1150 GS Clutch Gone

[joluken]

So...I knew something was up. Clutch started making a strange rattling sound about a week ago. Then I noticed the clutch lever getting kind of mushy after the engine warmed up a bit. So...I did a clutch fluid replacement by the book. Speed Bleeder. DOT 4. Bled it til it ran clear. Today on my way back from lunch the clutch went mushy all the way and I limped it home with no clutch. No clutch adds a new dimension to riding. Before the bleed the fluid in the master cylinder was laced with a strange floating black aura. However, after the bleed, the level of the new fluid has held constant. So...how do I know where the problem lies? Master cylinder? Slave cylinder? Clutch itself? There are only 5200 miles on this bike!!!

 

[PGlaves]

So...I knew something was up. Clutch started making a strange rattling sound about a week ago. Then I noticed the clutch lever getting kind of mushy after the engine warmed up a bit. So...I did a clutch fluid replacement by the book. Speed Bleeder. DOT 4. Bled it til it ran clear. Today on my way back from lunch the clutch went mushy all the way and I limped it home with no clutch. No clutch adds a new dimension to riding. Before the bleed the fluid in the master cylinder was laced with a strange floating black aura. However, after the bleed, the level of the new fluid has held constant. So...how do I know where the problem lies? Master cylinder? Slave cylinder? Clutch itself? There are only 5200 miles on this bike!!!

The clutch itself may be fine if a trashed seal didn't contaminate the surface with clutch fluid.

What I think happened is the throwout bearing failed, causing the slave cylinder piston to spin in the bore. This quickly turns the piston into "undersized", and it probably then failed to seal and collapsed, if that is a good term.

With luck the seal didn't allow enough fluid to escape and foul the clutch. If so, you need a new slave cylinder.

It is also possible the piston on the master cylinder failed - but that is less consistent with the rattling sound which I surmise was the throwout bearing.

I'd start at the slave cylinder. You will need to remove the wheel and shock to access it easily.

 

[joluken]

1150 Clutch gone--further

Thanks Paul,
I read your article in the latest March ON. Your clear treatment of the subject gave me the push to do the bleed. So....if I rip into it and take a peak at the slave cylinder and it looks OK, then I go to the master cylinder? Or do I just replace the master cylinder and keep my fingers crossed. And finally...is the throw-out bearing an integral part of the slave cylinder? When you say "it failed" is this like in a permanent death-like failure or a temporary go and come sense??

 

[PETDOC]

The throw out bearing is embedded in slave cylinder so you will have to replace slave cylinder. You will need not only new slave cylinder , but 4 washers for the 2 bolts which hold slave to transmission and allow fluid to pass through. Additionally it is wise, but not essential, to replace little cotton plug on posterior end of push rod which travels from top of bearing in slave cylinder through a hollow shaft in the transmission to the clutch diaphram spring. This however necessitates removing the rod; I'm not sure you can do that using the quick and easy method of slave cylinder replacement.

 

[colt03]

The Slave cylinder went on my my 04 GS, It was under warranty and they changed the fluid from Dot4 to Mineral oil. No problems since, BTW it happened around 20K.

HTH

 

[PGlaves]

Thanks Paul,
I read your article in the latest March ON. Your clear treatment of the subject gave me the push to do the bleed. So....if I rip into it and take a peak at the slave cylinder and it looks OK, then I go to the master cylinder? Or do I just replace the master cylinder and keep my fingers crossed. And finally...is the throw-out bearing an integral part of the slave cylinder? When you say "it failed" is this like in a permanent death-like failure or a temporary go and come sense??

In this case - a throwout bearing failure would mean it ground itself into smaller metal bits, then caused the piston to spin. It is part of the complete slave cylinder assembly so replacing the slave cylinder would replace that bearing assembly.

Given that it rattled a bit I would start at the slave cylinder rather than the master cylinder. It is most likely that the problem is at the bottom - not the top - and back of the transmission, not forward of the transmission unless it puked fluid all over the clutch disk. The sooner you loosen the bolts and get it out the better off you are.

 

[PETDOC]

The Slave cylinder went on my my 04 GS, It was under warranty and they changed the fluid from Dot4 to Mineral oil. No problems since, BTW it happened around 20K.

HTH

I have an '04 1150 GS and it went out around 31,000 miles. I replaced it myself and used DOT 4; now at 41,000 miles and no problems.
I've never heard of a BMW shop replacing DOT 4 with mineral oil in the clutch of an 1150--has anyone else seen this done? I'd love to decrease the amount of DOT 4 I have to use in the bike.

 

[PGlaves]

I have an '04 1150 GS and it went out around 31,000 miles. I replaced it myself and used DOT 4; now at 41,000 miles and no problems.
I've never heard of a BMW shop replacing DOT 4 with mineral oil in the clutch of an 1150--has anyone else seen this done? I'd love to decrease the amount of DOT 4 I have to use in the bike.

Don't even think about it!!!!! There are TWO DIFFERENT setups for clutch fluid. Originally they used DOT 4. They experienced some failures where, when a slave cylinder failed and leaked, the DOT 4 also ruined the transmission input shaft seal because the seal composed of material to retain oil was not compatible with DOT 4 fluid. Look on the lid of the master cylinder for which your bike has. I don't remember the model year of the switch.

Later models were switched to mineral oil. BUT - the components are not interchangeable. Rubber seals designed to retain DOT 4 fluid will fail in mineral oil and seals designed to retain mineral oil will fail in DOT 4. The chemistry is too different - or so I was emphatically told by a materials chemist.

If a dealership tech unknowingly simply switched a DOT 4 system to mineral oil by just adding mineral oil that bike will experience problems unless BMW did something very tricky with seals that nobody knows about. My opinion - Stick with what the bike started with.

 

[JimMoore]

The black goo in the master cylinder is a classic symptom af a slave cylinder failure. I'm told you have to remove the swingarm on the GS t get at it. Bleah. Maybe you copuld cut down one of your tools or something like that.

 

[joluken]

Indeed! Slave cylinder. New mystery..

Thank you for all the input. I attacked the problem on Sunday and indeed the slave cylinder was a mess of goo. Looked just like all the other pictures on the web. Pulled it out and cleaned out the hole. Seal to the tranny looks fine. Now my next question is this: Is there supposed to be felt bushing (AKA felt ring) in that hole? I found none. I did find a small washer on the back of the slave cylinder. Did the felt ring disintegrate or is it inside the tranny. I can't tell from the BMW parts fiche.

 

[PETDOC]

Felt bushing on my '04 1150 GS push rod was wrapped around the posterior end of rod. The reason I saw it was because I removed the entire rod. The felt bushing fits in a grove on the push rod and with a new one in place it is slightly difficult to insert the rod. The felt bushing is not compressed and does not easily fit up the small shaft through the transmission. I had my transmission off when I replaced the slave cylinder; hence, reason in my original post I could not tell you if you can remove the push rod when using the easier approach to changing the slave cylinder.

 

[sarelp]

Master cylinder ??? 1150GS

On the last leg of our 3500 mile trip, I noticed yesterday about 150 miles from home that I have to pull the clutch lever in all the way before it will disengage. Some times I had to pump it a few times or I wont have any cltuch at all. It almost acts as if there is air in the system. There are no noises or rattles or any other issues with the bike. The fluid looks clean and the level stayed constant. I suspect it to be the master cylinder. I dont see a repair kit for the master cylinder on the parts fiche. I would appreciate any help. BTW I made it home and it is an 01 1150GS with 27K miles on it.