A mini RC stunt car is a gearbox with a body on top, and both halves are moulded. The drivetrain parts carry load and wear; the body panels carry the crash. The two families fail differently and are quoted differently, and a programme that treats them as one part family ends up with a drivetrain that survives the crash and a body that does not, or the reverse.
We mould differential housings, gear covers and body panels for mini RC stunt cars and hobby-grade toy vehicles, for RC brands, hobby importers and private-label programmes.
Drivetrain parts: wear is the specification
A differential housing holds the diff gears under load and takes the reaction at the mounting points. The design points are the bushing bores, which are insert-moulded with brass or sintered bushings because a plain PP bore ovalises within a season, and the wall at the reaction points, which is set by the shock load rather than by the flow. Gear covers are the simpler half but they carry the mesh tolerance: a cover that holds the gear at the wrong centre distance produces whine and then wear, and the centre distance is a tool decision, not a design change.
Body panels: the crash is the specification
A stunt car body is moulded to be hit. The panel is thin, usually 1.2 to 1.5 mm, and the failure mode is cracking at the mounting boss rather than through the panel. The boss is reinforced with a rib that runs back into the panel rather than a standalone post, and the material is usually a PP copolymer rather than ABS, because PP survives the impact and ABS shatters at the boss. Where the programme sells replacement panels as an accessory line, the panel is quoted as a wear part and the tool is cut for the accessory volume as well.
Specification
| Diff housing | PP with brass bushings insert-moulded |
|---|---|
| Gear cover | ABS, mesh centre distance per programme |
| Body panel | PP copolymer, 1.2 to 1.5 mm, boss-reinforced |
| Bushing | Brass or sintered, insert moulded |
| Colour | Moulded-in for panels, natural for drivetrain |
| Packing | Drivetrain in bulk bags, panels on header cards |
| MOQ | 3,000 pieces per part number |
The bushing insert
Insert-moulded bushings are the cheapest durability upgrade on a toy drivetrain and the usual source of first-article failures. The bushing has to be held in the tool without flashing over the bore, the shot has to fill around it without a weld line at the root, and the part has to cool without pulling the bushing out of square. We pull-test and rotate-test first articles and report the break mode, because a bushing that rotates clean in the housing was under-supported in the tool, and no amount of material change fixes it afterwards.
Battery and electronics interface
Drivetrain parts also carry the battery tray and the wire routing, and the wire exit is where programmes fail in the field: a wire that exits through a sharp-edged hole chafes and shorts after a season of stunt landings. The exit is radiused and ribbed in the tool, and the wire route is reviewed with the electronics layout before the tool is cut, because moving a wire exit afterwards means a new tool. Where the programme ships with a rechargeable pack, the tray carries the contact retention and the moulding has to hold the contacts under the shock of repeated landings.
Compliance and shipping notes
RC parts declare to EN 71 and RoHS for the electronics interface, and the compound declaration covers the drivetrain parts that see no food contact and no skin contact beyond handling. The shipping note matters more than the compliance note: complete cars with lithium packs have transport restrictions that complete cars without them do not, and programmes that sell the car and the battery separately should confirm the transport class before the packing is designed, because the packing is what the carrier judges.
Related reading
Our RC truck chassis programme covers the larger scale, and the RC toy category lists the full range.
