Pelican Parts Forums - Can we compile definitive clutch slave cylinder fix thread?

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Can we compile definitive clutch slave cylinder fix thread?

I'm hoping by starting this thread that those who've had the dreaded clutch slave cylinder failure can share their experience by linking to past posts, sharing photos taken, and detailing solutions, both tried-and-failed and tried-and-true. I myself have recently had a slave cylinder failure. My first indication was not a performance shortfall of the clutch (which others have had -- see http://forums.pelicanparts.com/showthread.php?t=291411), but upon changing the fluid, I noted the distinctive smell of 90W gear oil. While I only have a little over 7000 miles on my second-hand '03 (manf. in 09/02) BCR, the bike has been unridden for long periods of time. I am not sure at this point if that is a contributing factor or not.

Another symptom is that upon emptying the clutch reservoir I discovered rust colored sediment at the bottom. Unfortunately, I only have a shot after I emptied it due to camera/computer issues. Because this sediment was heavier than the DOT 4, it sunk to the bottom so when I first took off the cover, everything appeared to be fine. That is, it looked honey colored although I was admittedly operating in low light. Actually on second thought, the fluid that I bled off initially from the bleed valve (by the rear shock) was pinkish in color so I should've realized at that point something wasn't quite right. I admittedly lack a lot of experience in twisting wrenches on a boxer, but I try to make up for that by not being afraid to try. Anyway, here's the shot of the sediment.
http://forums.pelicanparts.com/uploa...1222908005.jpg

When you see something suspicious like this, the next step is to trace it to its source. In this case, that's the slave cylinder which is located underneath the air box, in front of the swing arm / shock. Fortunately, you do not have to unbolt the rear subframe as the service manual indicates. You *only* have to remove the rear wheel and remove the rear shock. Be sure to support the Paralever. With the removal of three allen bolts, the slave cylinder comes out by tiltling it up at the rear to clear the "cross beam." See page two of "jweicht's" thread http://forums.pelicanparts.com/showthread.php?t=291411 for pics or below for how mine looked (not good).

Another thread that I found interesting was this one where a couple folks talk about drilling a weep hole. I don't quite know where specifically that weep hole should go or what specific symptoms indicate it is necessary. Don't bother reading to the end btw ... no conclusion to the original problem other than "it went away."
http://forums.pelicanparts.com/showthread.php?t=429196

More below and for those of you with more experience in this forum and/or with this problem specifically, can you please offer additional links and/or advice?

Quote:

Originally Posted by j_hurricane_y (Post 4213565)

For those of you with more experience in this forum and/or with the problem, can you please offer additional links and/or advice?

Sure: take the picture BEFORE you remove all the fluid.

My 02 came with Honey flavored fluid that I change every year... You got the model with the butterscotch fluid. :)

That color could be from moisture. Only way to tell anything is to pull the slave and inspect.

I detailed in the other thread that I was not able download my pics off my camera; therefore the pic I posted was taken with a different camera and is as you noted, after the fact. It still shows that the fluid is discolored. Furthermore, with the reservoir full, the discoloration was not apparent so not much point in posting that pic even if I had it. I have to say Anton, that for a thread that was created with the intent of helping others out, your reply was definitely contrary.

Bill, the reservoir and removed fluid (not yet thrown away) definitely smells like gear oil so I think it is more than just a little moisture affecting the color. As you point out, the only way to know is to pull the slave cylinder which I plan on doing tonight.

I don't plan on detailing my findings further unless I discover something new. My point in creating the thread was for others to detail their experiences so that all the info is consolidated on one thread. Maybe that was a misguided effort and this thread will die a quick death.

I didn't mean to be contrary. If you want this discussion to be about creating the definitive slave cylinder thread, you need to give more information for future readers. Pics of good fluid, pics of bad fluid, etc.

Sounds like you're just starting a 'my slave cylinder is bad' thread rather than what you suggest in the title.

Anton, w/o getting into a pissing contest, what you suggest is exactly what I thought I was asking the members of this forum compile. I quote, "For those of you with more experience in this forum and/or with the problem, can you please offer additional links and/or advice?" I'm a first time BMW owner with this BCR and the learning curve has been a bit steep. I don't have the experience to share on my own, but I reckon I'm gaining it in fairly short order. That said, your point is well taken in that I started off the thread detailing my problem and only later in the post suggested it become something more than just about me. I think I will edit it to remove the extraneous details and provide what I've learned so far.

Pics of ugly slave cylinder

Here's what my slave cylinder looked like. The rust colored sediment seen in the reservoir is a clumpy, greasy, clay-like mess in the "housing" (I don't know the proper name) where the cylinder contacts the clutch push rod. I believe it to be very similar to what jweicht's afforementioned post details.

