GPM BJ012 HPI Baja Rear Gear Box Alloy Upgrade  [BJ012]

Rear drivetrain housing for HPI Baja

The BJ012 is an aftermarket alloy rear gear box made for HPI Baja scale RC models. It acts as the rear drivetrain housing that holds spur gears and axle bearings and creates a firm mounting point for the rear differential and related drive parts.

This replacement part suits routine service tasks: swapping worn housings, correcting gear mesh, and replacing fragile plastic sections with a corrosion-resistant alloy alternative. The alloy build increases structural stiffness under typical off-road stresses while remaining sized for RC-scale use.

Installation notes: the BJ012 fits in place of the original rear gear box using the stock fastener positions and the HPI Baja internal gear layout. Follow normal workshop practice—clean mating faces, check gears and bearings before reassembly, and apply threadlocker where the chassis manual recommends it.

Tuning and maintenance role: fitting a stiffer rear housing can help keep gear mesh consistent when chasing drivetrain wear or after an impact. It does not change gear ratios or require electronic adjustments, but it can reduce flex-related backlash when combined with correct spur and pinion alignment.

The BJ012 alloy rear gear box is a direct aftermarket replacement focused on improved durability and consistent drivetrain alignment for HPI Baja models; use it during routine drivetrain maintenance and setup checks.