Traxxas UDR Unlimited Desert Racer Gearbox Housing Assembly TRX8591

Overview

The Traxxas Gearbox Housing (TRX8591) is an essential replacement or upgrade component for Traxxas UDR Unlimited Desert Racer Pro-Scale 4WD RTR Short Course Truck owners. This complete gearbox housing assembly includes the upper housing, lower housing, and gear cover — everything you need to rebuild or repair your transmission system. Whether you're a seasoned RC enthusiast restoring a damaged gearbox or upgrading your existing UDR, this genuine Traxxas spare part ensures your vehicle maintains peak performance and reliability on the track or trail.

As an authorised Traxxas retailer, RC Model Shop supplies only genuine original equipment manufacturer (OEM) parts that meet the exact specifications and quality standards established by Traxxas engineering. The gearbox is the heart of your RC short course truck's drivetrain, and using authentic Traxxas components guarantees compatibility, durability and long-term reliability. This housing is specifically engineered for the UDR platform and has been proven in competitive desert racing and high-performance off-road RC applications across the UK and internationally.

If you're investing in an RC car UK or maintaining your professional-grade UDR short course truck, selecting the correct replacement parts is critical to avoiding compatibility issues and premature wear. The TRX8591 housing delivers the strength and precision you need to keep your transmission running smoothly through aggressive driving, jumps, and challenging terrain.

Key Features

• Complete Housing Assembly — This part includes the upper housing, lower housing, and gear cover in one convenient package, so you have everything necessary to rebuild or replace your entire gearbox housing without purchasing multiple components separately.
• Genuine Traxxas Engineering — Manufactured to the exact original equipment specifications, this housing ensures perfect fitment and compatibility with your UDR platform without the need for modifications or adjustments.
• Heavy-Duty Construction — The housing is engineered for strength and durability to handle the demanding stresses of 4WD off-road driving, including jumps, landings, and high-torque acceleration.
• Metal Internal Gears — The all-new housing design features metal internal gears throughout the transmission, capable of handling all the torque that brushless motors can deliver without slipping or stripping.
• Sealed Differential Technology — The bevel-gear differential is sealed to hold silicone oil and is equipped with four spider gears for extra strength and durability during aggressive cornering and acceleration.
• Rubber-Sealed Ball Bearings — Precision rubber-sealed ball bearings are used throughout the transmission to reduce friction, improve efficiency, and extend the operational life of your gearbox.
• Advanced Slipper Clutch Design — The proven Torque Control slipper clutch features heavy-duty friction pads that provide long-lasting performance and consistent action, with the ability to change spur gears without altering the clutch setting.
• Hatch-Style Differential Access — The Pro Series housing design allows you to remove the differential without splitting the case halves — the diff simply slides out through a hatch in the transmission's underside, making maintenance and repairs faster and easier.
• Optimised for UDR Models — This housing is specifically designed for the Traxxas UDR Unlimited Desert Racer with both Fox Racing and Rigid Industries variants, ensuring seamless integration with your existing platform.

Technical Performance

The Traxxas Gearbox Housing TRX8591 is engineered using advanced materials and precision manufacturing techniques to deliver professional-grade performance. The housing features a heavy-duty design that has been proven in competitive desert racing environments, where extreme forces, high speeds, and challenging terrain demand absolute reliability. The all-metal internal gear construction eliminates the risk of composite gear failure under maximum throttle conditions with brushless electric motors. The sealed bevel-gear differential holds silicone oil and incorporates four spider gears, providing superior strength during aggressive cornering and directional changes. Rubber-sealed ball bearings throughout the assembly reduce friction and heat generation, which extends component life and improves overall drivetrain efficiency. The Torque Control slipper clutch system includes heavy-duty friction pads that won't wear prematurely, and the design allows rapid spur gear ratio changes for different driving conditions or track layouts without requiring slipper clutch readjustment. This housing represents the culmination of Traxxas's expertise in high-performance transmission design and is the direct result of competitive racing feedback and real-world testing on the most demanding courses.

