Final drive sprocket oil seal and gear change shaft oil seal....

[Athame57]

I had the left crankcase cover off the other day and found the whole surface beneath it was covered in a film of oil and the cables leading to alternator where wet with it too. The gasket does not appear to be leaking so I'm sure one or both of the seals there, the is the final drive sprocket oil seal and gear change shaft oil seals, but will this take splitting the cases to do. If not what should I have and need to know to proceed?

[JezzaPeach]

Mine is a 500/4, hopefully similar.
If you clean it all you may see a wear gap between the gearshift spindle and it’s seal. Some say this is the main culprit and mine was. I very carefully drilled a small hole in the middle of it’s ‘ring’ (didn’t need two). Under the coating it’s fairly hard metal but not thick, so patience and care not to let the drill slip pays off. I marked the case a tiny bit but no matter. Then screw in a smallish screw and mine wiggled out (seemed more effective than hard pulling) It wasn’t tight.
The new one drifted in easily with a length of white plastic overflow pipe which had the right thinness and rigidity to work. Mine really just pushed in not hit, but think I tapped it a little to hear the sound of it being firmly seated.
Re 500/4 only:
My drive shaft seal was fine. The clutch push rod (500) seal had been a bit rubbed by a wrong sized ring seal chain, so I replaced that. It sort of levered out with a bit of fiddling with the short end of an Allen key into the hole. Watch out not to lose inside a small circular spring that can come off the back of it, although behind there’s a partial disc with a hole for the clutch push rod. The chain had snapped the push rod (replacement from Julie/Trigger) the long part of which would only come out on the clutch side (another story)

[Athame57]

The new one drifted in easily with a length of white plastic overflow pipe which had the right thinness and rigidity to work.

Thanks for this Jeremy. I'm not sure what you mean with the white plastic overflow pipe though?

[robvangulik]

He used the plastic pipe to push the seal in...

[JezzaPeach]

Yes (if it’s the one that’s leaking) you just slide the seal over the gear spindle and push it evenly and carefully with a piece of tubing slid over the spindle. And just a thought about drilling the small hole, it might help to put an old spanner or something hard against the side of the drill bit to stop it trying to skate all over the place on the narrow surface of the old seal, so it can’t touch the nearby soft alloy casing. Very little space to play with on the 500/4.

[TrickyMicky]

I had the left crankcase cover off the other day and found the whole surface beneath it was covered in a film of oil and the cables leading to alternator where wet with it too. The gasket does not appear to be leaking so I'm sure one or both of the seals there, the is the final drive sprocket oil seal and gear change shaft oil seals, but will this take splitting the cases to do. If not what should I have and need to know to proceed?

  Before you do all this, look for simple first. Make sure it's not oil and crap that's been thrown off an over lubricated chain, over the years it can build up quite substantially and that cover is not one that's going to be removed every couple of weeks to be cleaned out!  When I renewed my rear chain a couple of months ago that is the sight which met my eyes upon dismantling, am now a definite convert to aerosol dry wax lubricant.

[Rob62]

As already stated, have a good clean round the area to degrease it so that you can determine exactly where the oil is coming from. Once you are sure its the oil seal you should be able to carefully prise it out either by drilling a small hole and screwing in a self tapping screw and then using this to pull, or my preferred option (less trouble) to carefully punch a small hole with a narrow flat bladed screwdriver and hammer and then prise it out... a hole at each side will help. Clean the whole area before refitting the new seal. As far as the seal is concerned you can buy good quality japanese or european lip seals from any industrial bearing supplier, usually over the counter, for just a few pounds. Get a couple of spares while you are there. When you come to refit the new seal be careful not to damage the lip of the seal on the sharp edges of the drive shaft (if you do you can go straight to the spare you just bought rather than back to the shop). You can wrap a length of sellotape over the splines to protect the lips and also use plenty of lithium grease to slide it over. You should be able to press the seal in by hand at least to get it started, then use a piece of tubing (without sharp edges) to gently tap it home. The concave side of the seal should face inwards. If you dont have any tube then use a flat ended punch or drift and gently tap whilst working around the edges of the seal to ensure it goes in flat and even. Good luck. Don't split the cases as that is an unnecessary waste of effort.