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clutch not holding

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zimmy

zimmy

Jedi Knight
Offline
when i push the pedal the clutch works about
4 seconds then it lets out by itself....
ALL of my clutch and components are new as of
last summer....a little over 1000 miles on it.
i just put in a brand new roller bearing and disk
last week.
i checked for leaks and found none, i also pushed
in the pedal and tried to push in the slave by
hand with no success....so, i pressure bled it again
and its still same as before.....hmmmmm.
any ideas? ...maybe rebuild my cylinders?
extend the rod? ..........signed,.. gettin frustrated!
 
Something is leaking down. I think I would suspect the slave cylinder first.
 
zimmy said:
could it leak pressure without any
fluid coming out? ....z
Click to expand...

Sure. Fluid will leak past the piston seals in the master back to the reservoir just like in a faulty brake master cylinder.
 
You guys are right, I stand corrected. Master cyl.
 
On a 74 you have separate brake and clutch masters, right? You should only need the one kit if the brakes work fine!!
 
I think he means clutch and slave, Mikey. :wink:
 
I don't think he really has a problem with the slave if there is no puddle under the car, but maybe... I guess he might as well do the whole system! :thumbsup:
 
I would. No sense in doin' that "bleed the clutch" routine any more than necessary, IYSWIM.
 
I just had this same problem about a month ago. Same issue with no leaks, but I noticed that by repeatedly pumping the pedal I could "build" up the pressure and cause the clutch to work for about 5 sec., then it would let itself back out. I bled the darn thing about 20 times and used every way in the book and many different suggestions. I replaced the clutch master and the slave, but still had no luck. I finally used a pressure bleeder from motive and bled the system, then pumped the pedal many times, then re-bled. It finally worked, however it still seems lower than it was before, but it does work. I'll look for some of the posts on it.
 
Try bleeding the clutch in the exact order the manual says (2 person method).I have never had luck pressure bleeding the clutch.
 
I was the author of "We got nowhere this weekend" thread. We had tried everything, but to no avail. Finally, we determined the pistons within the MC were not moving back and forth consistently, so fluid was not being built up properly within the MC. The MC had been rebuilt and re-sleeved, and we had all new components like the slave cylinder. Here is what I think happened:

- We were using a house brand of Advance Auto Parts DOT 5 brake fluid. I am convinced this was affecting the rubber seals within the system, causing them to swell and impeding the travel of the pistons.

Why? How?

Before you begin doubting me, let me explain further:

- We purchased an EZ Bleed system from Advanced Auto. It contained two plastic reservoir bottles that attached to the system and were used to allow the fluid to pass through. After several failed attempts at bleeding the system, we had brake fluid all over these things. We were told that if the EZ Bleed did not work that we could return them, so I began to clean these things up. Each time I disconnected the reservoirs from their tools the rubber seals around the necks of the reserviors popped off. When we tried to reinstall these seals they wouldn't fit. THEY SWELLED UP AND WOULD NOT FIT IN THE VERY GROOVES IN WHICH THEY FIRST CAME. In other words, contact with the DOT 5 caused these seals to swell to the point they were no longer any good.

We took the MC to a local, high end resto shop which had extensive experience with all types of British cars. They eventually determined that the pistons within the MC were not traveling freely. They ordered a simple rebuild kit from Moss, flushed the MC completely, rebuilt it (changed out the rubber parts), and bench bled it with DOT 3/4. We cleaned out the hydraulic system the best we could, re-installed it, and it works perfectly.

I believe, at the least, the DOT 5 was affecting the rubber parts (BTW: We replaced the slave after having the MC rebuilt because the seals in that were also affected). It could be that the house brand AA DOT 5 was misformulated, but the resto shop told me they had bad experiences using DOT 5 in their British cars and that they use only DOT 3/4.

That's my story and I'm sticking to it.

MXP
 
I think this points to one of the most common problems with hydraulic failures in these cars, and I am sure there are not too many of us who have played with them for a while who have not encountered it!! The type of hydraulic fluid is VERY important, as can also be the source of/for replacement rubber parts for the hydraulic system!! I wish someone would create/manufacture the "soft" pieces for the hydraulics out of some material that were totally impervious to the effects of hydraulic fluids!!! When one thinks about how important those little rubber cups and rings are to the overall operation of the vehicle it is a wonder that someone has not made some kind of improvement over the years for these old cars!!
 
mike, being just a pump between the pedal and the hose,
i would think u could use "any" master that would fit
the area provided assuming the travel distance is right.

i ordered kits for both my cylinders.....
ill post a thread on fluids and get some input.
i think u r probably right, and the fluid is
actually causing some premature wear....thx guys ....z
 
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