# A way to have a 2 gear system without a transmission...?



## nrXic (Sep 22, 2009)

Hello all,
I don't mean to spend a lot of time introducing myself, but I do have to warn everybody that I just registered to this site and I'm a newb to cars, EVs, the physics/concepts of electricity, and long-term relationships with women. But I am somewhat creative and I like to think about solutions to problems. Most times I tell these solutions to friends and they point out the flaws in them and tell me why they're impossible to achieve.

So I'm requesting the same here. I had an idea a few weeks ago and no one I know personally has any working knowledge of cars. 

I've done at least an hours worth of reading of various threads and so I hope I don't sound like a complete idiot here. (though I plan to read a whole lot more in the coming months because this is all fascinating)

/intro over

I was wondering how to solve the top speed issue of the Tesla Roadster, which to my limited knowledge is due to the fact that they had to go with a direct drive system. I've found some posts in the "What's holding EV racers back?" thread that seem to confirm this:



major said:


> As far as AC motors, about the only guys I know of running AC is (or was) BYU with the EV1. It didn't do too badly. Especially considering it is front wheel drive and used ultracapacitors.
> 
> The AC motor will never get the torque output per pound that the series DC does. But you can run the AC much faster and therefore gear in some of that lost torque. And the AC motor may be able to improve second half track power. But for ETs, getting going faster sooner is a big plus.
> 
> ...





JRP3 said:


> People will use hard acceleration from a stop much more often than top speed, so that's where the emphasis was put, and where EV's shine. Plus, as I mentioned, they kept breaking the two speed transmission. If they can do 125 with one speed they would certainly not need more than two if they did use a transmission.





Overlander23 said:


> In this case, a higher voltage (less torque, more speed) motor with a gearbox will be more efficient from a motor standpoint, not necessarily a system standpoint. You're fundamentally adding another point of frictional inefficiency into the system with a gearbox.


If I'm not mistaken they also refer to the advantage of DC motors having a lot of torque that dies out as RPMs go higher.

The solution of a 2-gear transmission was obviously something that Tesla did not go for (I don't know what reasons but one of the posts I quoted hints at mechanical issues). Secondly it can introduce a decrease in efficiency and lost mechanical energy. It also adds weight.

*Proposed solution:*
How about using an AC motor that is direct drive on the front axle, and another AC motor using direct drive but geared different on the rear axle?

When the car launches it uses the rear drive system (to maximize weight transfer) that is geared to provide more torque.

When the car reaches a certain speed a computer cuts power to the rear motor and directs it to the front motor, which resumes acceleration at say a 1:1 ratio (or whatever is most suitable).

To my naivety this seems like a way to get a "2 speed transmission" without using a transmission. To my limited knowledge there is no "engine braking" with AC motors, they can coast along fine when no power is given to them. The opposite axle will roll along to whatever work the other one provides.

I do recognize that another motor means added weight. I figured both motors would use the same battery system. 

There must be something wrong with this idea (as is usually the case with most of my "solutions") and I'm interested in hearing what. I realize that there are a lot of talented individuals on this forum and I'd like to hear outright why this doesn't work...rather than me wondering for weeks whether or not it would or wouldn't work.

I also had some other ideas but interestingly enough I found them to be already implemented. For example I had an idea to have 4 motors on all 4 wheels, and that has been implemented. So I was encouraged by that and I thought that I could be on the right track with some of these ideas.

As I mentioned, there seems to be a lot of talented people here and as such I hope I'm not wasting anyone's time here. Some of you are busy people I'm sure and so if you don't respond I completely understand. If you would like to be frank/blunt and keep your response to even one sentence I am fine with that.

Thanks for your time.

-addendum-
If this is the wrong forum for such questions I apologize in advance and understand if this is deleted.


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## a4111 (Feb 25, 2009)

Having 2 motors hooked up to the wheels at all times without a clutch would introduce a lot of mechanical losses, rotating mass, weight, and complexity to the point that simply hooking up a transmission would be more beneficial.

However they do have setups that utilize series/parallel shifting where 2 motors are used in series at low RPM (full pack current through each motor = full torque from each motor) and switches to parallel at high RPM (half pack current through each motor but full pack voltage = higher RPM for higher top speed). This is one way to sort of get a 2 speed setup without a transmission.


