Clutch Slave Cylinder Gone Bad

[STICKMAN]

The other day I was out riding my 1150RT and all of a sudden the clutch slave went bad and would not hold pressure, thus making the clutch useless. I have talked to few people plus motor officers that have ridden 1150RTs and they all have had failures of the slave cylinders at one time or another. I would like to know your experiences with this problem plus has BMW ever had a recall for this problem, especially since it is a major safety issue.

 

 

Thanks for your responses in advance.

[T__]

___Click on link below__

 

Clutch slave Cylinder Search on this Site

[Ken H.]

BMW has never had a recall on this problem.

 

While not unknown, general conversations on the various forums would not lead one to believe the problem is widespread.

 

LEO duty is probably by nature harder on clutch parts.

[LDHack]

Had the clutch master get weak at 80k, and just replaced it. Slave clutch cylinder is fine. Clutch disk is well within specs. Transmission input spline good at first lube at 93k, but had an input shaft seal weak which was replaced.

 

IMO, clutch cylinder wear depends on the kind of riding you do (city or highway), how much the clutch is used (lots of stop/start vs highway riding), and probably a little luck. Surprising yours went out all of a sudden. My master cylinder was showing signs of weakness all last summer.

 

I've always been one to leave the clutch disengaged at stop lights, transmission in neutral, and then shift into gear as the light turns green. Maybe that is good to reduce wear, maybe not... Just a very old habit.

[twins4life]

IMO it is a chronic problem. The design of the slave cylinder uses a spring to keep the piston in contact with the spinning pushrod. Thus keeping a 100% duty cycle on the release bearing. Failures are common. Ask any parts person. When I ordered my new slave cylinder (bearing failed at 27,000 miles) he just sort of laughed and said "we sell a lot of them". The mechanic at the BMW shop told me that there was a recall on some 2007 model for the clutch slave problems.

 

The way it is designed is like resting your foot on the clutch pedal in your cage. Would you do that? How long would the throwout bearing last?

 

See my point? Plain and simple the bearing needs to be dramatically improved, or you better learn to like replacing it.

 

I am so disgusted with the design and the idiotic amount of work to replace the slave, I have my 2002 for sale and will replace it with a older cable type of clutch release. I have never had a cable failure as I lube the "barrels" several times a year.

 

I love my 1150 but cutting the bike in half simply to remove a cross bolt (that could been engineered to exit the right side easily) is not something I want a long term relationship with.

 

I just dont see how the slave release bearing can last even though I have read of people with some decent mileage on it.

 

A common failure mode seems to be the bearing begins to fail, the fluid gets overheated. This explains the brown gunky fluid many talk about when they change the fluid. Then either the bearing fails rapidly (like mine) or fails slowly continuing to run hot until the seal fails and fluid wicks down the push rod destroying the clutch, as there is no weep hole or drain for escaping fluid.

 

I'm sure I'll get hammered for this post, so some one PELASE tell me where I am wrong, I really like the 1150 but cant deal with the 20,000 mile service including a slave cylinder replacement. (exaggerating? perhaps but anyone who has done this job will probably agree it is a ridiculous amount of labor involved)

 

Ok, I have my helmet and riding gear on and am ready for incoming rocks...

[Ken H.]

so some one PELASE tell me where I am wrong,

Well you're sure making a lot of unsubstantiated allegations, that much is for sure. Where is your MTBF data to support, "...it is a chronic problem."?

 

Nobody post to Internet forums about the problems they don't have. I've seen 100s and 100s of R1150s from model years 2002 - 2005 with no slave issues.

will replace it with a older cable type of clutch release.

Uh, yeah, sure, good luck with that. It's a totally different transmission housing, swing arm, and everything else from the engine rearward. And the cable clutch 1100 tranny doesn't fit an 1150 either.

