I will be replacing the rear output shaft seal on my 85 K100RS. I will be using a BMW seal. I have read articles that indicate the seal should be soaked in oil prior to installation and I have read articles that indicate it should be installed dry. I would appreciation any advise on this. It looks like it will be quite a bit of work and I do not want to have to redo it. Thank you.

The previous version(s) of the seal should be soaked in oil, latest one should be installed dry.
On the latest one it`s also is indicated at the seal "trocken montieren".

I`ll guess we speaking about the engine output, not gearbox or FD.

Inge K.

Why use a genuine when an after market at a considerable lower price will do the job. The genuine is 80mm x 50mm x 10mm and an after market is 2mm narrower and does the job. I have replaced a few and never had problems.

As for oiling the newer ones dont need it but remember to put a small smear of oil on the seal lip to prevent burning when first started.

My opinion (that's all it is, an opinion) is that when you go to the trouble to replace the seal, the little extra cost for genuine is nothing compared to a premature failure. True, other seals are fine, but I've learned my lesson on this with some diff pinion seals (which never had the oil flutes on the inside of the lip) and paid the price (cars & trucks). During the seal replacement, carefully examine the shaft running surface, if it's slighly grooved or highly polished take some 1200 grit wet'n dry paper and lightly rub in a radial motion. Then be sure to thoroughly was away any residue as it will contain carborundum dust. Slightly smear the seal with oil on the seal lip and dust lip before installing and be mindful of the depth to install it. Absolutely imperative that it ends up dead square and not deformed, take your time and be careful.

This seal also should be mounted protruding 0,5 mm above surface.
A drawing of a special tool for this you find here.

Inge K.

Thanks for all the responses. I am finally starting on this today.