GPM Racing 4140 Carbon Steel + 7075 Alloy Front Complete Diffs & Upper Bulkhead & Diffs Housing for Traxxas 1/6 4WD XRT 8S-78086-4 (XRT12KIT)

Front diffs and upper bulkhead overview

This GPM kit is an aftermarket RC-scale replacement set designed for TRAXXAS XRT and X-Maxx platforms, combining complete front differentials with an upper bulkhead and differential housing. The parts are intended to strengthen drivetrains exposed to heavy loads and repeated jumps on large-scale electric monster trucks.

The differential internals use 4140 carbon steel with heat treatment for improved torsional strength and wear resistance, featuring a 32T diff bevel gear and a 10T front pinion gear with module M1.6 as specified by the original source. The housing and upper bulkhead are CNC machined from 7075-T6 aluminium to increase rigidity while keeping weight reasonable for RC handling.

Installation is intended as a direct replacement for the factory front assembly on compatible models listed below. The kit’s role is primarily to provide a more durable drivetrain assembly for aggressive off-road use, rather than change vehicle geometry or handling characteristics.

Packing includes

• Differential Housing - 1pcs
• Front Upper Bulkhead - 1pcs
• Grade 12.9 Black Cap Head Screws 4x16 - 2pcs
• Grade 12.9 Black Cap Head Screws 4x18 - 2pcs
• Grade 12.9 Black Round Head Screws 4x12 - 2pcs
• Front Complete Differential - 1pcs
• Front Pinion Gear 10T - 1pcs
• Bearing 15x24x5 - 1pcs
• Black gasket - 1pcs

Original Name / Part No:

7780+7720?7727?7727X+7880+7790

Compatible Models

• TRAXXAS 1/5 X-Maxx 8S 4140 Carbon Steel + 7075 Alloy Front Complete Diffs & Upper Bulkhead & Diffs Housing
• TRAXXAS 1/5 X-Maxx 6S Monster Truck-77076-4
• TRAXXAS 1/6 4WD XRT 8S-78086-4
• TRAXXAS 1/5 X-Maxx 8S Ultimate-77097-4
• TRAXXAS 1/5 X-Maxx 8S Monster Truck-77096-4
• TRAXXAS 1/6 XRT Ultimate 8S-78097-4
• TRAXXAS 1/5 X-Monster BIGFOOT 50th-77136-4
• TRAXXAS 1/5 X-Monster Chassis Monster Truck-77036-4

For builders seeking a direct-replacement front drivetrain option for large TRAXXAS models, this GPM kit offers 4140 steel gearing and 7075 aluminium housings to address durability demands in heavy-duty RC operation.

Which TRAXXAS models are covered by this kit?

The kit lists compatibility with several large TRAXXAS models including X-Maxx and XRT variants; confirm by matching the model codes in the compatibility list before purchase.

Are the differential gears heat treated?

Yes, the differential gears are specified as 4140 carbon steel with heat treatment to improve torsional strength and wear resistance.

Does the kit include bearings and pinion gear?

The packing list includes one bearing (15x24x5) and one front pinion gear 10T among other fasteners and gaskets.

Is this a direct replacement for factory parts?

The product is described as a direct replacement for factory front components on the listed models, intended to increase drivetrain durability.

What maintenance is recommended after heavy use?

Regular inspection for gear wear, bearing play, and gasket condition is advised, and re-greasing or gear replacement should follow manufacturer best practices for large RC drivetrains. Write Product Review Please sign in your account before you can write any review. Sign In Close

Made to order: GPM Racing parts are shipped to us from GPM's factory, so please allow around 14 days for dispatch.