same cells on another project that saw 2-4C average. I imagine a few hundred times and they seem exactly the same as when I bought them originally. That's all qualitative though, no hard numbers to back it up. I think that 500 or less is usually assuming the abuse of its high discharge rating on RC toys. I'm speculating though.


Thank you.


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## Duncan (Dec 8, 2008)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Hi Jayl
Watching this with interest!
Look forwards to seeing what you find

Couple of comments
I have been using Headway cells (the old 16Ah ones)
They have been very good in replacing cells that died 
But they have been fragile
So from that
If you parallel your cells and one dies - it will take its brothers with it
I have ended up with four strings of cells so if one dies - it does not kill the rest
I top balanced - bad idea - bottom balancing is best

The Headways die quietly
I have had one LiPoly die - and I carried it outside as it was a bit energetic
Not sure what would have happened if that had been in the middle of a pack


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

What do you mean by "die"? It just unexpectedly ballooned up during charging? Did you let it go over 4.2v? What were the circumstances?


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## Karter2 (Nov 17, 2011)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



toddshotrods said:


> How many charge/discharge cycles do you think you have on them. One of the supposed drawbacks of LiPo is low cycle life, often spec'd at 500 or less, depending on how they're used. I plan to use them in the bike, so I am curious about what others have seen in real use.


Keeping the charge voltage below 4.15 , and min voltage above 3.65v , will pay back with orders of magnitude increase in cycle life on LiPo .
The RC guys kill their packs with max charge voltage and hard discharges to totally empty (<3v), repeatedly....that is not good.


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## Duncan (Dec 8, 2008)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Jayls5 said:


> What do you mean by "die"? It just unexpectedly ballooned up during charging? Did you let it go over 4.2v? What were the circumstances?


Hi Jayl

I have had cells just "die" - they go short circuit no volts - in the middle of a cycle

I have also killed some because they were 16Ah cells and I went - 80% of 16 = 12.8Ah
So I can use 12 Ah
Wrong!
Some of them were actually only 12Ah - so I killed them

Voltage is not a good measure as when you are using them they will sag
So the bottom voltage will change with load

If you have individual cell monitoring - then you can catch them

I now have four strings of 40 cells
So 16Ah x 4 and 130v
Last week I used 38Ah (I had decided 40 was a safe number) - one cell died in string 4!

As far as LiPo are concerned I have three packs I use regularly
(I repowered some old battery drills)
I have killed one pack - I overdischarged it 
My smart charger said - NO
So I tried with a dumb charger - one cell swelled up in a most alarming manner!

I'm using a "Lee Hart Battery Bridge" - one for each string


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Duncan said:


> Hi Jayl
> 
> I have had cells just "die" - they go short circuit no volts - in the middle of a cycle
> 
> ...


I'm not sure headway batteries are the best comparison, as they aren't the same chemistry. LIPO packs are typically LiCoO2 variety while headway are LiFePO4. They have different cell voltages and different discharge curves.

Did you ever use LIPO for your traction pack, or just stuff like power tools as you described? Yeah, over-discharging them in any scenario spells death for the battery.

I prefer voltage monitoring of the average paralleled cell. My cheap alarms have settings for whatever voltage I choose, so I hope to catch anything bad early on. Sorry to hear about your experiences.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Tested the temp sensor. Green light for safe temps, then it alarms and lights red at 125 degrees C just as planned:










Ed from "Juiced Racing" wasn't using his motor cooling bracket, so I took it off his hands for a very reasonable price. This should bring up my power handling a little bit:










I bought an "extended" 12 cell laptop battery for $15 and added them to make my 12v supply 17.2 AH now. They're essentially throwaway cells and only there to add capacity.










I put fireproof fiberglass mat between the wood box and the aluminum enclosure. The fiberglass particles were nasty, so I covered it all in plastic and glued it into place. I'm still planning on adding some emergency fire vents to direct flames out the back instead of towards the driver/passenger.










Got some heat/fire resistant velcro and lined the bottom to improve battery hold and reduce shock/vibration.










I painstakingly checked _every single cell within every battery_ under a 2C load to ensure they were all functioning properly. With all of the voltage almost equalized, I attached the parallel balance leads.



















At this point, I'm playing with spacing and where I want to mount everything. I still have to brace a lot of it and make the main power connectors, among other things. To be continued!

(If you reply to this, please take out the links to cut down on repeating the pics)


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## epyon (Mar 20, 2008)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Good job on every thing . Oh , just a thought . This what some people do to dune buggies .
View attachment 31730
Just a idea . A Sunday drive would rock .


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

So, I contacted Alltrax to try to resolve the "max throttle" if disconnected problem. They didn't really come up with a solution even after I sent them my controller settings. So, I had to come up with a solution on my own. Turns out, my fix also gave me an _awesome_ feature. I got a 5v IR relay. I'm going to connect the controller key-on through normally open. Only when my 5v relay is powered and turned on will the relay connect the key-on. That way, if for any reason I lose that 5v throttle signal everything gets shut down instead of 100% WOT as it currently does.

So, my watch has programmable IR... so instead of having a physical "key-on" switch, my watch is going to turn on my car  Tested and working:


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## tylerwatts (Feb 9, 2012)

Haha that is an awesome show piece Jay! Well done. And the build is looking good.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



tylerwatts said:


> Haha that is an awesome show piece Jay! Well done. And the build is looking good.


Thank you sir! I just finished 7 twelve hour shifts in a row, so I can finally get back to work on this build!

Series connectors:

Pre-oven shrinkwrap:










post-oven:










Lots of soldering to add on LIPO 4mm bullet connectors:










Still one last bit of shrink wrap to do, but a lot of the annoying stuff is finally done!


