Asuga Center diff axial play

[Atomic Skull]

My center diff has some axial play i.e it can move fore/aft in the bulkhead by about 1mm. When the motor revs up the diff and spur gear assembly "finds it's place" and stays put and doesn't move back and forth on the pinion or anything. Is it supposed to be this way or should I shim it?

 

[Nelson.81]

I would check your bearings are ok, I have saw some people melt the plastic diff mount it maybe be distorted allowing movement check it also. I wouldn’t shim it something else not right elsewhere I would guess but I had shim fail inside diff allowing drive cup to move but yours sounds like different issue.

 

[Horatio]

You can use shims on the centre diff to remove excessive end float. There should be a tick of play fore/aft only.

In the front and rear diffs, there should be no lateral movement of the diffs and the mesh between the pinion and crown should free of backlash/play. Basically - as close as you can without it being tight.

This is adjusted either by placing shim/s to move the crown closer to the pinion, or by placing shims on the opposite side, moving the crown further away. The number of shims depends entirely on the amount of play there is to begin with, which sides the shims go depends entirely on the requirements of the mesh.

On race kits, they usually supply the shims, but leave it down to the user to decide where's best to place them.

Example here on a front diff suggests 4 shims, one on the right side, 3 on the left as a starting point.

RTRs are ready built, so it's a lottery. But the process for setting perfect mesh is exactly the same. In most (not all) cases, the bearings sizes are similar too.

 

[Atomic Skull]

In my case the pinion is wide enough that the spur and pinion faces have full engagement regardless of fore/aft float. I have a feeling when I eventually get around to checking there will be no shims at all, the steering plate shims were also left out. I think someone on the assembly line figured out a way to save some time that nobody would notice.

 

[Niekname]

I had this play as well, partially it was the whole diff in the mount, and partially it was the diff cup and spur moving on the outdrives if that makes sense. When you have the diff open you can shim behind the pin that secures the outdrive in the cup. I added 2-3 (0.1) shims if I recall correctly. It still has a little play in the mount but not anything that needs to be shimmed out.