Final drive seal

[Athame57]

Is the final drive seal at the sprocket a seal that can be changed without splitting the crankcases?

[philward]

Not familiar with 350/400 but could try putting 4 self tapping screws into the seal and drawing the seal out?
If it doesn't work you are only back with splitting the cases. I have done this on seals but not one clamped by crankcase halfs

[Bryanj]

No there is a peg on it that locates in a hole in crankcase

[TrickyMicky]

Just a random, unprofessional, stupid thought:-  I assume that the reason for changing the seal is that it is already leaking. If as you say, the engine has to be split, the work involved in just getting the engine out is quite daunting just to access a seal that is readily visible. I think I would be tempted to try to remove the seal, by fair means or foul, have a go at removing the tit on the new seal, and tap it into place. If it does not work and still leaks, then put the Heath Robinson manual away, remove the engine and do it by the book. It has cost you an extra oil seal.

[Athame57]

Just a random, unprofessional, stupid thought:-

Mickey I don't agree with that, better people than me have asked this sort of question: http://www.sohc.co.uk/index.php/topic,9150.0.html
As it happens I'm not in immediate need, it is just I suspect some seepage has been going on and wonder if I might get away with a short cut if it gets worse.

[McCabe-Thiele (Ted)]

I would suspect that the seal has failed due to corrosion on the shaft creeping from the chain wheel end.
In that case the shaft has to be sorted so cases need splitting.

[Oddjob]

I would suspect that the seal has failed due to corrosion on the shaft creeping from the chain wheel end.
In that case the shaft has to be sorted so cases need splitting.

You'd think wouldn't you but in actual fact the spacer that the seal runs on isn't part of the shaft, I always thought it was machined in place but it's just knocked on. Sometimes you can get away with it by reversing the spacer OR even better having a new one made, maybe Max could do one in stainless?

[McCabe-Thiele (Ted)]

I thought the 750 might be like the 400 or is the 400 a fitted on part as well?

Does not sound any easy job to remove the part from the shaft in situ.

[Oddjob]

I think they are all built the same way Ted, could be wrong, all I can say 100% is that the 500/550 one is as I removed one earlier this year, up to that point I didn't think they were removable.