Solving Differential clunk with spring washer may not be a good idea

[sapote]

The obvious question is why all differentials have plays in the spider and side-gears, regardless open or LSD units? Why the factory didn't just have a cheap spring washer? I notice that the spiders rotate around a rod with flat machined on the rod under the spiders. The flat must be for oil to easily get in between. So spider rod wear is a big concern for the engineers.
Here is what I think: the plays or clearance in the spider and side-gears is needed so the spiders don't constantly press on the rod at same place, and the nature of the car being driven, there is no constant pressing of spider to the same spot on the rod.
Now come the clunk eliminator spring washer. It causes the spiders constantly press hard on the rod (the spring loaded side-gear pushes on the spiders against the rod), at the same spot. I think the rod will wear much faster in this case.
A better way to eliminate the clunk is to use flat shims and leave some plays in the spiders and side gears, for oil lubrication.

[bigjae46]

All gears have play, I believe its called lash.

The M variable lock unit is in the end cap or top plate. The locking unit presses clutch packs together and locks rear wheels. The clutches and steels wear out, develops excessive clearance and no longer locks up. The purpose of the spring is to provide some static preload so the locking action is quicker.

The ZF units can spec different belleville springs to provide static preload. Some preload is desirable for a more responsive limited slip unit at the expense of clutch wear and understeer.

You can use flat shims but you'd be constantly changing them out to account for wear in the clutch pack.

[sapote]

The purpose of the spring is to provide some static preload so the locking action is quicker..

The factory didn't use a spring shim for preloading the clutch (I called slippage threshold in other post), but a flat shim on V1, and adjusting the locking ring on V2 version diff. Racing Diff clutch pack includes the spring shim for the purpose. This preload spring is not what I was talking about.
Btw, do we know how close the Racing Diff clutch pack with spring shim with the target slippage threshold? I think they specified something like 100Nm (about 10Kg mass hanging on a meter long arm). If this is too high then the clutch wear will be faster.

I was talking about the spring shim on the right side-gear on V1 diff (and on left side-gear on V2 diff) to take out the spider gear lash. Clutch preload spring has no effect on the spider gear backlash.