# Dual Motor



## JRP3 (Mar 7, 2008)

Hey, I know you.  Welcome. How were you going to mount the motors, stacked on top of each other or inline? I'm guessing if you're using the s10 Diff you'll be hooking them inline, probably sticking into the gas tank tunnel?
I still think you'll have to get those motors re-shafted, the female slots probably aren't strong enough to drive a vehicle. Those are probably pump motors from the forklift that were hooked to hydraulic pumps, and running at 48 volts they would never see the kind of loads you'll be putting on them.


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## tj4fa (May 25, 2008)

Maybe just needs to be re-wound?

This site also has a cool ev/gas engine cost calculator.

http://www.manvillemotor.com/our_ev_motors.htm


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## Telco (Jun 28, 2008)

A Fiero is a mid-engine job, with a transaxle style transmission. You'd be better off not bothering with an S10 anything on it. 

I'd suggest doing this as direct drive. The Fiero comes with 25 inch diameter tires stock, which means you will need 810RPM from the motor to go 60MPH and 1620RPM from the motor to go 120MPH as a direct drive. So, look into what it takes to wire the motors for maximum torque with an 1800RPM redline, then connect the motors directly to the wheels. Due to the size of the car, I don't see how you'd be able to get a differential in the rear, and the motors to fit. There's no transmission tunnel in those cars, and very little room between the seats. Setting the motors up for direct drive will also allow a lot more room for batteries than any other method. The only way to put patteries up front would be to build some sort of a Ford Escape style battery pack that uses C-cell (or was it D-cell) batteries connected together. 

And, don't just go off my suggestion, wait for someone with more experience at it than I have posts up. I've not actually done an EV, but am quite talented with the wrench in the automotive world.

A notchback Fiero is a car I've wanted since they came out, only instead of an electric motor I wanted a supercharged 400 small block Chevy in it. 

On the math for determining direct drive RPMs required, 

(5280*12) / (tire diameter in inches*3.1416) = tire revolutions per mile
60MPH is one mile per minute, so 60MPH is tire revolutions per mile per minute, X2 for 120MPH


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## JRP3 (Mar 7, 2008)

The rear of the gas tank tunnel should easily fit a 7.5 inch diameter motor, not sure about 2 of them though. I don't think those motors are large enough to run without gear reduction even if they were rewired, unless you used forced cooling. 
Not sure what you mean by saying there isn't enough room up front for batteries, lot's of people have put some of their batteries in the front of Fieros.


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## Efiero (Feb 7, 2009)

well the way i was thinking is put the motors side by side and under the diff and using a tothed belt to join it all that way i could change the gearing by changing the pully on the diff to lower or higher the gear ratio to get the best all around preformance
Oh and hi JRP3


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## JRP3 (Mar 7, 2008)

Interesting idea, under the diff side by side. So the belt would form a triangle shape around the pulleys with the diff at the top. That might not give enough tooth contact on the diff pulley, unless you have idlers on each side squeezing the the belt together closer to the diff pulley. You'd definitely need a belly pan to keep dirt and water out of the motors and belt. I'm still not sure you can get your top speed without a trans and without lugging the motors at normal driving speeds. Remember torque drops off at higher RPMs in an E motor so to have enough torque to push a vehicle to 120mph you might have to gear it closer to 4000 RPM at top speed, which means around town at 30 mph you'd only be turning maybe 1000 RPM and drawing a lot of amps. Forced ducted cooling is a must on this setup.


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## Efiero (Feb 7, 2009)

i could use the stock automatic it would solve the speedo problem and i could put a switch in to lock the converter up when i want


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## JRP3 (Mar 7, 2008)

That would certainly be an easier setup to build.
http://www.evalbum.com/1396









You'd lose some efficiency with the auto over a manual of course, and there might be a lag when starting from a stop till pressure builds up. You might take a look at this thread about using an auto box, lots of different ideas: http://www.diyelectriccar.com/forums/showthread.php/reasons-why-automatic-gearboxes-wont-work-6239.html
Another shorter one: http://www.diyelectriccar.com/forums/showthread.php/automatic-transmission-question-27540.html


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## Efiero (Feb 7, 2009)

Ok i thought that the motor controller backed out volts and current and as you lessend the car speed the losd go's away so why would it be pulling high amps i dont see how that would happen if you have a 3.5 to 1 gear ratio then it stays that and I thought the Tesla uses no trany just gear reduction thats all i was thinking


