How to add Traxxas T-Lock Differentials to your TRX-4
T-Lock differentials require an extra channel to operate so you'll need the TQi 4-channel transmitter with 5-channel receiver. You can keep your Sport’s original radio system for another model, or use the Traxxas Power-Up Program to trade it in for a discount on the 4-channel system. Just follow these steps to upgrade your Sport.
T-Lock differentials
Complete differential kit
TQi 4-channel radio and receiverMetric Hex and Nut Driver Essentials Set
For a job like this, you'll appreciate the benefits of professional quality hobby tools like the 8712 7-Piece Metric Hex and Nut Driver Essentials tool kit. This set includes premium hex bits and nut drivers that will allow you to quickly and easily perform upgrades and maintain any Traxxas model. The kit also includes an overmolded grip and convenient embroidered storage case. The Traxxas Pit Mat will also help keep you organized and protect your work area while you're wrenching.
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Step 1: Remove the Front Axle
Begin by removing the body, wheels, and battery. Remove the screws that attach the shocks and links to the axle.
Remove the body, wheels, and battery
Remove shocks and lower links from the axleRemove the screws that secure the Panhard bar and steering linkage to the axle. With those removed, you can pull the axle out from under the vehicle.
Remove the Panhard bar and steering linkage
Remove the axle from the vehicleStep 2: Remove the Driveshafts
We need to remove the axle’s internal driveshafts to take out the spool and replace it with the T-Lock differential. Remove the kingpin screws from either portal assembly and slide the assembly out—the driveshaft will come with it. Be careful not to lose the steel bushings that are inserted into the caster blocks. Repeat for the other portal assembly.
Remove the kingpins from the axle
Pull the knuckle and driveshaft out of the axleStep 3: Remove the Spool
Remove the differential cover by taking out the four screws that secure it from behind the axle, then pulling the cover straight out. Pull the spool straight out of the axle housing. Remove the bearings from the axle because you'll install them on the new T-Lock differential. Finally, remove the cable plug from the housing by removing the E-clip and pushing the plug through the housing.
Unscrew the differential cover
Remove the spool
Remove the cable plugStep 4: Install the T-Lock Differential
Install the supplied 21x15 mm bearing onto the differential housing, followed by the crosspin and the locking slider. Align the slider’s slot with the crosspin, and install it so the slider’s “teeth” engage with the diff housing. Install the leftover bearings from the spool, and insert the differential into the axle housing.
Install the slider
Install bearings on the differential
Install the differentialInstall the locking fork onto the short T-Lock cable (the long cable is for the rear axle). Fully insert the cable’s hook so it sits flat on top of the fork, as shown. Thread the cable through the housing and align the fork with the bosses in the axle and the slot in the locking slider. Lubricate the ring gear with the included High Performance Grease, then reinstall the differential cover.
Install the T-Lock cable
Install the locking fork
Lubricate the ring gearSlip the supplied E-clip over the cable housing to secure it in the axle. On the other end of the cable, install the ball end so that all the threads are hidden.
Secure the cable in the axle with the E-clip
Install the ball end onto the T-Lock cableStep 5: Remove the Rear Axle
The rear axle removes just like front, but there are no steering parts to disconnect. Just remove the screws that secure the upper links, shocks and lower links.
Remove the rear axleStep 6: Remove the Driveshafts
Remove each portal assembly by taking out the two screws in the portal mount. If the driveshaft does not come out with the portal assembly, you’ll see it protruding from the axle housing. Just slide it out.
Unscrew the portal unit from the mount
Pull out the driveshaft from the axleStep 7: Replace the Spool with the T-Lock Differential
The rear diff installs just like the front, but you’ll use the long cable this time.
Step 8: Reinstall the Axles
Just reverse the disassembly steps. When plugging the driveshafts together, be sure to align the marks molded into the female halves. This will ensure the shafts’ universal joints are “in phase.”