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## Bfalken (Apr 29, 2009)

Ok I'll bite,
I can see 2 flaws in your plan. One is that the problem with running a dc motor at high speed is not that it loses power at high RPM's its because they fly apart at high RPM's so you would need to clutch your first speed motor when your in second. Secondly you would need two differentials which would have at least as much drag as a two speed transmission. So I think you end up with the same amount of equipment your trying to eliminate.


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## Electric Car-Nut (Jul 5, 2009)

Bfalken said:


> Ok I'll bite,
> I can see 2 flaws in your plan. One is that the problem with running a dc motor at high speed is not that it loses power at high RPM's its because they fly apart at high RPM's so you would need to clutch your first speed motor when your in second. Secondly you would need two differentials which would have at least as much drag as a two speed transmission. So I think you end up with the same amount of equipment your trying to eliminate.


Bfalken, You are right on the problems. Another alternative I have researched but haven't built yet is using the 2speed transfer case out of a jeep. gives 1:1 or 2:1 ratio can, can drive either axle so you can build a front or rear wheel drive. (A differential wasts 5 to 10 % on internal friction so don't use 4wd unless you want it for snow or mud... ) And motors are limited at above max RPM they do "Disassemble" themselves whether electric is applied or not! I'm glad this forum is available, lots of good advice here.


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## SpeedAddict81 (Oct 28, 2009)

Which Jeep Transfer Case you are looking at?

I looked on wikipedia and found a list with many options (including aftermarket, which one would assume are easy to get a hold of). This seems like a viable solution to the transmission issue. I suppose the best option would be a case with an electronic switch, saving the hassle of running shifter cable (or whatever it is a standard transfer case uses)


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## Electric Car-Nut (Jul 5, 2009)

SpeedAddict81 said:


> Which Jeep Transfer Case you are looking at?
> 
> I looked on wikipedia and found a list with many options (including aftermarket, which one would assume are easy to get a hold of). This seems like a viable solution to the transmission issue. I suppose the best option would be a case with an electronic switch, saving the hassle of running shifter cable (or whatever it is a standard transfer case uses)


Hi, Speedaddict81, Like I said on my post I haven't built one using the transfer case yet, but,having owned several jeep wagoneers with 4wd the floor shift lever was 2wd high only and 4wd high (1::1) or low (2::1) those models used a vacuum operated shift for 2 or 4 wd that was always troublesome, I had planned to install a push-pull cable but sold the jeep and suggested it to the buyer after I had the cash in hand... Mostly jeeps rust away, and engines wear out so the salvage yards have axles, transmissions, and transfer cases. the rebuild on a transfer is mostly replace the chain that links the rear drive part to the front drive part. otherwise there is a "Dog Clutch" and a two speed gearset in the one end and the front drive chain pulley and bearing in the other end. Why not go to a used car lot and look underneath a 4wd jeep? Or a "You Pull It" yard?
Contact me direct if you want to discuss it some more. (863) 289 - 0690


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## SpeedAddict81 (Oct 28, 2009)

After researching the subject some more it seems like it might be fairly easy to re-engineer a transfer case into a lighter 2-speed transmission. I have no idea what the cost of fabricating a case would be. The purpose, of course would be to eliminate the excess parts (all pieces associated with the front driveline), therefore reducing size and weight.

I would expect fairly high demand for a 2-speed transmission that can handle a decent amount of power for the DIY EV crowd. The appeal to me is the relative ease of converting a RWD vehicle if something like this were available and the ensuing availability of the under-hood area for batteries (or a range extending powerplant). 
My thought is Motor --> Transfer Case --> Differential all mounted together, given an IRS or connected with a driveshaft if a non-independent rear is used.


