Transmission Shim measurement

[chasbmw]

I was told that post rebuild, when you get an input shaft that is too tight, just give it a couple of whacks with a hard plastic mallet.

[DonW]

Jeez, what a pain this turned out to be. The first transmission went just fine. On the second, with the same careful measurements, every time I'd seal up the box the output shaft would become very difficult to turn. Take it apart, remeasure (always very close each time), re-shim, put it together, same thing.

I measured the depth of the bearing "pocket" in the case, and it varies around the circle. Same thing with the shims- plus or minus .001-2 mm at different parts. Or maybe it's my digital micrometer. I give up for the day, will try again tomorrow.

D

[ME 109]

I measured the depth of the bearing "pocket" in the case, and it varies around the circle. Same thing with the shims- plus or minus .001-2 mm at different parts. Or maybe it's my digital micrometer. I give up for the day, will try again tomorrow.

I found those differences too Don. Makes it frustrating.
I recalculated the shim stacks each time I found things tightening up until I got it right. That 'right' also included a whack on the input shaft as Chas mentions below. One hopes the whack is not a temporary freeing up of the shaft.
Another factor in measuring shim stacks is the flatness of the rear cover. It may be warped, giving a different end result to what the shim measuring plate says. The rear cover needs to be measured for warpage + or - and calculated with the other measures taken.