BMW 1150GS Clutch Splines spacer kit (CLOSED)

If anybody has an example of a hub where the splines do not engage fully other than bmw 6 speed transmission I would like to see it. As far as the misalignment theory I would like to say that perfect alignment does not exist. There is no 0.00000000000 match anywhere in the machine world. So, would it be possible to assume that tolerances for alignment were assumed for full spline engagement and due to lack of that engagement what should be " normal" misalignment becomes beginning of spline wear which is then positive feedback loop into destruction.

Agreed. My father-in-law worked 35 years as truck fleet mechanic, and saw a lot of clutch splines. When I described the R1150** clutch hub overhang to him and shared pics of various shredded transmission input shafts, he nodded grimly and confirmed that he'd never before seen splined mating clutch parts with such a flawed [my word] design.

The OE parts have/had some slop as new parts, according to local dealer service guys. Take that slop, multiply it by the hub overhang, apply whatever dynamic imbalance or parts misalignment might be present, and you get progressive pitting or spalling in the load zone defined by the wacky splined interface geometry. That's my theory.

So, tweaking the R1150 hub position to avoid most or all of the spline overhang seems like the smart move... Next winter I will do a spline inspection and install the tweaked clutch hub kit.

Btw, the old mechanic called BS on anything to do with spline lubrication, since many serviceable truck clutch hubs he worked on had little or no residual grease evident after long service periods.

Even with the extended hub, the input splines are still 4-6 mm short of passing through the clutch-web plane (holds the hub to the disc). Even with full engagement, there will still be an angular force on the hub if the crankshaft and input shaft are offset from one another.

I don't know if this is or isn't an issue but it seems worth discussion.

That has been discussed before and it was a real concern to some.
I don't have the thread handy, sorry.

Due to the greater positive response than originally anticipated I went ahead and placed and order for 10 hubs. There will be no prepayment. I am still working on the rivet solution. My original "proof of concept" was just 5mm thick spacer that I bolted in with M5 bolts with red locktite. I pulled it out after 500 miles and there was nothing to report. I have since removed the bolts and installed rivets using hammer and punch. I don't like the possibility of lose parts in the transmission housing.This is the part of the process that I want to get "normalized" to make sure it is repeatable. Those that expressed interest (or even those who could care less) and have scrap clutch plate to play with please send me a PM.
This is what is spinning inside my bike as we speak. I put about 300 miles and removed it and re-installed it over the weekend to check. Nothing to report.

I'll look for it. I'm interested in this point. Of course there isn't an option for a longer shaft

Someone had a longer shaft produced at one point. But it was upwards of a grand if I remember right.

Terry

Yes, it was GSAddict!

Ah yes. I only had to go back a couple of pages in this thread to be reminded of that!

Terry

That is the thing. Even if the shaft went all the way into a bushing on the crank it wouldn't solve this issue. It isn't like the shaft is flexing.

Find one of these on e-bay, link.

Just to clear up any confusion I placed the order for spacers not the hubs. If your hub is damaged you have to buy a new clutch plate from bmw.

Is it my imagination or do I see stepped wear on those splines?

You are absolutely right Anton. The clutch that is spinning is the original clutch that had beginning signs of wear on it, and reason for my experimentation with this modification.
Here are some more pictures of the hub and the shaft. This was at 24k miles.

You can see the wear on the hub and discoloration at the shaft which I believe is the beginning of the end. I figured I will use the old clutch and if everything is OK with it then I know it is going to be OK with the new one.
You can also see that it is just a basic spacer without the stepped design that the later one has. I have a new clutch disassembled and waiting to be the complete process test.

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Cele, what about a spacer between the end of the crank and flywheel?

That would be the beginning. Then either another spacer or custom clutch pushrods, and another spacer or custom starter and possibly custom starter cover, and......

Has anyone taken a hardness test of the shaft? If the shaft is surface hardened, as it should be, this may be interesting information.

All of the old parts I have here show about 16mm of engagement, with 4mm unused spline in the hub. The R1100 5-speed has 18mm engagement.

FWIW the input shaft for the Hexhead has the identical profile with a 4mm longer clutch spline... but the rear end is too long with flutes that keep you from machining it to fit. So close...