Clucth mushiness

[georryan]

For a while now I've been experiencing some clutch weirdness. Sometimes when I'm braking hard or letting the engine slow down the car and go to put in the clutch it sinks much further to the floor than normal. Once I let it up it seems to readjust itself and get back to the right spot. I changed out the master cylinder, no help. I also changed out the slave cylinder, and that seemed to help for a while. The problem is coming back, and so I'm thinking I may have to change the slave cylinder again, but the thing is I'm not completely sure that's it. It may be, but I'm wondering if that could happen as a result of bad engine/tranny mounts? There isn't any leaking in the lines and the fluid stays at the same level. I've blead it and there isn't any air in the lines.

What do you guys think? Do you think it is still the slave cylinder?

[vrg3]

Kind of a dumb question, but are you sure you're bleeding it out thoroughly?

And have you tried changing out the hoses too? I wonder if your hoses may be torn on the inside or something, allowing debris into the slave cylinder.

It could also have to do with the clutch damper. Maybe you could try bypassing it.

[georryan]

I'm not taking any question for a dumb question. I'm almost posative I've blead it out well enough. Changing the hose might be a good idea, but it sure looks fine from the outside. I don't remember exactly, but aren't all the hoses except for one metal lines. The one that isn't goes to the clutch damper...I think.

What exactly does the clutch damper do??

Here's the other thing, I was testing this thing today and I would come up on a stop sign and put it in neutral. Then I would pump the clutch to see how it felt coasting, then pump it under a light break, and then pump it under a much harder brake, and the clutch got a lot weaker feeling under the hard braking. Not only that, but once I came to a stop and pumped it, it felt normal.

That is kinda why I was wondering if it could be related to mounts and the engine's movements. Really I'm clueless, I'm just throwing ideas out there. In theory that shouldn't matter.

[vrg3]

Mounts shouldn't matter at all as far as I can see. The slave cylinder is bolted directly to the transmission.

I also don't see why braking would have anything to do with it except that maybe the car dives forward when it brakes and that changes something.

On the Legacy Turbo there actually aren't any hard lines. Look at the diagram here:

http://www.graphics.cornell.edu/~v/clutch_hydraulics/

There's a hose that goes from the master cylinder to the damper, and another hose from the damper to the slave cylinder.

There was a TSB a while back that applied to newer Subarus... It had to do with a sticky clutch pedal, and the solution involved replacing the slave cylinder and hoses if I remember right.

I don't know exactly what the damper does. It probably smooths out rapid oscillations in fluid pressure or something. I've been running my car without the damper for a long time now, though, with no adverse effects that I can see.

[georryan]

Really? They are all hoses? hmm...I'll have to take another look at that. Well, maybe I should get a replacement on my slave cylinder and change all the hoses out.

The braking having affect on the clutch mushiness is weird to me as well. I've done it several times and it is pretty consistant. So, I know that somehow it's related, I'm just not sure how. Well I feel better that it is weird to you as well, but a little dissapointed that you don't know why it may do that.

-Ryan

[vrg3]

Yup, two hoses with 10mm banjos on each end.

This is your second slave cylinder, right? You might want to try taking your stock one apart if you still have it first. You can see if anything looks amiss, and then you might be able to buy a rebuild kit instead of a new slave cylinder.

[georryan]

Well, I bought this slave cylinder maybe 6 months ago. So I think I should be able to just return it and get it replaced for free. We'll see. Good call on taking the origional apart, only....it is sitting in the garage I used to have in Washington.