legacycentral bbs

Ok, if Ive missed a prior thread that covers this exact issue, PLEASE let me know, I dont want to eat up space with repeat problems.

My issue, as follows.
After installing my '02 WRX clutch and flywheel with stg1 Exedy disc on my '92 5spd turbo, I ran great for a few months. Then, one day, the gears would not engage with ignition on. I freaked, thought I messed up the clutch install, read up on here and decided on the master cylinder as the probable cause. I got a replacement and pulled the old one off. Sure enough the old master was most definitely toast as evident by the fluid leaking around the seal at the firewall and by the black debris found in the rather dirty fluid. My replacement was not an exact fit, the piston penetrating the firewall and attached to the pedal was too long so I dremmeled off 1/2 inch of thread and had to slightly grind down the banjo bolt for the line to the damper.

Now the problem. Performed a traditional brake style bleed. Wife at the pedal, me at the bleed valve, she would press a few times and I would open it up, close it, and then she would pull up on the pedal and then repeat all over again. I went through one and one half reservoirs of fluid doing this and only achieved slight build of pressure with the pedal sticking to the floor of its own accord. So I bought a brake bleed kit consisting of a tube from the bleeder screw to a container, another tube from that to the bottom of the container creating a sealed system with a little fluid added to the bottom of the container. I pumped the pedal and held it, opened the valve to release air and repeated these steps until no more air (about another reservoir and a half of fluid) bubbles were seen in the tube. This achieved a slight increase in pressure, enough that the pedal pops back up on its own with only slight hesitation HOWEVER the pedal is still at only about 1/2 pressure and the clutch will not engage.

My question, as I open the valve I noticed that the clutch fork is slowly pulled back into the resting position. Does this mean that I have a leak somewhere or is it just the natural force of the clutch fingers doing the work? There is no fluid spilling out from any of the lines so I cant detect a leak and Ive not been able to disturb any more air from the system. OR is my slave cylinder suspect? How would I know if it went bad besides signs of fluid leakage? Ive bled this thing through almost a full quart of fresh fluid now and still can only achieve what feels like 1/2 pressure. My only other thought is that I dont have the pedal properly positioned on the piston to the master and am not achieving proper pressure when pressing the pedal? Im currently leaning towards replacing the slave and lines but wanted to check with The Experts before proceeding. Any advice at all would be greatly appreciated.

Ben

If I understand you right, what you're seeing is normal. When you open the bleeder valve, pressure in the system is relieved and so the fork moves back to where it was before pressure was applied using the pedal.

The clutch system can be hard to bleed. Part of the reason is that air gets trapped in the slave cylinder. It may be helpful to push the fork in the opposite direction from its usual operation direction -- you end up pushing the slave cylinder piston in. You shoud then see the air bubble out of the master cylinder.

It can also be helpful to park on a downhill slope when you do this.

Very good. Ill give that a shot. Dumb question, should I do that with the bleeder open? Thanks Vikash.

I suppose you could try it with the bleeder open, but I meant with it closed -- it'd push the air all the way up to the master cylinder. Maybe do it once each way?

That makes the most sense but I did not want to assume. I am prone to making mistakes when I first make assumptions.
Thank you again.

No problem; I hope it helps.

Are you also bleeding the damper unit? IIRC it also has a bleeder.

Oh, right, good point. I forgot about the damper because I removed mine. It does have a bleeder valve.

That's the best solution. I think it's better to not have to deal with that stupid thing.

I wonder if Speed Bleeder nippless on the slave and damper would make bleeding the clutch system any easier. I was working by myself and used a Mighty Mite hand vacuum pump, with the stock nipples. It was still a pain in the ass job. One suggestion is to remove the bleed nipple and put some grease on the threads to prevent air sucking in by the threads.

I have a speed bleeder on my slave cylinder, and had one on my damper when I had it too. In my experience, they didn't seem to help a whole heck of a lot; there just wasn't enough pressure built up in the system to force all the air out. Vacuum bleeding did help some.

I wouldn't put grease on bleeder valve threads; you wouldn't want to contaminate your brake fluid. Just use Teflon tape, properly wrapped.

AAaaarrrrrrgghhhhh.....................! Ok, I feel better now, thanks for letting me vent.