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## JRP3 (Mar 7, 2008)

Tesla uses an AC motor which can go to 14,000 RPM so it doesn't need to change gears, and high voltage, over 300 I think, so amp draw is less. AC motors also have different torque characteristics than series DC.
Accelerating a car at low speed means the voltage is low so amp draw will be high. So if it takes say 10hp, or 7456 watts to keep the car moving, at 30 mph you might be using 50 volts which means 149 amps, but at 60 mph to get those 7456 watts you're using maybe 100 volts which means 75 amps. These are somewhat random numbers but you should get the idea.
If your motors could rotate over 12,000 RPM and you were running high voltage then you could get away with no transmission and hit 120 and still be drivable around town. Or if they were physically larger motors and could handle higher amperage and generate more torque you might be able to do it with the right single speed gearing. Or if your vehicle were super light and didn't take much power to get it moving.


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## Efiero (Feb 7, 2009)

wouldent 2 7.5 inch motors be = to or about the same as a 15 inch motor i would think the amps would be lower due to using the two motors but i dont know if two motors = the same as one larger motor


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## JRP3 (Mar 7, 2008)

I don't think it's quite that simple. I can imagine a number of ways they wouldn't add up to the same thing but it would only be speculation on my part. One thing I do know is the simple mass of your two motors don't even add up to the mass of one Warp 11. Your motors are probably 70-80lbs each, so the two of them might be 160 lbs at most, where a single Warp 11 is about 230lbs. The Warp 13 is over 300 lbs I think. I don't think your motors have enough mass to handle the high amps that would be pulled at low RPM's, and I don't know if your motors can handle high voltage and high RPM's in their stock configuration to hit your top speed without a transmission. Hopefully one of our motor gurus will find this thread and comment further.


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## Efiero (Feb 7, 2009)

Ok i looked at one of the other thread and if you run the motors parrell they get the same voltage but half the amps and if in sieries they get the same amps but half the voltage. they siad that in sieries it dubles the torque so i think that they need to be run in sieries and up the batterie packs voltage instead of 120 you need 240. yes the motors need to be gone through for high voltage i know that from the other chats we had but if what i read was and is true than like i siad sieries is the way to go i think with high volts


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## JRP3 (Mar 7, 2008)

I suppose the ideal setup would be to switch between series and parallel on the go, so series for off the line torque then parallel for higher RPM's and top speed.


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## MalcolmB (Jun 10, 2008)

Efiero
I have a couple of motors that are very similar to the ones you're planning to use. Like JRP says, adding the diameters together doesn't give an accurate picture of the performance. You get a more realistic picture by looking at the combined weights, as this gives an idea of the amount of copper and the ability to soak up heat. My motors weigh 90 lbs each, so 180 lbs combined. That puts them somewhere between the weight of a 9" and an 11" motor.

My motors are also rated at 36V, but I want to run them at 108V. To avoid serious arcing at the commutator at the higher voltage I need to advance the timing of both motors, which means rotating the brush plate a few degrees opposite to the direction you want the motor to turn in. I plan to advance the motors about 8 degrees, which means drilling and tapping new holes in the end of the motor casing so that the brush plate can be mounted in the new position. Before you think of advancing the motors it's a good idea to check if they are neutrally timed at the moment. You can get a fairly good indication by testing the motors at 12V with an ammeter connected. Compare the current when the motor is running clockwise, and when it's running anticlockwise. If the currents are roughly the same then your motor is probably neutrally timed, in other words it will run equally well in either direction.

To be honest I think your performance goals may be a bit high, at least for a single ratio conversion. To get decent acceleration and 120 mph I think you'll need at least two gears. Hopefully someone with more real-life experience can chime in here.


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## Efiero (Feb 7, 2009)

I though the more watts you put at it the more power thats why the Zillas with 2000 amps and high volts and i will let some one who knows motor time it they need reshafting so i have a male ends not female like they are now


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## Qer (May 7, 2008)

JRP3 said:


> I suppose the ideal setup would be to switch between series and parallel on the go, so series for off the line torque then parallel for higher RPM's and top speed.


You're kinda reinventing the wheel here. This has been done and the Zilla can even do it automatically (or semi-automatically, not quite sure if you have to trig it) with an external contactor.