(exaggerating? perhaps

Agreed on that one.

but anyone who has done this job will probably agree it is a ridiculous amount of labor involved)

I've done several clutch slave cylinder replacements and I can do it in an hour and a half. YMMV.

[twins4life]

so some one PELASE tell me where I am wrong,

Well you're sure making a lot of unsubstantiated allegations, that much is for sure. Where is your MTBF data to support, "...it is a chronic problem."?

 

Nobody post to Internet forums about the problems they don't have. I've seen 100s and 100s of R1150s from model years 2002 - 2005 with no slave issues.

will replace it with a older cable type of clutch release.

Uh, yeah, sure, good luck with that. It's a totally different transmission housing, swing arm, and everything else from the engine rearward. And the cable clutch 1100 tranny doesn't fit an 1150 either.

(exaggerating? perhaps

Agreed on that one.

but anyone who has done this job will probably agree it is a ridiculous amount of labor involved)

I've done several clutch slave cylinder replacements and I can do it in an hour and a half. YMMV.

 

I followed the instructions to the letter. If you can get it done in 1.5 hours, you need to sell a video. How did you get so good at replacing slave cylinders? Sounds like you have practice, this was my first one. Splitting the frame seems drastic for a simple parts swap.

 

I'll leave the chronic problem statement stand.

 

The remark about switching it to a cable system was wishful thinking not a request for part numbers.

 

If you read my post you will see you didnt quote all of my statement. "IMO" = "In My Opinion" it is a chronic problem. This comes after talking to two parts departments and asking if they sell many slave cylinders. Both said "yes", one parts guy even laughed and said "yea, we sell a bunch". The mechanic I talked to said they replace a lot of them. My release bearing failed at 27k miles, the hydraulic part was ok, the bearing was shot. IMO due to the fact the bearing is loaded 100% of the time by the internal spring in the slave cylinder

[twins4life]

Never mind me, I was just grumbling at the prospect that this is going to be a recurring problem.

 

I sincerely hope I am wrong as I LOVE the 1150, 6 speed and the handling. And if the job can be done in 1.5 hours, that is a lot easier to deal with. And hopefully BMW will improve the slave cylinder over time.

[Boffin]

Why are you splitting the frame to swap out a clutch slave cylinder? All you need to do is remove the three bolts that hold it in then wiggle it out of there. It is snug but it fits.

 

I have only pulled mine once to give it a visual inspection, but the job took under two hours. It is a snap.

 

Andy

[T__]

George, there have been some reported clutch slave failures on the juice clutch BMW oil heads.. I can’t say as I have ever seen any data that points to one thing over another as far as failure mode goes..

 

I have personally been involved in helping (removing–the-slave) with 3 RT slave failures.. 2 on 02 RT’s & one on an 03 RT (none on my own bikes though).. Of the (3) I have been involved with NONE had bearing failures but all 3 did have the dark skanky fluid remnants in the system (what was left of the fluid anyhow).. On two of bikes involved they were bought used with no history of the clutch fluid ever being changed.. The third bike was purchased new by the owner & the clutch fluid was replaced once in 3 years time period..

 

I’m not sure I can agree with you on the failure mode being that the throw out bearing is spinning all the time.. An awful lot of newer cars trucks with hydraulic clutches do the very same thing without any problems.. It’s difficult to have much retraction with a hydraulic set up & still keep the take up movement short.. You either want continuous contact or complete retraction as just partial retraction leads to very early wear of the contact parts..

 

BTW BMW isn’t the only bike with a history of slave cylinder failures.. Ducati has a very high incidence of slave cylinder failure.. The only difference is not many complaints on the Ducati’s as it only takes a few minutes to change the slave out.. Ducati does have a lot of throw out bearing failures also but that throw out bearing is on the opposite end of the clutch push rod from the slave cylinder & sees a lot of clutch pack heat..

 

As far a replacement of the BMW slave goes I agree with Boffin & Ken H. It really isn’t rocket science & the bike DOES NOT HAVE TO COME APART.. I’ll bet you local dealer technician can change it out including bleeding the system in less than an hour..

