I think I found my answer on another thread
The "shim" is installed to bring this clearance back to somewhat normal for the clutch brake to travel or compress. A flywheel surfaced that many time is probably best replaced.
Thanks for posting video. I apologise in advance but I have never wrenched.
My old boss always added a "shim"
what was he trying to achieve
He said it made brake last longer
It did "soften"
VIN 1M2B209C1WM0xxxxx
Is this a decent dump truck motor?
I don't think It's the stock motor, truck is a 1998
T2070 Trans
1st time poster, long time follower!
Model number cross reference
https://www.macktrucks.com/parts-and-services/support/body-builders/news-and-events/new-mack-model-description-cross-reference-chart/