Hi guys, having some trouble with my RX8 again. I just replace the slave cylinder because I was losing pressure and my pedal was dropping to the floor. When bleeding it, I hand pump the pedal and it builds up pressure and then all of a sudden loses pressure. I'm not sure if I'm getting any fluid through to the slave but I don't see any leaks anywhere either. Nor do I see bubbles coming out through the reservoir. Any help would be appreciated. My next thought is to change the master cylinder.

 

did you bleed it?

 

Yes
it builds pressure and loses pressure during bleeding. I also confirmed that fluid is getting to the release cylinder. I warranty exchanged the master and ordered a new hydraulic hose. see if that works

 

I had the same problem and the master cylinder did it for me.

 

Thanks
Yea,That was the solution last time I had the problem,,, that is the time when it wasn't a clutch disc explosion. LOL. I haven't put it in yet I've been so busy in and outside of work. now my 12yo dog passed at 6am this morning and I have to look about cremation... the car is on jack stands now and I was going to put it back together today.

 

As a dog owner myself im sorry for your loss.

 

Thanks Man

 

So I finally got around to it. I replace the master cylinder slave cylinder and Brake hose or clutch hose. I had to get a Chevy brake hose because AutoZone ordered a clutch hose OEM spec that was 4 inch Too Short LOL. Anyway I replaced everything and found that my problem was neither. it was the hose clamp going from the fluid reservoir to the master cylinder. The clamp on the master cylinder side was very loose and was letting in air there....

Maybe I avoided something bigger in the grand scheme of Life by letting my car sit there for 2 weeks for nothing.

 

Hello everyone,

I couldn't find a thread with my particular issue relating to the clutch and I wanted to see if I could get some advice through here.

I recently replaced my clutch master cylinder due to the original one failing. I bench bled the CMC, installed it, vacuum bled, and old school bled the lines. Everything seemed to work fine afterwards with the clutch pedal regaining its original pressure and me being able to shift, but at least once a day (this is my daily driver) the clutch will start to stiffen and then soon after it would just drop to the floor. I crack the bleeder valve with the pedal stuck to the floor, allowing it to bleed a little, the tighten it up. I then pull the clutch pedal back up and instantaneously it pulls fluid from the reservoir and rebuilds its original pressure. A whole day will go by of driving to and from work and the clutch will start to stiffen again then drop to the floor.

Bleeding it to temporarily resolve the problem is easy, but I don't want to have to keep doing this every day the clutch fails. There is no leak at the CMC or the slave; everything is dry. I haven't checked under the boot of the slave. Could my original slave be bad? Could the build up of fluid pressure when the car heats up be blowing the fluid past some internal seals within the new CMC or original slave?

 

I'm trying to work this out logically, so bear with me.
It's a hydraulic system. Your foot pushed on a piston which pushes fluid that pushes on another piston that pushes the release bearing which is resisted by the fingers in the pressure plate. There aren't any check valves anywhere because it's just pistons pushing pistons.

So, the slave has positive pressure when the pedal is pressed. When you release, the PP pushes the slave piston back in.
I would think a seal failure with the slave would just allow fluid to leak around it and cause a soft pedal (if bad enough, the pedal probably won't even return).
I don't see how this would be solved by bleeding since air shouldn't have an easy time getting in since this system is always under a little pressure (if for no other reason than gravity due to the master being mounted higher than the slave).

Honestly, I'd check your master.

 

I appreciate the advice, NotAPreppie. I agree that there maybe a chance that my newly installed master could be faulty.

This is an odd situation for me because when my clutch does fail, it sticks to the floor and doesn't return. I then leave the clutch pedal where it is on the floor and crack the bleeder valve at the slave; fluid does come out. I then tighten the bleeder valve shut then pull the clutch pedal up by hand. Right after pulling the clutch pedal back up, it regains its resistance and I am able to drive again for a full day before it decides to fail once more.

Everything works completely fine until it doesn't, but I just crack the bleeder to fix everything and get on with my drive.

Also, when I say the pedal stiffens, I mean that it stiffens past what is normal to the point where there is no free play on the clutch pedal. So it becomes hyper stiff and at this point the next press of the clutch pedal will lead to failure. I don't understand why that would happen.

I'll probably exchange the faulty master with another one and see if that will resolve the problem.