Rear Main Seal Help

[SJK]

Hi Everyone,

Please can I pick your brains for some info. I have been rebuilding a K75 1989 and unfortunately there has been many hands on this bike before me.

The latest repair is a oil leak from underneath the Clutch. I have jumped in and found the leak to be from the Rear Main Seal.
I have ordered the parts and they have finally arrived

-11 11 7 666 186 (Main Seal
-11 21 1 460 673 (Nut
-11 21 1 460 696 (compression ring
-11 21 1 460 467 (O-ring

I have removed the Nut and reached the main seal , but there is no Compression ring or O-ring in there  :yow
the new Nut I now have is also different to the old one. I am now a little confused and afraid that I might be missing something .

Please can someone shed some light on my situation , do I have all the right parts?

[The Mighty Gryphon]

There appears to be two different nuts used on these bikes, and the earlier has been replaced by the one you have.  Can't see but one compression ring so not sure of that.  Since the output shaft that these parts are installed on doesn't appear to have been changed I would guess that your parts are good to go.

BTW, the earlier nut was used up to 8/83.  So it was probably old stock that was used because it was there.  It was probably originally a K100 part, but a lot of the K100 parts are used on the K75, and a service guy used it because he had it.

[SJK]

Thanks for the info Mighty Gryphon,

 Ive also spotted another part that was not in the setup , cant find this part on Max BMW

its number 10 in the image attached

[Motorhobo]

It's missing from the Bob's BMW fiche as well. Looks like another view of that O-ring (11) -- that's where it goes, isn't it? I don't remember anything else being there -- but it's been a long time since I did the RMS.

[SJK]

It's missing from the Bob's BMW fiche as well. Looks like another view of that O-ring (11) -- that's where it goes, isn't it? I don't remember anything else being there -- but it's been a long time since I did the RMS.

Hi Motorhobo, thx for the reply, I have been informed that the part #11 in the image is apparently only in the K100 models and not K75. so I will be going ahead with the repair with the parts I have. Thx Sir

[The Mighty Gryphon]

Are you talking about #10 or #11? 

#10 looks like some sort of thrust washer or shim that doesn't appear to be used in any of the engines anymore.  It isn't shown on any of the parts fiches and I haven't seen it in any of my bikes.

#11 is an o-ring that prevents engine oil from coming out through the output shaft.  You DON'T want to leave this part out.

[Motorhobo]

+1 Gryph -- in fact, get two, because if you nick or deform it during install, you will get engine oil slung around in your bell housing, your clutch disk will be oiled and start slipping in no time, and you'll be back in there to do it again within a few weeks.


How do I know this? It's just a tiny little nick, I said -- how much harm can that do?

[Kai Ju]

#10 is a thrust washer that fits between the flywheel and the rear bearing on the K100. It comes in two thicknesses and determines play for the flywheel.
I just looked in Max's parts catalog at several different versions of the K75 and it appears that this shim is omitted on that engine.

[SJK]

Are you talking about #10 or #11? 

#10 looks like some sort of thrust washer or shim that doesn't appear to be used in any of the engines anymore.  It isn't shown on any of the parts fiches and I haven't seen it in any of my bikes.

#11 is an o-ring that prevents engine oil from coming out through the output shaft.  You DON'T want to leave this part out.

sorry , was talking about #10

[SJK]

thanks everyone for the replies and advice , Im diving in tonight  :clap: