Rear Drive Shaft Oil Leak

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NickC

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I have a '88 R100GS and there appears to be an oil leak coming from the black cap just in front of the rear rubber gater on the rear drive shaft.

I thought this was a 'dry shaft' system? Anybody got any idea where the oil could be coming from and how I might fix it?

Thanks
 
do you mean the "black cap" on the paralever pivot , if so its gearbox or final drive oil, ( presuming you've checked its not rear shock oil dripping down), look at the oil levels in the two items and see if one is low. Thats your starter, when you know which it is, let us know and we can all give you dozens of different methods of curing/fixing it.
 
Had this on my 93' GS Paralever GS last year when I removed the Bevel box to lube the splines, oil leaked from the rear gaiter when I removed it..

The inside of the swingarm was clean & dry from the swingarm pivot back to the 2nd UJ pivot bearings, so I assumed it must the oil seal in the b/box that was leaking.

Sent the box to Sherlocks as you need a specialist tool to access the seal. They charged about £25.00 in total, inc. 30 mins workshop time, new seal & return P&P - good value IMO.

Steve
 
Had oil leaking out gaiter last year in Corsica - 'twas the gearbox output seal blown. Hopefully not on yours. If it is, consider gearbox rebuild (and new springs) and new clutch while on the job. Output seals are a bugger ! Had mine soon after again after letting a shop do it !
Plenty of advice on doing it yourself here if you search site.
 
Steptoe said:
do you mean the "black cap" on the paralever pivot , if so its gearbox or final drive oil, ( presuming you've checked its not rear shock oil dripping down), look at the oil levels in the two items and see if one is low. Thats your starter, when you know which it is, let us know and we can all give you dozens of different methods of curing/fixing it.
Click to expand...

Yes, the black cap on the paralever pivot - I have checked the final drive oil (located on wheel hub) and this is ok - I will now check the gearbox.

cheers
 
Definitely a 'they all do that, sir' problem. My '90 paralever has always had gearbox oil find it's way into the paralever, and I usually only notice it when fremoving the rear gaiter - usually get 50 to 150cc of oil out.

The paralever was originally designed to be a wet shaft like the monolever; that;s why you can see bosses on the upper and lower of the paralever - where the filler and drain would have ben drilled out. Legend has it that BMW bottled out pursuing the wet-shaft because of the potential legal consequences of 'the gaiter split and dumped oil all over my tyre - crash - law suit'.

I beleive that there is a breather from the gerabox into the paralever - that's where the oil comes from. The oil isn't going to be problem for the shaft and as long as the contents of the rear bevel and gearbox aren't rapidly transferring to the paralever, the seals are probably ok.

Chill out and consider that the oil is probably giving that frail drive shaft a few extra miles of life.

BTW, whilst on mongolia I managed to tear the rear gaiter (rocks cought in the spokes during river crossings. A local spotted a 'benzine leak' which turned out to be water coming out of the now-water-cooled paralever. Drained the water, changed the gearbox and bevel yoghurt (water in there too) and ok since then (30,000 miles-ish).


Simon
 
Simon
Appreciate what you've said, but, how do you know if the seal hasn't massively failed and emptied the contents of box into (and maybe out) of shaft housing at some point? I was too concerned to ride the GS back from Corsica (though of course I felt a bit of a puff doing that) as I was concerning in case it got much worse and the dry gearbox locked up, or oil spread over rear on a corner. However, in Mongolia, I'd be attempting to relax and live with it.
They do seem to be a weak point, and it could well be you have the right idea.........I'm not sure I can chill that much. I think I need a break to reconsider things !! ;)
 
Fritz

"how do you know if the seal hasn't massively failed and emptied the contents of box into (and maybe out) of shaft housing at some point"

Undo that plug on the left hand side of the gearbox - check the oil. Undo the plug on the rear bevel - check the oil. Check these as often as your personal balance between paranoia and boredom allows, or at the intervals indicated in the service schedule. I tend towards high boredom level, whcih precludes checking stuff, polishing, making sure I have enough petrol....

