Mid-Rear motor conversion for Tamiya XV-01

This is an unfinished model! The project never moved beyond the test assembly shown on photos. However the transmission spun, so it should work. But modifications will be needed, because the design was never properly optimised for 3D printing.

The idea was to make an "R" version of XV-01, similar to modern version of TA03R and eventually develop it into M-chassis, using XM-01 suspension, but the project has been abandoned.

The front gearbox was modified to move the motor low enough to let the drive belt pass over it. That allows transmission of power to the rear (now mounted at front) gearbox. 

The model was designed to reuse as many stock parts as possible. All gears, the motor mount, top link moint and the bottom differential cover are carried directly over from the stock front gearbox, damper stay mounts were modified to use the rear damper stay (3rd party parts should be compatible). To make reuse of the stock motor mount possible, and to provide more space for suspension mounts, an extra idler was added. That reverses the motor rotation, so it's mounted on the opposite side of the gearbox to compensate. As the result, the stock gear cover is no longer compatible and I didn't design a replacement part.

In order to assemble the gearbox, you need additional parts - an extra 33T idler gear assembly, two extra XV01 tensioner assemblies (or other tensioner with up to 10mm diameter) and some M3 screws and nuts:

• 3x M3x16-20 countersunk (gearbox)

• 1x M3x8 (motor mount)

• 4x M3x10 (diff cover)

• 1x M3x12 (rear tensioner)

• 2x M3x15 (front tensioner, front of the brace)

• 3x M3X30 (2x motor mount + rear of the brace)

• 5x M3 hex nut 

The test assembly used a stock belt, but it was older and possibly stretched out. It's likely that a fresh belt may be too short due to the portion that's been raised to clear the motor and you may need a belt with an extra tooth. 

The modification cannot use XV01 slipper anymore, because the slipper spring now interferes with belt. TD4 slipper with spring over the spur gear may work but this hasn't been tested and it may require additional modifications.

The intention was to use EmbieRacing all-in one chassis, which already allows to swap the gearboxes. However, due to different motor position, it will need modifications around the motor.

The brace and its mount are only placeholder models. They may work, but design isn't optimised at all.

For the conclusion, here's summary of things that need to be finished:

• Top link mounts - the original K2 part should fit, but since it's now used for the rear axle, link and stabiliser positions may need to be modified.

• Spur gear/pinion cover and its mounting to the gearbox 

• Belt cover

• Possibly belt tensioner - top of the belt is now under tension, it may require to move the tensioner to the bottom to reduce its wear.

• Proper design of the over-motor brace

• Adaptation of slipper clutch from TD4

• Reinforce the model to make it more suitable for FDM printing.

To allow easy modifications, I included step file. Feel free to share any modifications and experiences with the conversion.