# New here have the itch, and have a question about running an EV with no transmition.



## houseoffubar (Nov 18, 2007)

Hey Devon, Yes you can run without a transmission, even a differential, by running two smaller motors instead of the diff, one for each wheel. The limiting factor is the amount of amps required for take off. If you have a light enough vehicle, and a fairly large motor, this can be done without too much trouble. 
But for a larger vehicle, having a lower gear to take off with can reduce the amps required quite a bit.
I am building a car with no transmission, and an 8" DC motor. The car will be about 1500lbs. with about 4to1 reduction to the wheels. this limits top speed to about 75mph, but allows for good starts. This is about the limit for a single speed drive train, as far as weight, and speed are concerned (in my opinion). Some AC motors can be used without a transmission, and achieve much higher top speed, with a small sacrifice of starting torque. 
Google a few of these for examples:
Tango
Wrightspeed X-1
Tesla Roadster
Corbin Sparrow/Meyers NMG
t-zero

Hope that helps, Eric


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## Devon Hynes (Dec 7, 2007)

Kinda what I'm thinking of but with just the one motor,

http://jerryrig.com/convert/images/motor.gif

but set up like this

http://img212.imageshack.us/img212/6978/beforeaftervv9.png


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## houseoffubar (Nov 18, 2007)

Devon, The only problem is that without a differential to make up for the different wheel speeds, when going around corners, is that massive loads will be put through the motor shaft, and the inside tire will have to spin out every time you turn. 
If you try to turn a vehicle without a differential, it will try VERY hard to go straight. If you talk to a drag racer, or sprint car driver, using spool, or locked rear differential, they will tell you this is simply not practical for street use at all.
This is why I mentioned the use of two motors, as one can simply run a little faster, and the other lug down slightly to make the corner. Otherwise, a differential is required. Eric


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## Devon Hynes (Dec 7, 2007)

Stupid me gettin ahead of myself. A was actually quite into autocross and know all about the conciquneces of welded and simulair diffs, and the great fun of trying to park one, I can't imagine the load a parking lot would put on that motor. Now that I think about it modifing a bracket and adapter to the rear diff would be ALLOT easier/cost effiecent. Thanks allot for the help.


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## houseoffubar (Nov 18, 2007)

Devon, I've been helping my nephew build a drift car, with a locked rear differential, it works great for sliding around, but like you said, it lays rubber trying to pull into a parking spot. I'm building a car similar to my avatar, using one rear wheel. this allows you to license it as a motorcycle in most states, no insurance is required, and using a chain final drive is the most efficient system available, good enough for me. Have fun! Eric


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## david85 (Nov 12, 2007)

Its possible to adapt just about anything to anything, but the DC motor will have a lower maximum RPM, limiting your top speed.

I've been looking at these more closely lately, and while they are a neat idea, they tend to cost more than a conventional transaxle, even a reconditioned one. So for about the same cost, you end up with only one gear ratio as opposed to 4-5, and often a lower torque rating. You could get a nice transaxle from a porsche 914 for less than $2000 reman, or even less from something less exotic. 

Or for an even more compact setup, just pull a manual tranny from a front wheel drive car, KiwiEV's setup is a good example of this.


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## madie (Apr 23, 2008)

Lexus said:


> If you are running a AC motor you could use a Gearbox like the Solectria AT1200 gearbox with integrated differential ...
> 
> 
> 
> ...


 
Hi there,

This is my first post in this forum..I try to search for a picture on how to install AT1200 gearbox on my EV car..i don't have any idea on how they couple this gearbox to the wheels..do u have any idea? Right now I try to get as much idea as possible before I start to buy EV parts from Solectria..


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## dataman19 (Oct 7, 2009)

People bolt to the tranny with an adapter because it retains the original drive abiity. It also goes a long way to allowing for different drive characteristics for varying conditions. Who cares if you start and stop in 3rd gear in the snow. The fact that you can start in 2nd on dry pavement and accelerate thru 4th gear to highway speed is a definate plus as well...
..
dataman19


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