Pinion shaft seal replacement

[Lars]

I know, a boring on-topic technical thread...

While replacing the paralever pivot bearings on my R11 (at 15,000 miles) last week, I discovered oil around the pinion shaft area. It was obviously gear oil, leaking from the pinion seal- the swing arm housing was bone dry and clean inside, so no way that it was coming from the transmission. There wasn't a lot- I'd guess maybe a tablespoonfull or two, pooled in the final drive and dispersed around the boot. There was oil to the plug, so maybe it got slightly overfilled when I changed it over to synthetic at 12,000 miles earlier this year. May not be a serious leak, but it should probably be addressed

I'd like to replace the seal myself. I saw that Anton cautioned against that in this thread but then I found a how-to thread on advrider.com, describing a procedure. Having worked on a lot of 9" Ford differentials, and having lots of fancy tools that I need to justify owning, I feel confident that I can do this, especially if I take my time, remain sober, control my ADHD, etc.

So. What's stopping me? Lack of one specific tool. Specifically, BMW "pin wrench" #33 1 700. The guy who wrote the advrider.com thread made his own. I have enough fab equipment that I could make one too, but if it's cheap enough I'd just as soon buy one. So far I haven't found any on line, though I'll confess to not having called a dealer yet either. Still, I figured I'd ask in case anyone has a better idea.

Flame suit on...

Thanks, guys.

[wswartzwel]

I made one too... Not that hard to do.
Takes lots of heat and lots of torque to get the nut loose. After that it is gravy.

[Lars]

Originally Posted by wswartzwel

I made one too... Not that hard to do.
Takes lots of heat and lots of torque to get the nut loose. After that it is gravy.

Thanks Bill, I may well wind up doing that; gotta watch the budget since I just bought tires, too. Did you heat treat yours like the other guy did?

[wswartzwel]

No the material I used to make mine was already quite hard...

I used the outer half an old CV joint which is already hardened steel... Chucked it up in my lathe, and used a grinding fixture that I have, to remove metal where neccessary. Left me with 4 square Pins. Welded a nut on the threaded end of the CV joint so I could turn it, via Impact or torque wrench.

crude image

[jduke]

A lot of info has been coming out lately about the need for very precise shimming. And also measure the gear mesh. Anton found mine was off and did what was necessary to accurately set it.

[Lars]

Originally Posted by jduke

A lot of info has been coming out lately about the need for very precise shimming. And also measure the gear mesh. Anton found mine was off and did what was necessary to accurately set it.

I've seen some posts about that. It's possible that mine is bad, though so far it's behaving itself, and the final drive seal isn't leaking or loose.

For that matter, it's possible that I created the leaky mess by overfilling, or maybe even because I switched from dino to synthetic.

[jduke]

Like improper shimming can cause the seal at the hub to leak, I really believe improper gear mesh can cause extra pressure on the pinion gear which could cause the seal to leak. My bike had over 75,000 miles on it before the pinion seal started leaking, but once Anton got in there he found the gear mesh was off. I think the pinion / gear mesh problem isn't as major as the shim problem, but should cause any oilhead/hexhead rider to pay extra attention to any FD issues.

[Lars]

Originally Posted by jduke

Like improper shimming can cause the seal at the hub to leak, I really believe improper gear mesh can cause extra pressure on the pinion gear which could cause the seal to leak. My bike had over 75,000 miles on it before the pinion seal started leaking, but once Anton got in there he found the gear mesh was off. I think the pinion / gear mesh problem isn't as major as the shim problem, but should cause any oilhead/hexhead rider to pay extra attention to any FD issues.

Good point on shimming. In the case of the pinion, I imagine that too thick of a shim, which would create insufficient bearing preload, would take out the seal. Since at that point the shaft could whirl (wobble). I've seen that on Ford 9" pinion assemblies, which are somewhat similar. In that case, by the time the seal is leaking, the bearings are usually toast. On the other hand, when I ordered a replacement seal and compression ring, I found that the latter has supposedly been superseded. We'll see what parts I actually get when the order shows up.

[BMWR502]

There's no real need to make a special tool to do this. The ring with the 4 notches in it is the same as a chevy truck axle nut, tool is available at any auto parts store for cheap. I hadn't used this tool in close to 15 years, but sure am glad I held onto it. 36mm deep socket and some heat will get the first nut off. Hoping the dealer has parts on hand so I can get this knocked out this morning.

[BMWR502]

Built a very basic but effective jig to hold the FD in my vice, and to keep the internals from turning.





Definitely needed heat to get everything apart. Need to clean things up a bit, but I have time since the dealer won't get all the parts in until Tuesday.

[tjs]

Are you going to install a new 33 11 7 701 691 Compression Ring?

[BMWR502]

Originally Posted by tjs

Are you going to install a new 33 11 7 701 691 Compression Ring?

Yes. And that's the one part they did not have in stock.