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Hello everyone. New to the forum from Richmond VA. I am working on converting a vintage Rickshaw/ Tuk Tuk from a 187 CC 2-Cycle motor to EV. With much appreciated help from EVDrives we've sorted out the motor and controller we are going to start with but need to build a gearbox to hit a minimum 12:1 reduction.

Need help here. I understand the high level gear reduction but translating that into a design where we can tie into the existing drive shafts (likely modifying them) to connect to the gearbox. I don't know where to start. Is there anyone on the forum that can build this for me for $ or suppliers that can help.

Few pics are attached to get an idea of the space we are working with. The original motor/transmission is one unit centered in the engine compartment. Each wheel has a drive axle that goes into the transmission. That connection point is higher than the hub so the drive shafts are angled down, visible in the second picture. Replicating that was the original idea but now I am thinking it may be better to notch the bottom of the frame, cut out the pan in the bottom and put a straight axle in with a straight forward gearbox. I don't know :)

Specs so far:
- 48 Volts
- Motenergy ME1602 Motor
- Alltrax SR48400

Thank you for any feedback / direction.
 

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While the original combination of nearly swing-axle suspension geometry without the mechanical simplicity of an actual swing-axle is unusually bad, I'm not sure that I see the point of completely changing the design... what would be left of the original?

If keeping the suspension, those horrible hunks of rubber used as outer axle joints will have an easier time if you put the inner joints on the pivot axis of the suspension arm, not above them as they are now. With the inner joints on the pivot axis, the axle shaft length would not need to change with suspension travel. Even with the inner joints above the arms as they are now, an inner joint which allows plunge would take care of the axle shaft length change issue.

12:1 should not be a problem for a two-stage gearbox (which is what all of the production EVs use), but of course you wouldn't want to build a custom gearbox, or have one built.

For the low speed and power of this vehicle, have you considered a chain drive? To avoid an excessively large driven sprocket you would still presumably use two stages.
 

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Thank you Brian.

When you say put the inner joints on the pivot axis of the suspension arm, just want to make sure I am following. Are you saying lower the drive shaft angle so that it is parallel to the ground, essentially where the suspension arm is bolted to the frame? My concern here is that the axle would be right up on it without clearance and when the suspension loads it would hit the frame. I could notch the frame and cut out the pan area between the frame for the gearbox.

What are you suggesting regarding the gearbox ... not following "but of course you wouldn't want to build a custom gearbox, or have one built." My assumption is I have to build something or have something built.

Yes, assuming a chain drive with second reduction via jack shaft. Is that what you mean by two-stage?
 

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When you say put the inner joints on the pivot axis of the suspension arm, just want to make sure I am following. Are you saying lower the drive shaft angle so that it is parallel to the ground, essentially where the suspension arm is bolted to the frame?
Not so much parallel to the ground as in line with the suspension arm, but yes that means the inner joint in line with the points where the suspension arm is attached to the frame.

My concern here is that the axle would be right up on it without clearance and when the suspension loads it would hit the frame. I could notch the frame and cut out the pan area between the frame for the gearbox.
I would settle for as close the frame as possible, without resorting to modifying the frame. This vehicle is just not properly designed for a correctly mounted drive system.

What are you suggesting regarding the gearbox ... not following "but of course you wouldn't want to build a custom gearbox, or have one built." My assumption is I have to build something or have something built.
Unless you are a machinist who has the equipment and enjoys building gearboxes, a custom gearbox is an extreme measure - almost no one does it, and it would be expensive to have anyone else do it.

Yes, assuming a chain drive with second reduction via jack shaft. Is that what you mean by two-stage?
Yes, exactly... and nicely illustrated. :)
 

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What motor are you using and what are its specs (HP, torque, current, voltage, & rated rpm)?

What's the tire (not wheel) diameter?

What kind of top speed?

Target vehicle weight, including payload?
 
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