It does take some ingenuity to get to all the slave cylinder bolts (a ball ended allen on socket set up with a long extension seems to work pretty good).. I find it MUCH easier to do the work with the bike up on my bike lift table (but I’m old & hate to bend down anymore)..

 

I realize the manual says to remove the rear of the bike but it also states you need special tools to do a tune up & not to do the brake bleed yourself without special tools..

 

The manual is pretty good EXPERIENCE is much better..

 

 

Twisty

[twins4life]

Twisty, the tech said he split the frame as well per procedure. He agreed that the cross bolt necessitated this. I'm going to have to disagree with you on your statement that slippage between the release bearing and release fork would cause wear. The engine is a vibrating mass and when the clutch is engaged the vibration will push the release fork away from the bearing, it only has to move a very tiny amount to let the bearing unload. This is the same process as disc brakes where the brake pads are not in forceful contact with the brake rotors when the brakes are released. I know this is an apples to oranges comparison but it shows the principal that once you take the pressure off, hydraulic systems can relax. Imagine a spring inside the brake calipers holding the pads in contact with the rotors. That is just about what is happening on the BMW slaves. I've got an email off to a mechanic friend, he works for a Dodge dealership about (some) newer vehicles having permanently loaded release bearings and what the bearing / system looks like. I've never heard of that being done.

 

Andy, I wiggled the slave out before splitting the frame but couldn't get enough rotation to get at the banjos that held the lines on. Did you remove the line from the MS and pull down some slack? I'd like to know how you got away with not splitting the frame.

 

My conversations with parts people have returned the same as the opening post. This part fails frequently. Just like the pivot bearings in the FD. As one mechanic said, he has never seen a good pivot bearing when doing a FD bearing replacement. I have replaced two final drive bearings ($50/easy job) myself and replaced the pivot bearings on the 97 1100R with bushings.

[Ken H.]

Well it's clear this is just going to be tossed back and forth over the fence, so I'm just going to make one more post on this then quit:

 

1) Technicians that blindly follow procedures rather than common sense are lousy technicians.

 

2) The bearing in the slave cylinder most definitely does not spin at engine speed all the time. When the clutch lever is released, the clutch engaged, pressure on the push rod is released and the push rod can coast. There may be some residual drag that caused some occasional rotation, but it is not a full speed. The only time I have seen continuous full speed rotation is the rare case when the push rod became stuck in the center hole of the diaphragm spring.

 

3) When removing the slave, disconnect the lines first.

 

4) Still waiting to see the MTBF data...

[T__]

Twisty, the tech said he split the frame as well per procedure. He agreed that the cross bolt necessitated this. I'm going to have to disagree with you on your statement that slippage between the release bearing and release fork would cause wear. The engine is a vibrating mass and when the clutch is engaged the vibration will push the release fork away from the bearing, it only has to move a very tiny amount to let the bearing unload. This is the same process as disc brakes where the brake pads are not in forceful contact with the brake rotors when the brakes are released. I know this is an apples to oranges comparison but it shows the principal that once you take the pressure off, hydraulic systems can relax. Imagine a spring inside the brake calipers holding the pads in contact with the rotors. That is just about what is happening on the BMW slaves. I've got an email off to a mechanic friend, he works for a Dodge dealership about (some) newer vehicles having permanently loaded release bearings and what the bearing / system looks like. I've never heard of that being done.

 

Andy, I wiggled the slave out before splitting the frame but couldn't get enough rotation to get at the banjos that held the lines on. Did you remove the line from the MS and pull down some slack? I'd like to know how you got away with not splitting the frame.

 

My conversations with parts people have returned the same as the opening post. This part fails frequently. Just like the pivot bearings in the FD. As one mechanic said, he has never seen a good pivot bearing when doing a FD bearing replacement. I have replaced two final drive bearings ($50/easy job) myself and replaced the pivot bearings on the 97 1100R with bushings.

