How to Install the Traxxas Extreme Heavy Duty Upgrade Kit
Transform Your 4X4 with this All-Inclusive Upgrade Kit
The Extreme Heavy Duty Upgrade kit (EHD kit for short) is easy to install. No modifications are needed; all you have to do is remove your 4X4’s shock towers, caster blocks, steering blocks, rear hub carriers, and driveshafts and replace them with the EHD components. If you’re an experienced wrencher, your machine can be fully Extreme Heavy Duty-ized in less than an hour. You’re not an experienced wrencher? It’s still easy, and we’ve got you covered with a detailed step-by-step showing an installation on the Hoss 4X4. Follow along and enjoy the build.
Everything you need to complete the Extreme Heavy Duty conversion is included in the kit. We’re installing the green version, you can also get it with blue, red, orange, or black parts.The Extreme HD kit features massive telescoping driveshafts with oversized universal joints, true curvilinear splines, and super-strong 6mm stub axles with 20% larger bearings.
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Step 1: Remove Body and Wheels
Use your 7 mm nut driver to remove the wheel nuts and wheels.Step 2: Unplug the Accessory Power Supply
Unplug the leads from the Accessory Power Supply and thread them out of the shock towers. (LED-equipped models only) Pro Tip: Pull on the plug bodies to separate them, don’t yank on the wires.Step 3: Remove the Shocks
Use a 2 mm driver to remove the shock screws and set the hardware aside to be reused.Step 4: Remove the Shock Towers
Remove the screws that secure the camber links to the front shock tower, then remove the four screws that hold the tower to the gearbox. Remove the front shock tower then repeat the steps to remove the rear shock tower.
The shock tower and camber link screws will be reused for the EHD parts. We removed our Hoss 4X4’s front and rear bumpers for clarity, but the screws can be reached with the bumpers on.
After removing the screws, the tower will lift straight out.
Step 5: Remove the Caster Blocks
Remove the screws that secure the left front camber link and steering tie rod to the left caster and steering blocks, then remove the screw pin that secures the caster block to the suspension arm. Remove the caster block, steering block, and stub axle assembly as a unit. New hardware is supplied to assemble the EHD parts, so there’s no need to take apart the original assembly. Repeat for the right front suspension.
You’ll need your 2.5 mm driver to remove the large screw pin from the suspension armStep 6: Remove the Camber Links
Remove the camber link screw and screw pin from the left rear hub carrier. Remove the hub carrier and stub axle assembly as a unit. Repeat for the right rear suspension.
Step 7: Release the Half Shafts
Use a 1.5 mm driver to remove the screw pins that hold the male half shafts to the front and rear gearboxes, then slide the shafts off the gearboxes.
Step 8: Install the EHD Half Shafts
Install the EHD male half shafts onto the front and rear gearbox outputs and secure them using the 3x16 mm screw pins included with the EHD kit. The universal joints fit over flats on the output shafts. Just rotate the joint until it slips into place, then install the screw pin to capture it.Step 9: Install the Bearings
Install the 6x12x4 mm and 12x18x4 mm bearings into the EHD steering blocks and hub carriers, followed by the stub axle assembly. Note that the stub axle assemblies are fronts and rears and install accordingly.
Push the bearings straight in. They fit flush when fully seated.
The front and rear stub axles appear identical at first glance, here’s how to ID them.
Step 10: Install the EHD Steering Blocks
Install the EHD steering blocks into the caster blocks and secure them with the kit-supplied kingpins. The caster and steering blocks are labeled L and R to indicate left and right—just match L with L and R with R.
Thread the kingpins in until their shoulders bottom out on the steering block. If the steering block doesn’t turn freely in the caster block after installing the kingpins, just unthread them by a half-turn or so.Step 11: Install the Camber Links
Install the camber links onto the EHD shock towers. If you forgot which of the camber position holes to use, just examine the original shock towers—the holes that were used will be threaded and the unused positions will be smooth.
Each camber link has a groove machined into the flats. Install the camber links with all the grooves facing the same direction. We’ve installed them facing left. This is done so there’s no confusion about which way to turn the turnbuckles; no matter which corner of the truck we’re adjusting, turning the turnbuckle wrench toward the front of the truck will lengthen the link, and turning it toward the rear will shorten it Step 12: Install the EHD Shock Towers
Install the front and rear shock towers onto the gearboxes using the hardware you removed in Step 4.
Step 13: Install the Caster Block Assembly
Install the left front EHD assembly onto the left front suspension arm. Align the female and male driveshaft halves so they slide together, then guide the caster block over the arm and secure it with the kit-supplied 3x32 mm screw pin. Use the kit-supplied 3x20 mm screws to attach the camber link to the caster block, and to attach the steering tie rod to the steering block. Repeat for the right front EHD assembly.
Step 14: Install the Rear Axle Assembly
Install the left rear EHD assembly onto the left rear suspension arm. Align the female and male driveshaft halves so they slide together, then guide the hub carrier over the arm and secure it with the kit-supplied 3x40mm screw pin. Use the kit-supplied 3x20 mm screws to attach the camber link to the hub carrier. Repeat for the right rear EHD assembly.
Step 15: Reinstall the Shocks
Reinstall the shocks using the 3x15 mm screws you removed in Step 3.
Step 16: Install the Wheel Hubs
Install a 6x9.5 mm PTFE washer onto each stub axle then slip a 2x9.8 mm pin through the hole in the stub axle. Slide the steel drive hex over the axle so its slot captures the pin. Reinstall the wheels.
Step 17: Reattach the Power Supply (LED Models Only)
Thread the LED leads through the shock towers and plug them into the Accessory Power Supply. The power supply’s black plugs are identical, the bumpers can plug into either one.
Step 18: Install the Body Mounts (Slash 4X4 Only)
The EHD kit is compatible with the clipless body mounting system used by the Hoss 4X4 and Rustler 4X4. If you’re installing the kit on a Slash 4X4, use the included body mounts to complete the Extreme Heavy Duty conversion.
Step 19: Set the Front Camber
The EHD kit calls for the front camber links to be set to 81 mm from center to center. It’s easier to adjust the camber links when they’re on the truck, but difficult to measure them from center to center while installed. Instead, measure the distance between the shanks of the rod ends, as shown. Adjust the turnbuckle until it’s 28.5 mm and you’ll have the correct setting.
The front wheels will tilt in slightly when camber is set properly. To learn more about camber, check out our Suspension & Tuning Guide.
Mission Accomplished: Install a battery, snap the body onto the chassis, and hit the dirt—your 4X4 is officially Extreme Heavy Duty.