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## Electric Car-Nut (Jul 5, 2009)

Speed Addict 81; Hi from Electric Car-Nut, 
The cost of a new housing is just not worth it, just take out the belt/chain and front axle drive yoke and weld sheet metal over the holes to keep the oil in.
The cost of mold making and casting less than 10,000 units is prohibitive. 
And some of the mounts and shift linkages are on the center and left side so you would only cut the size from 18 inches to 12 inches. 
Be sure to leave some drive shaft and two universals and a slide in/out so the rear axle can move normally. 
Yes I agree that puts the new motor in the "Transmission Hump" and you can put battery packs in the spaces where the fuel tank and ICE used to be. 
The piece you take out that used to go to the front axle may be modifiable into a motor shaft adapter??? 
I agree that some converters may want to buy the overhauled transfer case /2 speed transmission. with a 4.11 rear axle that gives 1::4.11 and 1::8.22 ratios. 
But the Price must be competitive with others.


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## gor (Nov 25, 2009)

just a raw idea - one motor split to two (parts) : AC&DC - one helping other;
plus in case of gear sift- it can, like double clutch system, help to shift (catch rpm faster)

p.s. hmmm...1.weight penalty on EV faaar from if you wanted to do it on ICE engine : )

2. on shift it HAS to take some time for ICE to drop rpm, on "split" EV engine -it's just a part : ))) ...


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## gor (Nov 25, 2009)

related discussion:

double (dual) motor: series and parallel 

http://www.diyelectriccar.com/forums/showthread.php/pure-horse-power-dc-vs-ac-14110p20.html
















http://plasmaboyracing.com/reviews.php#2001

http://www.diyelectriccar.com/forums/showthread.php/pure-horse-power-dc-vs-ac-14110p21.html








also: re-rating method

http://www.diyelectriccar.com/forums/showpost.php?p=144872&postcount=272


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## dataman19 (Oct 7, 2009)

Ok gang - I have an idea (and not a novel one - just an old idea with a new project)..
..
How about an aftermarket Over Drive Unit? You know the Gear reduction drive that goes between tye Transmission (in this case the engine) and the drive train?
..
This would be the same as a Jeep transfer case, low range being without O.D. and hi range being with O.D. Engaged.
..
The last one I saw aws mounted under a chevy pickup and it hauled a$#.
..
Using an Over Drive Reduction Unit with an EV seems like a match made in heaven.
..
You use the Electric motor (with O.D. Disengaged) up to about 50 MPH and then engage the O.D. and accelerate to about 90 MPH --- OOOPS - I mean 75 MPH (the legal speed limit on the Interstate!!!).
..
Just food for thought, but I think JC Whitney sells them. A web search should turn up hundreds of sources.
..
dataman19


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## Woodsmith (Jun 5, 2008)

The over drive isn't a reduction unit, it is a 1:1 when it is off and something like 0.8:1 when it is engaged.
I have been looking at the old Laycock type overdrives with the cone clutch and epicyclic gears inside.

I have a transfer box that I am playing with at the moment. It is a full time 4x4 box from a Lada Niva so it has a locking diff in it and 1.2:1 and 2.135:1 ratios.
I was thinking that it could work if it was used as a trans axle in a light weight trike and was connected to a motor with a belt drive giving a suitable reduction ratio. The motor would have to be electrically reversed to make the trike go backwards.


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## few2many (Jun 23, 2009)

Transfer cases are a good idea for gear reduction. light weight, aluminum, not at all hard to adapt to. But, they really arent shift on the fly, or at high speed or torque(most anyhow). So my dad has this old ford truck. IT has a gear vendors under/overdrive unit behind the transmission(not a transfer case). What is it? A bolt on, 2 speed, electric, shift on the fly gearbox. It has an under 1:1 ratio for the low, and an over 1:1 for high.(sorry, not sure of exact numbers). I think this would be the way to go. Flip a switch, gearchange, done.


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## Woodsmith (Jun 5, 2008)

Those add on over/under drives are good. Last time I looked they were a bit costly and not that common over here.

The old Laycock type overdrives worked in a similar way with an electric solonoid to operate a hydraulic cone clutch. Smooth change and always at lower ratio when there is no drive.

In old UK sports cars I found that leaving the switch on meant that when I was in 3rd or 4th gear the over drive would switch itself on and off depending on road speed. It was almost automatic.


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## Harold in CR (Sep 8, 2008)

Many of the older cars (40's-50's) had the bolt on Overdrive on the end of the transmission. It was electric shift, OR, MIGHT HAVE HAD A GOVERNOR, and worked flawlessly. If I remember correctly, they were about 6" dia. and maybe 7" long, more or less ?? Not large at all. They could be locked out by pulling a choke cable assembly, that would deactivate it and the car would free wheel.

