Original or replaced clutch slave cylinder

[Diamicton]

Hi - I’ve looked but haven’t found an answer — is there a way to know if the clutch slave cylinder is the original or an aftermarket replacement from the outside? I have a new bike and plan to drill the weep hole, but am also looking to get a sense as to whether I should plan to replace the part as well and can order it and have it ready. If it’s original, I will plan to replace it. If aftermarket, probably not on the assumption someone already has.

I assume that either way, I will need to slide out the cylinder somewhat to drill the hole, correct? If so, can I do that without disconnecting the lines?

The bike just had its fluids replaced shortly before I got it and I don’t want to wait until the next interval to take care of that weep hole, and if I can avoid the extra bleeding work, why not.

Thanks

[njsax]

Slightly confused here. I think you are using the term "original" in the context of "this is the very same cylinder that was last touched by the factory person who installed it". But when applied in conjunction with the term "aftermarket", you are using "original" as in "Original Factory Equipment" (OEM), which are still availalble as replacements. With this dual context, your cylinder could be original (OEM), but not the one that's been in the bike since it was assembled in Berlin.

If the cylinder was replaced with an OEM part, then you need to know when it was replaced. If within the last 5 years or 15k miles, I would leave it alone, especially if the clutch fluid was changed on a regular basis (as it should be). On the other hand, if it's aftermarket and was only just installed yesterday, I would immediately remove it, crush it in a vise, and install a brand new OEM unit. I've heard nothing but bad about aftermarket slave cylinders. The cost of a replacement clutch is such that the small difference in price between an OEM (made by Magura) part and an aftermarket part is considered cheap insurance.

If in doubt about if or when the cylinder was ever replaced, regardless of the current part being OEM or aftermarket, I would replace it with OEM and ride-on, confident that my slave cylinder isn't going to fail and piss fluid all over my clutch.

I like the theory of a weep hole, but I question its actual effectiveness. Unless you keep your bike immaculately clean, and are always checking for drips, you still run the risk of a failed slave contaminating your clutch. I'm not that kind of person. I prefer to change my slave on a preventive basis. For me, that's 30K miles or 10 years, whichever comes first.

[Diamicton]

Thanks. I’m still learning as this is my first r11s. I’ve gathered that the slave cylinders were a risk, one should replace them, and assumed that oem wasn’t what to replace it with (being that they go bad in the first place). I also read that they can be rebuilt or one could just get a new one, which I assumed was aftermarket. Sounds like they should be replaced but with oem and then either monitored and/or continually replaced.

I was planning to replace with this, which they refer to as aftermarket identical to oem, so not sure exactly what that is.
https://www.beemerboneyard.com/21522335061n.html

Thank you.

[908/930]

If you are removing the slave cylinder inspect the bearing and place a small amount of thin grease in the bore and push behind the bearing to help keep it lubed. When that bearing fails it will rotate the slave cylinder piston.

[njsax]

Originally Posted by Diamicton

Thanks. I’m still learning as this is my first r11s. I’ve gathered that the slave cylinders were a risk, one should replace them, and assumed that oem wasn’t what to replace it with (being that they go bad in the first place). I also read that they can be rebuilt or one could just get a new one, which I assumed was aftermarket. Sounds like they should be replaced but with oem and then either monitored and/or continually replaced.

I was planning to replace with this, which they refer to as aftermarket identical to oem, so not sure exactly what that is.
https://www.beemerboneyard.com/21522335061n.html

Thank you.

It's the aftermarket parts that are questionable. The slave cylinder is not some forever part. It's a moving, spring loaded mechanism with seals in a hydraulic environment. Nobody can make one that lasts forever. This is definitely a periodic replaceable item. You don't want to wait until it fails because by the time you notice it, the clutch will already be toast. You must be proactive and not await the imminent failure.

Sure, you can take your chances with a rebuilding kit (don't know who makes one), but it'll probably be just as risky as an aftermarket one. Just to save a couple of dollars? Not a good alternative for me. I didn't get into BMWs to save money. I consider these to be throwaways.

You have to decide what amount of risk you are comfortable with.

[mosearch]

I replaced my factory original clutch slave cylinder at 40,000 miles...I used the Beemer Boneyard European aftermarket part (looked exactly like the Magura original). Not sure if there are particularly "bad" aftermarket versions out there...or what the souce might be.
In any case, I have 60,000 miles now (20,000 with the replacement slave), with no clutch problems. It does seem to pay to flush the clutch fluid every 18 months or so.

[Diamicton]

Thank you to you all for your help.

[sgoodwin]

In contrast to the others my '99 has the original clutch slave so far with no problems & rarely do I change fluid & as it's never been out, there is no weep hole either. So, it's not always a problem & I'm sure I'm not the only one as forums are usually whine & cry venues. Of course, by posting this I just doomed myself. Knock on wood, spin three times & jump on one leg.

