RC Bumper car (TPU bumper)

This is a rc bumper car with really simple conception.

UPDATE 5/9/26 : added seatbelt system

UPDATE 5/27/26 :

• updated some parts.

• added brushless motor mount.

• added some pictures of the build

BOM :

• Injora low profile servo or other cheap equivalent low profil servo

• 540 brushed motor (45T) or 3536 1000kv motor

• Cheap ESC

• Some 5mm rods (brass or steel) (107mm length)

• 5mm flanged connector

• some 5x14x5 flanged bearings

• all 4mm hole need a 3mm inserts

• various 3mm screws, and some 2mm for the front wheel

• 12T - 48T GT2 pulleys and 112mm gt2 belt (optional for 540 motor, required for brushless - take the 12T pulley bore hole according to you shaft diameter, 3.17 or 5mm)

Special instructions :

• print outer bumper with TPU (3 walls, 5% gyroid infill) and put a modifier around screw to increase infill, like 50% (see screenshot)

• Print tire and "oliver" in tpu.

• you can use the provided plastic gears, or use a 12T and 48T gt2 pulleys, with a 112mm belts (i you do, just put 2 wheel without gears.

• You can use any 540 like motor, i think around 1000kv is the best as ratio is low.

Build is straightforward, but don't hesite to ask if you need help.

Some photo of the motor mount assembly : 

3536 brushless motor : 

540 motor :