I abused the one on my first car, a 1951 Studebaker 6 cylinder. I could pull 6 speeds forward on my 3 speed trans, but, first was wound pretty tight before OD kicked in. I could outrun the flathead Fords on the back road drag strips. 

I have wondered for a good while why no one has suggested this option ???


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## SimonRafferty (Apr 13, 2009)

Twin motor - is a reasonably good idea. I did something similar to this for a completely different application where I wanted more torque and speed than a single motor could provide.

I used two identical motors geared differently plus a sprag clutch on the lower geared motor. The lower geared motor provides increased torque at low rpm. In the middle, both motors contribute and at high rpm the higher geared motor delivers the speed. However, the sprag clutch allows the lower geared motor not to over-speed and fly apart.

I'm currently using a Suzuki SJ410 transfer box in my EV. It reduces the drive by 1.6:1 in High range and 2.5:1 in low - which with the diff gives drive ratios of 6:1 and 9:1 (more or less) which are perfect for me!

I can climb 1:2 hills and have a top speed of 93mph!

Si


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## few2many (Jun 23, 2009)

Hey Si, Is that shift-on-the-fly?
Can you be up to speed in low and upshift to high? Or is it just shift at low speeds or stop?
These are very small, light t-cases, and some of them are even divorced(stand alone gearbox from the transmission, connected by a short drive shaft).


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## SimonRafferty (Apr 13, 2009)

You can shift on the fly - but it's a bit 'crunchy' - the box has no synchros so you have to crash it. However, without a clutch if you can match the motor speed to the new wheel speed, it goes in easily.

Best bet is to gently ramp up the motor speed while pushing the stick and when it's right, it just pops in. (or slowing down for changing up).

I chose the box based on the torque. The peak torque of a 1000cc engine in first gear is greater than the peak torque of my eleccy motor - so the transfer box is rated for the peak torque. Likewise max engine RPM in 5th gear gives an input to the transfer case of 7000rpm or so - which is probably fast enough.

Practice has born that out.

Best of all, the SJ transfer boxes are all separate from the gearbox and light enough that I can hold it in one hand at arms length (for a few seconds) - and I'm not that muscly! I guess about 40 to 50 Lbs.

I had originally intended to drive the AC pump from the drive that would normally go to the front axle (being rear wheel drive) but the pump was knackered and I didn't bother! You can disengage the drive to the front totally to minimize drag. Use a belt drive to increase the speed about 1:3 and it wil be perfect. Potentially use it for an Alternator plus AC pump!

Si


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## Sunking (Aug 10, 2009)

A F/R electric switch


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## few2many (Jun 23, 2009)

Hey, what does everyone think about a power glide? 2speed, small light, shifts auotmatically or with a manual shift kit.
Although it does use power for the pump system.


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## gor (Nov 25, 2009)

zombie and pinto curves http://www.diyelectriccar.com/forums/showpost.php?p=156701&postcount=274

in 3-section motor with one-by-one switch - can it reduce "gap" (charts)?


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## ScottRosa (Jul 7, 2009)

I'm a newbie also, but what about the old after market "overdrives" My Dad had one on his 1 ton truck in the 70's.

http://en.wikipedia.org/wiki/Overdrive_(mechanics)#Overdrive_in_North_America


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## Electric Car-Nut (Jul 5, 2009)

Scottrosa, 
The aftermarket overdrives are a possibility, installed backwards to give a "Step down."
If you can find one at a reasonable price. Generally a ratio in excess of 8::1 is needed. 
With an easily available 4.11 ratio rear axle, and another 2::1 gearset we are in business. 
a used transfer case is about $200 and used overdrives are about $300 if you can find one...
If you can find one I consider it a viable alternative.


