Clutch Slave Maintenance?

[Hadabadachada]

2013 camhead.

 

was just curious what information there is on clutch slave service if any?

I hear you don’t need to change the fluid, sounds weird, maybe a BMW thing, “don’t mess with it till it breaks then bring it to us to overcharge you.”

 

so I wondered about the slave cylinder, should we be checking, greasing the bearing? 
ive gone through a couple on the oilhead, and now that I’m at 25k on the camhead, I wonder what the thought is to maintain it.

 

thanks.

[6speedTi]

I just did a flush and bleed. Usually with mineral oil it's in the category of lifetime fluid. I still serviced it because over time the fluid gets dark. Nothing is really lifetime fluid but the clutch fluid goes a long way if you do not do any work on the clutch that drains fluid. I did not do any greasing.  Just a flushing. I have a 2012rt with 104,000 miles. The flush was done recently for the first time. 

[Lowndes]

Hadabadachada,

 

The clutch fluid can be different from brake fluid.  Brake fluid must have a very high boiling point because brakes do get very hot and boiling fluid will "apply the brakes", possibly not at an opportune time.  The clutch slave cyl does not get that hot.  If it does, you got bigger problems.  Anyway, the fluid can be any non corrosive lubricating liquid with a boiling point less than maybe 250° F.  

 

DOT4 brake fluid has a couple of bad habits, like eating paint and plastics and absorbing moisture.  Mineral oil doesn't do either so any moisture from condensation will collect in the  lowest point in the system (caliper cylinders) and begin to corrode the cyl walls.  Just doing a regular "brake flushing" will not remove this condensate from the calipers or from the clutch slave cyl.

 

On the clutch slave cyl, in the piston in the slave cyl, is a very small sealed ball bearing, the throw-out bearing for the clutch.  This bearing turns at all times with the crankshaft, clutch engaged or not engaged.  If the engine is running, this bearing is turning.   WHEN (not "IF") this little bearing fails, you have a larger problem.  Depending on the type engine, this will ruin your clutch plate and require a clutch plate replacement.  An easy fix for oilheads is to drill a weep hole in the housing to drain the fluid out before it travels down the clutch rod to the clutch.  AMHIK.

 

Therefore - the best "service" you can do on this slave cyl is to replace it with a NEW slave cyl and while you're there, drill a weep hole.  Yes, its a PITA, but a clutch replacement is a bigger PITA.  Also, AMHIK.

[dirtrider]

7 minutes ago, Lowndes said:

 

Therefore - the best "service" you can do on this slave cyl is to replace it with a NEW slave cyl and while you're there, drill a weep hole.  Yes, its a PITA, but a clutch replacement is a bigger PITA.  Also, AMHIK.

 

 

Morning  Lowndes

 

Hadabadachada, has a 2013 camhead, the camhead/hexhead does not use a slave cylinder gasket so fluid seepage can find it's way out. No need to drill a weephole on the camhead. 

[Hadabadachada]

Shoot I’ve gone through two of them on the oilhead. I didn’t drill a hole, I just ripped a piece of the gasket off incase it happens again. I was lucky, the clutch lever went soft, made it home 25 miles without pulling it again so the fluid didn’t get everywhere.

i just remember reading on one of these forums where someone said they take the slave out and re-grease the bearing every 20k or so, as a preventative thing.

 

I was wondering if that was suggested for the camhead. Or maybe these don’t suffer the same issues and will just keep going.

[Hati]

4 hours ago, Lowndes said:

Brake fluid must have a very high boiling point because brakes do get very hot and boiling fluid will "apply the brakes", possibly not at an opportune time. 

 

Never heard about boiling brake fluid "applying" the brakes. Boiling creates gases such as steam from the water trapped in the brake fluid. Steam can be compressed while fluids can not. So applying the brakes when there are gases present in the system will give you the exact opposite of brake application, spongy, inefficient brakes.

 

 

[DakarTimm]

None of this explains why the old iron head Sportsters that have the exhaust directly under the rear master cylinder would lock up the rear brake while idling in traffic 

[dirtrider]

27 minutes ago, DakarTimm said:

None of this explains why the old iron head Sportsters that have the exhaust directly under the rear master cylinder would lock up the rear brake while idling in traffic 

Afternoon DakarTimm

 

It takes basically two things to cause a brake to hydraulicly lock up from heat (assuming the calipers are working normally & the pads are releasing normally.

 

It takes fluid expansion (obviously moisture in the fluid turning to steam increases that expansion chance) plus it takes a plugged off take-up port on the master cylinder that prevents the expanded fluid/stream/air from expanding back into to master cylinder reservoir.

 

I'm not sure what the Harley deal was but the usual cause of a plugged-off take-up port is a misadjusted brake pedal, or improperly adjusted brake linkage preventing the master cylinder piston from FULLY retracting.  Or a sticking master cylinder piston preventing a full piston return. 

