This is a optional Traxxas Center Differential Kit, and is intended for use with the Traxxas 1/16 Slash, and 1/16 E-Revo vehicles.
The optional center differential helps balance the Slash or E-Revo VXL 4WD’s power distribution to reduce front end lift on acceleration and improve steering responsiveness. Differential action is fully tunable by changing the silicone fluid viscosity. Factory-filled with pure silicone oil; other viscosities sold separately.
AWESOME! You need this diff even if you'll never race. It's the anti-wheelie cure!
I run a Lipo 3s in my 1/16 revo (wicked fast) and I got tired of it constantly wanting to wheelie. Even at half throttle and over 30 mph when you stab the throttle it still wanted to flip over. I had the Traxxas wheelie bar that kept it from flipping over backwards but it was still real squirrely when the front wheels left the ground. The center diff completely solved that problem. I can now run without the wheelie bar and handling is so much better. Even at a standing start it won't wheelie. It just goes f-a-s-t.
The included instructions to make the change were clear and well written and it's relatively easy to do. However, the instructions also said it was pre-filled with 50k silicone oil but mine was not. Out of the box the output shafts felt too free to have 50k lube. After taking it apart, I found only enough lube to lightly coat the gears. I filled the diff with 50k (you'll need to fill both sides) and it then felt correct with the proper amount of resistance. There is a huge difference in handling and it's much more enjoyable to drive now. No more wheelies. The instructions say to set the nut that holds the spring for the slipper clutch to 3/4 turn from a bound spring. For those running a lipo 3s I'd recommend 1 full turn. This will allow the clutch to slip slightly more (to prevent the front end from lifting) but it still hooks up quick and feels smooth. You can always re-adjust the nut later if desired.
For those who want this diff I'd also recommend you take the diff apart and fill it with 50k before installing. You want 50k in this diff for it to be effective. I'm going to experiment with 100k to see if it will launch faster without the wheelies but 50k works very good.