Side to side movement in differential

[b*saint]

What is the spec for how much the differential internal assembly should move side to side? Also I am measuring my shims out and come up with a single shim instead of multiple to make up the gap. Were factory shims ground so they only needed a single shim?

My measurements are .087" on one side and .075" on the other. But real oem list 2.3mm as their biggest shim.

My problem is one side of my diff the flange has a lot of angular play without a load on it. The other side is tight. My two other diffs did not have this issue. I want to move in the flange but I can't know which shims I need until I measure side to side movement.

[b*saint]

Actually it looks like there needs to be no side to side movement once the shims are in and the flanges are assembled.

[jlevie]

I don't know where you can get the specs for setting up the differential, they aren't in the Bentley. But the basic process is to set the pinion preload and adjust output shaft shims for a certain amount of backlash on the ring gear with the pinion clamped. Then the pinion shaft shims are adjusted for correct gear engagement. There are a couple of videos on youtube that are a good tutorial.

[b*saint]

Yea I checked into it. I basically found that after this diff was "rebuilt" the factory shims were used probably because they didn't have a choice. So I reassembled it without shim (putting a certain amount of torque on the 4 bolts) and checking with the output flange for play similar to another factory diff I have lying around, and use a feeler gauge to get the correct thickness of the shim. So I'm making two shims .005" apart (.065" and .070") to see the best fitment. Here is one I cut today on the laser. Took a while because I had to write the Gcode myself. I'm having the engine machine shop surface grind it down for 10 bucks.

[jlevie]

Output shaft and pinion shim sets are available from BMW. No need to have the shims made up.

[TobyB]

Those are the side case shims to set both the carrier bearing preload and the ring gear depth-

and yep, the factory (after about 1978) started using a single shim of varying dimension.
SOME are available depending on the weather, star alignment and barometric pressure,
and sometimes you can stack 2 of the smaller ones to get the thickness you need.

I save 'em from trashed diffs- sometimes you get lucky...

...other times you have to have 'em ground.

The FLANGES will move around some- it's the carrier that needs to be preloaded
'tight' by a little bit...

yah, no new news here, I know...

t

[b*saint]

Output shaft and pinion shim sets are available from BMW. No need to have the shims made up.

Shims were free.

BMW was 40 bucks a set.

[b*saint]

Those are the side case shims to set both the carrier bearing preload and the ring gear depth-

and yep, the factory (after about 1978) started using a single shim of varying dimension.
SOME are available depending on the weather, star alignment and barometric pressure,
and sometimes you can stack 2 of the smaller ones to get the thickness you need.

I save 'em from trashed diffs- sometimes you get lucky...

...other times you have to have 'em ground.

The FLANGES will move around some- it's the carrier that needs to be preloaded
'tight' by a little bit...

yah, no new news here, I know...

t

Exactly. I already use blue marking dye to check ring gear depth and I like it. So Ill have the new shim back from the machine shop by Friday. Toby, if you want some 2.5mm raw ones that will need grinding I can cut you a bunch and send them to you for nothing.