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I just wanted to say that I _hate_ working with this fiberglass fireproofing. Not catching on fire is nice, but not when the trade-off is lung fibrosis from inhaling fiberglass. It slows down progress a lot, as a simple hole requires PPE and rocket surgery to remove the excess material.




























I bit the bullet and got a nice Gigavac disconnect switch instead of the dubious harbor freight one that many said melted the plastic while running high amps through it.










I must say, if you're going to be making a lot of 0 AWG connectors or larger, get a hydraulic crimper. They're awesome and pretty cheap on ebay. No more ghetto squishing in a vice or hammer smashing. They look better and make better connections. just heatshrink it when done, and you have some great looking connectors. Wiring is looking a _little_ more clean now. Most of the mess down below comes from the paralleled balance connectors.


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## akseminole (Jan 5, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I wish you a late merry Christmas.

So, again. My curiosity forces me to inquire about your build.


I have a few questions about your build, possibly information that has already been stated elsewhere.

Who was the manufacturer of your transmission adapter plate? What type of motor to transmission connector did you use (set screw vs taper lock?)? Did you retain the clutch or go clutchless? 

How is your buggy fairing so far? 
How is the motor doing? 
Have you driven it to the theoretical range limits yet?
How is the performance?

How much does it weigh as converted (with motor, batteries etc)?

Would you recommend the adapter plate or suggest a different route?

Thank you for your time, I await your reply.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



akseminole said:


> I wish you a late merry Christmas.
> 
> So, again. My curiosity forces me to inquire about your build.
> 
> ...


My adapter plate and "ev coupler" was made by an individual who was banned on this forum, so I'm not sure if I'm allowed to mention the exact website. Essentially, it's not much different than any other adapter plate other than screw holes and amount of depth to factor in the shaft length. I just sent him schematics for the ME1003 motor. You can order an off the shelf adapter plate made for another electric motor and drill your own holes + space it yourself if the depth is off.

The coupler is a keyed shaft with double set screw. No clutch. It uses part of the clutch assembly; I'm not sure if the springs assist with absorbing a bit of shock + misalignment or not. It's not my area of expertise.

I really only got a few test runs in so far around town on the old battery pack. I'm _finally_ finishing up the 4.44 kWh battery pack now that has the fireproof barrier I wanted.

Sandrails vary from design to design, so all I can tell you is weight involved with converting.

Batteries: 69.8 pounds
Controller: 5.64 pounds
Contactor: 2 lb?
Connectors/wire: 10 pounds?
900w 84v Charger: 5 pounds?
10AH 3S battery to run 12v system: 3 pounds?
12v charger: 1 pound?
Shunt: 1 pound?

So that's approximately 100 pounds inside the 25 lb aluminum box.

Motor: 39 pounds
Adapter plate: 25 pounds?
Coupler: 15 pounds?

That's 79 pounds attached.

I have no idea how much the combined weight of the gas components removed is, but a total weight of 204 pounds for converting everything electric is pretty good in my opinion. That's the weight of many people's EV motors _alone_. I think the Netgain Warp 9 is 156 lbs and Warp 11 is 223 lbs for reference.

Performance wise at 300A the thing feels quick. Tons of torque in first gear up to 20mph, feels peppy in 2nd gear (topping 35 mph), and can start and keep up in traffic in 3rd gear. On the test day where I was heavily abusing it, the motor got pretty hot but could be attributed to a loose wire I discovered. To play it safe, I am forced fan cooling which (per Motenergy) should raise continuous current up to 275-300A. 

The real performance and range details should be coming soon as I finish up the main components. Major updates to follow within the next day or so.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Tonight, I removed lead acid battery angle iron support with an angle grinder and some prying. I bolted up the bracket/fan, and it looks a little more beefy now. I did an initial charge from ~3.78v per cell, and it took 2 hours 45 minutes to reach 4v per cell using my 800w charger - seems good. I'm doing a bit of last minute balancing before I finish up the charge to a nice safe 4.1-4.15v. I discovered you can keep the LCD balance boards connected and reading the voltage indefinitely with minimal loss on a pack of this size. 3 weeks barely made a dent with all 5 hooked up... it just needed a tiny bit more balancing than usual to make them perfect.










Tomorrow: Drill/fabricate mount for throttle, put the main battery box on and secure it somehow, cut out instrumentation spots on my switch board, and do a lot of annoying wiring! If Murphy's law doesn't take effect, I might be driving it by the end of the day.


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## Yabert (Feb 7, 2010)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Nice fan for this motor! 
It will be interesting to see how this tiny motor will survive with good air flow.
Will you monitor the motor temperature?


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Yabert said:


> Nice fan for this motor!
> It will be interesting to see how this tiny motor will survive with good air flow.
> Will you monitor the motor temperature?


Yep, when corresponding with John Fiorenza from Motenergy, I asked about that specifically. I was told not to let the surface of the case get "above 240 F". The magnets "cannot exceed 300F", so I guess 60 F is the average difference between the them during operation. Earlier in the thread, I calibrated a temp sensor relay with green/red lights + alarm for the motor. I will be mounting it directly on the motor case and covering it with an insulating material so wind doesn't give an artificially low reading.

Ok, so I failed to bring my nice camera tonight so camera phone pics will have to suffice.

The box fits! Barely. The solar panel mount has to be cut off so I can easily get the waterproof top on and off. I got one bolt through the base that didn't intersect with any important equipment inside. Ratchet straps will be temporary until I find another couple solid mounting points.

I ran a set of 10 awg wires out a newly installed front grommet from my box for the lithium 12v system. I shielded the wire with automotive corrugated tubing and secured it along the frame. It's now properly grounded to the chassis, and just awaiting the positive connection to the existing wiring.










