Two clutch master cylinder implosions - ???

[Silk]

Can't quite figure this out. Lost my clutch master cylinder after only about 1000 miles. Figured it was just a defective part & replaced it. Now, after another 2500 miles, aparently the same thing. Thought it was the slave cylinder this time & replaced it. But still won't hold any pedal pressure at all. Lots of black stuff in the fluid when I bleed the system (same thing the first time, too). Using Castrol GT LMA - no silicon.

Any thoughts/suggestions would be much appreciated

Thanks

[Richard Hudgins]

Gary,

What are the components? Brand, sizing, etc.

The black stuff sounds odd. Like seals are disintegrating.

Castrol LMA should not hurt anything in a brake or clutch system.

[Whaler]

Richard that was my first thought too...chewed up particles of O-ring/seals will give you that blackness in the fluid...
Definitely stay away from Silicone as well as that to will degrade and breakdown in the system..which it sounds like you have.
As for no pressure..I would suspect you have lost your sealing ability to pressurize using the pedal.

Is the fluid in the remote/ reservoir contaminated as well??

Whaler

[Silk]

Richard,

They're standard components as provided by Unique in their roller. Haven't substituted a thing. Wilwood 3/4" master cylinder & Wagner externally mounted slave. It does seem as though the seals in the master cylinder are disintegrating, but for the life of me I can't understand why.

[Richard Hudgins]

Gary,

I would recommend that you take the MC off and disassemble the unit.

Castrol LMA should not cause any problem whatsoever. There must be some nature of contaminate in the fluid or Wilwood used the wrong materials for the seals. (This can happen, they are injection molded parts and the molder could have used the wrong material.)

I would call Wilwood after disassembly and describe what you are seeing. they are normally pretty good guys.

I am interested as the JBL has now gone to the Wilwood units from the Tilton. (The reason for this is the pedal assembly)

Please let us know what the boys say.

[Silk]

Richard,

I'll do that & e-mail you with their answer.

Just a thought - anything that I should be adjusting with the pedal? Too much travel putting too much pressure on the seal? Still seems very unusual to have two cyclinders fail in apparently the same way in such a short period of time.

Thanks.

[Richard Hudgins]

Gary,

Travel should not cause this sort of failure. High travel in a clutch master cylinder is normal.

One thought. Are your headers real close to the Master?

This is probably not the problem as you would be seeing it in your brakes as well.

[Dan Heck]

Grasping at straws at this point--is there anything unusual about the hard and/or flex lines in the system? Any chance a stainless braided segment might have a sub-par rubber lining rather than hi-pressure teflon?

Dan

[Tommy]

I removed and disassembled my leaky Tilton clutch master cylinder an hour ago and discovered lots of black sludge in the fluid. I subsequently discovered the inside bore of the master cylinder smooth except for score lines for the first inch or so on the top half of the cylinder. I suspect the clutch rod is not pushing parallel to the master cylinder bore when I depress the clutch, and that is causing the piston to rub the top of the cylinder. I believe the black sludge is finely ground aluminum from the scored cylinder. What do you guys think?

P.S.
I've seen several posts warning about the need for a stop on the clutch pedal to avoid over extending the slave cylinder. How do I determine where to put the stop to preclude this problem?

[Silk]

Richard, Dan -

Negative on both. Headers are not at all close, & the line is just flaired metal.

Tommy -

I think my alignment on the master cylinder is good, but that does give me something to check more carefully.

Thanks for the ideas.

CHIPPER,

YOU HAVEN'T BEEN LETTING THE DOC OPERATE ON IT, HAVE YOU??

HE HIDES HIS SPARE RAKI IN BRAKE FLUID CANS.

IF YOUR PEDAL IS MOVING AND THE CLUTCH IS NOT OPERATING AND THE "MECHANICAL" PARTS ARE CONNECTED YOUR DOWN TO TWO OPTIONS.

1. NOT ENOUGH FLUID - I'M SURE YOUR CHECKED THAT, OR,

2. ONE OR THE OTHER (OR BOTH) HYDRAULIC PISTON SEALS ARE LEAKING - BYPASSING FLUID INTERNALLY. THEY WOULD HAVE HAD TO HAVE A SIGNIFICANT FAILURE OR ELSE THE CLUTCH PEDAL WOULD BE NOTICEABLY SLOW IN RETURING TO IT'S NORMAL POSITION WHEN YOU LIFT YOUR FOOT.

IF YOU HAD CONTAMINANTS IN THE SYSTEM ORIGINALLY, AND DID NOT "FLUSH" IT THOROUGHLY WHEN RELACING THE LAST CYLINDER THEY WILL STILL BE THERE "DOING THEIR THING" ALBEIT SOMEWHAT SLOWER BECAUSE THE CONTAMINATION HAS BEEN DILUTED WITH THE ADDED FLUID.

OFTEN TIMES CYLINDERS (AND OTHER PARTS) ARE TREATED WITH A RUST/COROSION INHIBITOR TO PROTECT THEM WHILE "ON THE SHELF". IT'S POSSIBLE THAT AN INHIBITOR WAS USED THAT WAS NOT COMPATABLE WITH THE SEALS "OR THE FLUID" ALTERING IT'S CHARACTERISTICS ENOUGHT TO CAUSE SEAL DETERIORATION.

