HELP ! Hydraulic clutch conundrum

[CNIdog]

Hi, My friend has a Mk4 with a TKX trans with a Mcleod 1400 throwout bearing and Wilwood master with remote external reservior.

Has anyone had this issue:

Worked fine for 6 months after install, then one day the pedal noticeably lost back pressure with about a dozen full presses of the pedal. Went to the floor and won't disengage the clutch. No leaks anywhere.
Power flushed and bled the system. Seemed to work ok for a few months.
Now the pedal hits floor after gradually losing back pressure with 10 to 20 pushes. Again, no leaks.
Bled the system again. Same problem.

Back pressure seems to come back after just pushing the pedal just an inch or so a few dozen times very quickly. Back pressure comes back after half a minute, it works for a few full presses then bottoms out again.
We've bled the system, No bubbles. No leaks. Back pressure still disappears after a few pedal presses.

Short of taking off the body and pulling it all out, has anybody had this happen?

[J R Jones]

Without experience on a problem like yours, I will suggest that perhaps the push rod does not fully disengage the master cylinder piston. There should be a bit of pedal wasted motion before the push rod touches the piston.
This assures that the piston retracts fully for a complete stroke.
As long as you are at it, confirm that on the slave end, there is also free play on the throw-out so that it is not spinning when the clutch is engaged.
jim

[edwardb]

If it works properly and then stops working after some use, and it's not leaking fluid, that suggests to me either the MC or the hydraulic throw-out bearing is failing. O-rings, whatever. I'd start with the MC since it's the most accessible. Take it out and disassemble. One snap ring and the whole thing comes apart. Wilwood rebuild kits are relatively cheap. Replaces everything except the outer housing. If the bore is worn, then the whole thing should be replaced. Notwithstanding the Wilwood vs. Tilton MC discussion... If it's the hydraulic TOB, then the transmission has to be dropped. Not nice I know. Mcleods don't have the best reputation unfortunately. I'm a fan of hydraulic TOB's, but use Tilton. I'm not sure why either would require the body to come off.

[BornWestUSA]

It sounds like a bad master cylinder.

The body should not have to come off.

[danmas]

There have been a number of confirmed failures of the wilwood master cylinders reported here. I won’t get into the debate except to say I replaced mine immediately with Tiltons.

https://thefactoryfiveforum.com/show...draulic-clutch
https://thefactoryfiveforum.com/show...linder-leaking
https://thefactoryfiveforum.com/show...for-Wilwood-MC
https://thefactoryfiveforum.com/show...-cylinder-leak
https://thefactoryfiveforum.com/show...ster-Cylinders
https://thefactoryfiveforum.com/show...-coupe65-coupe
https://thefactoryfiveforum.com/show...-cylinder-leak

Might be worth a closer look…Edwardb knows what he is talking about…

Best,
Dan

[Mike.Bray]

There have been a number of confirmed failures of the wilwood master cylinders reported here. I won’t get into the debate except to say I replaced mine immediately with Tiltons.

https://thefactoryfiveforum.com/show...draulic-clutch
https://thefactoryfiveforum.com/show...linder-leaking
https://thefactoryfiveforum.com/show...for-Wilwood-MC
https://thefactoryfiveforum.com/show...-cylinder-leak
https://thefactoryfiveforum.com/show...ster-Cylinders
https://thefactoryfiveforum.com/show...-coupe65-coupe
https://thefactoryfiveforum.com/show...-cylinder-leak

Might be worth a closer look…Edwardb knows what he is talking about…

Best,
Dan

That's just the reported ones! Not to worry, 5 out of 6 people report they enjoy playing Russian Roulette

I've had lots of hydraulic throwout bearings and love them. The one time I had a McLeod it failed on me after a few months. IMO McLeod HRBs are the bargain basement while Tilton are top of the line and all the others I've had were Tilton. The Tilton's just work.

As Paul said it could be on either end, probably best to start with the MC since it's (somewhat) less work.