Traxxas Rear Differential Complete with Pinion Gear 1/10 4WD TRX6789

Overview

The Traxxas Differential, Rear (TRX6789) is a professional-grade replacement differential assembly designed specifically for 1/10-scale 4X4 brushless RC vehicles. This complete rear differential comes pre-assembled and ready for drop-in installation, making it an ideal upgrade or replacement part for enthusiasts running Traxxas Slash, Stampede, Rustler, and Rally models powered by VXL brushless systems. Whether you're a serious racer looking to maintain peak performance or a weekend basher who demands reliability from your RC car UK setup, this Pro-BUILT differential delivers the engineering quality that Traxxas is recognised for worldwide.

Built to handle the demands of Velineon brushless horsepower, this sealed differential assembly arrives pre-filled with premium 30k-weight silicone oil and features steel gears that can withstand the rigorous demands of high-performance RC racing and bashing. The Pro-BUILT philosophy means you get a factory-assembled, tested differential that requires no building or tuning—just install it and get back to driving. With its 13/37 gear ratio, this differential provides the perfect balance of acceleration and top-end speed for competitive 1/10 4WD short course trucks and rally vehicles across the UK RC community.

This rear differential is a direct replacement for VXL 4X4 models, ensuring perfect compatibility with your existing Traxxas 4WD platform. The complete assembly includes the pinion gear, differential plastics, and all internal components, so you have everything needed for installation. If you've experienced differential wear from aggressive driving, or you're simply looking to maintain your Traxxas RC vehicle in peak condition, the TRX6789 is the genuine OEM part trusted by RC enthusiasts and competitors alike.

Key Features

• Pro-BUILT Professional Assembly — The differential arrives fully assembled and sealed from the factory, eliminating the need for any building, calibration, or tuning before installation, allowing you to spend more time driving your RC short course truck and less time in the workshop.
• Steel Gears for Brushless Power — Manufactured from hardened steel rather than plastic, the internal gears are engineered to withstand the continuous high torque and acceleration demands of Velineon brushless motor systems without stripping or wearing prematurely.
• Pre-Filled with Premium Silicone Oil — Each differential comes pre-filled with 30k-weight silicone oil, which provides optimal lubrication, smoother engagement, and better longevity compared to standard differential oils, ensuring consistent performance lap after lap.
• Sealed Assembly Design — The sealed construction keeps dirt, dust, and moisture out of the differential housing, which is essential for maintaining performance reliability whether you're racing on UK circuits or bashing in outdoor terrain.
• 13/37 Gear Ratio — The 13-tooth pinion gear paired with a 37-tooth ring gear delivers a 13:37 ratio, providing responsive acceleration suitable for short course racing whilst maintaining adequate top-end speed for competitive driving.
• Complete with Pinion Gear and Plastics — Unlike some differential kits, this assembly includes the pinion gear and all differential plastic components, making it a true complete replacement that requires no additional parts for installation.
• Direct VXL 4X4 Replacement — Engineered as a direct replacement for Traxxas VXL 4X4 models including the Slash 4X4 VXL, Stampede 4X4 VXL, Rustler 4X4 VXL, and Rally VXL variants, ensuring perfect fitment and compatibility with zero modification required.
• OEM Traxxas Quality — As an official Traxxas part manufactured to exacting standards, this differential meets the same quality control and engineering specifications as the differentials installed in new RTR ready-to-run RC vehicles from the factory.

Technical Performance

The Traxxas TRX6789 rear differential is engineered with the performance requirements of modern 1/10-scale 4WD RC vehicles firmly in mind. The sealed assembly utilises premium-grade steel gears throughout, a specification that directly addresses the increased torque output of brushless motor systems like the Velineon platform. Traditional plastic gears can experience wear, backlash, or even catastrophic stripping when subjected to the continuous high-load demands of brushless acceleration, but steel construction provides dramatically improved durability and longevity. The 30k-weight silicone oil filling provides the optimal viscosity for smooth, responsive differential action whilst minimising friction losses—heavier oils reduce slippage but increase resistance, whilst lighter oils sacrifice engagement for smoother feel; 30k represents the sweet spot for 1/10 scale competitive driving. The 13/37 ratio (13-tooth pinion to 37-tooth ring gear) is calibrated for the acceleration and speed characteristics required in short course truck racing, where rapid corner exit and consistent mid-range performance take priority over absolute top speed. With a 4.85:1 overall reduction ratio (37÷13 = 2.846 multiplied by the transmission ratio), this differential delivers strong wheel torque whilst maintaining adequate RPM for competitive lap times. The sealed design is critical for reliability in UK weather conditions, where moisture ingress can cause corrosion of steel gears and degradation of differential oil performance. Installation is straightforward on compatible VXL 4X4 models—simply remove the worn differential assembly and drop this Pro-BUILT unit into place, making maintenance and repair accessible even to less experienced RC car UK owners.

