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Measuring 1150 spline wear interpretation


Stan Walker

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Stan Walker

I've always wanted to establish a relationship between clutch disk rotation as measured at the outer edge of the disk and the actual spline wear as seen at the input shaft.

 

Recently I've been able to play with an used R1150RT transmission. It's reported to have around 60K miles on it and the splines are in pretty good condition. See the following picture.

 

croppedSpline1-L.jpg

 

If you look closely you can just see the very slight narrowing of the splines on the right side of the picture. I would judge these splines to be in excellent condition.

 

I also have a brand new clutch disk, part number 21217670454. It was bought many years ago when I lubed my '02 RT splines at 70K miles. Turned out my splines and clutch disk were good to go and I didn't use it.

 

Using the new disk on the used tranny splines I can come up with two measurements as follows. With the disk fully pushed onto the splines (past the normal engagement) I am able to measure the rotation of a new clutch disk engaged with unworn tranny splines. Likewise returning the disk to it's normal partially engaged position allows the measurement of new disk with the 60K mile worn splines. To add to the information I also pulled the starter on my '02 RT with 129,300 miles. The input shaft and clutch disk on the RT are both original parts.

 

New disk to unworn input shaft splines = 2/64"

New disk to worn input shaft splines = 3/64"

R1150RT with 129,300 miles = 4/64"

 

New disk thickness = 6.52 mm

R1150RT disk thickness = 5.5 mm

R1150RT wear limit = 4.8 mm

 

At first glance it would seem that the RT has more spline wear compared to the used tranny but keep in mind that only 50% of that wear will be on the input shaft, the other 50% will be on the clutch disk. I would guess that my RT splines look as good or better then the used tranny in the picture above. I also have about 40% remaining clutch life before hitting the wear limit.

 

Current plans are to do a significant refresh of the RT this winter. New clutch (still original), new diaphragm spring (still original), new clutch slave (still original), grease the various splines (done once), new driveshaft (still original), new fuel pump (still original). At that time I'll append what I learn about the RT's actual spline wear to this post.

 

Stan

 

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Excellent and pertinent information.....Given in a manner that we can all understand. Thank you, for that.

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greiffster

Stan,

Thanks for the data. What's the deal with tan/brown hue of those splines? I've not seen that before.

 

 

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Stan Walker

What's the deal with tan/brown hue of those splines?

 

Bare incandescent light bulb used for lighting confused the camera I think. Didn't seem important so I didn't correct it.

 

Stan

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The shiny part of the shaft is the one that never gets used. Tanned part is the one that carries the load. But more importantly you see the "parting line" on the transmission side of the splines, and none on the engine side, because the shaft doesn't go all the way through the hub. Ideally, you would want the spline to "pull" the hub evenly (or other way around, depending) and not with the twist.

I believe that the wear comes from this slight twist that happens with every engagement of the clutch which, causes the initial "rub in" of the hub at the transmission end of the shaft.

This is how it starts. After that it gets easier.

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Relative wear on the two parts of a misaligned spline will depend on the relative hardness of the two parts. The wear will not be equal. I've so far never seen an example of a spline shaft with more wear at the shaft end vs towards the transmission. This is likely because of the induction heat & quench shaft heat treating process.

 

Bet the interior of the clutch bell housing nice and clean around the engine crankshaft.

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Stan before I pulled my trans I had measured the clutch disc movement on the shaft as being 8 to 9 mm. I just put the same shaft into my bench vise and put the clutch disc onto it. I now get a measurement of 6 mm. I can get variation by moving the clutch to different positions or if the disc is allowed to wobble on the shaft as it can when doing the measurement on the bike the measurement increases by a mm.

 

The clutch hub splines were worn the most.

 

83000 KM was on the original clutch when replaced.

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roger 04 rt

At 35,000 miles my 2004 R1150RT was 3/64 to 4/64 which I'm interpreting as some wear but not a lot.

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Stan Walker

before I pulled my trans I had measured the clutch disc movement on the shaft as being 8 to 9 mm.....I now get a measurement of 6 mm.

 

Something is not right. :) but you knew that!

 

Perhaps the input shaft rotated a bit during the on-the-bike measurement, or perhaps you are pushing the clutch disc too far onto the input shaft (engaging unworn portion of splines) during the bench measurement.

 

Any pictures of the input shaft? It would be beneficial to associate wear with your measurements.

 

Stan

 

 

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Stan Walker

At 35,000 miles my 2004 R1150RT was 3/64 to 4/64 which I'm interpreting as some wear but not a lot.

 

That would be my interpretation too.

 

Stan

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