Fabbed up a throttle mount. After lots of foot positioning, I was finally happy with the feel at this spot.










While it looks off, it's actually the most comfortable pedal position possible in the type of sitting position that the Sandrail provides. I get to pivot on the ball of my foot between the two pedals this way.










I finished my last two power wires to the motor, and I gave it some extra slack for suspension travel. 










The only things left before it's functionally driving is the motor controller turn on, fan connections, throttle input, and instrumentation! The rest will just be improvements along the way.


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## piotrsko (Dec 9, 2007)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

You do know that thermocouple and thermistors have a time lag measuring temprature and reported temperature because of sensor and object mass? I wouldn't let my motor case go above perhaps 200f, and I'd have a sensor in the cooling exhaust stream.


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## electron bom (Dec 4, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Great build thread, very inspiring! Thanks for posting.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



piotrsko said:


> You do know that thermocouple and thermistors have a time lag measuring temprature and reported temperature because of sensor and object mass? I wouldn't let my motor case go above perhaps 200f, and I'd have a sensor in the cooling exhaust stream.


 
I was under the impression that it was less than a second for the thermocouple to read the temperature it's currently touching. At least that has been my experience when connecting it to objects of known temperature.

Did you just mean that there's a delay between the heat source and time it takes to transfer through the case? I assumed that's what the 60 F difference was for. Either way, I was going to do set my case temp alarm for around 200 F just to allow time for some kind of intervention (mist? increase fan voltage?). What temp limit do you suggest for sampling the forced air exhaust? Thanks.

While I'm replying, I figure I may as well ask a general question. While double checking connection points, I discovered an anomoly in the "600A 25mv Shunt" that I bought. It seems to read a dead short (as it should), but then over a few seconds the resistance climb to around 3 Ohms!  I tried scratching the leads into it to bypass any potential metal oxidation to be sure. All other connection points are reading normal except for this. Is there any reason why this could be occuring?? I appreciate any input.


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## piotrsko (Dec 9, 2007)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Temp sensors only tell you the temp of the immediate surrounding. At the rocket site, it was not uncommon to see 15 seconds delay in temperature rise, the specs say minimum 5 secs on a bare junction tc. Add a motor case with limited heat transfer path and it could be lots longer after the rotor gets fried. I have No spec on the exhaust temp, I suggest watching that to see if it agrees with case temp because it is a shorter path. Probably not much over 275f. Until you establish a history, I would every so often pull over and check the motor carefully to see if it is blistering hot. This may not even be an issue. My motor is never warmer than hot to the touch and this is on a summer day.

Not sure whose shunt you bought, but my 1000 amp shunt was made of a magnetic steel. At 450 battery amps it gets warm which means voltage drop. We never measured shunt resistance during tests. I don't trust the readings for accuracy, and the car runs much stronger without it so it must have that huge resistance you've discovered. Crud. Now I have to figure out how to interface the inductive volt battery current sensor.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



piotrsko said:


> Not sure whose shunt you bought, but my 1000 amp shunt was made of a magnetic steel. At 450 battery amps it gets warm which means voltage drop. We never measured shunt resistance during tests. I don't trust the readings for accuracy, and the car runs much stronger without it so it must have that huge resistance you've discovered. Crud. Now I have to figure out how to interface the inductive volt battery current sensor.


 
Well, you'll probably be addressing this issue before I can. I may as well tell you how I would go about it. Do you already have the inductive current sensor? If not, I discovered the best search terminology is "current transducer". "Ammeter" doesn't work too well; you'll mostly find DMM clamp meters that way.

My plan is to program in a known current limit on my motor controller that's relatively low (100-150A maybe), then place the car in top gear. This way it stays under a relatively constant load (slowly accelerating) while you calibrate your instrumentation to match your known controller amp output.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Did a lot of stuff and finally got ready for a test drive, it felt weird... almost like it was skipping.

Calamity. Some kid shoved plastic into my motor from a 3d printer at our makerspace. It melted down into 3 blobs on the commutator, and now I get to attempt salvaging my motor. 

2 steps forward, 50 steps back.


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## tylerwatts (Feb 9, 2012)

Sorry to hear that Jay. Hopefully some Emery will remove the plastic gently.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

It's been a humbling experience recently. It turns out that correlation doesn't equal causation. The stars aligned to convince me of the wrong source of the problem. 

The makerspace currently had a very specific blue plastic in their 3D printer and a lot of little parts printed out in that color. It looked exactly the same color as what was on my commutator. Kids get taught there often, and I had the back of the motor plate off/open long enough for someone to possibly stuff something in there.










Looks the same, right? Nope. I had already begun chipping away at it when Motenergy got back to me and said it was epoxy for perfecting the balance of it to reduce the vibration.  This was for smooth operation when mounted on light equipment, like water pumps. On the bright side, it's unlikely I'll feel any imbalance through the big trans-axle and car tires.

So, I got to learn how to put this motor back together. For those who were interested in learning how to change the timing on Motenergy's brushed PMDC motors, I wanted to show how to do it. I was 99% sure I did it right already, but after screwing things up with the epoxy, I confirmed it with Motenergy before posting this:









Motor has been internally cleaned and put back together. I tested it indoors to see if it runs, and it's much better. This leads me to think part of the issue was the motor being _soaked_ from condensation last test. There's still a little shudder when babying the throttle in higher gears, but I'm hoping it's just the controller throttle curve that needs some tweaking. It's been freezing out, so a real test drive on the street has been on hold. Soon!


