Replacing leaky gearchange shaft oil seal (GPz750)

Hi - 

I've been struggling a bit to replace a leaky oil seal on the gearchange shaft of my '84 GPz750. 

Logic, general knowledge and specific advice indicated that the seal should pull straight out with use of a standard tool for such a job, a pick; or a self-tapping screw. Not having a pick with the right dimensions made me try the latter approach, but I was unable to get the seal to move even a gnat's willy length (technical term) outwards, even after heating the shift cover with a propane/butane flame to around 70-80 centigrades. I just pulled the screw out from the seal, leaving it even more leaky than before.

So I had to dig deeper; off with chain, sprocket and the shift mechanism cover. Then I had to punch the seal out, using a socket as a drift and a 2 pound hammer. I even had to warm up the cover again to get it to move.   

My first note to self is that if I ever come across another leaky shift shaft seal, I'll try and glue a new seal to the outside of the old one first. 

After this 'warning', I have a question. When I took off the shift mechanism cover, I noticed a tiny but long coil spring stuck behind (and above) the shift shaft - can anyone tell me where it's supposed to be? It is 1.5 mm in diameter, and approx. 45 mm long, but the ends are distorted. You can see it on the sheet of tissue in the picture, next to the seal. 

 

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That looks like the garter spring from inside the seal that applies pressure to the inside of the seal lip.

Kelly E wrote:

That looks like the garter spring from inside the seal that applies pressure to the inside of the seal lip.

 Obviously  

To my defence, I'll say that I never have come across a loose garter spring before, since they all have stayed inside the seals I've pulled out. 

And I once say someone else's picture of a Z shift fork mechanism, with a spring attached to control their movement. No such spring in my GPz, so I got slightly worried seeing a loose spring . . . 
 

OK, in the end I managed to install a hopefully working oil seal in the transmission cover. 

But whilst applying significant force when trying to pull the old seal out with the trans cover in situ, I managed to snap the lead off the flag terminal connector on the neutral switch. My hope of just replacing the connector faded quickly when I could not manage to pull it off the switch. I cannot see any other set of connectors on that lead. 

Is that how the signal transmitting wire from the neutral switch is supposed to be? 

 

You should be able to pull that connector off with your fingers or long nose pliers, slide the cover back and solder the wire back onto the terminal 

Wookie58 wrote:

You should be able to pull that connector off with your fingers or long nose pliers, slide the cover back and solder the wire back onto the terminal 

I tried to lever off the connector with a fork shaped 'tool' with the switch in a vise, but I only managed to push the switch loose from the vise. Looks like the connector has been crimped on to a flange on top of the switch. 

Then I tried to free up the end of the signal wire by cutting off the tip of the flag terminal. But it looks like I have bent an outer sheath onto the lead, since the switch now is 'on' all the time. Bugger. I've been thinking of applying an even stronger force to try prying off the terminal (after all, this bike must have become used to being worked on by ham fisted 'mechanics'). 

 

I suppose the starter engine circuit cannot be activated unless the neutral light circuit in 'on' ( green light shining)?  

Yes, It is part of the starter lock out circuit - below is what it should look like with the terminal removed so I guess it's just corrosion and years of crap that are holding it on. To be honest for the price I would just replace it and move on to the next job 

Wookie58 wrote:

Yes, It is part of the starter lock out circuit - below is what it should look like with the terminal removed so I guess it's just corrosion and years of crap that are holding it on. To be honest for the price I would just replace it and move on to the next job 

Many thanks for that, Wookie58; always useful to know how parts are designed under 'covers' I'll soak mine in penetrating oil and hope that I then can get the terminal off. 

I agree entirely wrt getting new parts and moving on, but here in Norway it can take ages to get parts delivered. And with high custom clearance fees, & ditto for shipment, it really pays to place just one order for all the needed parts in one go. I miss living in the UK, where I could get parts for my BMWs delivered in two days at very reasonable cost . . . . 

OK, thanks to @Wookie58, the additional challenge with the hesitant neutral switch connector has been resolved. Soaking overnight in penetrating oil, cleaning and 're-filling' with gear oil allowed me to lever off the reluctant connector without damaging the neutral switch itself. 

   
For now, I slid on a cheap standard automotive female connector to the switch, and crimped on a matching one to the bare wire. Testing shows I have a working neutral indicator switch  
I pressed in a new oil seal into the transmission cover, no problems with that. But my unsuccessful attempt to pull out the original seal with a self tapping screw resulted in damage to the shift shaft, which could allow oil to seep past the lip of the new seal. For now I just superglued another oil seal to the outside of the one I pressed into the transmission cover, assuming the lip of the 'external' seal might seal against an undamaged part of the shift shaft. 

 

I will conclude this operation with a WARNING; be careful if you are trying to pull out a defective oil seal with self tapping screws. You may risk damaging the SHAFT the lip of the seal is in contact with, so that a new seals will be torn into pieces immediately.  If possible, punching out the leaky seal with a suitable drift may be a better option.