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## kixGas (May 2, 2008)

Hey guys- I will throw this out there. Maybe someone already said this and I missed it but I see a major red flag in a lot of the discussion here. I have had several Jeeps and trucks and spent a great deal of my life involved in rockcrawling. If you have a transfercase that has the shift on the fly option then that allows you to shift from 2wd to 4wd. There is no gear reduction changes- all you are doing is engaging the front driveshaft. The gear reduction comes when you shift from 4wd hi to 4wd low. It is usually around a 2:1 ratio but you can get kits to make it a 4:1 ratio if you want. However- I have never seen or even heard of a transfercase that can shift on the fly into 4wd low. Therefore the idea of using a 4wd transfercase as a 2 speed transmission is going to be hard if every time you want to switch into 2nd gear you are going to have to come to a complete stop and make sure that your input shaft and output shaft are not spinning. kinda defeats the purpose. I would suggest exploring a powerglide or the Siamese series/parallel options.


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## dataman19 (Oct 7, 2009)

Drove a Mecedes 6WD Truck in Germany (a German Military vehicle). Shifted in and out of 6WD (Front and Back Axles) and 4WD (Rear Wheels only) while moving.
..
Our 80's (then new) US Military Trucks did the same (funny thing too - they were made by Jeep - Kaiser).
..
The Danes had the same features on their AWD Military Trucks.
..
While stationed in the Caribbean we obtained "Confiscated Vehicles" and had two Nearly new Jeer Grand Cherokees. They shifted in and out of low range while moving. Shifted out of low range better than into while moving, but it was do-able.
..
There are shift on the fly transfer cases out there (porche makes one for European Porche's - so does Mercedes).
..
I am quite sure our Australian Counterparts already have them as well. they seem to have a more bobust DIY crowd down under.
..
dataman19
..


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## kixGas (May 2, 2008)

dataman19 said:


> Drove a Mecedes 6WD Truck in Germany (a German Military vehicle). Shifted in and out of 6WD (Front and Back Axles) and 4WD (Rear Wheels only) while moving.
> ..
> Our 80's (then new) US Military Trucks did the same (funny thing too - they were made by Jeep - Kaiser).
> ..
> ...


Show me a shift on the fly transfercase when you shift into *LOW RANGE*.
I am not talking about whether shift on the fly exists if you are engaging another axle. Most of the transfercases that are out there are shift on the fly if all you are doing is engaging another axle. Your 6wd, US military truck, porsche and mercedes examples are all engaging another axle- not shifting into low range.

And having owned 2 generations of the Grand Cherokee (WJ and WK), a Cherokee (with a np231 transfercase), and a Comanche (with the np242 transfercase)- not a single one of them could shift on the fly into low range. I suppose you could do it if you were going under 5 mph but for purposes of this discussion that can be pretty much considered the same as being at a complete stop.


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## MJ Monterey (Aug 20, 2009)

A starting point for you guys. I have not used one but they claim shift on the fly.

http://advanceadapters.com/product/2060/915672-.html

This Overdrive unit is a 25% reduction. You would still need a front adapter plate with bearings and seals......


One thing to look at on all over and under drives is the percentage change of engine/motor speed. The gear splitter type drives only give an engine speed difference of 10%. Sports cars tend to have a 20% or so engine speed drop between gears. My Jeep (Comanche with ax-15) Has a 30% reduction on shifts. 

For an EV I would want a larger step between gears to better use the flat torque curve. So I would be looking for a reduction of 40% or more. The only way to do this that I know of is Powerglide or Lenco.


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## few2many (Jun 23, 2009)

Hey kixgas, yeah, it was mentioned. I'm pretty bad at skimming through a thread myself, and then posting a brilliant idea, thats been discussed or rejected! No transfer cases are shift on the fly. The electronic ones that claim to be only wait untill speed drops to a low safe amount. A t-case would be good for a permanent gear, though. put it in low and leave it for the gear reduction. Or maybe use a gear reduction section of a 203. maybe pull all the 4x internals from one to lighten nit up, using just the gaer reduction. There are, however, under/overdrive kits that are two speed and shift on the fly. Those would be great. 
I would love to convert my 63 wagoneer to ev, its just two heavy!


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## Electric Car-Nut (Jul 5, 2009)

Sorry for adding the confusion, but, many of the stick shift clutchless drivers I know drive in second all the time around town up to 45 mph then when they need to climb up onto a highway at 55 to 75 mph they slow to a stop and shift to fourth. after coming down the ramp to slow city traffic, at the first stop sign they shift to second again. This is not competing or "Sport" driving this is simple easy commuting. Like your grandma drives.