This is the end of the cylinder with the throw out bearing in center (right?). Ugly yes?
http://forums.pelicanparts.com/uploa...1222994409.jpg

Here's an admittedly shoddy pic (hard to get a good shot b/c of its location) of the clutch push rod and housing. It too is full of the rust colored gunk.
http://forums.pelicanparts.com/uploa...1222994615.jpg

I believe the next thing to check is if clutch (DOT4) fluid got in the gear box. I do not have a 14mm allen (I believe that is what it takes) to pull the gearbox drain plug, but I did open the fill plug. In my case, the gearbox was apparently over filled because I got quite a bit of gear oil out. What I did get out was a gloriously golden color and did not appear to be contaminated. I believe if there was clutch fluid in it that it would float on top so I think I have very similar symptoms to jweicht. I will get the proper tool and completely drain it to double check.

Any suggestions on how to clean the push rod housing? A tiny spoon perhaps?

One of the problems is that the seals are not compatible with the 'other' fluids. I think this is why BMW went to mineral oil on the R1200 clutches; it is not incompatible with gear oil.

This is what happens when DOT4 slave cylinder seals are exposed to mineral oil. Gear oil would be similar:

http://www.largiader.com/articles/mineral/

The rear surface of the input shaft (where the rear input seal rides) gets trashed when these seals go. I'll take pictures of a bad one at some point.

Basically, if you get a reservoir full of mud, you have a bad slave cylinder and you might need to replace the rear input seal. Fortunately that can be done without opening the tranny, but if the shaft surface is damaged it's very awkward to smooth that out in place.

Anton,
Wow! What a excellent repository of information you've compiled on your website. Thank you for sharing that! You are the man.

Initially I posted a question here, but figured it out with the service manual. Answer is that yes, it is a dry clutch (automotive style) but DUH!, the gearbox is between it and the slave cylinder. Still, I suppose it is possible for the DOT4 to travel down the clutch push rod to the clutch???

> Still, I suppose it is possible for the DOT4 to travel down the clutch push rod to the clutch???

Yes, it is, unfortunately. Not as rare of an event as one would like on oilheads.
BMW has went back and forth with Felt seals, rubber, and none on the pushrod, so they seem to be struggling with a definitive answer/solution too. And on some of the oilheads, the little seal (only replaceable from the inside - grrrr) on the end of the input shaft goes, and lets gearoil down the pushrod. I think the last R12GS I worked on had that problem. And its pushrod had NO felt bit or anything else to slow/minimize contamination. Very annoying.

Thanks Roger. I got less details but the same basic story from a tech at Bob's BMW; great customer service over the phone btw. Informed me my next step should be to start working my way through the various seals to verify how far the DOT4 got. Sounds like the two week upgrade/repair project I had in mind for my bike has now become a winter long project. Time to start reading up on how to pull the gear box ... good times. http://forums.pelicanparts.com/suppo...s/a_frusty.gif

sorry to hear about your woes...
this thread may be of some help in removing the tranny:
http://forums.pelicanparts.com/showthread.php?threadid=199637&highlight=crash

repoe3

OMG! Why is that not a Sticky?!! Glorious post man. That settles it. I'm tearing her apart; shoot, I'm nearly halfway there already. Might as well yank the gear box and check the splines ... maybe send the shaft off to get it coated as well. I'll have to inquire with Moybin if he's torn it back apart to take a look.

Repoe3, note I too am in the VA-DC area. Want to come over this weekend and help me tear apart a motorcycle? :) I've got a Giant just down the street that I'm certain must stock your favorite beer. I joke ... with your post, I think I'll be good to go!

I can't find the post about drilling a drain hole in the trans. cavity that the slave cylinder goes into. This seems like a good idea, while you are there. Fluid can drain out and let you know before it becomes a bigger problem.

Sorry I can't find the post with photos.

RB

http://forums.pelicanparts.com/showthread.php?t=385554

Page 2 of the thread is the picture of Essings Bike with the weep hole... That bike now belongs to GaryK

Try using "both hands" when looking for things next time RB.... :D

Quote:

Originally Posted by wswartzwel (Post 4217190)

Bill-

Thanks! I think?

I am trying to cut back on my meds. and it is not working so well.

WARNING! Do not drive or operate heavy equipment. Do computers count?

