Clutch Change - Look what I found!

[liamor]

Don't post to this board very often but have been an avid reader for years. Recently I began to experience clutch slip on my 2002 R1150R which has only 12,000 miles on the clock. All the indications pointed to contamination of the friction material. I read all the threads on this site related to this matter (thanks Cyclerob).

Well today I decided to take the bike apart and fix this problem. Based on what I had read, lifting the rear frame was not too bad. Took me and a friend about 3 hours to strip the bits off, cut all those cable ties and even get the damned airbox out!

Last job today was to take out the slave cylinder. Here's what we found!

http://picasaweb.google.com/liamoregan/ ... directlink

when we slid the cylinder out about 10/15 cc's of foul smelling brown oil poured out.

I\'m hoping someone on this site can interpret these photo's and tell me where they think the oil is coming from. The clutch master cylinder level is fine. I have never had to top it up. Could it be gearbox oil getting past the seal behind the slave cylinder or could it be oil running down the actuation rod from the engine back seal?

Having taken out the starter motor there is no sign of oil around the clutch housing. It is totally dry.

I guess I will find out tomorrow when I remove the gearbox/ Paralever assembly. I'm just waiting for a pair of dowels to insert before I slide the gearbox off. Hopefully they will arrive in tomorrows post.

Any thoughts or suggestions appreciated.

[AndyRR]

"foul smelling brown oil" sounds like gearbox oil. DOT fluid has an almost sweet smell. The culprit is the transmission seal in front of the slave. It can be replaced without taking the transmission apart. Also get the felt ring on the clutch rod. It is supposed to soak up a small amount of fluid to prevent it from reaching the clutch, but was overwhelmed.

[iowabeakster]

Flush the fluid out of the slave cylinder...what does it look like?

[liamor]

Andy RR - I'm inclined to agree with you. There was a large quantity of this oil that pooled on the bikestand after withdrawing the slave cylinder. I can't imagine that this much hydraulic fluid could escape without me spotting it. The sight glass on the clutch master cylinder shows the fluid level is correct.

Next question I have is How do you extract the oil seal behind the slave cylinder? and equally, how do you press the new one in? Are their special tools I need to get?

iowabeakster - not quite sure what you're getting at. I assume you mean bleed the fluid from the slave cylinder to see what colour it is? Haven't done this yet. I hoped I might not have to interfere with the clutch hydraulic circuit. My thinking is coming roud to replacing both the clutch slave cylinder and the oil seal behind it.

Thank you both for your thoughts.

[boxermania]

It's brake fluid, exposed and contaminated. As mentioned by iowabeakster you need to flush the clutch circuit if it hasn't been done on a 2002 bike. You will se once the tranny is out that the inpt shaft seal is not leaking. The slave is the source!!!

The clutch disc will have to be replaced and all components cleaned. You might want to drill the bleed hole a la CycleRob to prevent soaking the clutch disc the next time.

Best of luck......

[iowabeakster]

Sorry, reading your post left me with more questions than answers. You said that you never needed to top it up. That confused me. You will only replace the fluid...NEVER add to it. I was wondering what the condition of the hydraulic fluid was. The change interval on the clutch fluid is "At LEAST every 2 years". With an '02, and a brake system flush done annually, most would do the clutch at the same time.

Hydraulic brake fluid turns dark and yucky when it spoils...and it expands as it aborbs water. Then it will boil and leak.

[AndyRR]

The slave is the source!!!

Care for a friendly wager? I'll buy you a beer next time I'm in town if I'm wrong.

The sight glass on the clutch master cylinder shows the fluid level is correct.

The level of the clutch fluid in the reservoir, the mess of fluid in the pics and especially the foul smell leads me to GB fluid. That clutch rod spins at engine RPMs inside the rubber seal and it does not have a high level of polish like the input shaft. I think I'm going to chuck mine up in a drill and give it a good polishing with steel wool where it meets the seal. I'm really beginning to understand the wisdom of CycleRob's mod. The clutch slave seal and the clutch slave itself are both under a lot of stress and clutch slippage (too late!) is the first sign of failure.
I agree that failure of the slave is more likely to cause a clutch failure because it is under pressure and the GB oil is only splashing around; but in this case, I think I am correct.
I predict we will see more and more failures here as that rubber seal ages and becomes brittle.
Has anyone actually used up their clutch conventionally?