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## MJ Monterey (Aug 20, 2009)

Most standard transmissions built recently have syncro rings. These act as a speed matching clutch between component in the trans.

Truck/Jeep transfer cases do not have these niceties. They are clunky and will not change gear (except to neutral) unless you are at a crawl.


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## Electric Car-Nut (Jul 5, 2009)

MJ Monterey, I agree with you, but still my observation is, with the broad power/torque range of the electric motor drivers, often, simply use second around town and fourth on the 55 mph or faster highways. That is just an observation of fact I am not trying to argue with you.


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## MJ Monterey (Aug 20, 2009)

Electric Car-nut, No argument from my side and an apology if I came across too strong.

And yes I agree that a two speed trans would be effective and great. And as you have noticed a larger than standard jump (equivalent to 2nd to 4th) would be ideal.


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## Bowser330 (Jun 15, 2008)

I want to see a 13" interpoled high voltage motor hooked up to a powerglide! ahhhh if only i had the extra tinkering money...


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## Electric Car-Nut (Jul 5, 2009)

Bowser330, I think I have said this a few weeks ago, but it is an idea that may have merit, We need someone to set up a home business converting Powerglides into EV transmissions, with torque converter removed, seals replaced if needed to let the shift hyd. pressure hold for 10 minutes or so for shifting without idling, an easy to locate drive/park/shifter perhaps mounted directly on top of the tranny so just a 6 in. square hole and a simple rubber boot to fit gives control to the driver, and a universal adapter plate with bolt holes for several popular motors and a shaft adapter too. A lot of us would gladly pay a reasonable amount for a "Universal" setup for rear wheel drive. It would replace buying an adapter for the shaft from motor to tranny, the plate from tranny to motor,the tranny itself, a nice shifter setup, A parking brake function in the tranny. Heck except for a bracket for the front of the motor to the frame and battery boxes, all the most difficult aspects of an EV conversion would be accomplished. that would be worth about a thousand dollars! Like I said a nice business to work out of the home for an accomplished automatic transmission technician!


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## Bowser330 (Jun 15, 2008)

Electric Car-Nut said:


> Bowser330, I think I have said this a few weeks ago, but it is an idea that may have merit, We need someone to set up a home business converting Powerglides into EV transmissions, with torque converter removed, seals replaced if needed to let the shift hyd. pressure hold for 10 minutes or so for shifting without idling, an easy to locate drive/park/shifter perhaps mounted directly on top of the tranny so just a 6 in. square hole and a simple rubber boot to fit gives control to the driver, and a universal adapter plate with bolt holes for several popular motors and a shaft adapter too. A lot of us would gladly pay a reasonable amount for a "Universal" setup for rear wheel drive. It would replace buying an adapter for the shaft from motor to tranny, the plate from tranny to motor,the tranny itself, a nice shifter setup, A parking brake function in the tranny. Heck except for a bracket for the front of the motor to the frame and battery boxes, all the most difficult aspects of an EV conversion would be accomplished. that would be worth about a thousand dollars! Like I said a nice business to work out of the home for an accomplished automatic transmission technician!


I agree with your idea, and i fully understand that if I had a 13" motor and 1000A controller i would need to pay more for a trans that could handle more torque..The builder of those "EVglides" could have different max-torque stages for different prices, for people who just want a regular EVglide AND those who want a performance EVglide..


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## rankhornjp (Nov 26, 2007)

Interesting conversation so far.

Something I thought about when reading this.... When you shift to/from low range in an ICE vehicle you are combating the motor turning the input shaft at a different speed than the output shaft. I dont THINK you would have this problem with an electric motor, due to no power being applied and little resistance in the turning of the motor. Not saying the shift would be perfect.... you would have to coast while shifting, to keep the gear clash to a min. If someone had one that could be tested (even out of the car), it would give a better idea if this would work.

IMHO, the best transfer case for this would be the NP203. Its gear reduction box is removable from the 4x4 part of the transfer case. In the picture below, the gear reduction box is on the right. It has a 2:1 low range, neutral, 1:1 high. 










