contact pattern

I never seen a CS fail, between my stuff and all my customers i don't have any failures.

I have seen nuts back off, seen issues where the preloads were never right from the get go, i can't tell you how many people set preload and never got the bearings seated, or think that checking it off of standing start and not making a full revolution with the same force and that its set at the right preload.
Now imagine having 20" lbs on a unseated bearing, in reality you have no preload once it seats, and in a short time you beat your bearings up and then if you drive thru that noise you wreck your gears.

Most failures are all attributed to people thinking that SOME noise is acceptable, nothing a car makes for noise other than out the exhaust is an acceptable noise to ignore.
In a diff as little as .001 is a problem in the wrong direction, and .001 isn't even something you can see, but at .001 you wind up opening that up to .002 and then you have noise thats ignored and then it continues to loosen up and now its really bad.
The crush sleeve can not be further crushed unless you are able to squeeze the front bearing against the main bearing, which can not happen since there is only relieving effects.

Setting the preload with a cs or shim simply sets the tq needed for the stretch for everything to be set properly that is all it performs.

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