# Mount motor directly to rearend



## bobkoonce (Oct 5, 2011)

Hello,

I'm new at all this electric car/truck conversion stuff and am excited to begin my project, an S-10 conversion.

I was just wondering how to go about mounting the electric motor to the rearend of an S-10 so I can get rid of the transmission.

Would this be difficult to do? 
And what about reverse?
Is there any place I can go to find out how to do it?

Thank you in advance for your response,
Bob K.


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## Roy Von Rogers (Mar 21, 2009)

bobkoonce said:


> Hello,
> 
> I'm new at all this electric car/truck conversion stuff and am excited to begin my project, an S-10 conversion.
> 
> ...


The question is why would you want to remove the transmission ?? If you think it will simplify things, it wont.

Since your join date was last year, I'm assuming you have read some stuff in here, and the answer should be obvious, if not, do some more reading in here and educate yourself, before attempting such a project.


Roy


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## evnz (Jul 24, 2010)

They do not normally go to the diff because of the amps to get the truck moving are high the cooling for the motor is low and the speed of the truck is limited to the max rpm's the motor puts out. 
If you have a manual gear box you as the driver can have more control. 
I know of a car conversion the owner stayed in second gear in town (50 km/h ) and third gear out of town (100 km/h) and his amp draw was just over 200 
Hope this helps
Owen


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## subcooledheatpump (Mar 5, 2012)

A while ago I actually did this very thing, mounted a motor right to the rear end of a van, literally, no driveshaft. 

In hindsight, there were serious problems with the design, not enough room for the rear end to move. 

If you are going directly to the driveshaft though, you want AC. The DC motors used in EVs (brushed, field wound or permanent magnet) cannot be operated at full current when stalled, making a transmission a requirement. They also don't like high speeds, again making a transmission a requirement for decent road speeds. 

If you are persistent in going direct drive and you want AC, you'll have to either spend alot of money on a good AC system that is "made for EV" or you'll have to modify an industrial controller and/or motor. 

That being said, my van is direct to driveshaft with AC with a modified industrial controller. Not easy but worth it if you want a good power electronics project.


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## bobkoonce (Oct 5, 2011)

Thanks for all your input,
Bob k.


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## mizlplix (May 1, 2011)

In a nut shell:

1-You need some kind of a step-down set up. Belt, chain or gears. It requires a ratio of 7:1 or more (total) to let the motor accelerate a load without huge amperage draws and the top road speed comes from the motors high RPMs.

2-Most all directly driven systems are AC because the rpm range is greater than most DC systems.

3-Reversing is usually done electrically in the controller, I guess you could do it with a reversing contactor in two of the AC motor leads.

The above system is costly because of the motor/controller required.

You can use a two/three speed transmission and almost any good motor, AC or DC to do the same thing. One gear to drive around town, 0-45 MPH and shift up to go on express ways up to 100MPH. You can still electrically reverse like the above example. (And you can use a cheaper DC system too, providing you do not advance your motor too much).

Miz


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## steiner (Dec 8, 2008)

People need to understand the efficiency curve of an electric motor. Most DC motors run very close to their maximum efficiency at about 90% of their no-load speed. You always want to run your motor at the RPM that gives maximum efficiency. The no-load speed of a motor will vary as a function of the voltage you plan to run the motor at. Determine your no-load speed, then take 90% of that speed and then see what gear ratio you need to make your vehicle go the typical speed you anticipate driving.

If you have a low speed high torque motor, it is possible that connecting it directly to the rear differential is the correct approach. Most of the time this is not the case. As previously mentioned, many people find that driving in town requires 2nd gear and on the highway requires 3rd gear for most typical DC motors. I have seen a few that required 4th gear in town and 5th gear on the highway. This was due to the vehicle having a higher than normal gear reduction in the differential.


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