Then you could use something like this:









This kit changes the output shaft of the gear reduction box and provides a mounting face that replicates the rear of a transmission (without the tail shaft) so that another transfer case can be bolted to it to provide more gears for off road use.

I think this idea can be modified to use a tailshaft from a transmission instead of another t-case. It would kinda be like the Transwarp motors, but with gear reduction!

ETA: For those unfamiliar with 4x4 systems. The transfer case is usually bolted to the rear of a 2wd transmission AFTER the tail shaft is removed. So the bolt pattern on the front of the gearbox is the same as the transmission it is designed to attached to. So it goes to say that the tail shaft of the same transmission SHOULD bolt to the rear of this adapter.....
I have emailed the company that makes these to hear their thoughts on the idea, I will let ya'll know what I find out from them

Here is what the adapter kit looks like when used the way it is intended(the gear reduction unit is on the LEFT):










Discuss......


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## SpeedAddict81 (Oct 28, 2009)

I don't think the downshift capability is that important, anytime you would want to shift down you would be going very slow already (in order to regain the acceleration advantage of the gears). Also, I think it is important to consider the difference between an ICE and an Electric motor, as someone else already stated, the motor can be controlled to match speed between input and output shaft much easier than an ICE (whether manually or by computer). I think with the electric motor a RPM dependent actuator could be used to make the clutchless shifts as well as speed-matching the motor. I suppose the goal there would be a lighter-weight "automatic" gearbox with a shift as quick or quicker than our current auto transmissions.

I like the look of the sectional NP203, should have considerable weight saving over a 4wd case. Thanks for posting that!

PS: What company makes the adapter to remove the 4wd on that?


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## rankhornjp (Nov 26, 2007)

SpeedAddict81 said:


> I like the look of the sectional NP203, should have considerable weight saving over a 4wd case. Thanks for posting that!
> 
> PS: What company makes the adapter to remove the 4wd on that?


Offroad Design http://www.offroaddesign.com/catalog/doubler.htm
It's called a "Doubler". Several other places make something similar... you can Google "np203 doubler" and come up with a lot of hits.


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## few2many (Jun 23, 2009)

Actually, the doubler is used to attach the np203 gear reduction section to an np205 transfer case. This is used to give the added reduction to a 4x4 vehicle for low range crawling. The same company makes a kit to use just the gear reduction section for added low range on a trucks transmission. 
I had posted about using the 203, but the all iron case and huge gears make it very heavy. A standard alum transfer case would be lighter, could possibly remove the internal 4x compnents. Also, these are shifted while at stop, shouldnt even be moving.
Still, I think the best option is a powerglide or similar gm auto tranny. The powerglide transaxle from the corvair would be great. 2 speed, aaxle, differential, all in a packge smaller than a normal auto.
When I get my ev going, it'll be a 700r4 or th400 possibly without torque converter, with a manual shift valve body.that way, no worry about the vacuum modulator, no concerns with the tv cable. It would be basically a manual, but the gear shift would be seamless, no clutch or syncros.


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## rankhornjp (Nov 26, 2007)

few2many said:


> Actually, the doubler is used to attach the np203 gear reduction section to an np205 transfer case.


You are correct. However, they way the adapter attaches to the np205 lends the idea that you could use a tailshaft instead of the np205.

The np205 is designed to attach to the rear of a transmission, in place of the tail shaft. This kit doesn't change that.



few2many said:


> Also, these are shifted while at stop, shouldnt even be moving.


 while attached to an ICE.... I think there is a BIG difference, here.



few2many said:


> The same company makes a kit to use just the gear reduction section for added low range on a trucks transmission


do you have a link?


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## few2many (Jun 23, 2009)

Yes, you're right, there is a tail shaft kit and a doubler kit for the np203.
As far as shifting, you're trying to mesh gears at speed with no syncros. Semi tractor trailers transmissions dont use syncros, and it is possible. Its not too hard to shift a manual without a clutch using the syncros. But, transfer cases are different. I had a th350 and np203 in my 63 wagoneer(now a 700r4 and 208 with sye) I had to be less than 5mph to shift the range box, and at that, it didnt even like it.
An ice is definitely different than a motor, but youre still spinnin gears. Whether its an ice or motor, doesnt change much.
But still, a gear vendors under/over drive, electric shift on the fly, underload or no load, seems the best.


