# Gearing down a leaf motor



## Rusted B&B (Nov 6, 2020)

Right now I have the gs450h and I may have a dead motor but I'll need to do a ton more QC work to verify it really is dead. In the mean time I've been looking into the leaf motor as its very cheap and much simpler to get running. The only issue that I can see is I only need a single output and need to gear it down a lot. For my build I need a ton of torque and not a ton of speed. Without making something custom(aka pricey) has anyone done such a thing?


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## brian_ (Feb 7, 2017)

The requirement is for a reduction gearbox, and the obvious solution would be an ev-TorqueBox, but it doesn't appear to be currently available ready to bolt onto a Leaf motor.


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## Bratitude (Jan 23, 2020)

Torque box. Or one of the many transfer case planetary reduction sets you can get for Toyota gearboxes.


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## remy_martian (Feb 4, 2019)

Or...a 4x4 transfer case. They're around 3:1 in low gear.


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## brian_ (Feb 7, 2017)

Transfer case low gear reduction ratios vary widely, most commonly around 2:1 to 3:1 (e.g. 2.7:1 in the standard equipment of a recent Jeep Wrangler) but there are some readily available around 4:1 (e.g. the optional transfer case in a recent Jeep Wrangler) and some more extreme reductions in aftermarket products (especially those with multiple low ratios). An entire transfer case is awkward if only one output is needed, which is presumably why _Bratitude _suggested a planetary reduction gear set of the type used as either the first stage of some transfer cases (especially ones with chain drive to the front output) or as an additional reduction stage ahead of another transfer case (commonly called a "doubler"). Most "doublers" are simply the reduction stage taken from a transfer case and fit with adapters, rather than designed specifically as just a reduction gearbox.

_Electric Land Cruiser_ is using a BlackBox-c doubler between a Leaf motor and a transfer case
The Electric Land Cruiser EVJ80 - Nissan LEAF + Resolve-EV

One thing to watch is the input speed rating of any gearbox - to use the full operating range of the Leaf motor means a higher speed than a typical engine would ever reach. A planetary gear set can easily handle that, if the gear set and bearings and seals are designed for that speed.

Another issue is the output: doublers are intended to output to a transfer case, not to support a slip yoke (as used at the front of a traditional propeller shaft) or a flange for a CV or flex joint (as now commonly used at the front of a propeller shaft)... in other words, it doesn't have an end like a transmission tail housing.


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## remy_martian (Feb 4, 2019)

Yeah...but you can get them for $100


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