[boxermania]

AndyRR

Lip seals, like the ones used in the GB are designed to contain oils plash as oppossed to direct contact with an oil level, that is why the oil level in the tranny is well below the bottom of the seal(s), so I seriously doubt your hypothesis.

The trow-out bearing rod can't possibly spin at engine rpm, it does ride inside the input shaft on its way to the TO bearing. Just think how long the end(s) of the rod would last every time the clutch was actuated......

Last but not least, CycleRob's fix is to allow the hydrulic fluid leaking out of the slave cylinder to find a way out instead of traveling along the rod and contaminating the clutch disc, a loss of a few cc's can still show good level at the MC depending on how full it was originally and the position of the handlebars.

That being said I have been known to mess-up now and again and I will graciously bow to superior knowhow.

[combustor777]

Well I'm not the expert like some of you but if that is oil and not gnarly brake fluid in the pics then you need to change the 8 year old 0 weight oil to some 75w140 immediately!

[CycleRob]

It's the GB oil seal, since the clutch M/C fluid level has not gone down. The foul smell is also GB oil. The seal will have to be replaced. You can put 2 opposing sheet metal screws, like at 3 & 9 O`Clock (with minutely dulled points) into the outer diameter of the seal to get a hold on it to pull it out. Clean out and lightly grease the surface the seal will slide on once it gets loose and moves. You must NOT go in too far with those screws where they will forcefully contact the ball cage or ball bearings!!!! Good judgment and feel is required.

AndyRR, The BMW pushrod isn't like all other bikes (Japanese) where the pushrod passes thru an oil seal. There isn't any seal between the pushrod and the much larger ID of the hollow and dry input shaft. There's only an airspace. The felt ring only seems to be there to keep clutch wear dust away from the slave piston, where it would cause accelerated wear. Both ends of the input shaft have oil seals on them, but the clutch pushrod has none. The clutch pushrod always spins with the crankshaft, but the input shaft turns with it only when the clutch is released (out). When you pull in the clutch and put it into 1st gear at a stop, the input shaft stops while the pushrod turns with the engine. It's spinning in the airspace between it and the input shaft with it's ball socket end in the very small ball thrust bearing encased in the clutch slave piston. That little thrust bearing has quite a heavy axial load on it, holding the clutch released.


.

[liamor]

Found some more time to work on the bike today. Took out gearbox/transmission. Learned quite a lot. We did a little test with the slave cylinder yesterday. Cleaned it up and dried it out totally. Fitted it to gearbox and Cable tied the clutch lever down and left it overnight to see what would happen.

Took out slave this morning and inspected it. Absolutely no sign of any fluid weeping out. Good circumstantial evidence i think. Next we drained the gearbox into a measuring jug. Got just over 600 ml. The manual seems to suggest that the oil change volume is 800 ml. More evidence!

Several comments on the board have suggested that the fluid that came out when we took out the slave was in fact clutch fluid. I had a little difficulty with this as there was about 1/4 to 1/3 of a cup of fluid. looking at the clutch hydraulics I can't imagine that there is more than a cupful of fluid (if that) in the whole circuit. If I lost (say) 1/3 of my hydraulic fluid surely I would need to refill the master cylinder. The master cylinder level never seems to change and I have never had to top it up.

It seems reasonable that the oil we found is from the gearbox (same awful smell, similar (but not identical) colour. Inspection of the clutch and housing shows contamination of the plate which looks like it came down the actuation shaft. All the other seals seem to be doing their job and so I will not touch them but I'm going to change the seal behind the slave cylinder. Not looking forward to the job. Thanks for the tips CycleRob. I was hoping you might get involved. I intend to try your drain mod before putting everything back.

Hopefully my parts will arrive from Motorworks tomorrow. I've ordered a slave cylinder but I think I may not use it as the original seems just fine.

Here are the latest pictures I took today. Quality isn't great but I didn't want to ruin a good camera!

http://picasaweb.google.com/liamoregan/ ... directlink

Thanks to everyone who has contributed to this thread. I don't always agree with what you say but I really do value your input.

I'll finish this thread when I have assembled the bike, hopefully over the weekend. Don't be surprised if I'm back for more help!

[combustor777]

thanks for sharing! the water explains why it looks so damn thin.

[Boxer]

I've ordered a slave cylinder but I think I may not use it as the original seems just fine.

Conventional wisdom says put the new one in. I would, even though the old one seems to be fine. When I took mine out, it was like new still and since I didn't have a new one on hand, I just put it back in...But if I had had a new one....?