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## rankhornjp (Nov 26, 2007)

The problem with gear vendors is the price, $2800 and up. You can have the np203 doubler for $770 plus the cost of a transfer case, if you find one that the 4x4 is busted in (which you dont need anyway), you can get them pretty cheap (sometimes FREE). Another option is: http://www.high-impact.net/transmission_and_gear/extreme_underdrive_brochure.htm
This gear box is offer in 2.8:1 ratio and 4:1 ratio








Also available with a cable shifter. *PRICE: ~$1900*


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## few2many (Jun 23, 2009)

Yeah, those have been around the 4x4 aftermarket since the doubler. like the doubler, can it be shifted on the fly or under load like a transmission? Not much point in having a tranny if you have to stop or slow down to shift. Kinda counter productive to accelerate and shift.


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## rankhornjp (Nov 26, 2007)

few2many said:


> Yeah, those have been around the 4x4 aftermarket since the doubler. like the doubler, can it be shifted on the fly or under load like a transmission? Not much point in having a tranny if you have to stop or slow down to shift. Kinda counter productive to accelerate and shift.


I've never used one, but as far as I know, all you have to do is lift your foot off the accelerator, shift, and go.


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## RIPPERTON (Jan 26, 2010)

Using an overdrive would give you a 1;1 and an overdrive
Using an overdrive unit flipped around in reverse would give you a reduction and a 1;1.

http://www.google.com.au/imgres?img...mage_result&resnum=7&ct=image&ved=0CBgQ9QEwBg


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## Jan (Oct 5, 2009)

RIPPERTON said:


> Using an overdrive would give you a 1;1 and an overdrive
> Using an overdrive unit flipped around in reverse would give you a reduction and a 1;1.


Hi Ripperton, what do you mean with 'flipped around'? How can you do that?


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## SpeedAddict81 (Oct 28, 2009)

The OD unit shouldn't care which way it is installed, so if you have, say a .75 OD then the inverse or 1.33 would be the result if the unit was installed backwards.

The trouble I see with the OD unit is that the ratio is not large enough for our intentions. I think we want around a 2:1 "first gear" to give a final drive ratio/torque multiplication around 8:1 with our "second gear in the 4:1 range (which is not uncommon on modern rear-wheel drive cars). The powerglide at 1.87 is a compromise which may be simple and cheap (not quite as light-weight as a simpler gearset, though). Dimitri's work on his Protege showed us that even a stock modern auto trans can work well in an EV.


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## Crash (Oct 20, 2009)

What about two motors connected to a planetary gear train?


Imagine that motor "A" is directly driving the sun gear, motor "B" drives the ring gear from the outside and the planet carrier drives the output shaft.

For low end torque, motor "A" drives the sun gear clockwise. The ring gear would not move. The planet carrier would be driven as if it were a reduced gearing. Then, when more speed than motor "A" could provide is required, motor "B" would spin counter clockwise driving the ring gear clock-wise thus increasing the speed of the plant carrier's speed beyond that of what the sun gear alone would drive it.


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## few2many (Jun 23, 2009)

Interesting idea, no reason why it won't work. You then have to be concerned with weight, two motors, two controllers? and so on.


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## SpeedAddict81 (Oct 28, 2009)

I believe a lighter weight solution which eliminates the need for such a gearset is series/parallel switching with a larger motor (some of the fastest drag cars use this as it is effectively like having 2 gears).


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## Crash (Oct 20, 2009)

How does I understand how parallel works, I believe, where the two motors receive equal power and act as one larger motor, correct? How does series work? And how does switching between them happen?


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## DavidDymaxion (Dec 1, 2008)

In series, you get more torque -- all the current goes through both motors. You also get more back EMF, so the motor runs out of breath sooner. Then you switch to parallel. Now both motors get double the voltage, so they can deliver better torque at higher rpm. An analog is you can think of it as acting like a 2 speed transmission -- more wheel torque but less speed in the lower gear, and greater speed in the higher gear.

A Zilla controller can drive the switching automatically at the optimal time.


Crash said:


> How does I understand how parallel works, I believe, where the two motors receive equal power and act as one larger motor, correct? How does series work? And how does switching between them happen?


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