TRX-4 Body Conversion Guide
Everything You Need to Know About Converting Your TRX-4 to a New Body Style
The Traxxas trail-truck lineup is strong with officially licensed replicas of all-time favorite 4X4s from Ford, Chevy, Land Rover and Mercedes-Benz. Since all feature the award-winning TRX-4 platform under their authentic bodies, it’s reasonable to think converting your TRX-4 from one look to another is a simple matter of swapping the body, wheels, and tires. However, quite a bit more goes into making each TRX-4 unique than you may realize. We’ll take a deep dive now into the differences between the trucks and what you need to know to get all the correct parts for a model conversion.
What’s the Wheelbase?
The standard wheelbase for TRX-4 trucks and bodies is 12.3″ (312 mm) except for the Defender and 2021 Ford Bronco, which are slightly longer at 12.8″ (324 mm). This keeps their body dimensions in scale with the full-size vehicles. Traxxas makes it easy to convert your truck’s wheelbase by collecting the required parts in one package: 8057 converts 12.3″ to 12.8″, and 8058 will convert a 12.8″ chassis to 12.3″.
The standard wheelbase for TRX-4 trucks and bodies is 12.3″ (312 mm) except for the Defender and 2021 Ford Bronco, which are slightly longer at 12.8″ (324 mm). This keeps their body dimensions in scale with the full-size vehicles. Traxxas makes it easy to convert your truck’s wheelbase by collecting the required parts in one package: 8057 converts 12.3″ to 12.8″, and 8058 will convert a 12.8″ chassis to 12.3″.
Bodies, Tires, and Wheels
Traxxas’ officially licensed replica bodies are incredibly detailed and loaded with separately molded parts to make TRX-4s the most realistic trucks on the trail. You can outfit your TRX-4 with a fully painted, decaled, and assembled body, or choose a clear body and create your own look with ProGraphix® paints. You’ll find part numbers in the chart below for painted and clear options. Note that the clear TRX-4 Sport body is offered with or without pre-cut openings for the 8085 LED light kit.
TRX-4 wheels are generally interchangeable, so you can mix and match them with different body styles if you like. The replica wheels for the Mercedes models and vintage Ford and Chevy trucks require 8255A stub axles which are a few millimeters longer than the 8255 axles. The extra length allows the axles to accept the covers that hide the wheel nuts on the Mercedes, Ford, and Chevy trucks. The wheels will still fit on the 8255 axles, but you’ll have to leave the nut covers off.
Find Your Fenders
Unless you’re converting your model to Sport or Land Rover Defender specs, you’ll also need the correct chassis-mounted inner fenders to go with the body you choose. The fenders are available in “narrow” and “wide” versions to suit the different body styles, and they’re sold in complete sets: 8072 wide, 8080 narrow. If you’re giving your TRX-4 a 2021 Bronco makeover, you’ll need the 8080X fenders, which work with the Bronco’s quick-release body system. The chart below shows which bodies require wide or narrow fenders.
Bumper Options
The body, wheels, and tires are most responsible for each TRX-4’s replica looks, but the bumpers play a big role too. The chart below shows the correct bumpers for each model, as well as the mounts they require, and the optional winch-compatible bumper.
Adding High/Low Capability and T-Lock Differentials to the TRX-4 Sport
T-Lock differentials and a High/Low transmission don’t affect the look of your TRX-4, but if you want the total TRX-4 performance and versatility experience, they’re must-haves. Traxxas makes it simple to upgrade to remote-locking diffs and shift-on-the-fly capability with complete upgrade kits that include the parts you need, right down to the servos. You'll still need a 4-channel TQi radio and receiver to control your new electronics, but those are available in the 6507R package. The 8195 T-Lock Differential Kit kit will equip your Sport with front and rear T-Lock differentials, and the 8196 2-Speed Conversion Kit adds High gears and the shifting components to the transmission.
You’ll also need to upgrade your Sport’s TQ transmitter and receiver to the TQi 4-channel radio system to operate the T-Lock diffs and High/Low transmission. You can use the Sport’s TQ system in another model, or trade it in for a discount on a new TQi using the Traxxas Power-Up Program.
Diffferential Covers
The front and rear portal axles use the same differential cover, which you can get in black, grey, red, and chrome. They’re inexpensive to replace when they get torn up from trail scrapes or if you just want a different look. If model-accurate color is important to you, TRX-4 Sports get red covers, Mercedes-Benz trucks get black, the 2021 Ford Bronco and TRX-4 Chassis Kit have grey covers, and the 1979 Bronco and Chevy K5 Blazer wear chrome diff covers. You can change up your TRX-6 differential cover too, but only the front because of the rear driveshafts.
That about covers it! When you add up the cost of a full model conversion, you’ll probably decide it makes more sense to just treat yourself to the TRX-4 model you planned to recreate and add another truck to your fleet. If you’ve already got correct chassis configuration and wheel-tire combo for the body style you like (or you’re not concerned about being 100% “model correct”), you can give your TRX-4 a new look with just a body swap and a set of fenders. But what about converting a TRX-4 to a TRX-6, you ask? That’s an easy one: just get a TRX-6!