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Checking for spline wear 1999 R1100S

ahdoman

New member
I thought I saw a thread somewhere that briefly mentioned that if you remove the starter you can see if your splines are wearing. Is this true? I can't seem to locate the thread that mentioned it but I've got my left TB pulled because I just did the cam tensioner up grade and I figured while that's out of the way I'd pull the starter to see what I can see.
 
I thought I saw a thread somewhere that briefly mentioned that if you remove the starter you can see if your splines are wearing. Is this true? I can't seem to locate the thread that mentioned it but I've got my left TB pulled because I just did the cam tensioner up grade and I figured while that's out of the way I'd pull the starter to see what I can see.

I have my R1150RS in pieces now for a spline inspection / lube. FWIW, I measure about 6 to 7 mm of free play between the clutch plate and the input shaft. Since my eye's are not as good as they used to be, I took hi res photos of the splines on both the clutch and shaft. On the computer I can zoom in for the visual inspection with very good resolution. Its difficult to estimate, but I think the shaft has worn perhaps 20% off the leading edge. On the other hand, the clutch spline is likely closer to about 40-50% wear. Most of that wear is on the leading edge, but perhaps 10% is on the trailing edge. Of course through the starter opening, it may be a little harder to measure the free play. As noted in many threads before, the clutch plate hangs off the edge of the shaft and does not fully engage. This from a company that prides itself on engineering? I have to wonder if its a case of built in obsolesence.

paul
 
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These spline threads raise an interesting question. If one wished to actually ask BMW "Why did you design this part this way?" just how would one go about doing that in order to get a meaningful answer?

You certainly can't do it at a dealer, that much I know. Most are busy towing the company line or they just don't know. Maybe the MOA carries enough weight with the US Motorrad guys to ask such engineering and design questions on behalf of a a lot of owners?
 
Yes, it's true. A new condition spline will have no perceptible play. i don't have a good mental calibration of a 50% worn one because I never take them apart to know they are 50% worn. I know what a stripped one is like...

I suppose you could calculate the wear by number-crunching the spline dimensions. Haven't done that myself.
 
I thought I saw a thread somewhere that briefly mentioned that if you remove the starter you can see if your splines are wearing. Is this true? I can't seem to locate the thread that mentioned it but I've got my left TB pulled because I just did the cam tensioner up grade and I figured while that's out of the way I'd pull the starter to see what I can see.

I did some digging and found a short and pretty crappy video I shot a couple years ago of my 1100RT clutch disk play with the starter removed. I had zip tied the clutch pulled in all the way to release the clutch, put a paint mark across the pressure plate, disc and cover plate and then just wiggled it up and down. This is what splines in great condition with 21,800 miles should look like when you do this. Note that I am pushing up and down a bit more than the actual "bump" points to feel out and sort of test the limits, and the shorter "bump" points are where contact was felt. If you crank up the volume you can sort of hear the contact limits. So just a couple of millimeters play I think. Apologies for the background radio and left handed phone cam amateur hour but it gives you an idea of what you are looking for. An easy non invasive way to check up on things in there.
Click on the image to play.

th_video-2012-02-24-12-56-46_zpse6dd1cf6.jpg
[/URL][/IMG]
 
HW,
That's about how mine looked.

I've read in other posts that debris (reddish or blackish) in the flywheel/clutch housing area is an indication of wear. It looks like you have some reddish dust in the video. What do you attribute that to and also I'd be interested in what kind of dust clutch disk wear (normal) would deposit.
RB
 
That spline in the video has probably +/- 1 mm of motion at the disk OD, which would suggest to me that it is only about 1/3 worn out. Plus-minus 3 mm (about 1/4 inch total backlash) is probably the wear limit and spline failure will be happening soon. The tangential clearance in the spline teeth is about 1/10 the backlash at the OD of the clutch disk.

The red stuff and the grey stuff in the clutch housing (especially around the spline area) is from metal-metal steel fretting wear products. The gray is ferrous oxide, the red is ferric oxide. FWIW the clutch housing in my R1100RT at 24000 miles was clean and free of both. I probably should not have taken it apart & instead just greased it with a hypodermic system.
 
That is a very astute observation.

That spline in the video has probably +/- 1 mm of motion at the disk OD, which would suggest to me that it is only about 1/3 worn out. Plus-minus 3 mm (about 1/4 inch total backlash) is probably the wear limit and spline failure will be happening soon. The tangential clearance in the spline teeth is about 1/10 the backlash at the OD of the clutch disk.

The red stuff and the grey stuff in the clutch housing (especially around the spline area) is from metal-metal steel fretting wear products. The gray is ferrous oxide, the red is ferric oxide. FWIW the clutch housing in my R1100RT at 24000 miles was clean and free of both. I probably should not have taken it apart & instead just greased it with a hypodermic system.


I remember a time when I understood the difference between Ferric and Ferrous. Gone now. Really though, some of the greases that wick should work fine? Warm the grease in the syringe like you do for Torrington bearings? Why not try?

You would know after some miles when you saw the Ferric or Ferrous oxides. Ferric Oxides are the crystal formation?
 
Here are a some pictures of the clutch plate splines. Measured free play was 6-7mm total. It would be difficult to determine how many more miles before these would fail, but I doubt failure was imminent. Mileage is 117k KM, or 72k miles.
 

