# HELP! EV Speed Reducer Transmission Help



## madderscience (Jun 28, 2008)

0) Use a regular old manual transmission with about the right ratios and leave it in 2nd or 3rd gear. There is something to be said for the old standby.

1) take that manual transmission with a helical gear ratio (not 1st gear, basically) near the 2.36 number, then remove all unneeded gear ratios and all the shifter components, and lock the remaining gears into position to make a single speed reduction. Ensure that the remaining moving parts dip into the oil sump for proper lubrication. you may need to fabricate spacers, lock rings, and such and/or weld parts together but with some expirementation it may be doable.

1.5) do the same thing with an automatic transmission. Probably harder than with the manual.

2) Use a synchronous belt and a pair of pulleys selected to give 2.3:1 reduction. I did this to get a 6:1 overall reduction (later changed to 4.8:1) using a 4.1:1 toyota diff. See relevant page on my website at http://amphibike.org/blog/scion-xb-ev/scion-xb-ev-construction/scion-xb-ev-drivetrain/

3) With certain differentials, you can change gear ratios, and some diffs will go to a pretty high ratio. Some ford and chevy rear ends in sizes found for 4x4s and such you can get an 8:1 diff ratio I believe. Would that be close enough? Could you make up the rest of the difference with a tire size change? As long as it is about the right size, a rear end swap on solid axle cars is not /that/ hard to do.

4) Go totally junkyard wars and take two 3:1 differentails, lock the spider gears in one, and use it to drive the second one to get 9:1 overall reduction. Might make an awkward drive arrangement though.

Good luck.


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## snyster37 (Nov 1, 2013)

madderscience said:


> 0) Use a regular old manual transmission with about the right ratios and leave it in 2nd or 3rd gear. There is something to be said for the old standby.
> 
> 1) take that manual transmission with a helical gear ratio (not 1st gear, basically) near the 2.36 number, then remove all unneeded gear ratios and all the shifter components, and lock the remaining gears into position to make a single speed reduction. Ensure that the remaining moving parts dip into the oil sump for proper lubrication. you may need to fabricate spacers, lock rings, and such and/or weld parts together but with some expirementation it may be doable.
> 
> ...


Thanks alot madderscience. Your really open up my mind to some solutions. Though i find the getting two differential quite amusing, it does solve to get the gear ratio. apreciate your kind help.


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## Woodsmith (Jun 5, 2008)

The transfer gearbox from a Lada Niva 4x4 is a remote mounted permanent 4x4 gearbox that gives two ratios, 1.2:1 in high and 2.135 in low. So not as low as you need but close.
The centre diff can be locked to drive a single axle but also opens up the possibility of driving a second axle for a 4x4 if it were appropriate.

I have one and have been trying to decide which of my projects to use it for. I have been told it is pretty much bullet proof up to around 250bhp.


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