 

As long as that small hole in the top of the master cylinder piston bore is open at brake release then any fluid expansion just backs up into the reservoir without making pressure in the system or applying anything.   

 

There are outlier things like ply separation in a brake hose that can, under the right circumstances, act like a check valve preventing fluid return but with something like that it isn't necessarily a heat thing as all it takes is normal brake apply pressure that gets trapped then can't release the applied brake. 

[Hadabadachada]

Speaking of dragging brakes, I gotta get in a clean my front pistons again, I can hear my fronts dragging a bit after flushing and changing my fronts. I thought I did a decent job cleaning the pistons, but, still dragging. Maybe probably almost normal, but I should check it out.

them super sintered EBC pads have that noise they make when you brake. Mine can be heard lightly all the time.

 

can’t say that my rotors feel overly hot when I stop and feel them. But they do drag a bit when I spin the front wheel.

[dirtrider]

15 minutes ago, Hadabadachada said:

Speaking of dragging brakes, I gotta get in a clean my front pistons again, I can hear my fronts dragging a bit after flushing and changing my fronts. I thought I did a decent job cleaning the pistons, but, still dragging. Maybe probably almost normal, but I should check it out.

them super sintered EBC pads have that noise they make when you brake. Mine can be heard lightly all the time.

 

can’t say that my rotors feel overly hot when I stop and feel them. But they do drag a bit when I spin the front wheel.

Afternoon  Hadabadachada

 

The disk brakes have no real return springs, the only things that give a very slight positive brake pad retraction is due to the piston "O" ring cut & on some helped by the piston dirt seals. 

 

The natural movement of the brake rotors & slight flex of the wheel can also add a very slight amount of pad kickback but that can't be depended on. 

 

The pads do lightly drag on the rotors but shouldn't make the brake rotors hot.

 

If you can hear the pads buzz on the spinning rotor  holes then sometimes lightly chamfering the edges of the brake pads with a file or sanding block can decrease or eliminate the noise. 

 

Also make sure that you master cylinder isn't overfull as there needs to be room above the fluid or an air space above the bladder to allow the fluid to expand into. 

[Hadabadachada]

I’ll check the fluid, I think it’s full to the bottom of the diaphragm, so I should leave a bit of air there…

[dirtrider]

13 hours ago, Hadabadachada said:

I’ll check the fluid, I think it’s full to the bottom of the diaphragm, so I should leave a bit of air there…

Morning Hadabadachada

 

Just make sure that you have some air space, either below the diaphragm or above the diaphragm. There is a full mark inside the fluid reservoir but it is sometimes difficult to figure out. 

[jdub53]

I've experienced two Boxer clutch throw-out/release bearing failures; one on my '94 R1100RS at 30k miles (cable actuated clutch) and one on my '99 R1100S at 42k miles (hydraulic clutch). Both failures modes were nearly identical - noticeable and progressive change in lever free play when pulling the clutch lever over several shifts until the clutch finally no longer disengaged at all. Rode home both times using clutchless shifting like when a cable breaks.

 

Only took pics of the failure on the S, which revealed dry balls in the bearing and some had already fallen out of the race. In both instances, the new/replacement OEM bearings had just a small dab of grease in them which I figured had to be the cause of the eventual failures. I added more grease to that new bearing on the S, and then started removing and greasing that bearing at 30k mile intervals as preventive maintenance on every dry clutch Boxer I've owned since. Never a problem with that bearing again even on my '07 GSA that I sold with 145k miles.    

 

 

[Hadabadachada]

What kinda grease do you use? It’s gotta be good with all that spinning.

 

I bought some cv2 grease last time I put a new slave on my 1100S but basically stopped riding it with the electric issue it has, and got the camhead. 
still want to get that sorted.

 

 But after having two slaves fail on the S, I wondered the the camhead slave was improved. 
 

I always thought it was stupid that you could buy a new seal for the old slave, but it was always the bearing that would fail and you couldn’t buy that, so, new slave. 

[jdub53]

53 minutes ago, Hadabadachada said:

What kinda grease do you use? It’s gotta be good with all that spinning.

 

I bought some cv2 grease last time I put a new slave on my 1100S but basically stopped riding it with the electric issue it has, and got the camhead. 
still want to get that sorted.

 

 But after having two slaves fail on the S, I wondered the the camhead slave was improved. 
 

I always thought it was stupid that you could buy a new seal for the old slave, but it was always the bearing that would fail and you couldn’t buy that, so, new slave. 

 

I've been using this reddish grease that BMW sold in the '90s as, I believe, an all purpose grease. I had the exact name/number written on the cap, but it's been on the shelf so long the writing is too faded to read. The grease hasn't broken down in the container though.

 

[Hadabadachada]

grease on that cap looks similar to this CV2 stuff I bought