Does Radial Clutch Play = Clutch Spline Wear????

Folks,

Just a thought after visiting with Roger04T. I recently removed my transmission to inspect for spline wear and found the inevitable. With the transmission removed I held the original clutch disk on the input shaft and measured the radial play/movement of the clutch disc at 5/8" radial backlash. I then installed a new clutch with a 5mm spacer and measured < 1/16" radial backlash.

What are peoples thoughts as whether this radial backlash would indicate the condition of clutch & input splines. I have photos of mine which I could share. Just wanted to get the topic started for discussion.

Backlash = Surge

Also, I have been chasing the surge problem on this bike as well and I think this clutch backlash could be the main culprit of my surge.

Thoughts?

You do mean Tangential play at the clutch disk OD, not radial play - right? At 5/8 inch she was ready to blow.....

There's sure been a lot of these lately.

I'm fairly sure he is measuring rotary slop at the outside edge of the disk. He installed a disk providing full length engagement on the already somewhat worn input shaft. Since it is now partly riding on the unworn part of the shaft the rotary slop is much less.

If this understanding (guess) is wrong let me know.

Paul you are correct rotational slop is what I am measuring. Not sure if this is radial or tangential

dagear said:

Paul you are correct rotational slop is what I am measuring. Not sure if this is radial or tangential

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Me neither - which is why I called it rotary slop. The engineers and machinists can educate us.

Alignment fix?

So what causes the misalignment could installing gearbox without guide pins cause misalignment?

I don't mind fixing things I just hate fixing things twice

dagear said:

So what causes the misalignment could installing gearbox without guide pins cause misalignment?

I don't mind fixing things I just hate fixing things twice

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No - the guide pins are just an assembly help. There are two "alignment dowels" around two of the mounting bolt holes. These alignmnet dowels are a snug fit in the transmission case and a snug fit in the bellhousing or engine case. When bolted together these alignment dowels control the position of the transmission relative to the bellhousing or engine case.

Alignment Fix?

Paul

After doing more research I can see how the alignment cause the shaft wear. Paul is there a fix to the Alignment issue.

Is adding the spacer to provide full engagement the best I can do for a 12 year old bike?

Call it what you will, once you see the rotational slop / backlash / freeplay increasing, you already have wear. I don't know what the baseline measurement is for a good assembly. As for misalignment, the only way to know is to mount the front gearbox bell housing / cover on the engine and measure the input shaft bearing bore with a dial indicator on the crankshaft. Take crankshaft freeplay into account and determine much misalignment you think is acceptable. Relocating the dowels has been rumored to help in some situations, but I don't think there is a large enough sample size with reliable enough measurements to really make a claim. Runout in the crankshaft bolt pattern and flywheel / clutch components may also contribute. Runout in the flywheel / clutch housing has been clearly documented in the past. Anecdotally, with a fair sample size, replacing the input shaft and all clutch components (including the flywheel / clutch housing) seems to cure the condition in most occurrences. The incomplete spline engagement issue pertains to the R1150 6 speed bikes, not the R1100 5 speeds. Spacing the clutch hub back towards the gearbox will improve spline engagement and presumably allow some extra life to be nursed from a worn shaft. If you are in that boat, I'd plan on regular teardowns for inspection and lubrication.

For reference, my spline issue:
http://forums.bmwmoa.org/showthread...-job-reveals-damaged-splines&highlight=spline

Trick for holding the input shaft from DAVIS2X1:
http://forums.bmwmoa.org/showthread.php?74186-Clutch-spline-measurement&highlight=spline

Post from happy wanderer with some details on measurement and the hypodermic lube that may work, but doesn't allow visual inspection:
http://forums.bmwmoa.org/showthread...Input-Spline-Wear-Pattern&p=932078#post932078

rxcrider said:

Call it what you will, once you see the rotational slop / backlash / freeplay increasing, you already have wear. I don't know what the baseline measurement is for a good assembly. As for misalignment, the only way to know is to mount the front gearbox bell housing / cover on the engine and measure the input shaft bearing bore with a dial indicator on the crankshaft. Take crankshaft freeplay into account and determine much misalignment you think is acceptable. Relocating the dowels has been rumored to help in some situations, but I don't think there is a large enough sample size with reliable enough measurements to really make a claim. Runout in the crankshaft bolt pattern and flywheel / clutch components may also contribute. Runout in the flywheel / clutch housing has been clearly documented in the past. Anecdotally, with a fair sample size, replacing the input shaft and all clutch components (including the flywheel / clutch housing) seems to cure the condition in most occurrences. The incomplete spline engagement issue pertains to the R1150 6 speed bikes, not the R1100 5 speeds. Spacing the clutch hub back towards the gearbox will improve spline engagement and presumably allow some extra life to be nursed from a worn shaft. If you are in that boat, I'd plan on regular teardowns for inspection and lubrication.

