'91 K75S clutch replacement

[johnpeter]

I have to do a trans input shaft spline lube real soon and my inquiory is about judging clutch disc wear. Having a new disc in-hand at the time of spline lube would be nice.

I have put about 4k on this bike in the last 2 months(just purchased). I like a clutch lever with alot of freeplay, like nearly half of the clutch lever movement.
With the lever adjusted so there are 7 threads exposed or just about 1/2" between the adjusting screw and its lock nut at the rear of the transmission.

So, how many threads exposed is considered clutch disc replacement time?
I gotta hunch someone knows...:ear

If the disc does need replacement, does anyone have a link to disc alignment home-brew tooling?
Guess I could grind down an old socket while it spins in the drill press to where it just fits the disc, then bolt it to two metel bars and make my own that way.

Any input welcome on this. ;)

[roy]

I have to do a trans input shaft spline lube real soon and my inquiory is about judging clutch disc wear. Having a new disc in-hand at the time of spline lube would be nice.

I have put about 4k on this bike in the last 2 months(just purchased). I like a clutch lever with alot of freeplay, like nearly half of the clutch lever movement.
With the lever adjusted so there are 7 threads exposed or just about 1/2" between the adjusting screw and its lock nut at the rear of the transmission.

So, how many threads exposed is considered clutch disc replacement time?
I gotta hunch someone knows...:ear

If the disc does need replacement, does anyone have a link to disc alignment home-brew tooling?
Guess I could grind down an old socket while it spins in the drill press to where it just fits the disc, then bolt it to two metel bars and make my own that way.

Any input welcome on this. ;)

Not sure if there is any correlation between number of threads exposed and clutch wear.

How many miles are on the bike?

Does the clutch slip while accelerating hard in 4th or 5th gear?

On my K100 the clutch disk measured to new specs with 65K on the current odometer.

[johnpeter]

The bike has 70k on it ATM.
EDIT: Don't think it has rolled-over.

No the clutch locks up good in all gears. If it is slipped in 4th gear it will lock up good when the lever is fully released. I did this several times at about 50mph and was just checking the clutch.

Reason I am asking is that I adjusted the hand lever to where I like it and that freeplay has been taken up in the last month and I am not hard on clutches...ever.
So I had to turn out the adjustment at the release arm at the rear of the trans 1.5 turns to get the adjustment back at the hand-lever.

Hand-lever adjustment would be considered a minor adjustment.
At the rear of the trans it would be a major adjustment.

The adjustment at the rear of the trans takes care of manufactuing differences in parts tolerances and wear to the clutch itself. As the clutch wears the diaphram spring at the release bearing will move toward the rear of the trans, this is normal and to be expected.

So my question might be, how many threads are exposed when the clutch is new?...typically. Like maybe three when new and ten threads when nearing replacement?

This is my first K bike and if I ever replace a clutch this would be an adjustment that would have to be re-done or re-set. I was an OTR truck mechanic for many years and when a clutch was replaced the adjusting linkage would get turned back. A K bike guru would be able to note how bad a clutch was worn by looking at the major adjustment, or so I would think.:ear

[roy]

John,
does your bike have the linkage on the clutch to raise the side stand? Not sure if your bike would have the electrical switch or mechanical lift. If it has the mechanical linkage the adjustment on the back of the trans is used to set throw out bearing clearance after a specified cable length is achieved between the clutch arm and swing arm housing. This could probably be used as a reference for clutch wear. I do not know for sure so maybe one of the K gurus can be of more help.

Roy the unguru

[deilenberger]

The adjustment at the rear of the trans takes care of manufactuing differences in parts tolerances and wear to the clutch itself. As the clutch wears the diaphram spring at the release bearing will move toward the rear of the trans, this is normal and to be expected.
The only reason for the adjustment at the rear of the transmission is to get adequate movement of the mechanism that retracts the sidestand. If you don't adjust the clutch correctly there - the sidestand won't automatically retract. There is a writeup on exactly how to correctly adjust it on the IBMWR K-tech pages. It involves measuring the exposed cable length where it connects to the transmission clutch lever.

So my question might be, how many threads are exposed when the clutch is new?...typically. Like maybe three when new and ten threads when nearing replacement?
I have no idea. And I've done a lot of K bike clutches... It is really rare to find a worn K bike clutch disk. If it is worn enough to replace, normally it's been abused and the pressure plate is blued and should be replaced with it.
This is my first K bike and if I ever replace a clutch this would be an adjustment that would have to be re-done or re-set. I was an OTR truck mechanic for many years and when a clutch was replaced the adjusting linkage would get turned back. A K bike guru would be able to note how bad a clutch was word by looking at the major adjustment, or so I would think.:earNo - not really. Once the bottom adjustment is done - you shouldn't have to touch it for MANY miles (in the 10's of thousands). K bike clutches, especially the K75 - less powerful of the K's - don't wear out by themselves. They need abuse to be worn out quickly. I have measured disks with over 100k miles on them where the wear was 1/3rd of the wear limit allowed.

[98lee]

If the disc does need replacement, does anyone have a link to disc alignment home-brew tooling? ;)

I believe I saw a factory tool on Ebay.

Edit: I just checked and it looks like someone is making them and selling them on Ebay. The one I saw sold this morning. He's sold 4-5 this past week for between $24 and $27. He'll probably be listing some more. Not a bad profit for 10 min. on a lathe.


:dance :dance :dance

[98lee]

The bike has 70k on it ATM.
EDIT: Don't think it has rolled-over.

They don't rollover until 1,000,000 miles.

Reason I am asking is that I adjusted the hand lever to where I like it and that freeplay has been taken up in the last month and I am not hard on clutches...ever.
So I had to turn out the adjustment at the release arm at the rear of the trans 1.5 turns to get the adjustment back at the hand-lever.

I would be more inclined to believe that is clutch cable stretch, soon to be followed by clutch cable failure.


:dance :dance :dance

[johnpeter]

Thanks for all replies!


Don,
I will do the proceedure outlined in the tech page@IBMWR.

[98lee]

Now that I rethink my late night reply to your loosing freeplay at the lever, I retract my suggestion of cable stretch. Cable stretch results in MORE freeplay , not less.

THINK THEN TYPE. THINK THEN TYPE. :banghead :banghead :banghead

:dance :dance :dance

[98lee]

The guy just listed another alignment tool on Ebay.

http://cgi.ebay.com/ebaymotors/_Motorcycle-Parts-Accessories__BMW-CLUTCH-PILOT-ALIGNMENT-TOOL-K75-K100-K1100-1984-97_W0QQitemZ140242752324QQadnZMotorcycleQ20PartsQ2 0Q26Q20AccessoriesQQadiZ2863QQcmdZViewItem?hash=it em140242752324&


:dance :dance :dance