TRAXXAS TRX4 Trail Crawler Aluminum Outer Portal Drive Housing Set by GPM TRX4021A  [TRX4021A]

Aluminum Outer Portal Drive Housing for TRX4

This GPM TRX4021A aftermarket outer portal drive housing is an RC-scale replacement intended for TRAXXAS TRX4 Trail Crawler knuckle assemblies, provided as an 18pcs set for either front or rear fitment. Machined from 6061-T6 aluminum, the housings are designed to replace original plastic outer portal shells to deliver a firmer mounting platform that helps keep inner gears aligned under load while crawling.

The set includes stainless steel cap head screws for assembly and is dimensioned for straightforward replacement with original plastic neighbours, allowing a mostly plug-and-play swap without modifying adjacent components. The housings feature a 3D-machined streamlined profile and precision cut edges to maintain proper mesh and clearance in portal gear stacks.

Functionally this part is used to stabilise inner gears inside the portal housing, reducing flex that can affect gear engagement and steering response on demanding trail sections. It supports use on either front or rear portals and references a midpoint distance between damper and tie rod of 93mm for basic siting purposes when fitting to standard TRX4 knuckle layouts.