My personal approach is to check such things if:

- a service requires it
- if I spot a strange noise or the gearbox seems to be notchier than usual
- if I've a long run planned (like thousands of miles in one go)
- if I fear the bike has swallowed a load of muck and water again.
- if it drops a bit of oil unexpectedly (which it does occassionally)

On stuff like 'seal blowing' I tend to work on the basis of:

- 'it will happen when it's least expected, so there's no point worrying about it too much
- if it ain't broke don't fix it, cos you'll probably break something else in the process

Guess I'm preaching to the converted ;-)

Simon
 
I had to empty my paralever and top up my gearbox every 500 miles on my 100. I did this for over 30000 miles after two attempts at changing the seal failed. Empty and refill only took 10 mins. I chose to live with it.

BTW Nick - check your gearbox breather isn't blocked. There should be a hole in the earth cable bolt by the speedo drive.
 
Agree with all the above i.e. They all do that sir.

However, if it's more than a thimble full at service times, it's odds on that your g/box rear seal has gone AWOL or is starting to.
If the rear seal is leaking so much that you first notice it because there's oil coming out of the breather on the bevel box (like my last time) then your g/box is empty and you need to fix it NOW!

Bloody things! We do love tinkering though!
 
Resurecting an old thread :(

Decided to have a look at the bearings etc at the back end, the ones between the bevel drive and the paralever. So undid the gaiter clamps and black oil started to flow out :tears Got a container and its about 120 cc that came out, all black and smelling of gearbox oil. Checked the bevel drive, up to the fill plug :) checked the gearbox and it's low, :( but the oil is nice and clean. Took about 120 cc to refill the gearbox up. Speedo drive / earth bolt is open and clear.

Bike serviced about 500 miles ago along with its MOT etc.

So in a leap of assumption of major proportions, I'll assume that the oil from the gearbox has leaked into the para since the service, and that its got dirty from the muck inside the paralever. I've read the "they all do that sir" and "leave it and top the gearbox up each time you do the engine oil" type posts, but has the collective wisdom changed since 2004?

And why would it start to leak now, may have been doing it for a while but there's been no leak from the gaiters / breather to give it away? I'll admit that I haven't checked the gearbox oil since I bought the bike about 1500 miles before the service.

And if I don't choose to ignore it, how long does it take to just change the seal?
 
There is a small notch above the seal. On paralevers this notch should be filled with silicon (or similar) to stop oil going from the gearbox to the shaft.
It might be that the notch is open, you can inspect (and repair) this if you loosen up the front gaiter, some people like to remove the shaft to do the job.
 
While you are in there check the rear gearbox bearing if you can - if you can turn the output flange by hand, perhaps assisting the rear wheel with the other hand , you might be able to detect a bit roughness in the bearing.

If you can it is box out time and you may as well do all the bearing, seals and selector springs while you are in there, check the clutch clutch for wear , stip, clean and repack all the paralever pivot bearings, get the shock regassed if you have a good one , and try and get some grease into the UJs on the drive shaft----------
 
Another," they all do that sir". I regularly release the rubber gaiter and see if any oil comes out. Sometimes a small teaspoon full, ( dont do millithingies). Check gearbox and refill if necessary. I find that overfilling the box often leads to oild blowing out into the para. Sort of got a self cure now though.

Ive a small hole in the rather worn front gaiter which allows any excess oil leaking from the gearbox to exit. No danger of it covering the tarmac with the slippy stuff though as it drops onto the collecter box and burns off.
Job done...... Must get it fixed next time I ........ well next time anyway.:D
 
Undone the front gaiter and found the unblocked breather hole :)

Not exactly easy to see / get at when the bikes not in bits :(

Time to get some rtv plastered :)

Does the gearbox oil help or hinder the driveshaft and UJ bearing lubrication?

I'm guessing that the undoing the lower gaiter clamp is one way of checking the gearbox oil level / how good the sealing is on the breather hole?
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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