Final drive shims 1983 R65

After some learning processes, I have to reshim the final drive. I replaced the nose bearing as it was in two pieces and one piece had been on a shelf getting rusty. As there was some doubt what was going on inside due to a seal being pressed in too far and various stripped plug threads, I took off the lid, checked the bearings and looked at the teeth. All good. However, I have zero backlash on the bench with the lid off or with the lid on.

My friend has the original workshop manual in it's BMW binder. I have dial gauges and blue but I can't find a source of shims - particularly the input bearing one. I'm fairly sure that is the issue as there is no clearance with the crownwheel sat on it's shim with the lid off.

Anybody else had this issue i.e. pinion bearing replacement causing misalignment? especially old split type to new single piece? Also an online link to the workshop manual or other proper sequence (the manual is in good nick and my friend won't appreciate grubby oily hand marks on it!).

A few people will come out of the woodwork who might have the shims you re after - but the Moorespeeds, Roger Bennett's, Mikeyboy, Jim Cray of the world will have them. I think I have a few, too, and no plans to use them.

I Hope so, although I will measure them as the bearings and seals are all standard metric (freely available). Except for the top hat needle.

Pics of wear on pinion and blue on crownwheel I just did.

I cut some temporary shims and need about + 0.2mm on the gear side. These seem to be a standard metric shim you can get (like the seals and shims for wheel bearings), so I bought a bunch of 0.1s. This also feels very much smoother (unsurprisingly).

Shims are 37x47 1.4mm on gear side and 90x100 0.6mm + 0.4mm (1mm) on plain side. 90x120 seems to be standard.



Where do you measure to set the crown wheel float on these? The manual we have is for the earlier one where the bearing is flush. I assume I just need to add 0.2 on the gear side and deduct 0.2 on the plain side to be close.

There is a cap on the driveshaft side which is held in with Loctite and can be removed aand it will let you measure end float.
Float depends on what type of bearing you have on the pinion side.
If you have a taper roller then you want 1 thou preload, with a needle roller 1 thou clearance.
Easiest way to measure is to grind down a output bearing so it slides easily in the case and on the pinion and you can measure the end float from the opening at the drive end. Or have a spacer turned up.
The output bearing should have Loctite applied to the OD, grade is in the manual, and if you work quick yo can knock it into the case from the drive end too!
I would stick with " Genuine" BMW output bearing and seal from MB/MW -----!
Munich Motorcycles in Perth , Australia had all the shims, bearings and seal; last time I looked and they can arrange swift shipping.
A drive with anywhere between 10 thou to tight and 10 thou too slack will work for a limited time so if your plans do not include high mileage don't fixated on the end float, the factory ones that came out with 6/8 thou too much preload still managed between 8,000 and 20,000 km!

Shim shimminey, shim shimmeney, shim shim sharoo....

The big ones OD is 10mm too big. I have tinsnips...

Hi all, still struggling here. I cleaned the gear oil out and re-checked using light oil. I can feel what is going on now. The original Belville shim washer gives a little too much clearance as expected (wear). When assembled using just that and the original big shims the other side, backlash is very similar to my original (untouched and runs pwefectly) unit. Both are nearer 0.5 than 0.2mm.

I also swapped the big ball bearing as it was a bit rough with gear oil out of it. Easy job.

However, I still have horrible noises in the drive direction tested using my gun drill. Pinion dual ball race has been swapped. Crownwheel large ball race also swapped. I haven't replaced either needle roller - the big one being a special and around £90. The small one is available and I could pull that one as that could conceivably be allowing some movement. However, can someone give me an experienced opinion of this gear please? It's definitely worn, but is it knackered?

To complete this, the pinion is no good. I've learned a lot about shims, belville washers, engineers blue on gears and how these work. Top and bottom is that no combination of backlash or nose shimming produces proper marks or quiet. Instead of leading-in to the next tooth, the wear means it hits it instead.

I have learned that changing any bearing apart from the little needle if you have the right tools and get things hot with a heat gun is easy.

Now casually looking for a reasonably priced higher ratio FD. My standard R65 is in good condition, this is just to cope with the 860 engine as a nice to have. This one has cost me in time and off the shelf metric seals and bearings. It came in pieces, cheap and I can easily recover the two new bearings and the nose seal (which is not OTS). I do recommend a gun drill to test an unknown unit and that would have saved me a lot of guessing! If its quiet with a gun drill, it's likely all good.

Smug Mode

This fits 860 very nicely. 650 would not have pulled it. Quiet, 1st not noticeably affected (my worry), 2nd and 3rd much more usable and top is like it should be when cruising. This FD was got for £150 plus some seals for good luck.

I think 6 months of pain, scrap parts and learning is worth a little smugness?

Thought I'd chuck this pic in for info, as the new FD was originally for disk

If anyone wants further info on converting an FD for disk to drum, it's easy and I will post it up.