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For what it is worth, I agree.

PGlaves said:

For what it is worth, I agree.

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Good thing - half of it is probably just regurgitated info that you wrote in the first place.

The scheme I suggest for detecting radial misalignment is pictured here:

http://bmwsporttouring.com/ubbthreads/ubbthreads.php?ubb=showflat&Number=703209&page=3

I have that fixture & can send it and the indicator to you. You would have to disassemble the transmission to get to the input bearing housing bore. Then I can make a set of offset alignment pins in my metal lathe, mark them, and mail them to you. Since you would be the first to try this stunt, it would be no charge except postage. I don't want to get in the business (at 76+) but I do have time on my hands before things warm up for riding here in MN.

Do you or a friend have any experience working with dial indicators? They are kind of fragile but they also are only ~$25. I would need to know how far off you are, and especially which way. I'd also need the diameter dimensions of your present alignment bushings. Do you have access to a 1 inch micrometer?

This same offer was recently made over at the Pelican Parts site but the guy there declined to go with the agony. I'd also like to see what your spline looks like if you can get a clear picture from the side. Very possibly it can be salvaged even if it looks horrible (well sorta!).

Clutch & SPline Pictures

Pull your starter often. That is a lot of wear.

rxcrider said:

Pull your starter often. That is a lot of wear.

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I assume this implies that one can/should check for wear frequently by removing the starter and turning something to see how much slop there is.

I personally prefer to clean and lubricate things often enought to prevent the wear in the first place. Yes - it is a lot of work. But in the long run it is a more reliable and less expensive practice.

PGlaves said:

I assume this implies that one can/should check for wear frequently by removing the starter and turning something to see how much slop there is.

I personally prefer to clean and lubricate things often enought to prevent the wear in the first place. Yes - it is a lot of work. But in the long run it is a more reliable and less expensive practice.

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Paul - With as much wear as is shown in the photos (assuming this is the input that was put back into service with a new clutch disk and a spacer on the hub) I'm thinking I'd be pulling the starter every 5k miles to see how fast the backlash is growing. That would just be making sure I didn't get stranded. I'd probably be pulling the gearbox to clean and re-lube every 10 - 20k if trying to nurse that mess along. Maybe someone else can chime in who has gone this route, but what looks like up to 50% thinning on the input shaft splines sort of scares me.

Assumption that shaft is back in service is based on this: http://forums.bmwmoa.org/showthread...l-at-60K-miles&p=977148&viewfull=1#post977148
Did I jump to the wrong conclusion?

The splines in the photos look pretty much done to my eyes. Installing a lengthened clutch hub (good idea) on a set of splines which are already severely worn (bad idea) may not work for very long. What I imagine happening is the extra length on the clutch hub is going to take all the strain because it will prevent the already worn area of the splines from doing anything at all. This limited engagement area will do all the work until it wears down the splines to be even with where the worn out splines are now. No idea what that will do to your new lengthened hub but I suspect it won't be good.

My bike? I would bite the bullet and install a new input shaft now. Put that together with the new lengthened hub for a more permanent solution.

These are just my opinions of course and I am far from an expert.

Input Shaft

At this point I don't know how long I will own this bike. The first setup lasted 38,000 miles with initial lube. Hoping with the extended clutch hub that it will be good for another 30,000 with yearly lubes.

At this point I can't afford the $700 in parts for the new input shaft.

Good spline pictures! A classic radial spline alignment problem.

To those who have taken an oilhead transmission apart:

How big a job is it to strip a transmission enough to gain access to the input bearing housing bore? (To make the TIR measurement is maybe 1 hr) and then reassemble it without changing any of the bearing spacers? That would allow us to accurately measure the engine - crankshaft alignment error. My guess (from a sample of one) is that there would be about .015 TIR (total indicator run out) between the crank rotation and the bearing bore for this to have lasted as long as it did.

New clutch disk of course, add the 4 mm spacer, keep the present transmission input shaft, replace the transmission input seal as long as it is so accessible, install appropriate alignment bushing offsets, & button her up.

I think at least another run can be gotten on that input shaft - especially if things are now made to run true.

Keeping track of the tangential spline clearance via the starter opening is a good idea, but if there isn't any significant wear there's no reason to repeat the check as often, unless to add a little bit of lube via a hypodermic needle. Arbitrarily tearing apart the transmission from the engine just to relube if there is no wear, just might be introducing an alignment problem.