# Direct Drive Vs. Existing ICE Transmission



## xrotaryguy (Jul 26, 2007)

If you can find a differential that is geared low enough, then direct drive is probably the way to go. I would imagine that a 5:1 diff would work very well. I know that many drag racers use a 5.13:1 diff in old muscle cars. A 4.88:1 would probably work reasonably well too. 

Can-EV sells a gear box that is intended to go in where a front wheel drive car's transmission would normally be. I think that unit is geared 10:1. That is probably intended for AC motors though. I don't know if a DC motor would appreciate spinning that fast.

Another option is to build a tadpole trike and run the motor to the rear wheel via a motorcycle-type drive train.


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## captndiet (Apr 3, 2008)

Just today I was looking at a Winters quick change rearend that is used in small oval track cars. 

They have is available with a 5.13 ring & pinion. 
http://www.wintersperformance.com/catalogs/2005WintersPerformance/0181024.htm

And by changing the spur gears you can change final drive ratios anywhere from 3.40 to 7.70.
http://www.wintersperformance.com/catalogs/2005WintersPerformance/1171024.htm

With axles and brakes it weighs right at 100 lbs. Yes it's not too cheap but I buy from them and get a discount.

My project is a 1200 lb. t-bucket based car. 45 mph 15-20 miles a day. 72 volt.

I would like to hear other opinions of direct drive cars.

Jeff


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## xrotaryguy (Jul 26, 2007)

Sounds Awesome! So will you end up with a differential? The type of kit that you're talking about is often a spool-type setup. That would really suck on the street. 

What is your donor car? You might be able to recoup some of your losses by selling the donor car's transmission and drive shaft. 

Also, do a google search for the type of parts you want; something like QUICK CHANGE FOR SALE. You might be able to find something on Craigslist. I found a computer and harness for a turbocharged Rx7 for $125.00 that way one time. Those computers generally go for about $250 and the harnesses can be another $100 used. Craigslist is a great way to get parts cheap.


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## Coley (Jul 26, 2007)

One thing I have found with my car. is that by having a 5 speed trans, you can adapt to daily conditions.
Weather temp, battery life, wind and rain can require a different attack.
By having at least 3 gears, you can adapt well. Just my opine......
3210 miles and counting....


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## michaeljayclark (Apr 3, 2008)

after reading the forums here and driving my 2005 civic hybrid manual 5 speed i have a better understanding of the importance of low gearing.

the civic definitely has low gearing. downshifting to 2nd from 4th you can really feel the torque of low gearing. If I red line it in 1st and shift to 2nd quickly it spins the tires. there is only a little 1.3 ICE in it, for it to spin the tires in 2nd it would need some torque!

Im getting the impression here that direct drive will work nicely if the differential is low. Ill try to get more info from the transwarp people since they built a yoke for direct drive situations. Ill ask them what they recommend the differential to be and post it here.


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## Ioku (Sep 27, 2007)

I have been doing a lot of thinking about direct drive vs. a trans, the one thing I really like about the direct drive idea is you get to lose all the weight and moving parts of the trans and the inefficiencies and power loses. But with direct drive you cant change gears for different situations. So you would have to chose gearing based on what you want to do with the car, like a 5 or 6 to 1 ratio for high torque and good acceleration but poor high speed, or a 3 or 4 to 1 for more high speed but less acceleration.


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## aeroscott (Jan 5, 2008)

I like the idea of changing out gears or the hole rear end . with power tools I can drop a bmw rear end in 15 minutes . that is with my cordless impact .


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## michaeljayclark (Apr 3, 2008)

a solution to different torque choices would be achieved by using two different motors. 

one for low end and another for high end for faster speeds, etc...

http://www.jouleinjected.com/ has two motors back to back with direct drive


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## veperformance (Aug 17, 2007)

I am still working on my prototype but the first test run was very good with direct drive. i believe that if you have a large diameter motor it should handle direct drive.plus with direct drive you save weight , space and get maximum reliability since differential are quite resistant.I use a posi 3.27 diff.


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## JRP3 (Mar 7, 2008)

I agree that with a large enough motor direct drive can work. Probably works better with an AC setup than DC because of the larger RPM range available, but with a big enough DC motor that can handle the load at low RPM's and enough battery to keep up with it it should do alright. This is mostly speculation on my part so don't take it as law


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## michaeljayclark (Apr 3, 2008)

so it seems you would want the motor to not be a load rpm when taking off. A one to one ration might hurt the motor.

white zombie has 4:11 gears when using lead acid but then again has 2 motors.


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## aeroscott (Jan 5, 2008)

today i talked to a auto trans guy he showed me how they change the displacement of the pump to less flow when they lock the torque converter . but we went on to figure how to get rid of the 3ed member by using a hallow shaft on the motor and putting the spider gear on the end of the motor , running one shaft through the motor to the spider and the other shaft to the spider . I was planning on a hallow shaft first to put in the drive line of a diesel for a hybrid . then as we get the batteries pull the engine and trans and use the hallow shaft for air cooling the rotor . now maybe we can eliminate the 3ed member except for the spider .


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## michaeljayclark (Apr 3, 2008)

what would be the gear ratio then? at what rpm of the motor do the wheels start turning?


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## aeroscott (Jan 5, 2008)

it's a wheel drive without the unsprung weight and no limit on motor size so about 1000 rpm at highway speeds . direct so one to one . my friend said you could do a planet gear instead of the spider . you get 4 to1 and diff by running the ring gear to one side and the planets to the other. small package very high efficiency


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## dataman19 (Oct 7, 2009)

I would think that the planetary gear drive would be excellent for eliminating the Manual or Automatic Transmission. But it still would not be direct drive.
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The planetary gear set would eliminate the failure prone motor-to-motor direct connection between the two motors. This is a weak link in durability for any multi-engine configuration. Not to mention the micro cracks that develop due to stress, but the hassle of alignment and ballancing the total assembly.
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Then add the problem of not tearing the shaft coupler out from between the motors and differential when accelerating and the direct connection between two motors and the rear differential and you have an engeneering challenge of nightmare potential.
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The Planetary gear drive arrangement allows for varying the loads between the two power plants, and still providing seamless acceleration from start to stop.
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I totally agree and think that AC Drive is the way to go. The first time you stall your DC Motor you will be chasing the magic smoke for days (ie: you will fry the motor - if not the controller as well).
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The transmission will also providea shock buffer between the power plant and the drive train. A buffer that will provide for durability and longevity.
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The only thoughts that I have with auto transmissions is the shift control. Is your Automatic an Electronic Shift Control, or Manual Shift Control. Hint: Does it have an automatic overdrive feature (like the Ford F-150). If so it is an electronic shift control and you need to retain and make tweeks to the Transmission Control Box. This Control box will allow you to adjust shift points and a thorough understanding of how it works is crusial to get the transmission to shift correctly, and also allow for the use of a lock-up torque converter.
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This is the one issue that I have not seen addressed in this forum anywhere (at least not that I have read so far - and I have read a lot of the posts so far).
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In either case - good luck with your conversion
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dataman19


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