Step 9: Remove the Battery Tray
We will remove the battery tray for better access to the screws we’ll be installing ahead. Remove the four screws shown, then lift the front of the tray and swing rotate it to the side to free the rear bosses from the chassis rails. Note: if you have a TRX-4 with Traxx, the arrowed screws in the chassis rails will be inside the fender wells.
Remove the battery tray screws
Swing the tray out of the wayStep 10: Install the T-Lock Servos
The servos are installed on their bracket for you. Make sure the servo wires are tucked into the guides as shown. Locate the bracket on the chassis and secure it with the supplied 3x8 mm screws. Be careful not to pinch the steering servo’s wires under the bracket.
Route the servo wires
Find the bracket bosses
Secure the servo bracketStep 11: Install the T-Lock Cables
Pass the cables up through the chassis, and snap the ball ends onto the servos. Fit the cable housings into their holders, and secure them with the supplied 2.6x8mm screws. Now it’s time to set up the TQi radio system.
TQi Transmitter Installation & Setup
We’re installing the 6507R TQi transmitter with included 6511 Traxxas Link module, so we can program and adjust the radio system via Bluetooth and the Traxxas Link smart-device app. We’ll use the app to “tell” the receiver it’s installed in a TRX-4 with T-Lock differentials, and the correct settings for the T-Lock servos will be uploaded automatically.
Step 1: Receiver Installation
Remove the set screw that holds the antenna tube, and slide the tube off of the antenna wire. Unplug the steering servo and speed control plugs. We’re working on a TRX-4 with Traxx, so we have an extra wire for the lighting system to unplug. Gently pry the receiver out of the receiver box using a flat-blade screwdriver. Tip: as you remove each plug, label it with tape for goof-proof reinstallation.
Remove the antenna tube
Open the receiver box
Pry out the receiverThread the new receiver’s antenna through the wire clamp, and use the supplied mounting tape to secure it in the receiver box in the same position as the original receiver. Plug the steering servo into either CH1 port, and plug the speed control into the CH2 port. Thread the T-Lock servo leads through the wire clamp, and plug them into the receiver. Plug the front T-Lock servo into the CH4 port, and the rear servo into the BATT/CH5 port. After all the wires are plugged in, reinstall the antenna tube, wire clamp, and receiver box lid. Make sure the blue o-ring and foam clamp seals are in place and greased for proper sealing.
Route the receiver wires
Receiver plug guideStep 2: Traxxas Link Connection & Model Selection
Download and install the Traxxas Link app on your smart device, switch Bluetooth on, and allow new connections. Install a battery in the model, and switch the transmitter and receiver on.
Press the link button on the Bluetooth module, and go to “Garage” in the Traxxas Link app. Select “Traxas Link Wireless Module” to connect to Bluetooth. Install any firmware updates, if alerted (just follow the prompts).
Press the link button
Link your phone to the transmitterThe receiver is not assigned to a model, so the app will ask you to select the model you’ve installed the receiver into. Just swipe until you reach your model, or the one closest to the configuration you want. Since we installed T-Lock differentials in our Sport, we chose the TRX-4 Chassis Kit because it’s T-Lock equipped.
Assign a model
Choose the closest truckThe app will ask if you want to rename the model. We switched “Chassis Kit” to “Sport.” Hit “Save,” and we’re back at the home screen. Notice that the picture in the upper left corner has changed to the TRX-4 Chassis Kit.
Rename the model
Updated Garage screen
The TRX-4 Sport with Traxx includes the latest Deep Terrain treads plus a full set of Canyon Trail tires, so there’s no challenge it can’t conquer. T-Lock differentials further refine performance for total control no matter where your off-road adventures lead.
BONUS: Add Real-Time Inclinometers to Your Traxxas Link Dashboard
Traxxas Link makes it easy to add inclinometers to your dashboard. There’s nothing else to install, it’s all built into the app. You can even set warning thresholds to alert you if your TRX-4 is reaching its tipping point! Traxxas makes it easy, click here to learn how.
Check out some of the helpful Traxxas how-to videos on the Traxxas Support channel, Like, and subscribe. Click here to go to the channel now.
