Igordiver

As I’m going through the process of replacing both differential bearings I also have to measure shims thickness and backlash. Basically there’s some specialized tools needed to do these measurements but during research I’ve found some topics that have their own way of doing things.

https://rennlist.com/forums/928-foru...-seem-big.html

https://rennlist.com/forums/928-foru...djusments.html

This got me thinking and I’ve made my own tool to do the measurement.
Apparently VW tool 521/4 (the big “bolt”/adjusting device) is 32mm wide which means its 16 mm’s out of differential-center and VW 388 has to be set 80mm away from the adjusting device. Add these facts up and one can say that backlash is measured 96 mm away from differential center.





I’ve taken a 10mm thread rod, this will screw into the differential (U can see this as an extended axle flange bolt) and with epoxy I’ve glued a bolt and another part of the 10mm thread rod together to get the same “construction” as U would get with the special tools.
If I set my clock about 96mm away from center I’m guessing I’ll get an accurate result.
Friday I’m expecting delivery of some shims and I’ll probably measure up. keep U posted on this one.

a4sfed928

If you have the diff cover off you can use a side deflection dial indicator on a tooth of the ring gear. I would assume the 96 mm would land somewhere in the middle of the expected contact patch of the ring and pinion gears.