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Getting Started

Raise the Bumpers
This is a very easy modification that you can make using only a 2 mm wrench. All you have to do is remove the bumpers, flip their mounts, and reinstall the bumpers. For about two minutes worth of wrenching, you’ll get an 11 mm lift (a little less than half an inch) for the front bumper, and a 26 mm boost (just over an inch) for the rear bumper. Begin by removing the screw pins that secure the bumper, and pull the bumper out of its mount.

Remove the screw pins

Pull the bumper out

Remove the 3x10 mm button-head screws that secure the mount to the chassis rails. Pull the mount straight out, flip it over, and reinstall with the 3x10 mm button-head screws. Reinstall the bumper and secure it with the screw pins (you’ll have to turn the truck over since the bumper mount is now upside-down).

Remove mount screws

Flip the mount

Reinstall the bumper

Repeat the process for the rear bumper. As you can see, it makes a big difference! For a less dramatic change, you can pick up an extra 8237 TRX-4 bumper mount set and utilize the front bumper mount in the rear.

Raise the Rock Sliders
This is another easy mod, but you’ll need some extra parts. By placing spacers between the rock sliders and the floor pans, you can raise the sliders as much as you like. If you install 4365 shock spacers, you’ll raise the rock sliders by 8 mm. To adjust height in smaller increments, get the 2539 aluminum spacer set. Each set includes two each of 1.5, 2.5, and 3.8 mm spacers. You’ll also need longer 3 mm screws; to determine the length you need, just add ten to the amount of lift you want. For example, if you want to raise the rock sliders by 12 mm, you’ll need 3x22 mm button-head screws.

You can use aluminum spacers or plastic shock spacers to lift the sliders—we’ll use the shock spacers. They’ll lift the sliders by 8 mm, so we’re replacing the 3x10 mm screws with 3x18 mm screws 2583. Remove the four 3x10 mm button-head screws that secure the rock sliders

Shock spacers

Remove the rock slider screws

Insert the longer screws into the sliders followed by the shock spacers, and reinstall the sliders. Hold the truck and rock slider sideways so the spacers don’t fall off as you line up the screws with the bosses in the floor pan. Tighten up the screws and you’re good to go. The spacers are highlighted here so you can see the lift.

Insert the spacers

Lifted rock sliders

Trimming the Body for Raised Bumpers and Rock Sliders
You can simply raise your truck’s body to clear the higher bumpers and rock sliders, but this will also raise the truck’s center of gravity. To maintain the stock body ride height, you’ll need to trim the tailgate and door panels. The body will clear the flipped front bumper without modification, but for maximum approach angle, you can push the bumper into its fully-inserted position and do some additional trimming. Remove the area below the grille to create more clearance for the front bumper. With the body trimmed, you can insert the front bumper all the way back into its mount.

Trim around the bumper

Move the bumper back

For the rear bumper, start by marking the body where it contacts the bumper extensions. You may want to remove the screw pins that secure the bumper so you can extend it for a better view, as we have here. Use a body reamer 3433 to make 10 mm holes at the marks. Start the ream about 18 mm above the bottom edge of the body. Use body scissors to cut straight up to the holes to create slots as shown. Traxxas straight-blade scissors 3431 are shown, you can also get them with curved blades 3432.

Mark the body

Start the holes

Cut slots into the body

The body will fit over the bumper just by slotting it, but for maximum obstacle clearance, you can trim below the tailgate as shown. To accommodate the raised rock sliders, just trim the body using the rocker-panel decal as your guide. You can trim away more if needed, but start here.

Trim around the rear bumper

Trim the rocker panels

You can see the difference in the completed body below. The approach and departure angles have been improved significantly for improved performance out on the trail.

Battery Options for Improved Weight Distribution
As one of the heaviest components on the chassis, moving the battery’s position can have a significant impact on weight distribution. The TRX-4 designers had the foresight to build a few options into the truck’s design. Here’s how to put them to work:

Install a Mini Battery in the Battery Tray Recess
A no-tool option is to use a mini-size battery instead of a full-size pack. The TRX-4’s battery tray has a recessed area just for this purpose. The 2820X 2200 mAh 2-cell and 2823X 1400 mAh 3-cell LiPo packs will both lower the truck’s center of gravity for enhanced side-hill performance. To secure the battery, use the 8222 battery strap. This recess in the battery tray allows lightweight mini-packs to be installed. The tray is slotted to accept the 8222 battery strap. With a full-size 2-cell or 3-cell LiPo on board, the TRX-4 carries 53.3% of its weight on the front axle. By switching to a mini battery, that goes up to 55%, and the truck’s center of gravity is significantly lower.

Recessed battery tray

8222 battery strap

Mini battery installed

Install a Mini Battery on the Front of the Chassis
With the exception of the Land Rover Defender and TRX-4 Sport models, all of the TRX-4 trucks have inner fenders and a shelf between the front fenders that can hold a Traxxas 2200 mAh 2-cell mini LiPo (2820X) or the 1400 mAh 3-cell mini LiPo (2823X). To use this location, all you need is a 8222 battery strap. For maximum front-weight bias, you can remove the main battery tray. See the chart below for weight distribution with the mini battery options.

Front mini battery mounted

Weight bias chart

Narrow fender set

You can add the front battery shelf to the Sport or Defender TRX-4 models by installing an inner fender kit. The narrow set (8080) is compatible with the Sport and Mercedes-Benz® bodies. The “standard” width inner fender set (8072) is used with the Chevrolet® Blazer and Ford® Bronco bodies.

Add Weight to the Wheels
If you’re setting up your TRX-4 as a dedicated crawler, adding weight to the front wheels will help them get a lot more grab. If 3-cell, high-gear driving is your thing, or you’ve outfitted your TRX-4 with a higher-rpm motor, weighted wheels are not recommended as they may overstress the drivetrain. Weighted wheels are for low-speed crawling only.

Traxxas Method beadlocks make it easy to install and remove the tires to experiment with wheel weights. The wheels are available in black chrome and gray, and the rings are sold separately in blue, green, black, orange, and satin silver. Adhesive-backed wheel weights are the easiest way to add weight to the wheels. If your local hobby store doesn’t stock them, you can find the weights at auto parts stores. Stick the weights around the wheel’s circumference. This 1.9″ Method Race Wheel is wearing twelve quarter-ounce weights, for a total of three ounces. For extra security, give the wheel a wrap with fiberglass strapping tape before installing the tires. For even more forward weight bias, install a set of 8267 portal weights and 8251A/G/R/X aluminum portal covers. Check out our TRX-4 Comp Crawler Build to see how these install.

Finally, for extra insurance when adding significant amounts of weight, it is beneficial to add the 8061 Heavy Duty Axles and 8062 Hardened Steel Portal Gears to ensure rock-solid reliability on the trail.

Traxxas beadlock wheels

Adhesive wheel weights

Weights applied

Body Options
Body selection also affects weigh distribution, but only slightly; see the chart below. The bigger difference is in center of gravity, and a lighter, lower body is always better in that regard. The standard Sport body is the lightest, lowest option, and best for a low center of gravity. You’ll never feel it on the trail, but the Camper body is a few grams heavier than the pickup. Here’s how each Sport body option hits the scales on a stock truck with a 2-cell, 5800 mAh LiPo on board:

TRX-4 Sport body

Sport camper body

Weight chart

A fully decked-out Expedition rack will add 202 grams to the Sport, so it may not be the hot setup for a “comp build” (unless they award scale points). But the Sport still has 50-50 weight distribution with the rack installed, and of course, it looks fantastic.

Expedition Rack

Completed rig