hi all,
I have a problem with my k100rs 1984.
I thought I would lube the splines on the driveshaft on the diff end , when I pulled the diff off the whole shaft came with the diff, noticed the snap ring had broken due to all the sliding move ment being done at the gearbox end. this maybe why the shaft has become seized at the diff end.
Any suggestions as to how I can free this off.

Under normal conditions you don't get any real movement at the rear spline but without the front uni being clipped home properly you will get movement both ends which I would expect to damage the uni joint due to being out of line with the pivot axis of the swing arm.
I would suspect rust as the culprit for siezure to the pinion shaft. Try tapping around the drive shaft where it goes over the pinion shaft to break up the rust but dont expect any fast solution as 1mm of steel will give 25mm of rust thus the solid siezure. You may even have to resort to cutting the shaft off.
Motobins do have replacement splines that weld on in place of a damaged spline so it may pay to get one of those and hand the whole job over to an engineering shop and get the drive shaft repaired by them.

ok took it to a bmw bike shop, where they tried a hot air gun to heat the shaft , then used a slide hammer attached to the u-joint to free it , but did not move.
today taking it to a shaft u-joint rebuild workshop hope they can free it off.

Sounds like it's really rusted on. I guess they used a hot air gun instead of a flame so they aren't responsible for melting seals

bugger, suggest diesel or kero - oil soak around spline interface if poss, rubber band a tough placi bag ie wine bladder, around shaft with shaft hanging down use a rope rope from a rafter to tie up the bevel box, form a funnel by tying the bag opening high around the bevel box and fill the up to the spline interface with diesel, or kero engine oil mix 50-50 let it soak, the earth suxs the oil down slowly for a few days at least flooding the spline interface. could use proper penetrating oil, marine industry shops carry it.
take it down from rafter and attempt knock out, honestly the BMW guy with a hot air gun was pushing his luck, good try though, its been years rusting in so a week soaking out isn't too long I guess. All the best.
rick

ok , finally got them apart , took 3 of us to do it.
big slide hammer and heat .

yahhhh, well done, how are the splines?

How are the splines, any good?

just spent an hour cleaning surfaces and splines and they seem in very good condition for what they been through.
will be assembling using Castrol molly paste.

fantastic effort. Amazing how seized closely fitting parts can become. Sorry re my rave yesterday, penetrating oil has worked on vintage car pistons for me. Hope the bevel box bearings are ok after the hammering.