BEFORE REPLACING ANY MORE EXPENSIVE PARTS YOU SHOULD CONSIDER A THOROUGH "FLUSHING" OF THE ENTIRE SYSTEM.

IS THE DISCOLORATION NOTICABLE IN THE RESERVOIS FLUID AS WELL??

GOOD LUCK. IF YOU CAN USE A HAND - CALL ME. (AT LEAST I KEEP MY RAKI IN THE ORIGINAL BOTTLES).

Y'ALL HAVE A REALLY GREAT DAY,

SUNDANCE

[Kirby Nelson]

Gary:
I too have a Unique/289 with a 351W. My clutch fluid was showing the blackening also, after about 150 miles or so. The car is completely apart now, with the body at the paint shop. Was going to address the problem when every thing starts going back together. My MC-rod alignment looks fine, the slave-rod alignment is a couple degrees off maybe. The brake MCs and fluids seem fine. I am very interested in what you find out. Kirby Nelson, Marshall, VA

[Silk]

Richard,

I spoke with the tech folks at Wilwood today, and they didn't offer any real explantion for the problem. Their only suggestion was to use fluid with a higher boiling point, but they didn't really think that would solve things. My MC is one of their lower end products, and doesn't have rebuild capability. So, it wasn't really possible to do much internal analysis.

However, I looked closely again today at the pedal assembly and discovered a 1/16" washer on the front bolt between the top of the footwell and the pedal assembly. No washer on the rear bolt. This could very well be causing the piston to move inside the cylinder at an angle - perhaps the same problem Tommy noted in his post. What do you think? In any event, I think I'll add a washer and level things out when I install the new MC. Hope that's the cure, 'cause it's getting a bit pricy to replace MCs every few thousand miles.


Sundance,

I purged the whole system last time I replaced the MC, so I don't think contamination is an issue. Hopefully, the cure is the missing washer. If that fails, I'll get together with you and Doc and we'll fill all reservoirs with Raki and hope for the best (assuming we don't drink it all first).


Kirby,

I got your e-mail, and I'll give you a call in the next day or so. When do you think your car will be on the road? Soon, I hope. Look forward to seeing it. Power to FIAs!!

[rldunn7]

Replaced the innerds(Southern term for those pieces inside the slave cylinder) of the slave cylinder in the parking lot last year in Pigeon Forge and will offer my opinion. The black stuff is coming from the slave cylinder. With the extreme heat you need a good high wet-boiling point fluid Dot 3 or 4...no silicon. Replace your fluid at least each 3-6 months. (That per the design engineer at Valvoline for their Synthetic fluid.) Also, check the travel in the slave cylinder. If you set the rod too tight it will bottom out when you have the clutch released and will cause the rubber piece in the slave cylinder to fail...(I did this so I know this is true.) Another thing, for some reason the slave cylinder (which is raw iron on the inside) only requires a small amount of moisture to rust/corode and for some reason moisture will accumulate in this piece.

Good Luck! Been there and done it on my back in the parking lot...not fun!

[spencer]

Gary,
I had the same problem your experiencing approximately four year ago. I used up two Wilwood unit within a year. I took both units and a sample of the discolored fluid to Wilwood, they're about a 90 minute drive from me in Camarillo, CA. I ask that a tech inspect the units to determine the problem. Two tech's inspected the units and could not determine the cause for failure or the reason for the fluid turning black. As I was leaving a third tech suggested that I buy their rebuilding kit, he said the unit should be rebuilt once a year and if the car is being raced it should be inspected / rebuild more often. So I bought three rebuild kits and rebuilt both units.
Not long after that I was talking (bench racing) to a guy that builds / races salt flat cars. He suggested that I have a brass sleeve pressed in the cylinder, because this is what he found to prevent failure to cylinders. I had it done to both units at a local machine shop and I've had the same unit in since. I think it cost me $150 for both.
Oh, just for information, I'm using the Mcleod throw out bearing instead of a second cylinder for the clutch.
Another possible solution, Good Luck.....
Spence..

[Bob Putnam]

Gary,

Are the fluid reservoirs integral with the master or remote? I've seen black discoloration from some hoses.

[Richard Hudgins]

Silk,

Don't your master cylinders bolt to the pedal assembly?

Also, the rod that goes from the pedal to the MC pivots at the MC piston. Therefore, a little misalignment should not cause this problem.

It seems to me that Wilwood must have a material problem in the seals. Glycerin (the base for normal brake fluid) should not effect buna-n or viton, which are the nromal materials for brake seals.

I am going to take some Wilwood MC's apart and soak the seals in hot brake fluid (195 f) and see if there is any rapid degredation of the material.

[Silk]

Bob,

No hoses. Just a flaired metal line between master & slave cylinders.

Richard,

Cylinders do bolt to the pedal assemply, but with the nuts tightned, the assembly could be out of square. Might not make much of a difference, especially with the rod feeding into the cylinder cup, but it's about the only thing I can think of - other than the materials problem.

Thanks for all your suggestions. They're much appreciated.

Yours in hydraulic stasis,

[CobraEd]

Gary, I don't have an answer to your problem, but here is a site that tells everything there is to know about brake fluid types.

http://www.vtr.org/maintain/brake-fluids.html

Ed

[Silk]

Thanks, Ed. Good info. But I cringed when I saw it's on the Vintage Triumph site. Drove those things for 25 years, and smelled like hydraulic fluid or gas for most of them. Plus having to deal with The Prince of Darkness!!