MalcolmB said:


> To be honest I think your performance goals may be a bit high, at least for a single ratio conversion. To get decent acceleration and 120 mph I think you'll need at least two gears. Hopefully someone with more real-life experience can chime in here.


It's not impossible with direct drive, just expensive. White Zombie does 0-110 mph in less than 12 seconds. No gears, but two 8" motors in siamese connection, optimum geared differential and, well, the whole drive train is replaced to get as much performance as possible.

It doesn't come cheap though, only the motor costs somewhere around (or even above) $6000 and they blow a lead acid battery every now and then because of the brutal amount of current they draw.

Read more here:

http://www.plasmaboyracing.com/whitezombie.php

So the big question is not if it's doable, it's can you afford it and do you have the knowledge?


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## Efiero (Feb 7, 2009)

lets see when i first thought about this i was going to go with a trany thought about a hydrstatic drive but was told not a good idea and was going to control speed with it now i am being told to have a trany so i can select a gear for the speed Hmmmm well i dont need a clutch so dont need the clutch pedal so thats one way or the auto just not efficiant i mean i dont mind running a trany but dam i wish to many people telling different things


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## JRP3 (Mar 7, 2008)

Here's how to tell if the brushes are advanced or not, but I highly doubt it. There should be no need to advance the brushes on a motor designed to run at 36/48 volts unless it was being run higher than that, and I don't know why it would in a forklift.
http://hitorqueelectric.com/gallery...2_GALLERYSID=e0c3792c3410ed82141d2923375067b8
I know the Zilla can do series parallel switching, but since we can't buy them you'd have to figure it out on your own. As for the Zombie, since they are siamesed do they still function as 2 motors that can be switched from series to parallel? I guess if they still have two comms and brush sets they could be. Also that's a very lightweight vehicle running two 8 inch motors that were heavily modified by Jim and running the now unobtainable Z2K. So yes it is possible but, in a Fiero running two 7.5 inch motors at less than 300 volts without Jim Husted's magic touch and without a Zilla, probably not.
Of course I don't think he's looking for Zombie performance, I just don't know about the 120 mph top end he is looking for without using a transmission.


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## JRP3 (Mar 7, 2008)

Bottom line is this. You have a lot of work ahead of you. The easiest thing is to use the existing transmission, (or if you can get a manual that would be more efficient), then build it that way. Anything else is going to be a lot more work and more money for unknown results.


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## Efiero (Feb 7, 2009)

I will need to get a standard trans i dont need the clutch right


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## JRP3 (Mar 7, 2008)

Right. You might want to keep the old clutch disc as you'll need something to fit the transmission spline. Here's my thread on different ideas for making couplers: http://www.diyelectriccar.com/forums/showthread.php/coupler-ideasi-27260.html


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## Efiero (Feb 7, 2009)

Well got a ansewer about reshafting they will be custom i am told


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## Efiero (Feb 7, 2009)

? I am planing on runing the motors in series so they see all the amps but half the volts I am wondering how many volts a motor can take before arcing problems and are the motors more efficiant at higher volts


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## JRP3 (Mar 7, 2008)

It really depends on the motor and how it's built. Most EV series DC motors are fine up to 144 volts, the Warps with more advance seem to be good to 170 or so. Some have been run higher, but these are all larger motors than yours. I think you'll need 10-12 degrees of advance on the brushes, really good insulation inside the motor, and it also depends on the number and size of the brushes in the motor, plus the number of sections in the commutator. Count the number of bars on the commutator and measure how big the comm area is and how many brushes you have. If it's like mine I think the brush area is too small to safely go above 120 volts, but I could be wrong.


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## Efiero (Feb 7, 2009)

ok so if i want 120 volts to each motor then i will realy need 240 due to each will see half of the total voltage if wirered in series


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## MalcolmB (Jun 10, 2008)

Not wanting to confuse things even more  but an alternative approach is to wire the motors in parallel and choose a controller that can deliver twice the maximum current you need for each motor. So, if you expect to feed each motor with a maximum of 500A you would need a 1000A 120V controller. I think that may be cheaper and easier to find than a 240V controller.


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## Efiero (Feb 7, 2009)

It seems zilla is or was the only one that did amps or voltage that high all the others will need moding and i will need some one who knows there stuff to do it pluse i want 1000 amp to each motor so you would need 2000 amp controller


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## MalcolmB (Jun 10, 2008)

1000A seems like a lot to be pushing through a little motor like that. I'm not saying it can't be done (for a few seconds at least), but do you have any information about the rating of these motors. Can you give us the numbers off the rating plate?


