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Discussion Starter · #1 ·
Is there any evidence that the current slave cylinder is more reliable than the OEM in my 00?

My 00 is imitating an HD, leaking oil. Since the seepage is between the engine and transmission, I’m assuming it is a rear seal leak.

So, I’m wondering if it will be worth while to replace the slave cylinder if my seal needs to be replaced.

If the cylinder has been redesigned, or has improved seals, I’d consider replacing it a prudent, preemptive strike.

Bob
 

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How many miles on your bike? Mine was replaced around 65K miles, and there was definite signs of fluid seepage, but no complete failure yet. We did another bike at around the same mileage and it seemed dry.

I don't believe the slave cylinder has been changed, but the clutch push rod has been upgraded to have a groove to hold a felt seal in place. My '02 (manufactured in 01/01) had the new rod in it, but I don't know when they started using it.

If you're in there already, then just replace the clutch slave cylinder as they do wear out. It's cheap insurance. And drill a hole to let any further leeks seep out before they cause a major clutch failure. A search on "clutch slave drilled" will give you lots of info, including this thread.

The common wisdom here is to spend $100 in parts and 4 hours to change it out and also to drill a drain hole at around 60K miles, just to be safe. It may save you a $1,500 clutch replacement.
 

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meese said:
A search on "clutch slave drilled" will give you lots of info, including this thread.
Or checkout the HoW. I would definitely replace the slave if I had the bike stripped down anyway, even if the specs haven't changed. They have a finite life. As Ken said, drill the weep hole too.
 

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What I do not understand is why a little $8.00 seal is manufactured so bad. On my 00LT, the seal that sits under the rear main seal was hard as a rock and leaking, why this would leak past the rear main seal, I do not know. But I agree with everyone else, change out the slave cylinder while you are there. I had mine replaced one month ago and now notice another very small leak that I could not find where it was coming from. It looked like clear fluid which was leaking around the cover plate for the oil filter. I determined that this has to be motor oil and am going to replace the cover plate o-ring. I am sure that the BMW mechanics replace about 10 a day, I am just the lucky one that developed a leak. I checked the bolts and they seem tight.
 

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Looks to me like the Slave Cylinder failure rate is about as random as the Rear Drive Failure. My '99 went 93,000 miles with neither a rear drive or slave cylinder failure. Where-as just yesterday, my new to me, used '05 has suffered a Slave Cylinder leak at just under 30,000 miles. I've not had any external evidence of a leak. I did however loose enough fluid out of the reservoir that the clutch would not release with the lever adjustment set at #1. I topped off the reservoir yesterday and went for a short ride. Unfortunately, rolling on the throttle in 5th gear at about 45 mph causes the clutch to slip.
 

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Lynn_Keen said:
Looks to me like the Slave Cylinder failure rate is about as random as the Rear Drive Failure. My '99 went 93,000 miles with neither a rear drive or slave cylinder failure. Where-as just yesterday, my new to me, used '05 has suffered a Slave Cylinder leak at just under 30,000 miles. I've not had any external evidence of a leak. I did however loose enough fluid out of the reservoir that the clutch would not release with the lever adjustment set at #1. I topped off the reservoir yesterday and went for a short ride. Unfortunately, rolling on the throttle in 5th gear at about 45 mph causes the clutch to slip.
At least this one is still under warranty!

What is surprising to me is that even though BMW knows of the problems we have had with slave cylinders, '05s seem to be suffering WORSE than before! Even more surprising is that BMW still has not gotten smart enough to build in a drain so that a failed cylinder (2 hour job) does not automatically turn into a far more time consuming and very expensive clutch replacement!
 

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Mine went out just prior to my 12K service. I had it taken care of and a new clutch put in then. Thank God for warranty work. I have just a couple thousand miles on the new one, but no problems for what it's worth.

Keith
 

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Discussion Starter · #8 · (Edited)
May be the corollary question is how long before they ware out?

When they ware out, what wares out? Same thing, the seal?

Bob
 

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BecketMa said:
May be the corollary question is how long before they ware out?

When they ware out, what wares out? Same thing, the seal?
Bob - did you read through the HoW links I mentioned above? If so, you would have seen David S's recommendation to change out the slave cylinder routinely every 60k - 72k miles. You would also have read about another failure type (apart from seal failure): the ball thrust bearing in the end of the piston can fail, resulting in the piston spinning within the slave cylinder. Again, one of David S's posts shows the resultant grooves worn into the piston.
 

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Discussion Starter · #10 ·
Yes I did Dave.

I didn’t find Dave’s original post about his slave cylinder warring out. As far as I can recall, only one person has reported replacing a slave cylinder because it wore out.

I’ve followed Greg’s clutch experiments, even though the theory behind his mods eluded me.

To me, the problem boils down to, given the present cylinder doesn’t leak, will replacing it with a new cylinder reduce the probability of a cylinder leak. If the probability of a leak is equal between all cylinders, there isn’t a reason to change it to avoid a leak.

Drilling a weep hole to avoid clutch contamination, is the probability of clutch contamination from the weep hole lower than contamination from cylinder leakage? I don’t have any experience that enables me to guess at that one.

Bob
 

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BecketMa said:
Yes I did Dave.

I didn’t find Dave’s original post about his slave cylinder warring out. As far as I can recall, only one person has reported replacing a slave cylinder because it wore out.
There have been a LOT of slave cylinder failures posted on the LT groups, starting on Yahoo years ago.
To me, the problem boils down to, given the present cylinder doesn’t leak, will replacing it with a new cylinder reduce the probability of a cylinder leak. If the probability of a leak is equal between all cylinders, there isn’t a reason to change it to avoid a leak.
The key is to replace it after some mileage, before it fails, then run that one until it is time to replace it. We don't know what that mileage should be overall, but my suggestion is 60,000 miles. Be well aware that several have failed EARLIER than that. Me included.
Drilling a weep hole to avoid clutch contamination, is the probability of clutch contamination from the weep hole lower than contamination from cylinder leakage? I don’t have any experience that enables me to guess at that one.

Bob
There is little probabality that the drain hole drilled in the location shown in earlier posts will cause nearly the problem that the slave cylinders themselves cause when they fail. That hole is in a very protected area, under the slave mounting boss on the tranny, and behind the swing arm. Allowing the brake fluid from a failed slave to drain out instead of ruining the clutch is a HUGE improvement in likely cost of repairs WHEN (not if) the slave fails.
 
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