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Discussion Starter #1
about the clutch slave failures on the K1200LT. Lots of folks have had to replace a KLT clutch contaminated by a leaking clutch slave, and others (yeah, me too) have drilled a weep hole in hopes of preventing a clutch failure. (I also swapped out a working clutch slave for a new one in hopes of preventing a problem).

Toyota has issued a recall for our Highlander to replace the seal in the brake master cylinder. The recall notice states: " ....Toyota uses brake fluid containing polymers that act as lubricants for certain brake system components. If replacement brake fluid is used that does not contain such polymers, or contains only small amounts, a part of the rubber seal....may become dry....If this occurs a small amount of brake fluid could slowly leak....." The recall involves replacing the rubber seal with one that supposedly won't leak if non-Toyota brake fluid is used.

So I'm thinking that the seal used in the KLT clutch slave maybe "fussy" about fluid, similar to the seals used in the toyota brake systems affected by the above recall.

I'm just thinking that it may make sense to be careful when selecting replacement fluid when doing the KLT clutch service.
 

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All well and good, but what is the recommended clutch fluid? Something we have to purchase from the dealer? Anybody know?
 

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We could start an oil thread, a tire thread, a seat thread, a windshield thread, and now a clutch fluid thread. We'll all chime in and it can then deteriorate into a "if you don't use the same clutch fluid as me, you're a frickin' idiot" thread. Then it'll get deleted, and, and. Oh, never mind. :wave


Interesting thought though. Any idea how to figure it out?
 

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fpmlt said:
We could start an oil thread, a tire thread, a seat thread, a windshield thread, and now a clutch fluid thread. We'll all chime in and it can then deteriorate into a "if you don't use the same clutch fluid as me, you're a frickin' idiot" thread. Then it'll get deleted, and, and. Oh, never mind. :wave


Interesting thought though. Any idea how to figure it out?

Yes but having an outlet to argue over really meaningless stuff probably prevents us from arguing about really meaningless stuff at home.
 

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Discussion Starter #5 (Edited)
I wasn't trying to start an oil thread. Oil threads go like: "what's the best oil to use?" followed by lots of opinions based on a plethora of opinions and a dearth of data.

Years ago someone posted pics of a failed KLT clutch slave seal. The margins of the seal were degraded, clearly the "rubber" of the seal was degraded for some reason. At the time there was speculation of bad seals.

I posted this information about a known Toyota brake master cylinder seal problem because of the similarity of the system to the KLT clutch.

The "take home" data is that there are seals manufactured for application in hydraulic systems (brake and clutch) that are used my major manufacturers (Toyota in this case) that are not compatible with all commercially available clutch fluids. I thought that was a pretty significant point.

It struck me as a distinct possibility that the reason some folks have had a clutch failure and others have not may be related to the clutch fluid used.

As to what the correct fluid is I dunno. I haven't yet researched to see if there is a BMW specific brand, nor have I yet checked for clutch fluid specifications in the owner's manual or service manual. But I will because it seems to me it may be significant.

There are nice descriptions/video on how to drill a weep hole to prevent a leaking clutch slave from taking out a clutch. Drilling a weep hole is a lot of trouble to go to in the hopes of preventing a clutch failure. I thought I might be adding possible information to the clutch slave problem.

Frankly, I have always assumed that all brake fluids are basically the same, and having done numerous brake and clutch flushes on my 2000 KLT I couldn't tell you what different brands I have used over the years, but I generally take the time to make sure that the DOT type specified in the manual is what I use and I generally use a major brand.

Does it matter for the KLT what fluid is used when flushing the clutch system? Who knows? What I do know is that some folks have reported a clutch slave failure which also cost them a clutch, and I know that Toyota has leaking brake systems because the seal they used in manufacture isn't compatible with all commercially available fluids to the point that they are recalling a large number of vehicles and changing the seals at no cost.
 

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I think the $1,000 question is: Have any seals failed while having the OEM (BMW) fluid installed? If so, then this thread is invalid. But if all failures have happened without OEM fluid, we have something to talk about.

fpmlt, did you even read the OP's post? :confused: This isn't about what fluid is best (opinion), the OP is simply investigating the cause of failure.
 

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Hmmm... It may be why I like the synthetic choice in my system...

Synthetic fluid refers to a liquid type fluid made out of some silicone substance. Most brake fluids, etc. are mineral based, what some call "Dino"...

In actual use, it doesn't make a difference whether you use synthetic brake fluid or not as far as I can see. What really makes the difference is the type (bring on the heat guys) of brake fluid. The main types of brake fluid are DOT3, DOT4 and DOT5. The first two absorb water... not a good thing. Some manufacturers put additives in the DOT3/4 compound to bind to the water. No matter what, it still absorbs water. DOT5 does not. Gimme a seal that can stand up to DOT5 and I'd be a happy camper...

If I think about it, it could be why DOT4 Dino causes slave failures... Or maybe a mix-n-match of the different types.

I just started synthetic... so I'll have to see... So far so good...

So maybe a question could be... Who runs synthetic with some miles using it and has had a slave failure?
 

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So, Maybe the real question is. What came in your bike...Each year could be different..
Heck, Even between serial numbers of a model year it could change...