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## Efiero (Feb 7, 2009)

it is alot to ask of them and i dont have any thing on them but even if i put 500 amps through them if run in parallel i would need batteries that can discharge at 1000 amps and it is more efficaint to go higher volts than higher amps


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## MalcolmB (Jun 10, 2008)

You're right of course, efficiency-wise it makes sense to go to higher voltage.


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## Telco (Jun 28, 2008)

JRP3 said:


> Not sure what you mean by saying there isn't enough room up front for batteries, lot's of people have put some of their batteries in the front of Fieros.


This is what I mean. There;s almost no room under the hood of a Fiero. It would take major restructuring to get more than a couple three batteries under the hood up front, and that would require losing the spare tire. If you have pics of one that does have a lot of batteries up there though, I'd love to see it because I just don't see how.

In case the image doesn't work, paste this in.

http://alfazulu.freeservers.com/car7.JPG










That pic showing the stacked motors was pretty slick looking. I can see that working, but would have to wonder about where batteries would go. Due to the room constraint I'd think it would be better to have a single larger motor under there, as that would allow more batteries to be installed. 

A more flexible alternative on the batteries though, would be a custom battery tray that uses D-cell rechargable batteries. A lot of them. You'd need a recharge controller that would allow them to be charged safely, but you can build a batter pack that allows you to wire them up to the voltage needed, and fit them into tighter areas that a standard battery won't fit in. This would allow more battery capacity to be packed in. This strategy is used in the production hybrids. Here's a slide show showing 5 different hybrid packs, along with a description of what makes them up. It also looks like a Prius battery pack runs about 2500 bucks USD. That's not nearly as bad as I thought it might be, and might make a viable battery source.


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## Efiero (Feb 7, 2009)

the fuel tank tunnel can house many batteries like you said D or C cell in a long PVC tube's can make up some of it no need to be able to get at them unless they go bad the fiero you need to be a bit more creative and cant realy use car batteries


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## JRP3 (Mar 7, 2008)

I count 7 batteries in the front here plus the battery charger.









I'll be able to fit about 16 of the large format 100 ah lithium Thundersky cells in the gas tank tunnel, another 16 in the motor bay, and not use the front or rear trunk at all for batteries.


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## Efiero (Feb 7, 2009)

well there you go there is room enough then and that would be ample power 100 AH x 240 V 24000 WH divide by 248 WHM = 96 miles


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## JRP3 (Mar 7, 2008)

I'll be using 32 of these:


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## Efiero (Feb 7, 2009)

Ok what and who makes how much if i dare ask


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## JRP3 (Mar 7, 2008)

I thought everyone knew  Those are Thunder sky LiFePo4, 3.2 volt, 100 ah batteries. Price will depend on if I get them from a US reseller, (as an example, they don't actually have the 100 ah version):
http://shop.junglemotors.com/catego...97B0D0CA934F3806FA0.qscstrfrnt04?categoryId=2
or take a chance and buy direct from China. Or I'll go with the same spec cells from the place Technologic is testing, if they turn out good and the price holds true.


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## Efiero (Feb 7, 2009)

just about 60 cents a WH


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## JRP3 (Mar 7, 2008)

Yeah I think they go around 50 cents direct from China, plus shipping, so it's probably worth it to get them locally. I really hope Technologics cells pan out though.


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## Efiero (Feb 7, 2009)

this is the only thing that holds it back the batteries are to much money they have the charging time down to resnable and they will go a decent distance for the size and weight if it where 15 to 20 cents a WH


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## JRP3 (Mar 7, 2008)

Think about how much money you'll be saving every year in gas and the batteries don't seem as expensive.


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## dolinick (Feb 4, 2009)

I am trying to build low budget EV from a Chevette. Would dual low voltage low amp golf cart motors be an option for me? My car has rear wheel drive and a 4 speed transmission. I also like the idea mentioned in this thread about the "D" cell battery packs. If they are relatively inexpensive I can stuff them and hide them all inside the body, fenders, doors and everywhere.
I might even be able to put a back seat back in the car. it was missing when I purchased the car. The '82 Chevette is tiny but has lots of cargo room. It's a hatchback. Today I hauled some 10' foot 2x4s in it with the back opened and my mountain bike fits in there and I can even close the lid.

