Hi all just wondering if when replacing the rear main if the output shaft nut has to be a new one each time of whether it be reused thanks

BMW say replace it but I never have and so far no clutches spinning away into orbit or anywhere else

It should really be replaced each time it's removed, but I have heard that the splits in the nut can be pried open so the nut can be reused. That nut is only cheap, so I would just replace it.

looks like I'll be going in to search out an oil leak amongst the clutch casing shortly . I'm thinking it is the rear main seal.
what should I be purchasing for this little adventure. There is an an advantage of having PMS at the moment , at least some serious maintenance can take place. just not as much play time outdoors.

You will need the nut that we were just talking about plus the O ring behind the nut & washer in the clutch housing, the rear main seal , and it would be a good idea to order 6 new clutch retaining bolts and lock washers.
A lot of the time you find that the rear main seal is fine, and it's just the O ring that's leaking, but a good idea to change both while your there.

more likely the oring around the output shaft ...which goes hard ed ..and a bugger to remove unless you break it up with a very fine screwdriver or some such ...so it breaks away in sections

but whilst your in there, might as well linish the shaft for a good surface to wear into and replace the output seal as well

Hey Charles99

I am at that point with one of mine. Will you remind me what you do your 'linishing' with?

Also - a guy called Vince here in Perth who rebuilds mainly Old R series bikes - told me that he always installs the new O ring with a loctite brand of silicone sealant. I wondered if you or anyone else would like to comment as to how this fits with your own experience? Personally I am not in favour as I plan to re use the original nut with loctite thread lock and I don't want to risk getting anything on the shaft threads after I have cleaned these with meths prior to installing clutch housing.

I have done quite a few and never seen the need for anything other than a new O-ring.
I clean the area where the seal runs with a scotchbrite pad and if you can feel any groove or lip with your fingernail then replace the clutch carrier with a good one.

Rick - I've only been an Ozzie for 8 years so I Googled Scotch Brite Pad!

Are you talking about the - usually green - pad for hand cleaning of pots (for example). They market a wire wool which they also refer to as a pad - the one I have to use every time my dear wife forgets something on the stove.....

The green ones are the go but if my wife burns the porridge then she cleans the mess  
Did you know that the word porridge is derived from 3 other words Putrid horrid sludge.

"I clean the area where the seal runs with a scotchbrite pad and if you can feel any groove or lip with your fingernail then replace the clutch carrier with a good one."

To drag you away from the porridge issue Rick - can I conclude from the above that you are not comfortable with the practice of installing the new seal to a depth that is just slightly less than that to which the original seal was installed?

Some more of the story of the 0.5mm has surfaced and apparently it is because the new seal runs the lip at a different spot unless installed as said.
I have been using a seal that is 80mm x 50mm x 8mm "Viton" where the OEM is 10mm. I remember checking where the lip runs in relation to the OEM and it was about 1mm different but whether it was in or out (more likely out) I don't recall so all I do is make it flush and that has worked well for me. The 8mm seal works out about $12 cheaper than Motobins.