What's in the Box

• Traxxas Rear Complete Differential Assembly (TRX6789)
• Pre-assembled differential housing with sealed construction
• 13-tooth pinion gear (pre-installed)
• 37-tooth ring gear (pre-installed)
• Internal steel differential gears
• Differential plastic components and covers
• Pre-filled with 30k-weight silicone oil

Frequently Asked Questions

• Is the Traxxas TRX6789 rear differential compatible with all Traxxas 4X4 models? — No, this differential is specifically designed as a direct replacement for Traxxas VXL 4X4 models only, including the Slash 4X4 VXL, Stampede 4X4 VXL, Rustler 4X4 VXL, and Rally VXL variants. It is not compatible with Titan-powered 4X4 models or 2WD vehicles. Always verify your model number before ordering to ensure compatibility with your specific RC vehicle.
• What does Pro-BUILT mean, and why should I choose a Pro-BUILT differential? — Pro-BUILT is Traxxas's designation for factory-assembled, sealed differential units that arrive ready to install without any building, calibration, or tuning required. This eliminates potential assembly errors, ensures consistent quality control, and saves you valuable time—you simply install it and drive. For busy enthusiasts and competitive drivers, Pro-BUILT components represent genuine convenience and reliability.
• Why does this differential use steel gears instead of plastic? — Brushless motor systems deliver significantly higher torque and acceleration than older brushed motors, and plastic gears can wear, slip, or even strip under sustained high loads. Steel gears are vastly more durable, maintain tighter tolerances, provide better engagement, and resist wear over thousands of drive cycles, making them essential for modern brushless RC performance vehicles.
• What is the gear ratio, and what does it mean for my RC vehicle's performance? — This differential features a 13/37 gear ratio, meaning the pinion gear (13 teeth) drives the ring gear (37 teeth), creating a 2.846:1 reduction multiplied by your transmission ratio. This ratio is optimised for short course truck racing, delivering responsive acceleration for corner exit whilst maintaining sufficient top speed for competitive lap times. Higher ratios (more teeth on ring gear) increase torque but reduce speed; lower ratios increase speed but reduce acceleration.
• How often should I replace my differential, and what are the signs of wear? — Differential wear depends on driving style and maintenance. Signs of a worn differential include grinding noises during acceleration, delayed or inconsistent engagement, visible backlash or play in the driveshaft when the vehicle is stationary, or reduced traction during acceleration. Regular inspection of your differential oil colour (it should remain amber; dark brown indicates excessive wear) and replacing the assembly every 50-100 hours of heavy driving is recommended for competitive use.
• Is this differential suitable for wet weather racing in the UK? — Yes, the sealed assembly design is specifically engineered to keep moisture and dirt out of the differential housing, making it ideal for UK weather conditions. The steel gears and premium silicone oil are both resistant to corrosion, and the sealed construction provides genuine weather protection that open differentials cannot match. However, always rinse your RC vehicle with fresh water after wet weather use to remove salt residue.
• Do I need to refill the silicone oil in this differential? — The TRX6789 arrives pre-filled with 30k-weight silicone oil, and for typical maintenance intervals (every 50-100 hours of driving), the sealed assembly does not require refilling. However, if you experience an oil leak or require complete differential rebuild, you can purchase genuine Traxxas differential oil separately. Some enthusiasts choose to use heavier or lighter oils for specific conditions—consult your vehicle manual or local RC shop for recommendations.
• What is the difference between this rear differential and the front differential? — Rear differentials (TRX6789) and front differentials are engineered with different engagement characteristics and gear ratios to account for the different handling demands at each axle. The rear differential provides the primary drive torque and handles acceleration loads, whilst the front differential must allow the wheels to rotate at different speeds during cornering. They are not interchangeable, and using the incorrect differential will cause poor handling and drivetrain damage.
• Can I upgrade this differential with aftermarket components? — The Pro-BUILT sealed assembly arrives as a complete, integrated unit not designed for field modification. For competitors seeking maximum performance customisation, Traxxas offers alternative differential solutions with adjustable engagement, but for most drivers, the TRX6789 provides plug-and-play reliability that simply works. Consult Traxxas documentation or your local UK RC retailer for advanced upgrade options.

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 Differential, Rear (Complete With Pinion Gear And Differential Plastics) (fits 1:10 4X4 Slash, Stampede, Rustler, Rally) TRX6789 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.