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Turns out the 11.1v cheapo battery just didn’t have enough capacity for what I plan on doing. I decided to use some of my extra 4S lipo batteries to make a 30AH 14.8v nominal (16.4v peak) system. This meant that anything that takes the 12-14v of the original system needs to handle the higher voltage. I wanted to change everything to LED anyway…
I went to upgrade the headlight bulb, and I discovered they were “sealed” units. In addition, the housing was rusted. I went to upgrade everything at once: 4”x6” rectangular housing, replaceable bulb reflector, and crazy high output LED upgrade.










What a nightmare.
First of all, the housing was smaller than it should have been. The first reflector I bought wasn’t even close to fitting. I had to fork over more money for another (lower profile) 4x6 reflector, and that one also didn’t fit. 










I had to dremel the glass corners down and in the middle portion to get the housing’s retaining screws to thread. Great.










I was just barely able to fit the LED upgrade in the housing with the drivers. The regular halogen can be seen next to the new one.










New turn signals in front of my headlights: 










It is a “fan cooled” CREE MTG2 LED, giving me HID performance at 70W total power consumption for both. The light output is phenomenal, so I feel a lot safer about being noticed on the road. Since the reflector is DOT approved and the LED module is spaced properly for low/hi beam, I will also not be blinding other drivers when I position everything properly.



















I discovered some of the wire was corroded, so I decided to redo everything.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

The fuse box was so rusted, I had no idea how it was still conducting. Everything replaced.
The old center console sucked. It was too low and out of reach, and I couldn’t fit everything in the way I wanted. My roommate made a quick mock-up wooden box. It helped me get the right dimensions to maximize leg room and still fit everything within reach. Still deciding what material to replace the wood with, but at least I know the optimum dimensions.
Temporary wiring: 



















The wood was too thick for the switches to thread, so I had to annoyingly use my dremel as a router to make the panel thin enough to mount them. 










Suitable for now until I find the right material to replace it...










I bought a dedicated turn signal unit. I upgraded all of the turn signals to smaller (more streamline) housings and put in LED modules that accepted higher voltages. Since the old turn signal relays were designed for incandescent, they also needed to be replaced to get a normal flash rate. 










Throttle signal is not clean. When I run the 5v hall throttle through my laptop USB, the controller output is 100% smooth. When trying off the shelf 5v converters (stepping down off my 16v), I get a crappy high frequency judder from the motor when lightly pressing the throttle.
I put the cheap waterproof unit on the roommate’s oscilloscope, and it had a 300 mV variance with a sawtooth waveform:










By comparison, my laptop usb appeared linear and had a 60 mV variance:










I took some random capacitors I had lying around and threw them in parallel with the bad driver to see if it improved things, and it reduced the variance to 80-100 mV, still with the depressed sawtooth waveform. My roommate suggested I add an inductor. We’ll see if the caps do the trick first; I’ll be testing when I’m free from work.
My “Cycle analyst” ammeter reading appears accurate and is averaging within 2-5% of the controller data readout. While charging, my ammeter reads a proper negative 8.6-9A right where it should be.
Motor works great, no vibration at high RPM, didn’t seem to heat up as much with the fan blasting.
I’m tired of the setbacks, but at least things are moving forward.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I did a good day of testing, and I made a video for your enjoyment running 325A: 



While it looks sufficiently quick, output is not where it should be. I bought the SPM model of Alltrax specifically because they said it didn’t need external heatsinking. It has plenty of open airspace in the box, but it’s still increasing temps and cutting amp output on the higher settings. After discussing with several people, I’m going to try to try to add some airflow and/or add some metal heatsinking. (I’m not even sure if the bottom is thermally conductive on this particular model)


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## Firehuntah (Apr 1, 2011)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Looks great Jay.  Seems pretty quick. I really like the LED headlights also, they're definately very bright. Hopefully you won't blind anyone with them. 

Too bad you're having temperature issues with the controller, hope you can find a solution for it. Providing more airflow to it should always help.


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## tylerwatts (Feb 9, 2012)

Looks very good Jay. Is the fan running constantly? It seems quite loud in the shots from outside the vehicle. Maybe it needs a thermistor switch to only come on when the motor is hot. Those lights look great. What is the beam pattern like?


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## akseminole (Jan 5, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Is it that loud inside the sandrail? Or does the sound of the fan just sound louder on the video?

Awesome video, btw!


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Firehuntah said:


> Looks great Jay.  Seems pretty quick. I really like the LED headlights also, they're definately very bright. Hopefully you won't blind anyone with them.
> 
> Too bad you're having temperature issues with the controller, hope you can find a solution for it. Providing more airflow to it should always help.


Yeah, even if the fans work, I'm more annoyed with having to drill holes through my 3 layer fireproof box to accomplish it. 



tylerwatts said:


> Looks very good Jay. Is the fan running constantly? It seems quite loud in the shots from outside the vehicle. Maybe it needs a thermistor switch to only come on when the motor is hot. Those lights look great. What is the beam pattern like?


For the test run, I went for maximum cooling. It's an automotive ~14v fan, and it's being overdriven on my 16.4v LIPO pack. It's going to be loud until I adjust things accordingly 

The light pattern is floody like it should be, and not too patchy. The beam pattern is mostly a product of my 4x6 reflector, not the actual LED... just wanted you to know that in case you're considering purchasing one. I pointed the lights down really far in the test video, partly because I couldn't even remember whether I had high beam or low beam temporarily connected. It was just kind of thrown together last minute.

I've got a temp controlled relay ready to go when the time comes, just needs to be wired through the car.



akseminole said:


> Is it that loud inside the sandrail? Or does the sound of the fan just sound louder on the video?
> 
> Awesome video, btw!