RB

You guys are awesome. Thanks for digging up the link Bill. I've got the rear subframe off now and have drained the 90W to take a look. I'm going to move my step by step progress back over the the "Am I a masochist..." thread and will update this thread with pertinent "lesson's learned." Anyone else who has gone through the failure and repair of the clutch slave cylinder / gear oil in the clutch fluid problem, please post your experience here. Links to past threads are so helpful as the search engine is a bit cumbersome and the volume of posts you get with this topic is fat. I did find this thread with some more details about initial symptoms and a photo of a seemingly good looking slave cylinder (compared to mine) that also had issues; thought it worthy to include here --> http://forums.pelicanparts.com/showthread.php?t=366411

Quote:

Originally Posted by j_hurricane_y (Post 4216969)

OMG! Why is that not a Sticky?!! Glorious post man.

Eventually the truth will be revealed to the inner sanctum. Stickies are for whooses...

Do you think you can simply stroll into the Pelican and turn a page of a book for all to be revealed...

The knowledge you need is here grasshopper....

Yopu have actually attracted the three wise men of the board...

Quote:

Originally Posted by RBMann (Post 4217281)

Bill-
I am trying to cut back on my meds. and it is not working so well.count?

RB

Get out! Get out of the cinema... Can you distinguish reality from celluloid... :)

If not, return to Paonia...

Quote:

Originally Posted by ckcarr (Post 4217812)

Yopu have actually attracted the three wise men of the board...

The average lurker only attracts the resident Wise Asssses.

Quote:

Originally Posted by ckcarr (Post 4217816)

Get out! Get out of the cinema... Can you distinguish reality from celluloid... :)

If not, return to Paonia...

Like, 3 people on this board will get that joke :)

I'm starting to figure out how this forum works ... knowledge is power, right Sen-se? ;) Thanks to the knowledge bestowed upon me, by you the Almighty Wise Men, I was able to get this far tonight:
http://forums.pelicanparts.com/uploa...1223089839.jpg

While I have your attention, however briefly that may be, is this much metal on the tranny mag drain plug normal with 7K in miles?
http://forums.pelicanparts.com/uploa...1223089927.jpg

Yes normal... small bits are OK.... large bits with readable casting numbers on them are not OK. ;)

Nice nails BTW... Manicured??

:D

With all the wrenching I did tonight, I almost forgot to share a couple PM's I got from jweicht who as I mentioned earlier seemed to have similar symptoms to what I experienced. Here's his first reply to my request to share more details of his experience and what he did to fix it:

Quote:

After a few more years and a lot of other similar threads to think about it, I'm convinced the root issue on my bike was only failure of the clutch throw-out bearing. As the bearing was going bad, I believe that it set up enough wobble/vibration in the bearing/slave cylinder/push rod/gearbox seal area that gearbox oil was allowed to seep past the gearbox seal and into the slave cylinder and past its seal, thereby contaminating the clutch fluid with gearbox oil. I don't believe that any DOT 4 fluid escaped from the clutch system, it was all gearbox oil into the DOT 4 fluid. It's probable that gearbox oil was mixed with my clutch fluid for a while but everything still functioned normally. I only knew there was an issue when the throw-out bearing totally failed and I effectively lost the ability to disengage the clutch (exactly like a clutch cable breaking). I believe that the slave cylinder was still functioning properly (for the most part), there was just essentially no bearing to push on the push rod anymore.

As part of the fix for my bike, I was convinced that the rear gearbox seal was shot so I replaced it as well as installing a new slave cylinder/throw-out bearing and flushing the system with fresh DOT 4 fluid. As was stated in the thread you started, I knew that if enough gearbox oil leaked from that seal it could work its way forward through the gear shaft hole (alongside the clutch push rod) and contaminate the clutch (didn't want that, already had to change the clutch on my '94 R1100RS due to a bad "early model" design by BMW). To change the gearbox seal I had to pull the gearbox for adequate access, that's a real joy if you haven't done one yet.

In hindsight and if I had to do it all over again, I would not have changed the gearbox seal at that time. After changing the slave cylinder and flushing the system with DOT 4, I would have just run the bike and pulled the slave cylinder in 500 or 1,000 mile increments for a while to see if the seal was still leaking. In the end, I still think the only reason the seal leaked was due to the bad throw-out bearing and once that was no longer an issue the shaft may have run perfectly concentric again. If indeed the seal was bad and I saw gearbox oil after pulling the new slave cylinder, only then would I have pulled the gearbox and changed the seal.

On your bike, the amount of "liquid rust" present makes me think there was somehow an excess amount of moisture in the area of your slave cylinder. I didn't see anything in your thread about the actual condition of your throw-out bearing, or if had actually totally failed like mine.

