Today I want to share with you how to replace the front diff case on the Losi Tenacity Monster Truck. In an earlier post I wrote and showed a video of running the Tenacity monster truck crashing into a tree that broke the diff case and chassis. My parts have come in so, today I am going to be fixing it up.

Replacing the front diff case on the Losi Tenacity Monster Truck is not that difficult to do. It took me about an hour to replace. Which is a long time but, I also replaced the front bumper assembly and the front lower chassis bracket. I messed up a little and installed the lower chassis bracket before the putting the front end back in place, a learning experience.

Losi Tenacity Monster Truck Parts

I had to replace the front chassis skid plate or front lower bracket, the front bumper and the front differential case. The only way you can get the lower chassis skid plate is, to purchase a complete chassis kit. As well as the front diff case only comes in a complete set. This is a set with both front and rear diff cases and the bumpers come in sets as well. The parts are fairly cheap so, that is a good thing at least.

The parts that were used in this repair:

Chassis kit – LOS231035 $25.46

Differential case set – LOS232023 $13.9

Bumper set – LOS231036 $14.99

Removing The Front Diff Case

OK, enough of that. Let’s go through the process, shall we?

The tools you will need are a 2.0mm and 2.5mm Allen driver and the 4 way wheel wrench.

The first thing you are going to need to do is, Remove the body and the front wheels using the 4 way wrench.

Next, remove the screw (2.0mm) holding the steering links to the steering block. Remove them both left and right side from the steering blocks and let them hang from the steering linkage.

Find the 2 (2.0mm) screws on the top of the chassis behind the front shock tower and remove them. Now, remove the 4 (2.0mm) screws holding the shock tower to the diff case.

On the under side of the vehicle, there are 4 (2.0mm) screws that hold the front lower chassis brace to the chassis, remove the 4 screws. You will have to pull and pop the bracket and differential off the chassis. Guide the driveshaft out of the yoke at the same time.

Now remove the 4 (2.5mm) screws holding the differential to the lower bracket and the 2 (2.0mm) upper bumper bracket screws and remove the bumper assembly.

There are 2 (2.0mm) screws holding the suspension arm pin retainers in place on the front and on the back side of the differential. Remove these 2 front screws and the retainer bracket. Then remove the 2 rear screws and retaining bracket.

The diff case can now be split. Put a clean paper towel down under the diff case. Remove the 4 (2.0mm) screws holding the two case halves together. Pull the halves apart.

Turn the pinion shaft with your fingers, to check the bearings. If they turn hard or feel rough, replace them. Do this with the side bearings as well. If the differential is still good and your just replacing the case, then slide the differential out of the case and then slide the pinion shaft out. Use a small flat blade screwdriver and careful push out the pinion bearings.

Front Differential Installation

Make sure the bearings are pushed in the new case fully and completely seated. Slide the pinion shaft into the case and then put the differential into the case, making sure the bearings are fully seated in to the grooves of the case.

Apply some diff fluid to the ring gear, be sure to spin the differential while applying fluid to ensure the teeth are covered. No need to fill the case.

Set the other case half onto the top of the case with differential installed, making sure they fit snugly together. Install the 4 2.0mm screws and tighten them down. Spin the pinion shaft with your fingers, to ensure smooth operation and that it spins freely. If it does, then it is ready to be installed.

Install the rear suspension pin retaining bracket and the 2 (2.0mm) securing screws. Slide the arms in place, placing the rear end of pin into the retainer. Set the front retainer bracket on to the front of the pins and put into place, install the 2 holding screws.

Place the differential on the lower chassis bracket and install the 2 rear (2.5mm) screws. Leave the front 2 out for now. Install the lower bracket assembly onto the chassis, making sure to push it into place fully and secure it with the 4 (2.0mm) screws. Then reinstall the (2.0mm) 2 upper chassis screws.

Set the shock tower in place and secure it with the 4 (2.0mm) screws that were removed earlier. Install the two steering links to the steering blocks. Now, install the front bumper by sliding it in between the differential and lower bracket. Install the 2 front lower (2.5mm) screws and the 2 upper bumper bracket (2.0mm) screws.
Put the front wheels back on and tighten them down. Install your body and you Losi Tenacity Monster Truck is all set and ready to rip.

Gearing Up The Tenacity

Now that your Losi Tenacity Monster Truck is fixed up and put back together, It is time to grab your battery and charge it up. Once your battery is fully charged, put it into the truck and grab your radio. It is time for some fun. Go run and have some fun, you earned it!

to learn more about the Losi Tenacity MT click here.