It seems louder on camera than in person, but it's certainly audible. It's louder from the back, not annoying at all from in the vehicle.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Update:

Throttle judder under light accel has existed on every single step down regulator I have tried to use to power the hall throttle. Only while using a step _up_ module from a _battery_ source did it become fixed (or stable laptop out). This is what I was trying to avoid from the start. I bought a precision reference voltage module to give me the best possible 99.999% stable signal. It has battery back-up and can run off my 16v system. It's on the way from china. 










I noticed some major structural weld problems where the rear suspension attaches to the frame. Got those done. Unfortunately, it required disconnecting any sensitive electronics attached to the frame. I decided to increase the battery pack size once more while everything is in pure chaos. Complete pack redesign required, which is good because I hated the last layout. I'm ditching the independent bus on each "parallel" set and just connecting the batteries in series directly. HUGE space saver.

Sizing things up for the new array:









I can stack batteries horizontally 5 high in my current box, 9 across. Two rows of these means 90 packs of 74 Wh = 6.66 kWh. Unintentionally demonic.  I'll post some pics as it comes together, but I'm also squeezing in thermisters into one battery along each battery in series for temp monitoring. I'm cutting all of the battery leads shorter for organization... crimping + heat shrinking all of them them. So 90 batteries, 2 wires per battery, 2 crimps per wire. I'm almost done and my hand is bruised from the constant pressure, lol.

I'm REALLY hoping this new pack will give me a reliable 35-40 miles of range at 80% DOD.


While the tires were off, I had them balanced to get rid of the whobble at higher speeds I experienced testing on the jack stands. I go to put the wheel back on, and I noticed one of the hubs whobble.  










I'm told it's likely a wheel bearing. Since they're wear items, I'm probably going to have to replace both bearings on both sides now. It's a vintage IRS VW suspension. I have no dea if I should just source the parts and attempt it myself or have it flat-bed towed to a shop at this point.  I don't even know what to expect to be charged. 
I need:
1) E-brake cables installed on both sides, accompanying boot + hand lever
2) Wheel bearings and any accompanying items (greese / replace worn seals)

I found one of the reasons my shifting has been terrible is the shifter can spin around completely. There's a hole in the ball joint designed to have something go through it to keep it from spinning, but I have no idea what it is. It's too wide for a cotter pin. No pics handy of that at the moment...

Got a nicer aluminum center console that the previous owner remembered he had lying around, been drilling out holes for all my buttons. Pics will be updated when installed!

Once again, 1 step forward 4 steps back. I'm committed now.


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## electron bom (Dec 4, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I too am experiencing 'judder' at partial throttle inputs. I have a PB-6 throttle that is mechanically connected to the original accelerator pedal. I had no issues when at 51.2V but since stepping up to 76.8 its almost intolerable. I haven't been able to log actual throttle values during the occurrence, but I'd guess its between 10-30%


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I've been a little busy lately... but the car was worn pretty bad. Welds were full of slag and never cleaned up, intermittent surface rust on the car, and the yellow had faded all the way to white in some areas.

Little did I know what I would be getting into with tube frame and no sand blaster, but I never want to paint this kind of body ever again. I feel like I could have done 3 regular cars.

Sanded first, fixed welds, etching primer for areas of light rust in pitting the sander couldn't get to, then white primer, then metallic blue. I think it turned out pretty good for a rattle can paint job 






































The camera doesn't quite pick up the the metallic flake look as much as you can see in person, but I think it's much improved. I'm trying to throw everything back together as fast as possible at this point.


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## Firehuntah (Apr 1, 2011)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

That's looking great Jay! Very nice color.


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## ragged89 (May 12, 2015)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Very nice work Jayls5! I just found your project while looking to see who out there has thought to pair a sand rail with electric power. 

I'll be following with great interest. I'm a gear head, but not too up on electrics (yet), so this is fascinating stuff for me. Did I see Virginia plates on your rail?


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



ragged89 said:


> Very nice work Jayls5! I just found your project while looking to see who out there has thought to pair a sand rail with electric power.
> 
> I'll be following with great interest. I'm a gear head, but not too up on electrics (yet), so this is fascinating stuff for me. Did I see Virginia plates on your rail?


That's correct. Hampton roads area. You're welcome to take a ride when I'm finished, which should be relatively soon


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## electron bom (Dec 4, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Excellent rattle can job!


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Old aluminum diamond plating had residual rust from old hardware, yellow over-spray from the prior paint job, dirt, and oxidation.

Pressure washed the dirt off, then rubbing compound, then polishing compound:



















Took FOREVER.

Battery box is now painted matching blue instead of the old military green. Maybe I'll get that wired and mounted tomorrow...


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## ragged89 (May 12, 2015)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Jayls5 said:


> That's correct. Hampton roads area. You're welcome to take a ride when I'm finished, which should be relatively soon


I just might take you up on that! I live in Chesapeake but I'm in Charlottesville most of the time, as that's where my job is these days. I have a project vehicle I've been working on for a while (not electric though). It kills me that I have so little time to devote to it. Its an '89 Dakota convertible truck that I put a V8 in. I plan to convert it to natural gas eventually.

By the way, that blue paint looks good with the aluminum floor pan.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

My girlfriend was kind enough to drill out all of the holes on my center console and mount my switches:










I finally got the box mounted back in place with the new battery array 95% wired up. It looks _way_ better now. 6.66 kWh weighing in at ~120 pounds for the batteries, bus bars, and balance connectors.










Pack design minus final balance leads and main bus bar. Looks better:


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

16v fried my cooling fan... it has intermittent connectivity now from the inside. Replacement "S" blade version of the same type just arrived in the mail, which should be quieter.

Made the control box for my fan motor. Drops down the voltage to safe running levels for the fan. I can have it run quietly at 8-10v now. Temp sensing relay module is there as well, which I can activate a higher output to the fan when it trips the temp setting I select. 

