# Automatic transmission comment thread.



## mizlplix (May 1, 2011)

I started this thread to hear from all of you who have used an automatic transmission in your EV. I am curious to hear your comments, good or bad, Converter or direct coupled. 


Here is my comment:

I used a powerglide. It was converted to manual shift. It had a drive coupler instead of a torque converter.

I put 335 miles on it before taking it out and changing the car to direct drive.

The take offs were rapid and the upshifts were solid. The downshifts were solid too, unfortunately. I do not recommend a full manual, racing valve body in a 1,900# street car. It was otherwise a dream to drive, just do not put it in low gear except when stopped. (Everyone thinks you are a spaz of some type or showing off)

This transmission is still recommended by me if left a little closer to stock condition, shift wise.

I used no trans cooler, I just looped the hoses. It ran at 140F even during Arizona 109F summers. No heat problems at all.

I used a 150PSI 2.2GPM auxiliary pump to keep the low gear band engaged. It was tried various ways, but the best was just key switched on and let the pressure switch that came with the pump shut it off when the trans pump kicks in.

Removing the transmission had nothing to do with me being dis satisfied with it. I just discovered that it drove really nice with high gear only.

Miz


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## Emd (Jan 17, 2011)

Wow, thanks Miz -- this is exactly the kind of helpful post I'm looking for on this forum!

I'm curious if you could extrapolate to estimate how my application will perform. I'm months away from the first drive.

My application:
-4000# car
-11" NetGain motor w/ Soliton1
-TurboHydramatic 400 (TH400) (TCI "Streetfighter" light competition model)
-Direct coupled (no torque converter)
-Fully-manual reverse-pattern valve body (P-R-N-1-2-3)
-External electric pump to pressurize the transmission to 50-60psi
-Florida driving conditions

You seem to suggest that downshifts are harsh. I'm wondering if the 4,000# weight of the car will help this. If so, the bands might take a hit and wear out prematurely... I should also plan on even heftier motor mounts.

Overall, I'm curious about your opinion because the car is a Mercedes SL, so it needs to exhibit good manners 

Again, thanks for the great post Miz!


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## shortbus (Sep 27, 2011)

While probably not relevant to this thread, why don't people use a Lenco type planetary transmission in an EV? Both a low and direct drive in a small package. Kind of like a modern Model T transmission.


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## mizlplix (May 1, 2011)

> While probably not relevant to this thread, why don't people use a Lenco type planetary transmission in an EV? Both a low and direct drive in a small package. Kind of like a modern Model T transmission.


C O S T.........


EMD: The car weight will help, but if your transmission is an auto or manual shift model,it probably will work OK. But if it is really a full manual model, it will have rather harsh downshifts. During the conversion process to manual shift, the downshift delay valve is removed from the front pump. Plus you removed the other shift softener... The converter. Any competition based trans will necessarily be harsh.

A half-assed street/strip transmission is all around best for an EV. and you can manually shift them too. 

Miz


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## piotrsko (Dec 9, 2007)

my nickel: stay at the stock factory rates in the SOL1 unless you like to wear neck braces.


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## gunnarhs (Apr 24, 2012)

mizlplix said:


> I started this thread to hear from all of you who have used an automatic transmission in your EV. I am curious to hear your comments, good or bad, Converter or direct coupled.
> Miz


We did put a 4 speed automatic tramsmission (torque converter) on a chinese electric car which used a normal gearbox and a standard inverter (Teco-Westinghouse). There was an improvement during lower speeds but we have not been able to test higher speeds ( > 60 km/h) due to the worn battery pack.
The pack is now getting replaced this summer and the inverter too.
It seems that using a ATM (together with an AC - Induction - Motor) gives us a range improvement over direkt drive of about 10-20% but this still needs to be verified better, especially driving at higher speeds.


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## JRP3 (Mar 7, 2008)

I did a direct drive TH125 auto in my Fiero, external 12V Delavan pump at 2 GPM and 60 PSI pressure, plumbed into the transmission test port with a one way check valve, pulling fluid from the dipstick hole. The pump is probably just a little small for the trans, I'd reommend trying 65PSI and/or more than 2GPM. The gearing is not great and first and 2nd seem to be inefficient but 3rd seems to be OK. Getting the coupler built right was a pain.