 

George, not many release forks anymore on most front wheel ( & even a lot of rear wheel) drive vehicles with juice clutches.. Most use a combo hydraulic cylinder/release bearing as one assembly.. Some of our original vehicles that used a hydraulic clutch did allow some back off of the release bearing but that caused excessive clutch pressure plate finger wear & grooving of the throw-out bearing surface (as well as a clutch rattle).. Disk brakes are a different matter as they MUST retract slightly to prevent heat build up, wear, & drag.. That is accomplished on the disk brake with very exact engineering of the caliper piston seal(s) to have a slight amount of memory to retract the piston slightly while at rest.. Also as the brakes get some heating & cooling during use the rotor warps slightly causing additional pad kick back.. Unfortunately on a clutch throw-out system you either need to retract it a lot or not at all.. If just a little retraction the bearing will keep hitting as the crank works on it’s endplay & clutch/flywheel vibration.. I’m not saying ALL vehicles with hydraulic clutches allow constant bearing contact but most do on the vehicles of the company I work for.. Both my Ducati & Honda have constant contact release bearings..

 

Twisty

[twins4life]

How do you make the claim the release bearing doesnt spin 100% of the time?

 

When you put the slave back on, first you have to compress the internal spring. There is NO WAY this bearing can retract. When the pushrod retracts, the internal spring will force the piston forward.

 

MS= Master Cylinder.

 

Do you REALLY think that all problems are documented by the government?

[twins4life]

Twisty, the tech said he split the frame as well per procedure. He agreed that the cross bolt necessitated this. I'm going to have to disagree with you on your statement that slippage between the release bearing and release fork would cause wear. The engine is a vibrating mass and when the clutch is engaged the vibration will push the release fork away from the bearing, it only has to move a very tiny amount to let the bearing unload. This is the same process as disc brakes where the brake pads are not in forceful contact with the brake rotors when the brakes are released. I know this is an apples to oranges comparison but it shows the principal that once you take the pressure off, hydraulic systems can relax. Imagine a spring inside the brake calipers holding the pads in contact with the rotors. That is just about what is happening on the BMW slaves. I've got an email off to a mechanic friend, he works for a Dodge dealership about (some) newer vehicles having permanently loaded release bearings and what the bearing / system looks like. I've never heard of that being done.

 

Andy, I wiggled the slave out before splitting the frame but couldn't get enough rotation to get at the banjos that held the lines on. Did you remove the line from the MS and pull down some slack? I'd like to know how you got away with not splitting the frame.

 

My conversations with parts people have returned the same as the opening post. This part fails frequently. Just like the pivot bearings in the FD. As one mechanic said, he has never seen a good pivot bearing when doing a FD bearing replacement. I have replaced two final drive bearings ($50/easy job) myself and replaced the pivot bearings on the 97 1100R with bushings.

 

George, not many release forks anymore on most front wheel ( & even a lot of rear wheel) drive vehicles with juice clutches.. Most use a combo hydraulic cylinder/release bearing as one assembly.. Some of our original vehicles that used a hydraulic clutch did allow some back off of the release bearing but that caused excessive clutch pressure plate finger wear & grooving of the throw-out bearing surface (as well as a clutch rattle).. Disk brakes are a different matter as they MUST retract slightly to prevent heat build up, wear, & drag.. That is accomplished on the disk brake with very exact engineering of the caliper piston seal(s) to have a slight amount of memory to retract the piston slightly while at rest.. Also as the brakes get some heating & cooling during use the rotor warps slightly causing additional pad kick back.. Unfortunately on a clutch throw-out system you either need to retract it a lot or not at all.. If just a little retraction the bearing will keep hitting as the crank works on it’s endplay & clutch/flywheel vibration.. I’m not saying ALL vehicles with hydraulic clutches allow constant bearing contact but most do on the vehicles of the company I work for.. Both my Ducati & Honda have constant contact release bearings..