Cost of parts: $15 including the box 




















Finally made my wristwatch activated turn-on system. It's a waterproof buck step-down circuit to power a 5v relay infrared relay module. I snipped off the infrared receiver and soldered on extension wire. This is the first iteration, mainly for anti-theft:










Basically, once all of the regular switches of my car are flipped on, the watch is the "final step" to turn on the car. Tested and working!  I will be remaking this with a mult-relay version so I can control car lights and other stuff from my watch 

Total cost for that little perk was about $12

Got a larger big red horn button installed. The klaxon horn I had was red and kind of looked like it belonged on a clown car, so I painted it black. No pics handy at the moment. It's now mounted in front of the center console and working great. At 16v bursts, the thing is hilariously loud. 

I'm going to take the car to a mechanic for a final check of the essentials (brakes/suspension) to make sure it's roadworthy this week. Other than that, it's just a bunch of little busy work things to do.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I currently have a 5 bolt VW lug adapter to some unknown type of wheel lug spacing. Does anyone happen to recognized this lug pattern? (measurement is from edge of one bolt to center of the other as you're supposedly supposed to):


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## BWA (Mar 14, 2015)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

That is not a correct method of measuring the pitch circle on a 5 bolt pattern.

You have to measure from the center of the axle, or, hub, to the center of any stud, then, double it.

On a four bolt pattern, you can just measure from the center of one stud, to, the center of it's opposite one, and, that will be the pitch circle.


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## ken will (Dec 19, 2009)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Jayls5 said:


> I currently have a 5 bolt VW lug adapter to some unknown type of wheel lug spacing. Does anyone happen to recognized this lug pattern? (measurement is from edge of one bolt to center of the other as you're supposedly supposed to):


Some Fords, some Chryslers, some Jeeps.
Possibly Volvo?

http://www.crawlpedia.com/bolt_patterns.htm


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## BWA (Mar 14, 2015)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Well, apparently you are right on that 5 bolt measurement. Outside of one stud to center of the other opposite one.

That has to be the dumbest way to measure anything to do with pitch circles I have ever come across. Who makes this stuff up.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



BWA said:


> Well, apparently you are right on that 5 bolt measurement. Outside of one stud to center of the other opposite one.
> 
> That has to be the dumbest way to measure anything to do with pitch circles I have ever come across. Who makes this stuff up.


I don't know, I just saw it in the manual.

*I finally discovered why I have been having SO many problems with the wheels in the back.* The wheel bearings gave out because the axle nut likely wasn't torqued correctly. It wasn't torqued correctly because it had some weird non-factory washers spacing it out, but not appropriately. It was being spaced out because the previous owner used a 5 lug drum which is a big difference in width. They picked the 5 lug drum to get non-standard wheel spacers (assuming 4.5" ford) on to mount these large rims/tires.

So, to get things appropriate, I have to get all new 4 lug drums and new corresponding brake shoes. When I change that, I can no longer use my rear tires since they don't make 4 lug adapters for the wheels I have.  This means I get to find new rims and tires on top of it all. I can't even get them to work on it until I get a crappy 4 lug rim/tire just to be able to roll it out of the shop. Nothing available short range on craigslist or junk yards, so I'm kind of stuck here in repair purgatory. I have officially decided to name this car Murphy.


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## piotrsko (Dec 9, 2007)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Following rant:

Being an old bug head: stoopid washers won't destroy bearings because they are external to the load. Over torque is the first cause, followed by incorrect shaft spacer height. Without fail EVERY VW I have ever bought used took a 6 foot breaker tool to remove the axle nut and I weigh over 250 lbs. The inner ball bearings are very sensitive to side loads, they are primarily for carrying the weight of the vehicle. The outer bearing is for side loads only as it is way too small for anything else. 

You can buy shaft spacers new. I used to know the stock height but it's been a while.

If the nut was over-torqued, I would guess the spacer has collapsed. One used to be able to buy the 5 lug hubs as a kit because it was very popular with the sand crowd, but everybody I knew home built their own much like what you have. Set up properly, they run maybe 50,000 miles otherwise maybe 500 miles.

My $.02 (USD) YMMV


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



piotrsko said:


> Following rant:
> 
> Being an old bug head: stoopid washers won't destroy bearings because they are external to the load. Over torque is the first cause, followed by incorrect shaft spacer height. Without fail EVERY VW I have ever bought used took a 6 foot breaker tool to remove the axle nut and I weigh over 250 lbs. The inner ball bearings are very sensitive to side loads, they are primarily for carrying the weight of the vehicle. The outer bearing is for side loads only as it is way too small for anything else.
> 
> ...


I appreciate your input.


The axle stub splines extended past the drum, so I actually needed two different diameter washers. I needed 2 larger diameter washers to go over the spline, then 2-3 more washers of smaller diameter for the shaft. No combination of hardware store washer thicknesses or diameters ever had all of them 100% centered along the shaft due to the tapering between spline and shaft portion. I would basically have to eyeball it and try to center this stack of washers, and then I still had no idea if it was the appropriate extension to get that 247 ft-lb torque requirement of the castle nut.

That's the problem with getting someone else's project car; you have no idea what parts are in it. I couldn't find spacers that looked like they would work. I decided to just swap to 4 lug to get proper spacing and be done with it. I found compatible 4 lug rims at a reasonable price that will fit my current tires. By no longer needing an adapter, the stance won't be quite as wide. This is actually preferable for me, as I felt it was a tad too wide in current form.


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## BWA (Mar 14, 2015)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Hardware store washers are not up to the kinds of loads of this application.

They are generally very soft Mild Steel, and, will compress and distort under 247 Ft pounds torque. The nuts could eventually become loose because of this.