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## RIPPERTON (Jan 26, 2010)

mizlplix said:


> I used a 150PSI 2.2GPM auxiliary pump to keep the low gear band engaged. It was tried various ways, but the best was just key switched on and let the pressure switch that came with the pump shut it off when the trans pump kicks in.
> Miz


So did you try it without the aux pump just letting the trans pump engage first ?


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## JRP3 (Mar 7, 2008)

I tried that with mine. Reverse was no problem, but there was some chatter in first.


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## mizlplix (May 1, 2011)

Low gear is a band.









Reverse is a clutch pack.









Clutches have a solid initial engagement, while bands are torque energizing. That means they start to clamp at the leading end and the grip will progress along the band as it takes up the torque, leaving more opportunity to chatter.

My aux pump was 150 PSI to help mitigate the weaker initial clamping of the low band. I also used an aggressive band material.

Lastly, if you are using Dexron and have a chatter, switch to type "F" fluid.
It is perfectly compatible and will make those bands grip about 200% better.
(that alone will probably stop your problem)
Miz


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## Russco (Dec 23, 2008)

JRP3 said:


> I tried that with mine. Reverse was no problem, but there was some chatter in first.


My Metro has an automatic with torque converter but no pump. It the accelerator is depressed VERY slowly and gently, the motor will spin at a low speed and the car takes off in 1 (low) very well. But, if the accelerator is depressed in the usual manner, the pump pressure comes up so abruptly, the car lunges forward, spinning the front tires and invariably will break something. 

An auxiliary pump is mandatory.


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## Roy Von Rogers (Mar 21, 2009)

Russco said:


> My Metro has an automatic with torque converter but no pump. It the accelerator is depressed VERY slowly and gently, the motor will spin at a low speed and the car takes off in 1 (low) very well. But, if the accelerator is depressed in the usual manner, the pump pressure comes up so abruptly, the car lunges forward, spinning the front tires and invariably will break something.
> 
> An auxiliary pump is mandatory.


You don't have an idle set up ??

Roy


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## Russco (Dec 23, 2008)

Roy Von Rogers said:


> You don't have an idle set up ??
> 
> Roy


There is no idle set up at this time. It takes a whopping 11 amps to idle the motor. That works out to 128 Volts x 11 A = 1408 watts = 2 Hp.

There is also the difficulty of the high pedal disable interlocking the Curtis controller OFF on power up if the pot input is set to idle. Can be worked around, but the 2 Hp for idle is way too much power anyway.

I will use an auxiliary 12 volt diaphragm pump set to 60 PSI feeding through the pressure test port. The port looks like an 8 mm cap screw with a rubber O ring, so it may be difficult to get 2-3 GPM flowing thru a 3/16" hole bored through an 8 mm screw.


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## mizlplix (May 1, 2011)

<I have not tested or used this mod>


The oval track guys have a mod they do to their converterless automatics that acts like a centrifugal clutch.

They use a 1/4" I.D. hose with a hydraulic needle valve in the hose coming from the front pump to drain into the sump.

If you close the valve fully, with an electric motor, the car sits there and you must rev up the motor to get the car to move, eventually it jumps and chirps the tires.

As you open the valve, (dumping main pump flow to the sump) the car starts to move slower and somewhere in the middle valve setting, the car takes off smoothly and does not seem to suffer at high speeds.

Acting like a centrifugal clutch. They even claim to be able to drive the car up on the trailer that way too.

It might be an answer to what you need without an external pump.

Miz


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## JRP3 (Mar 7, 2008)

Russco said:


> I will use an auxiliary 12 volt diaphragm pump set to 60 PSI feeding through the pressure test port. The port looks like an 8 mm cap screw with a rubber O ring, so it may be difficult to get 2-3 GPM flowing thru a 3/16" hole bored through an 8 mm screw.


Mine was just a threaded plug, no O ring, 1/8th pipe thread. I unscrewed the plug, screwed in a 4 inch long piece of 1/8 pipe, then an adapter to connect it to the 1/4 inch check valve, then adapted that up to the 3/8 fittings for the pump.


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## mizlplix (May 1, 2011)

Being the obsessive person I am, I even ported out the fittings for flow. After drilling, I smoothed the inlets and outlets, spending hours doing so in the knowledge it would work somehow better...LOL NOT.

Well, maybe it did, but I could not tell.

Point: Inlet was 1/4" NPT and my pressure side was 1/8" NPT at the smallest points and worked fine at these flow rates.

Miz


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