Monolever Final Drive Shim

[QuixotesHorse]

Hi Everyone,
I was doing some work on my '85 r80 final drive and I noticed that the shims installed were not giving enough preload (shims measure 0.87mm but bearing to case surface measures 0.95). I ordered a 1mm shim (part 33122310554) for the necessary 0.05mm preload, but when I received it, the the outer diameters were the same while the inner diameter was noticeably larger than the ones already installed (110mm vs 105mm).
In the picture you can see the original shim on the left and the mark left by the crown bearing. When I overlap the two shims the new narrower one does completely cover the marked region so the bearing should still be properly supported. So my question is, can I still use this shim? If not, does anyone know the part number that I should be looking for instead?

 

[20774]

Welcome to the forum! I'm probably over my head here, but the part number you provide doesn't bring up the '85 R80 model...it brings up many more models. I get to a fiche page for "Gears with bearings, angle gearbox rear". So when I go back to the fiche and find the pages for an '85 R80, and go to the same page, I find this:

https://www.realoem.com/bmw/enUS/showparts?id=0463-USA-03-1985-2472-BMW-R_80&diagId=33_1573

But it only shows one shim 0.5mm thick. So not sure what to make of this.

 

[kinterridge]

The r80 G/S, GS, ST all use different size shims as listed. Do you have a G/S, GS, or ST?
That might explain the difference.

 

[pauls1150]

Welcome, 'Horse!
5 mm is almost two-tenths of an inch ... I don't know for sure, but I would Not use a shim that could "float around" between the seal and the bearing.
If it was a Harley, maybe one could hammer it thinner to make up the diff...

 

[QuixotesHorse]

Thanks everyone for the replies. The bike is an r80 RT.
With regards to the part number, I noticed the same thing only the .5 mm is listed for the r80. If I look at the K100 parts list for example, all the shim thicknesses are sequential starting with .1mm (33122310544) to 1.7 (...561). the R80 .5mm in between at 33122310549 which is why assumed it was just a weird issue with the bike fitment list. The other thing is that all of these bikes K100, R100, R80 etc. all use the same crown bearing 33121242211
As for the 5mm diameter difference, the spacer is actually supported on the outside diameter when it is placed into the case and the inner diameter does not run against anything so it shouldn't float in theory. I can try and take a picture later this evening if needed.

 

[AntonLargiader]

You're just seeing the wider version that was used earlier on. It's the right part.

 

[QuixotesHorse]

Exactly what I was hoping to hear thanks!