You need properly machined spacers of the right grade of steel.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



BWA said:


> Hardware store washers are not up to the kinds of loads of this application.
> 
> They are generally very soft Mild Steel, and, will compress and distort under 247 Ft pounds torque. The nuts could eventually become loose because of this.
> 
> You need properly machined spacers of the right grade of steel.


Yeah, I discovered that the hard way. I stopped torquing the moment it distorted and figured it wasn't enough.

I knew at that point I would be dealing with a special machined spacer that tapered just right as it transitioned between exposed spline diameter and axle stub shaft, and I still didn't know the proper depth at the end of the day. If they are a premade aftermarket conversion part, then I admit that I failed at online searching. That being said, I just ordered some new custom rims to made for this 4 lug setup which should be done within a few weeks. In the meantime, I'll roll around on some cheap little steelies.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

I got everything repaired.... Drums + shoes replaced with correct type, rear brake face was the wrong type so that was replaced, another wheel bearing replaced on the other side, missing e-brake hardware is now installed on the other side, e-brake cable installed, and the seal near the axle boot of the transmission replaced.

I was able to drive a whole mile during testing with no major problems. The next day and saw transmission oil leaking underneath the bell housing of the trans-axle. Looks like the seal is going in there too, so I have to remove the motor to get to it. I think the philosophical question at this point is: If I replace everything on a car, is it still the same car? haha.


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## gte718p (Jul 30, 2009)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Jayls5 said:


> That's correct. Hampton roads area. You're welcome to take a ride when I'm finished, which should be relatively soon


You said you were working out of a maker space. Are you working out of 757 or another one?


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



gte718p said:


> You said you were working out of a maker space. Are you working out of 757 or another one?


757makerspace, correct. The car is currently good for a spin around the block, but not much more than that until I get some adequate cooling on the motor controller and fix that transmission seal.

Oh yeah, and I'm making an electric E-brake system. There's no space for a hand brake system, so I'm mounting a linear actuator to do the work for me.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Pulled the motor out to get to the mainshaft transmission seal:










Definitely shot:










New seal installed:


















I was surprised how little fluid was lost in the process, not nearly as bad as I was expecting.

Rubberized the inside of the box because the ceramic kept coming unsecured. Rubberized coating still drying in this pic:










New rear rims arrived:










30w flexible lightweight Solar panel added to top of box: 










The solar panel wired to buck converter with voltage readout, and I 3d printed case for the PCB. Will power box cooling fan for hot days, and/or top off low voltage battery pack.

Cell monitors showing everything is right where it needs to be with no balancing intervention turned on at the moment, a good thing. Charged it up to 80% and took it for a spin with a friend, video will be posted later today when he gets back from work to upload it.









I decided to stop fiddling with the SPM72400 controller that keeps cutting back current, so a SPM72650 is currently on the way . I measured my box, and the new gigantic controller will fit with about half an inch of clearance. This means the vent holes will line up perfectly and require no additional airflow tubing. Yes, this controller is overkill for this motor, but if I ever fry it... I'll just go bigger.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

While testing to see if the new seal held up, friend filmed his first ever ride in it:


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

My SPM72400 motor controller kept getting too hot. Instead of fiddling with a bunch of complex cooling pipes and fan extensions, I measured to see if a bigger controller would fit.

Turns out my box was the perfect size for Alltrax's biggest motor controller, the SPM72650:










Here's my old one sitting next to the big boy:










Tonight I squeezed it in the box. Initial mounting:










Air inlet faces forward on car:










Exhaust pumps out the back of car:










This controller is rated to 450A continuous, which is more than my motor can take max. Should be fun


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## Firehuntah (Apr 1, 2011)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Wow that looks massive compared to the 72400. Hope it works great with this one now.  Have you tested it yet?


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Firehuntah said:


> Wow that looks massive compared to the 72400. Hope it works great with this one now.  Have you tested it yet?


I would have, but the new controller terminal bolts are larger diameter than the old ones. I just figured I'd make new connectors now that the spacing of the wires is off, so I ordered 10 more feet of 0 guage wire to cut/crimp.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Ok, I'm perplexed. I got the new controller working, and while better, it still has the same eventual problem. After spirited runs, the car gets slower and slower the more I drive it.

It's not the batteries. I'm barely getting 1-2v of sag on max acceleration.

It's not the motor. At the end of the runs that result in the slowdown, I checked the motor case temp to be 49C at the hottest point, blowing out about 48C air. It's very hot to the touch, but by no means cooking.

The controller has a direct cooling path through the box now, and it's rated to 450A continuous. No excuses. Is Alltrax just overrating their SPM line of controllers???


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## akseminole (Jan 5, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Can you define "slowing down" and going slower and slower? 

Like your car isn't maintaining speed driving down the road or at stop signs your take offs are less vigorus?


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## akseminole (Jan 5, 2014)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Also, what is your motor drawing (amps) when you notice it going "slower" vs what the motor is drawing when it isn't slow?


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



akseminole said:


> Can you define "slowing down" and going slower and slower?
> 
> Like your car isn't maintaining speed driving down the road or at stop signs your take offs are less vigorus?
> 
> Also, what is your motor drawing (amps) when you notice it going "slower" vs what the motor is drawing when it isn't slow?



Ok, "slowing down" was poor wording. More accurately, it is slower to accelerate and can't deliver enough current to reach top speed for the gear I am in. Let's say I decide to just keep it in 2nd gear the whole drive. At the beginning, it accelerates hard up to the ~40 mph top speed. As I continue to do more full throttle acceleration runs, the current output goes down each time until it might only be able to reach 30-35 mph.