What's in the Box

• Upper gearbox housing
• Lower gearbox housing
• Gear cover

Frequently Asked Questions

• Is the Traxxas TRX8591 gearbox housing compatible with all UDR models? — Yes, this housing is compatible with both the Traxxas UDR Unlimited Desert Racer Pro-Scale 4WD RTR with Rigid Industries and the Fox Racing variant. Always verify your specific model number before ordering to ensure compatibility with your platform.
• Do I need any special tools to install this gearbox housing? — Installation requires standard metric hex wrenches and nut drivers (7mm, 2.5mm, 2.0mm, and 1.5mm). The Traxxas 4-Way Wrench and the #8712 7-Piece Essentials kit include all necessary tools, and the installation process takes approximately 20 minutes once you've removed the transmission assembly from the chassis.
• What makes this housing different from the original equipment? — This is genuine OEM Traxxas equipment designed specifically for the UDR platform. It features heavy-duty arm mounts, sealed differential technology, metal internal gears, and the advanced hatch-style differential access system that allows maintenance without splitting case halves — features that provide superior durability compared to older designs.
• Can I use this housing as a drop-in replacement? — Yes, the TRX8591 housing is engineered as a direct replacement for damaged or worn gearbox assemblies on compatible UDR models. It requires no modifications and will bolt directly into place when installed following Traxxas installation procedures.
• How do I set the gear mesh correctly after installation? — When gear mesh is properly set, there should be just a tick of free play between the pinion and spur gear. Use a strip of paper approximately four inches long and half an inch wide: mesh the gears together, rotate the spur gear to pull the paper into the mesh, tighten the motor screws, then rotate the spur gear to back out the paper. You should be able to rock the spur gear just slightly without the pinion moving.
• What is the Torque Control slipper clutch and how do I adjust it? — The Torque Control slipper clutch protects your drivetrain from damage during hard landings and power-on jumps by allowing the clutch to slip rather than transmitting all force directly to the driveshafts and gears. The factory setting is spring fully compressed, which is appropriate for drag racing. For off-road use, loosen the adjusting nut one full turn to allow dirt roosts, controlled slides, and power-on traction loss. You can further adjust by listening for a high-pitched whining sound that indicates slipping — avoid excessive slipping that continues for more than two feet on high-traction surfaces, as this causes premature friction pad wear and heat damage to the spur gear.
• Is this suitable for both Fox Racing and Rigid Industries UDR variants? — Yes, the TRX8591 housing is compatible with both UDR variants. Always confirm your specific model number (TRX85086-4-RGD1 for Rigid Industries or TRX85086-4-FOX1 for Fox Racing) to ensure proper fitment.
• How often should I replace or service this gearbox housing? — With proper maintenance and use of appropriate driving techniques, the TRX8591 housing should provide years of reliable service. Regular maintenance includes checking silicone oil levels in the differential, inspecting ball bearings for wear, and monitoring slipper clutch friction pad condition. If you experience gear grinding, metal particles in the oil, or excessive noise during operation, inspect the housing and internal components immediately.

Why Buy from RC Model Shop?

RC Model Shop is a trusted UK RC retailer and authorised dealer for all the brands we stock, including Traxxas, ARRMA, Losi, FTX, Hobbywing, Spektrum and more. Based in Walsall, we have a physical store where customers are welcome to come in, view products and purchase in store. Whether you are a seasoned competitor, a weekend basher, or just discovering the world of RC for the first time, our team of experienced RC enthusiasts is here to help you find the perfect setup and provide ongoing support. Order the Traxxas Gearbox housing (includes upper housing, lower housing, & gear cover) TRX8591 today with confidence, knowing you are buying from an authorised retailer with genuine products, expert knowledge and a commitment to customer satisfaction. Shop online or visit us in Walsall — we look forward to helping you get the most out of your RC experience.