[wswartzwel]

My 2002 has 52,000 on it with original slave. I have greased the throwout bearing in it twice, when doing spline inspections/grease

[Ridgetopboy]

When in doubt whip it out.

[Diamicton]

This is how things looked when I removed the slave cylinder. I’m not sure what fluids mixed here - is it some mixture of brake fluid and transmission fluid or is it just congealed brake fluid? Can any experts advise? The goo in the cylinder shaft was hard and caked on. Clutch plates are dry so nothing made it to there.

Given what you see, do I need to replace the seal in the cylinder shaft? Do I need to take things apart further and replace a seal in the transmission? It’s a R1100S so it’s tough to get to with the frame bar running right across the access area.

Also, what exactly is the process to add more grease to the new slave cylinder? I feel like I’ve read to just put some high temp wheel grease into the slave cylinder bearing hole and push in with a pencil eraser but also read that I need to disassemble the slave cylinder to add more grease.

Thanks!

Interestingly, here’s what it looked like when I cleaned up the slave cylinder a bit. It looks like the bearing is not even up against the snap ring.

[njsax]

Originally Posted by Diamicton

I’m not sure what fluids mixed here - is it some mixture of brake fluid and transmission fluid or is it just congealed brake fluid?

Looks like grease or oil. Taste it (yes, seriously). If it's bitter, then there's brake fluid and it's leaking out of the slave. Then wipe off your tongue.

Originally Posted by Diamicton

Clutch plates are dry so nothing made it to there.

This is good, if true. How did you determine this?

Originally Posted by Diamicton

Given what you see, do I need to replace the seal in the cylinder shaft?

No, replace the slave assembly with a new BMW /Magura unit.

Originally Posted by Diamicton

Do I need to take things apart further and replace a seal in the transmission?

Not if the clutch is dry, as you say.

Originally Posted by Diamicton

It’s a R1100S so it’s tough to get to with the frame bar running right across the access area.

Irrelevant.

Originally Posted by Diamicton

Also, what exactly is the process to add more grease to the new slave cylinder?

The slave cylinder doesn't use grease. The goo that you see doesn't belong there. The slave and its cavity should be bone dry.

Originally Posted by Diamicton

I feel like I’ve read to just put some high temp wheel grease into the slave cylinder bearing hole and push in with a pencil eraser but also read that I need to disassemble the slave cylinder to add more grease.

Never heard that, so unless you can provide a credible source, I'll call bullschit.

Originally Posted by Diamicton

Interestingly, here’s what it looked like when I cleaned up the slave cylinder a bit. It looks like the bearing is not even up against the snap ring.

Irrelevant. Replace the slave cylinder with a new BMW/Magura unit.

In case I haven't mentioned it. Replace the slave cylinder. Ensure the clutch is dry. Otherwise, take the bike apart, replace the clutch and the engine rear main seal, and the gearbox input seal, and inspect the clutch splines and grease them with the BMW approved grease referenced in your Rider's Manual. If you don't have a BMW Rider's Manual, one can be downloaded for free from BMW Motorrrad website.

[Diamicton]

Thanks very much for your quick response.

I don’t think anything reached my clutch because I wasn’t having any clutch issues and everything looked dry when removing the starter and looking at the clutch.

Here are some references that I’m trying to figure out how they may relate to my situation.

https://forums.pelicanparts.com/bmw-r1100s-r1200s-tech-forum/291411-clutch-not-disengaging-advice-2.html
Post 21 talks about gearbox oil mixing in. The slave cylinder definitely had a smell to it when I pulled it out. It wasn’t exactly the same as gear oil but had me wondering if some mixed in, and if so, what that means in terms of failing seals.

https://forums.pelicanparts.com/bmw-r1100s-r1200s-tech-forum/433422-can-we-compile-definitive-clutch-slave-cylinder-fix-thread-2.html
Post 38 suggests replacing seals if there is any goo. Looking at my seal, it definitely doesn’t look clean and not sure if the goo has degraded it at all. I’d rather not mess with things if I don’t need to but want to make sure I fix things right and reduce the chances of future problems while I have things apart.

The following two posts talk about the bearing grease not being enough on the new slave cylinders. I bought an oem cylinder from BMW as you suggested.
https://www.ukgser.com/community/threads/new-clutch-slave-cylinder-what-grease-in-the-bearing.308542/
Post 11 - add grease with a pencil eraser

https://www.bmwsporttouring.com/topic/99327-clutch-slave-cylinder-longevity/
I don’t see post numbers but in the post from November people talk about adding grease but seem to say the bearing needs to come out to avoid airlock when pushing in grease and to get the grease in the right spot.

Thanks again.

[njsax]

Originally Posted by Diamicton

. . . Post 21 talks about gearbox oil mixing in.

Gearbox oil cannot reach the slave cylinder without first soaking the inside of the bellhousing and clutch. Since your clutch is dry, then it cannot be gearbox oil. Maybe the previous owner of your bike is the person who thought packing the slave cavity with grease was a good idea.