 

Twisty

 

Very interesting, you sound like a engineer. Good points but it is interesting that both of my vehicles have release forks and hydraulic release systems. All I have ever seen is a slight polishing where the release bearing contacts the fork and where the diaphragm spring fingers touch the bearing. The constant contact clutches you refer to, are they operated by a push rod through the gearbox like the R bikes? I would like to know how they work.

 

I'm still interested in how you removed the slave with the cross bolt in place. Were you able to just rotate the slave or did you get some extra slack in the MS line?

 

I worked for 30 minutes and couldn't get enough rotation to get at both banjos.

[twins4life]

FWIW to those interested in the principal of operation of the clutch on the R bikes:

http://www.tpub.com/basae/90.htm

 

The only real difference is the R bike has no release fork but has a pushrod through a hollow shaft in the transmission. And the release bearing is inside the clutch slave and spring loaded, for reasons unknown. The slave cylinder/release bearing is located on the rear of the transmission.

 

What is interesting in the diagram is the fork return spring, something I have never seen in a production vehicle.

[Stan Walker]

4) Still waiting to see the MTBF data...

 

Here's one data point. I've got 95,000 miles on my original slave cylinder on my '02 RT. It will get another 44 miles today riding to work and back.

 

I did re-lube the throwout bearing at 70,000 miles when I did a spline lube.

 

I did buy a slave cylinder just in case, so I count in that column It's still siting in my spare parts box.

 

For the record, I stay in gear at stop lights with the clutch pulled all the way to the bar.

 

Stan

[twins4life]

Thats good news.

 

My MTBF is <27k miles.

 

How did you relube the release bearing?

[Stan Walker]

How did you relube the release bearing?

 

With a grease gun and a cone shaped tip. Same one I use to grease my side stand. Probably didn't have the best grease in it for the job but better than nothing.

 

Stan

[twins4life]

Really? Thats good info to file away. My bearing was so chewed up I couldnt even prove there ever was a bearing there.

 

Thanks!

[T__]

FWIW to those interested in the principal of operation of the clutch on the R bikes:

http://www.tpub.com/basae/90.htm

 

The only real difference is the R bike has no release fork but has a pushrod through a hollow shaft in the transmission. And the release bearing is inside the clutch slave and spring loaded, for reasons unknown. The slave cylinder/release bearing is located on the rear of the transmission.

 

What is interesting in the diagram is the fork return spring, something I have never seen in a production vehicle.

 

George, a lot (most) older solid rod clutch linkage (especially using an equalizer bell crank between the engine & frame) used a return tension spring of some sort.. Without that spring the rods would tend to fall out of their pivot holes & the clutch linkage would rattle like crazy.. Still a lot of modern cable & hydraulic clutches use a return or return tensioning spring on the pedal itself..

 

As far as using a clutch fork & sliding release bearing.. That era is coming to an end very quickly most front wheel drive American vehicles either use now or are going to use a combination slave cylinder/release bearing (as pictured).. Due to limited space between the transmission & flywheel,, dual mass flywheels,, tighter packaging area the internal (inside the bell housing) slave cylinder is in wide usage today & pretty well speced out for the future..

 

See that spring on the slave cylinder? What do you think that does for constant bearing to clutch PP finger contact?

 

 

 

 

 

 

Twisty

[T__]

 

Very interesting, you sound like a engineer. Good points but it is interesting that both of my vehicles have release forks and hydraulic release systems. All I have ever seen is a slight polishing where the release bearing contacts the fork and where the diaphragm spring fingers touch the bearing. The constant contact clutches you refer to, are they operated by a push rod through the gearbox like the R bikes? I would like to know how they work.

 

I'm still interested in how you removed the slave with the cross bolt in place. Were you able to just rotate the slave or did you get some extra slack in the MS line?