I replied with "Thanks so much for your throrough reply! I am debating the gear box pull for the seal install. If I drain the gear box and see no evidence of DOT4 in it, can I safely conclude the mixing of the clutch fluid and gear oil was only one way? ... or is it possible the clutch fluid can travel all the way through the gear box w/o contaminating it, but still contaminate the clutch? I obviously don't have a handle on how it's all configured in there and the service manual doesn't make it clear to me. Re my throw out bearing, again I'm not sure how it's supposed to look. Mine didn't come apart as your did; no ball bearings. However it does flex/pivot; should it be rigid?"

His response:

Quote:

Glad if I was able to help at all. Again I have to say that all of my response was based upon my experience and opinion, as I recognize that there are those who certainly have more experience than me in these areas.

Having said that, I'd say that yes, if you cannot discern any brake fluid in your gearbox oil then the liquid transfer was only one way (just like my experience, only gearbox oil into the clutch system).

On your second question, the answer is again yes, because there really is no direct connection between the two possibilities. By that I mean the gearbox input shaft is hollow and this is where the clutch pushrod resides and where it moves back and forth to disengage the clutch. The outside of the shaft rides in two seals (and bearings, of course), one at the front of the gearbox (just aft of the splined end of the shaft which engages the clutch splines) and one seal at the rear (just forward of the forward end of the clutch slave cylinder/throw-out bearing when installed on the gearbox). If DOT 4 fluid were to leak/escape from the slave cylinder it has two possible places to go: forward past the shaft seal into the gearbox and/or forward through the inside of the hollow shaft toward the clutch. So, even though fluid could go "through the gearbox to the clutch", it would only do so via a hollow shaft (the gearbox input shaft) and be totally isolated from the gearbox internals.

On my S, even with all of the gearbox oil/gunk I found when I pulled the slave cylinder the inside of the hollow shaft was dry (as it's supposed to be). There have definitely been cases where the rear gearbox seal leaked and the oil made its way forward through the shaft and contaminated the clutch, maybe I just caught mine before that happened or instead of going that route it went instead past the slave cylinder and into the clutch fluid because the bad throw-out bearing's gyrations made that the path of least resistance. That is my opinion of what happened to my bike: it all comes back to that bad throw-out bearing being the source of all the problems. Can't say that I ever read/heard of DOT 4 fluid leaking forward to the clutch but that's not to say that it hasn't happened.

As for your throw-out bearing, if there is much "play" at all on the end that engages with the pushrod, the bearing is going bad in my opinion. It is not a demountable ball bearing (not meant to be disassembled), therefore it should freely rotate but not really have play (or flex/pivot) to speak of. If you've already gotten your new slave cylinder you'll be able to compare a new/good bearing with your old one. Per my thread on the forum, I recommend that you liberally grease the balls of that bearing before installing it. My bearing was dry when I took it apart, I'd bet money that's why it failed in the first place and started my bike's chain reaction.

I don't mind you using in the forum any of the info (or my opinions) I've provided, and I'll be glad to help in any way I can.

Gotta love the kind souls out there willing to help a noob like me.

Note that despite what I believe to be good advice from jweicht regarding simply changing the slave cylinder and monitoring periodically, I decided that I had the bike far enough apart already that I might as well do a spline check and lube if necessary per repoe3's Dr. Splinelube thread.

You also should be commended for your inexpensive yet stable and efficient platform.. Way to use your head...

Hope the straps are not tied to the garage door... your wife might hit the button to close the door. :D

...the things you pay attention to, Bill...

glad to see that you are in touch with the finer details of manhood... :D

Bill,
Yes, the nails are the latest thing. Takes going into the garage for a few hours each day for 9 days straight to get that look. It's only for the dedicated. I'm certain you've sported it out and about as well; probably much more often than I. Thanks for noticing. http://forums.pelicanparts.com/suppo...leys/smi65.gif

Yeah, I know I don't have much right to, but for some reason I'm pretty proud of my little platform...mainly for being able to make due with what I had lying around. I only had a ~50" length of 2x4 so I cut it into six 8" long pieces, screwed 'em together, and capped 'em off with particle board from a broken bookcase. Ghetto right? Not quite your custom engine stand mounted to a hydraulic lift, but it should see me through well enough. And no, the straps are not attached to the door. They are hooked through the brackets attached to the ceiling. I obviously try not to load them too much.