Is there anybody who can say what comes in the bikes to start with ?

Then, What has it had since then....

John:rotf:
 

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messenger13_ver2 said:
I think the $1,000 question is: Have any seals failed while having the OEM (BMW) fluid installed? If so, then this thread is invalid. But if all failures have happened without OEM fluid, we have something to talk about.

fpmlt, did you even read the OP's post? :confused: This isn't about what fluid is best (opinion), the OP is simply investigating the cause of failure.
\
Yes Joe, I did. I was being a smartass in the first part. Was serious about wondering if there would be a way to identify a problem.
Sorry. My bad.
 

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Discussion Starter #11
bmwriderm said:
Most recalls are only called for when, its a safety type issue. I don't think a clutch would qualify.
Did anyone suggest that BMW should/would issue a recall? Yeah, that's likely. A pig might fly. :histerica

Okay, I'll grant you that this thread may be much ado about nothing, on the other hand there's an outside change the information will prevent a clutch slave failure.

As far as gathering past data regarding what fluid was in the bikes that have had a failure I doubt anything meaningful could be obtained. Even regarding those bikes that failed with the original fluid we can't be sure BMW consistently used the same fluid. And who knows what fluid is used in the various BWM dealership service departments? And do DIYers remember what fluid they used in past fluid changes, I know I don't recall the brands.

And it could be that it simply was a bunch of "bad" seals.

There is a BMW 0-fish-all clutch fluid, note that it is mineral oil !?!:
http://www.sierrabmwonline.com/product_info.php?products_id=1511&osCsid=3f8c6f3c101e647593e5249b808fcba1

On the other hand, my BMW Service Manual for the K1200LT refers to brake fluid in the "Changing the Clutch Fluid" section of the manual and specifies DOT4.

I don't know much about brake fluids, but I wouldn't assume that DOT4 must be better than DOT3, and that DOT5 must be better than DOT4, and on that basis choose to use DOT5.
I'm going to stay with a major brand of brake fluid and use DOT4 as specified in the BMW Service Manual. While DOT5 may not be hydrophilic compared to DOT3 and 4, but unless specified by the manufacturer, I wouldn't assume that it is compatible with all the components in the system.

I also use a fresh unopened container and change at intervals as specified in the owner's/service manuals. Beyond that, I don't think any objective conclusions can be made. My original point was that it is possible for the "wrong" fluid can damage the "wrong" seal leaking to a leak, witness: the Toyota recall.
 

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How about keeping it simple?

Use DOT 4 brake fluid with the highest boiling point you can find. When you look closely at the container you will find and be surprised by the variation found from brand to brand on DOT4.

And by now word has gotten around that changing brake fluid is essential for optimum performance. For cars it is generally agreed that 2 years is a good interval. More will not hurt.

If you have high humidity conditions and large temperature swings consider doing it annually.
After you did it the first time you can judge by the color of the old fluid if it should have been done earlier or later. The old fluid should have only minimal discoloration.
 

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Bikes like the KTM use mineral oil in their clutches. I don't believe that mineral oil is hygroscopic, as is brake fluid.
Is it possible that the water content in older fluid is the contaminant? If so, Wolfgang is on the right track.
Does anyone know for sure whether or not mineral oil can be substituted for brake fluid in a small system such as a clutch? I certainly wouldn't try it in a braking system, but the clutch is pretty basic.
 

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fpmlt said:
Bikes like the KTM use mineral oil in their clutches. I don't believe that mineral oil is hygroscopic, as is brake fluid.
Is it possible that the water content in older fluid is the contaminant? If so, Wolfgang is on the right track.
Does anyone know for sure whether or not mineral oil can be substituted for brake fluid in a small system such as a clutch? I certainly wouldn't try it in a braking system, but the clutch is pretty basic.
Mineral oil for the purpose of this discussion is similar to Silicon fluid. Since it will not mix with water you will have little pockets of water in the system leading to a soft pedal/handle feel and localized corrosion.
 

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Methinks we have a thread of fluids? :rolleyes:
(or is that a fluid thread)
 

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Has anyone thought of the fact that Toyota messed up on what type of seal compound they used............ they needed to replace the rubber seal since it was not made of the right compound to stand up to the brake fluid.

Just a thought....

Mugz
 

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Mugszy said:
Has anyone thought of the fact that Toyota messed up on what type of seal compound they used............ they needed to replace the rubber seal since it was not made of the right compound to stand up to the brake fluid.

Just a thought....

Mugz

Oh crap, now it's deteriorated from a fluid thread to a rubber thread. Maybe we need "the wisdom of dick" to sort this all out.

Lord knows what's next :p
 

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Nope, it's now a conspiracy thread. Toyota might just be trying to cover their butts by referring to those "certain polymers" when they just installed crappy components. :rotf:

Seriously, my suspicion is that at least some clutch slave failures are caused by contaminated fluid due to using a pressure washer on the bike. Anybody know of a failure where the fluid was regularly changed and kept uncontaminated?
 

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deanwoolsey said:
Anybody know of a failure where the fluid was regularly changed and kept uncontaminated?
+1 I think you hit it on the head. Brake / clutch hydraulics rarely fail if the recommended fluid is used and changed according to the service recommendations, adjusted to the environmental conditions.
 
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