Replace or bodge GPZ 305 gear shaft oil seal

[Rogerborg]

This is likely a question for stinkwheel, but who am I to deny the wits of BCF an opportunity for mockage?

My GPZ 305 has had a very slight and intermittent leak from the oil seal around the gear selector shaft since I got it about 6 months ago. I'm planning to have a look at it this weekend. Yes, I'll double check that it's not from (e.g.) the neutral sensor first, but let's assume it's the shaft seal for now.

I've read that on some bikes you can pry the seal off from the outside and drift a new one in, but I suspect the GPZ isn't going to be as obliging. From looking at a picture of the selector, there's a circlip groove on it, and a cursory inspection didn't reveal a circlip visible outside the case.

https://i.ebayimg.com/15/%21BzlqZD%21EWk%7E$%28KGrHqMOKkME%29NP2F%29NhBMWtwuw5eg%7E%7E_12.JPG

If it's a case split to replace it, then forget that, I'll try to ghetto bodge it first. I'll likely go with poking something between the seal and shaft - thin plastic, dental pick or feeler guage, haterz - then maybe put a ring of gasket sealant around a washer, slide that up the shaft against the outside of the seal and then follow it with an o-ring to hold it in place.

Commence advice / mocking in 3... 2...
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Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[stinkwheel]

I did replace one but I had the engine split at the time.

I have a vague memory that you can pull the whole gear shaft without splitting the engine. I'm sure I saw a special tool for guiding it back into place.

Procedure was something like pull the shaft, replace the seal, put the guide tool into the seal and use it to feed the shaft back through... Then nick the new seal with the gearshift splines as you feed it through, take it back out again, fit a second new seal, wrap the splines in PVC tape before refitting this time... Loose the bit of PVC tape in the sump, cant be bothered splitting the engine. Experience top-end seizure, do post mortem, find PVC tape in end of oil pickup.

Something like that anyway.
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“Rule one: Always stick around for one more drink. That's when things happen. That's when you find out everything you want to know.”
I did the 2010 Round Britain Rally on my 350 Bullet. 89 landmarks, 3 months, 9,500 miles.

[Rogerborg]

Sounds like a plan! However, I've already cut the end off the pickup gauze, so I'll have to settle for seizing the oil pump.

Of course, you realise this thread has immediately become the 3rd search result for GPZ 305 gear shaft tool so now I'm obliged to provide a post mortem for the benefit of posterity.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike

[Rogerborg]

Good news, everyone. It can be pulled (well, screwdrivered and prised) from the outside, it just requires spending a Man Point to believe that you're punching a gash in the seal rather than the engine case.

The process is shown in this YouTube video. The GPZ has the same kind of seal but much more limited access. It'd be easier with the front pulley and belt removed, but it can be done with them in situ. Clean the heck out of the area and the long stretch of outer gear shift before fitting the (well oiled) replacement.
____________________
Biking is 1/20th as dangerous as horse riding.
GONE: HN125-8, LF-250B, GPz 305, GPZ 500S, Burgman 400 // RIDING: F650GS (800 twin), Royal Enfield Bullet Electra 500 AVL, Ninja 250R because racebike