I have a shop manual around here somewhere, and near the front of the book, one of the hand models has a blackened thumb nail from hitting it with a hammer... Near the end of the book, the nail has let go and is missing. :)

Next time I bloody a knuckle, I'll get a shot for you. :)

Tuition is never cheap if you want a good education.... ;)

I popped awake this morning dreaming of blown slave cylinders and dry spline shafts ... er, that didn't come out right. :eek: I got an early start and was able to get my gearbox off. Here's a couple shots that fill in the gaps in the process detailed by repoe3:
Airbox off (note I didn't find it necessary to disconnect the fuel lines from the tank, but may do so to make more room for reassembly).
http://forums.pelicanparts.com/uploa...1223139747.jpg

Here's a shot with the starter off.
http://forums.pelicanparts.com/uploa...1223139813.jpg

And here's just after the magic moment when the gear box was freed. Came off pretty easily actually; I'm sure it helps to only have 7K miles. Note I used a floor jack to support the weight of the gear box to keep things aligned as they came apart.
http://forums.pelicanparts.com/uploa...1223140026.jpg

Fortunately the interior (input side) shaft seal looks nearly new. The felt is not stained by clutch/90W goo. The felt "seal" on the clutch rod seems to have done it's job, but it is saturated and was probably only a matter of time before it let the goo past. Here's a shot.
http://forums.pelicanparts.com/uploa...1223140251.jpg

Last pic I have is of the throw out bearing in the center of the slave cylinder. You can see that the bearing race (I think that's what it is) is loose. When I get a new one, I will compare the two and post an update.
http://forums.pelicanparts.com/uploa...1223140429.jpg

BTW, the splines on the input shaft look great. There's a Honda shop nearby so I got down there this morning to pick up their Moly 60 paste which I'll apply before assembly.

Back to the goo, I'm definitely going to change the "input shaft sealing ring at output end" (service manual language). Question, are the Bimmer tools the only way to go? Perhaps I'll take the entire gear box to Bob's and have 'em do it ... but I've done the rest of the job by myself so seems like wuss'n out to involve someone else now. Hmm ... maybe I can borrow a slide hammer from work ....

PS. Found this thread on an alternative method to getting to the gearbox/clutch. Looks trick.
http://forums.pelicanparts.com/showthread.php?t=401556

Quote:

Originally Posted by j

PS. Found this thread on an alternative method to getting to the gearbox/clutch. Looks trick.
[url

http://forums.pelicanparts.com/showthread.php?t=401556[/url]

That was mine. Having done three now I will give you my 3 cents worth. You can only hinge up the sub-frame on non-ABS models. Advantage- the wire harness stays in place, no need to remember routing and where the zip ties go, and the bolts line up for reassembly much easier. Disadvantage- the headers need to be loosened to allow the frame to swing up.

If you have goo in the trans. chamber where the slave goes then replace the slave cylinder, trans. shaft seal and the push rod felt. It does not matter weather the goo is trans. fluid, clutch fluid or water, you need to replace all the pieces. Trans. fluid ruins the slave seal and clutch fluid ruins the shaft seal.

And now my pet issue with this problem. Since the clutch fluid is under pressure, when you pull the clutch lever, and the trans. fluid is not, except thermal expansion, I do not see how trans. fluid can make its way to the master cylinder.

A link for seal replacement-

http://forums.pelicanparts.com/showthread.php?threadid=336607

The cheap work stand with 1" bore holes in the leg ends for straps. I bought a small baking sheet that will fit between the legs and catch debris.

Good luck, RB

http://forums.pelicanparts.com/uploa...1223145578.jpg

http://forums.pelicanparts.com/uploa...1223145608.jpg

You 'da "Mann" RB. :)

Quote:

If you have goo in the trans. chamber where the slave goes then replace the slave cylinder, trans. shaft seal and the push rod felt. It does not matter weather the goo is trans. fluid, clutch fluid or water, you need to replace all the pieces.

Exactly my plan; happy to have confirmation my t'inking is correct.

Quote:

Since the clutch fluid is under pressure, when you pull the clutch lever, and the trans. fluid is not, except thermal expansion, I do not see how trans. fluid can make its way to the master cylinder.

Indeed! I clearly have nothing more to offer in way of explaination, but inquiring minds want to know!

Your stand is mo' better than mine; mine could defintely use some bigger feet for stability. Will have to swing by Ho' Depot at some point.

Thanks greatly for the seal install link. That's exactly what I've been searching for and the next step in making this thread comprehensive. I love this forum.

Quote:

Originally Posted by j_hurricane_y (Post 4218587)

Last pic I have is of the throw out bearing in the center of the slave cylinder. You can see that the bearing race (I think that's what it is) is loose. When I get a new one, I will compare the two and post an update.
http://forums.pelicanparts.com/uploa...1223140429.jpg

Well jy, since you got my curiosity up during our PM exchanges, I decided to follow the thread you created here. From that picture of the business end of your throw-out bearing, let me assure you that your bearing is garbage. The inner race should not be cocked/loose like that.

And for all the familiar names I see who posted in the thread, SmileWavy.