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Now the input shaft splines. If you look close, the wear is not even. There seems to be a slight taper with more wear closer to the case. I am not sure how that is even possible. It's as if the clutch disk which we know is not fully engaged on the shaft, and is left hanging off the end, was actually wobbling! But we know that's impossible, because the disk is sandwiched tightly by the pressure plate, and the clutch plate, right? Since the plate mounts properly on the 1100 models, I am curious if the wear pattern is the same or more uniform as one would expect.
 

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Now the input shaft splines. If you look close, the wear is not even. There seems to be a slight taper with more wear closer to the case. I am not sure how that is even possible. It's as if the clutch disk which we know is not fully engaged on the shaft, and is left hanging off the end, was actually wobbling! But we know that's impossible, because the disk is sandwiched tightly by the pressure plate, and the clutch plate, right? Since the plate mounts properly on the 1100 models, I am curious if the wear pattern is the same or more uniform as one would expect.

It's very typical of what I have observed on the 6 speeds. Agreed it's hard to believe its possible, one would think the front of the spline would have the worse wear.
 
These spline threads raise an interesting question. If one wished to actually ask BMW "Why did you design this part this way?" just how would one go about doing that in order to get a meaningful answer?

You certainly can't do it at a dealer, that much I know. Most are busy towing the company line or they just don't know. Maybe the MOA carries enough weight with the US Motorrad guys to ask such engineering and design questions on behalf of a a lot of owners?

Simple, the clutch plate was designed for the R1100 not the 1150's. The 1150's have a 6 speed transmission and a hydraulic clutch. Instead of updating the part for the newer transmission, BMW decided to save a few bucks and reuse the older part. What other possible conclusion can be drawn?. I always find it interesting how all of us owners analyze, discuss, argue and speculate as to why these failures occur. BMW knows exactly what causes these failures. They have engineers that do failure analysis. But the truth will never be known due to liability and possibly loss of reputation. In the end, its always about the $$
 
I remember a time when I understood the difference between Ferric and Ferrous. Gone now. Really though, some of the greases that wick should work fine? Warm the grease in the syringe like you do for Torrington bearings? Why not try?

You would know after some miles when you saw the Ferric or Ferrous oxides. Ferric Oxides are the crystal formation?

One of the things you have to be really careful about is to not get any grease on the clutch side or it will spin off and foul the friction disc.
The best spline maintenance to date seems to be:
Disassembly.
Thorough cleaning.
Grease only the input shaft, not the clutch spline, with something heavy and sticky like 'guard dog moly'.

I'd be concerned about anything thin enough to run going all the way through to the clutch side.
 
If you compare the shaft spline tooth wear with the clutch hub wear, you will see that the tooth wear on both will remain compatible (and that's not the official word I want). It has to wear that way as if there is a high point on one only, it will wear to a low point on the other element. What you are looking at is the differential hardness of the two elements. Where one is harder, it will wear the softer opposite, and vice versa. It has to be this way.

I had not thought of using heat to soften the grease for injection, but that may work using a heat gun. (good idea!) I have proposed using a small amount of volatile solvent (like lacquer thinner) to thin the grease temporarily so it can be injected into the gap. The solvent would evaporate in a few minutes. It takes very little solvent to thin grease. Experiments are in order.

It is important that ALL spline face surfaces get some lubrication as in operation there is no exchange of lubrication between teeth of a spline, much less even across the teeth. Some way of injecting a controlled but minute amount of lube is needed. I thought maybe an insulin syringe with a larger needle might work. The needle diameter has be to be less than about .030 inch according to my measurements. Frankly I've never tried it though.

The potential of an extra 20% of spline engagement would be nice I suppose but it really isn't the golden screw solution when spline wear is encountered. Alignment is what causes the fretting corrosion. Lubrication will cover some of the wear problem. Misalignment won't be helped by a longer spline.
 
If you compare the shaft spline tooth wear with the clutch hub wear, you will see that the tooth wear on both will remain compatible (and that's not the official word I want).

What is the official word you want?

If you mean that the parts will mate properly, I would expect a person with no experience at all to hypothesize that way. In reality, the clutch disc wears straight and the shaft splines wear curved, with a scallop at the rear. There are pictures of this all over the internet, you don't even have to leave your computer. Haven't you seen them?
 
What is the official word you want?

If you mean that the parts will mate properly, I would expect a person with no experience at all to hypothesize that way. In reality, the clutch disc wears straight and the shaft splines wear curved, with a scallop at the rear. There are pictures of this all over the internet, you don't even have to leave your computer. Haven't you seen them?

I thought of it later - Conjugal.

If the input shaft teeth are narrowest at the transmission end (as you describe), and the disk hub teeth unworn, why doesn't the engine end carry all the torque and alignment-caused radial load? (Actually the alignment-caused radial load is the killer here)

You would have to measure the shaft teeth and hub teeth with pins etc or use bluing to determine how the teeth flanks are contacting. Photography has no way of showing the hub wear profile without cutting the hub in half longitudinally. If you did cut it longitudinally, the surfaces would be visually conjugal, I'm certain.

Is there a clear pair of pictures elsewhere you are referencing? The pictures above show a conjugal wear pattern.
 
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