New Clutch and gearbox leak

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Soliton
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New Clutch and gearbox leak

Post by Soliton »

Ok this is a bit of a combo question.

I have an oil leak and I need a new clutch.

Oil leak
I was recently fiddling with the back end to fit the shorter paralever. The boot came off at the swingarm/bevel box junction and I noticed a lot of oil. When I followed up there was also oil around the area at the back of the gear box near the output shaft. My thinking is that the issue is the seal around the output shaft (BMW part # - 23122330135)

I am up for a new clutch. If I do that I will of course need to pull the gearbox. Should I replace all the seals while I am at it.

Clutch
1- Do I always need to replace the whole shebang (friction plate, diaphragm, pressure plate/ cover plate) or canI just replace the friction plate.

2 - Motorworks in the UK offer an oil resistant friction plate (still works even if the rear crank seal starts leaking) with extended splines to mate more reliably with the input shaft

Has anyone used one of these and if so...opinions?

Regards,

Sol
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Buckster
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Re: New Clutch and gearbox leak

Post by Buckster »

I don't have an answer for the first question....but I'll definitely go with the aftermarket input shaft with the extended length.
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kirby
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Re: New Clutch and gearbox leak

Post by kirby »

How many miles on the machine? Have you ever had to add fluid to the gearbox? Has the machine set up for an extended time?

You may have only a small seep that over time can add up.

Is the clutch slipping? If not why change it out? If you pull the rear drive and can get to the rear gearbox seal (if its leaking) then a fairly quick job. If it was mine I would run it for a few miles and check the inside of the boot to make sure you really have a gearbox leak.

If you do tear it down then you will need all new bolts especially if you pull the flywheel. Its a tricky job.

You can pull the starter and inspect the clutch plate for signs of oil contamination and also for width. I seem to remember a new plate(friction) is 3/16"

Installing a new input shaft will require a gearbox teardown.

FWIW
mike Mojave CA
'04 ROCKSTER
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Re: New Clutch and gearbox leak

Post by riceburner »

As I understand it - the gearbox output shaft is 'above' the normal level of the oil (ie the static level). So- if it's leaking, a) it won't leak much b) it's acting a bit like an excess overflow. Yes you might get some seepage because of the oil being splashed about, but it won't leave the gearbox starved.

Re the clutch plate - I'd say the extended spline fitting is a no brainer. (ie - do it!)
Non quod, sed quomodo.

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kirby
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Re: New Clutch and gearbox leak

Post by kirby »

Let me add this:

I have rebuilt two 1150 gearboxes both w/ high mileage (153K, 135K miles) one because of dog damage and the other because of a "singing bearing.

I have a 30 ton press and about a dozen pullers so it was pretty straight forward. One was a GS and the other a std. Roadster.

Neither had any input shaft ware of any concern, both had straight splines. The ones that I have seen pictures of with trashed splines were determined to be caused by miss alignment of the gearbox flange and the mating engine flange. Getrag has its machined surface limits and BMW has theirs and when a matchup of the two from the factory are both at the limit and they add together you can get a significant misalignment which will cause damage to the splines.

The input shaft is lubed mainly for anti corrosion. The clutch plate only moves a very small fraction when in operation, (actually when the clutch leaver is pulled it only unloads the pressure plate and allows the clutch to slip.)

I checked very carefully the the mating surfaces on the two gearbox rebuilds and they were aligned (less than 1 deg. from true square))

I have well over 300K on my Rockster w/no gearbox problems.

Of course there are probably other reasons that input shafts fail on oilheads other than miss alignment but it seems that after having a long discussion with the largest and oldest BMW dealer in SoCal about their experiences they have had very few. Some were traced to the machine being grossly overloaded (over the gross weight limit stated in the manual) of which some folks I've talked to are not even aware of such a limit.

So if an rider wants to go to the expense of a gear box teardown for installing an extend shaft, well then, far be it for me to argue.

FWIW
mike Mojave CA
'04 ROCKSTER
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