 

I worked for 30 minutes and couldn't get enough rotation to get at both banjos.

 

 

George, you can work around that cross shaft.. I usually pull the cylinder out with the lines still attached then remove them with the slave pulled out a ways..

 

I have a very difficult time believing that a BMW tec would pull the rear of the bike apart to remove a slave cylinder.. They might TELL YOU THAT as the flat rate pays more to remove that stuff but I'll bet if you actually watched them they would pull that cylinder without removing the rear of the bike.. If the tec does pull the bike part he/she is not the brightest tool in the shop that is for sure..

 

Twisty

[twins4life]

Question 1: 100% contact. What is that out of?

Question 2: I never thought of that being a trusting sort of person, I just took his word, but I have seen what you said in shops in other cases. He definately said you "had to" remove the cross shaft and he probably had to say that "officially".

 

Well, I feel better about the design now, especially hearing a few more success stories.

 

I was getting pretty gloomy before. And the procedure I followed was from here, but I looked at the title again and it was for a spline relube, the note just said where to stop if replacing the slave only.

 

With just a tiny bit of additional slack in the MS line, I could have got it out over the cross shaft.

[T__]

Question 1: 100% contact. What is that out of?

Question 2: I never thought of that being a trusting sort of person, I just took his word, but I have seen what you said in shops in other cases. He definately said you "had to" remove the cross shaft and he probably had to say that "officially".

 

Well, I feel better about the design now, especially hearing a few more success stories.

 

I was getting pretty gloomy before. And the procedure I followed was from here, but I looked at the title again and it was for a spline relube, the note just said where to stop if replacing the slave only.

 

With just a tiny bit of additional slack in the MS line, I could have got it out over the cross shaft.

 

 

(1) _George, not exactly sure as they all look about the same but would guess an 07 or 08 Corvette.. Most GM front wheel drives use a very similar with a lot of the late model RWD going that way also.. I have difficult time keeping up with current production as I work advanced engineering so current production is usually 3-5 years old to me by the time the public sees it..

 

(2)_ Yes, if you hold your mouth just right it will come out without a lot of cussing or pulling the bike apart.. Ask your tec about bleeding the late model servo brakes & I’ll bet he will tell you it must be done using his special equipment (we know that isn’t so either)..

 

A lot of dealers try to intimidate customers into thinking they NEED top have their bikes serviced at the dealer or the world will end.. Some of that is just trying to intimidate,, some is to try & force expensive service,, & some is probably just vanity.. And if you think BMW is bad for this just try to ask a Ducati dealer about engine service.. First words out of their mouth is you MUST bring it in for service or you will ruin it for ever.. Everything from you aren’t qualified to,, you aren’t smart enough,, to you need special tools,, to you need to be factory trained in Italy.. It probably isn’t for everybody but if you are mechanically inclined,, can read & comprehend,, have a decent tool kit,, & can adapt you can easily service them yourself.. It’s all in how it’s presented..

 

You want to try something difficult? Try to talk someone through tying a shoe lace over the phone that has never seen a lace type shoe before (now there is challenge)..

 

Twisty

[twins4life]

Thanks for the information, I feel better about the design now.

[twins4life]

Update: New slave cylinder installed today, very easy. I removed the left side trim and foot peg plate, cut all the zip ties on the brake line. Removed 4 bolts from the left handle bar, this gave plenty of slack to wiggle the slave cylinder out.

 

The removed slave cylinder was about 1 month old and I was shocked at how little lubricant was there. Two other people looked at it and were amazed at the dry appearance of the balls and bearing cage. This would have been one of them that lasted 6k miles I would suspect.

 

Got the new slave cylinder packed with synthetic coupling grease and installed. Tomorrow afternoon a careful air purge and function test.

 

Then all the tupperware goes to the painter.

 

The picture shows a new bearing and credit for the excellent shot goes to GSaddict on the MOA.