I sit the car for a little while, let it cool off, and it's back to normal. As a reminder, my batteries are 90AH worth of LIPO only seeing about 4C per cell with minimal voltage drop.

My ammeter is on the battery side, just a display with no data logging. It clearly shows the amp output dropping as I do these test drives.

To see simultaneous battery + motor amps and corresponding controller temperatures, I would have to get a passenger to ride along with a laptop connected up to the controller.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Took the car out again for a night run:










After some spirited driving, I finally started experiencing the slowdown effect. Battery voltage sag was negligible during the event, like a few tenths of a volt. The car actually began dropping in speed with the accelerator maxed in 3rd gear when the error code started to pop up on the controller:

"1 Green and 4 Red LED Flash = M- Over temperature"

I waited a few minutes to cool down, and the car was hauling ass again. So... I don't know what's wrong here.


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## Firehuntah (Apr 1, 2011)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Did you try yet with the lid of the box opened? Since the controller is sitting in a closed box it might not get enough cool air. I see you have the air intake and exhaust of the controller opened but the case of the controller itself might act as a heatsink and need cooling too. Not sure though, don't know anything about these Alltrax controllers to be honest.  Or maybe if the bottom of the controller is flat adding a chill plate might help? Don't know how hot it gets, can you actually see the temperature of the controller?


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



Firehuntah said:


> Did you try yet with the lid of the box opened? Since the controller is sitting in a closed box it might not get enough cool air. I see you have the air intake and exhaust of the controller opened but the case of the controller itself might act as a heatsink and need cooling too. Not sure though, don't know anything about these Alltrax controllers to be honest.  Or maybe if the bottom of the controller is flat adding a chill plate might help? Don't know how hot it gets, can you actually see the temperature of the controller?



I'm pretty sure in my discussion with Alltrax at some point, they said it is thermally isolated and wouldn't benefit from mounting cooling heatsinks to the bottom like the older models. That would be fine if.... you know.... it performed to specifications. I got worried when I saw the free fuse they sent me with the 72650 was rated for 400A.

The box was open when i did those test runs so I could see the error code, so the controller had open space even if the case was getting hot. I could only work off the error codes while I have no passenger to read the temps directly, but it simply does seem that it just isn't performing to advertised specs.


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## piotrsko (Dec 9, 2007)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Go buy an cheapo Co2 fire extinguisher at your favorite home hardware store. Or can of spray freeze at an office store. Set the nozzle to spray a short burst into the controller box. 

I vaguely recall back a couple years that there were issues with alltrax not making ratings they claimed and releasing smoke. Probably why there aren't a lot of them in conversions.


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



piotrsko said:


> I vaguely recall back a couple years that there were issues with alltrax not making ratings they claimed and releasing smoke. Probably why there aren't a lot of them in conversions.


Well that's concerning. 

I contacted them with the problem, and they said it is definitely a problem with the controller. It's either an issue with the temp probe or the board itself. I get to ship it back to them now and wait for a replacement.


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## tylerwatts (Feb 9, 2012)

Well good news Jay that you might have it solved at least. Fingers crossed for you sir


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Long awaited update. I got the brakes working well, alltrax replacement came in with better performance, and this thing is hauling ass.

3rd gear is doing 55-56 mph peak, and I can start in that gear in traffic with nobody complaining about slow acceleration. 2nd gear acceleration is awesome, peaking ~42 mph depending on state of charge. 1st gear is rape torque, but only hits ~20 mph top speed.

I'm learning clutchless shifting better, and I'm still tweaking motor controller settings for maximum output. I'll try to put up a video of some basic driving soon.


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## MrDude_1 (Oct 14, 2009)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

So looking up something completely unrelated (cycle analyst rear mount bolt thread size) I found this thread.

and kept reading.. and reading... and then I get to the end and you havent posted anything in months. total disappointment. I love this build.

Did you ever figure out the controller issue? Did the replacement fix it? Did you have to move the controller to open air? Are you daily driving this now around town, or is it just sitting there? What range are you getting? etc... 

inquiring minds need to know!


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## major (Apr 4, 2008)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*

Hi dude,

You can click on the member's name and then on all posts to see what they're up to. In this case: 
http://www.diyelectriccar.com/forums/showthread.php?t=169857 

Regards, 

major


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## Jayls5 (Apr 1, 2012)

*Re: Street legal VW Sandrail dune buggy project. "Time will tell if it works"*



MrDude_1 said:


> So looking up something completely unrelated (cycle analyst rear mount bolt thread size) I found this thread.
> 
> and kept reading.. and reading... and then I get to the end and you havent posted anything in months. total disappointment. I love this build.
> 
> ...


The build was pretty much complete as originally conceived. The SPM-72650 controller took care of things. The holes I put in the battery box worked perfectly with the stock ventilation holes of the controller. It needed no further modification on the controller end of things.

That being said, I fried the brushes while taking someone out for a ride one day. I was running far more current than I should have, but it just left me with a lack of confidence that it could reliably do highway driving at that vehicle weight. I had read of a few other people who had cars running this motor, and they all eventually ran into the same issue of fried brushes (albeit after a decent amount of miles, just not enough for me to consider reliable). I got an easy 30-35 miles of range with my driving habits and could sustain 40-45 mph no problem with the 6.6 kWh. 

So, I replaced the brushes and got it running again as I sourced parts for changing to an AC-20 motor. I put about 300 miles on it before wanting to switch.

This was one of the last recorded runs I did in peak amp mode with the old motor. It got too hot with the type of driving I like to do:






After all this, I made a separate thread for swapping out controllers and motors; I figured that would be something people might search for a comparison. As major already pointed out, here's the continuation of the swap:

http://www.diyelectriccar.com/forums/showthread.php?t=169857


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