Dan


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## Efiero (Feb 7, 2009)

Hmm i think there gona be to small there even smaller than what i am useing i think they would move it but i dont think to fast a forklift motor would be better


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## JRP3 (Mar 7, 2008)

Depends on the motor. Many golf cart motors are 6 inch diameter, two of those would certainly move a Chevette. The "D" cell batteries are not cheap, probably the most expensive way to go. If you want cheap you need to go with lead. Next choice is large format prismatic lithium like I'm using, after that the cylindrical laptop type cells.


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## Efiero (Feb 7, 2009)

I went out and looked at the motors and they have 4 brushes and 49 segments is this the same as yours JRP3


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## Telco (Jun 28, 2008)

JRP3 - Neat, there's more room up there than I thought there was. I stand corrected.


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## JRP3 (Mar 7, 2008)

Efiero said:


> I went out and looked at the motors and they have 4 brushes and 49 segments is this the same as yours JRP3


I never counted my comms but it sounds about the same. I'll check mine when I get a chance. Basically a larger number of comm bars and larger comm and brush surface area the higher voltage it can take.


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## Efiero (Feb 7, 2009)

well i talked to a friend whos dad will make me some shafts that will fit the female part of the motors the will be made from tool steel


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## JRP3 (Mar 7, 2008)

I'm still concerned about the strength of a shaft cut down enough to fit into those slots, especially with the load you'll be putting on them. How will you be connecting the two motors together? How will you connect them to the transmission spline? If you stack them on top of each other, then connect them with pulleys on the front shaft, that means the rear shaft of the bottom motor will take the full load when connected to the transmission. I don't think the cut down shaft will handle that.


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## Efiero (Feb 7, 2009)

I Still will be going side by side with belts and got thinking how strong is a good 1/2 drive breaker bar well it will take 350 ft lbs torque the shafts will be 1 inch then they go to 3/8 thick by 1 inch wide and made of tool steel that is super strong i dont think there will be any problems. the load will be shared by both shafts


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## Efiero (Feb 7, 2009)

I am still thinking about useing a automatic trany i know there are some bad things but i think there are some good things to i thiink it would accelerate faster by steping on the gas and the brake to preload the torque converter like when you go drag racing . you can make a switch to have the torque converter lock up when you want it to so once you got moving it you would lock it up this would help efficiency due to the torque converter not sliping in lower gears


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## JRP3 (Mar 7, 2008)

The only reason you preload the torque converter in an ICE is to get RPM's up into the torque range to build up torque. Since full torque is available at 0 RPM in an E motor there is no point in preloading.


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## Efiero (Feb 7, 2009)

well then just need to hook the converter lock up to a pressure switch as soon as enough pressure builds it locks up no since in having the converter slip mide as well have it lock asap


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## Efiero (Feb 7, 2009)

It is starting the price on ebay for Li-Ion polymer batteries is starting to fall i think in about 6 months it will be 20 cents a WH


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## Efiero (Feb 7, 2009)

I thought i would post this site
http://ecomodder.com/forum/tool-aero-rolling-resistance.php


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## epyon (Mar 20, 2008)

I have to ask , why didn't you just put the the motor to a driveshaft to a spindle on each rear wheel ? The ELLICA does 220 MPH and smoke a 911 Turbo with no diff or trany . Your car should be lighter with a lighter amount of battery's your using . And one motor on each wheel should be fine . Torque from two motors is still torque , no matter how you hook them up or apply them , right ? If need be , get some 2.1-1 gear reducers to help with a hole shot . I'm doing mine on a even lower budget then you . Are you gonna stripe it down and get it as lite as you can be for you put your stuff in ? I'v had to get this THUNDERBIRD I have lite before . and it will and did surprise alot of people .


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## iti_uk (Oct 24, 2011)

Efiero said:


> I Still will be going side by side with belts and got thinking how strong is a good 1/2 drive breaker bar well it will take 350 ft lbs torque the shafts will be 1 inch then they go to 3/8 thick by 1 inch wide and made of tool steel that is super strong i dont think there will be any problems. the load will be shared by both shafts


Tool steel is very hard but very brittle - wouldn't you expect the shafts to fracture with any shock loads through the drivetrain?

Chris


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## epyon (Mar 20, 2008)

Are you gonna use a electric pump for the trany when it's at idle or off ? They run best between 30 an 65 psi . Are you gonna just set the motor for 700 rpm idle ?


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