Unusual clutch issue (Page 5/8)
stevep914 JUL 29, 11:39 AM
Sorry to answer the question: master has been on the car since I bought it years ago. Slave is a Dickman unit replaced several years ago. I have only put 9000 miles on the car since I bought it (“2012 or so)
fierofool JUL 29, 01:51 PM
The Dickman slave is the double seal design and though possible, it isn't likely that it's leaking or sucking air. Though you didn't experience any loss of pedal with the overnight test, because of the design of the umbrella seals in the master cylinder, if it's allowing air into the system, it will be on the release stroke. The compression stroke makes the umbrella seal flare outward and the release stroke can allow it to fold inward a bit and let air pass.
stevep914 JUL 29, 04:34 PM
Did Plan B last night and blocked the pedal fully depressed ( and yes, it does go all the way to the floor) . Left it all night like that. This morning, removed the piece of wood, and the pedal snapped right back firm. So , if I interpret this correctly, I have no internal or external leaks. I will try to get a picture of the banjo sometime today; One step at a time! Unfortunately our main AC unit for the house got surged by a lightning strike last night, and a new unit is the project of priority right now. We have over 90 degree heat here every day now. I will get back at this once I have THAT issue sorted out. Steve
stevep914 JUL 29, 05:03 PM
So if air is escaping the seals in the master, I should have some air in the system, right? Before I do anything else now, I should do another gravity bleed, and see if air bubbles pop up? BEFORE I do any more pumping of the pedal? The car is still elevated to do this.
fierofool JUL 29, 05:23 PM
If it is the seal in the MC then air probably wont be ingested until you use the clutch for a bit. One or two or 6 operations might not ingest enough to notice.

I think your problem is either seal or heat related, not mechanical.
Patrick JUL 29, 06:01 PM

Just to muddy the waters further... when the seal in my Formula's clutch master cylinder failed, it allowed fluid to escape from where the banjo connects. I allowed this to continue for several months before I finally replaced the cylinder. The point I want to make though is that air was never drawn into the system with that seal failure. Yes, I had to keep adding fluid, but I never once had a soft pedal.

Having said that, there may be failing internal seals within the master cylinder that replicate the feel of air in the system (soft pedal), simply because fluid isn't being pushed when the pedal is being depressed. I admit to this being conjecture, as I don't know the internal workings of a clutch master cylinder.

Steve, considering the amount of grief that you've had over the years, and the fact that this is the original master cylinder... I'd just change the damn thing.
stevep914 JUL 29, 07:32 PM
Patrick, I have a few pictures I could send you. I am basically computer illiterate, and do not know how to post them on this website. I DO know how to send them to an email. Steve
Patrick JUL 29, 07:49 PM

Steve... sure, send them to me and I'll post them here. Use the email address in my Profile.
stevep914 JUL 29, 07:50 PM
Patrick, I have a few pictures I could send you. I am basically computer illiterate, and do not know how to post them on this website. I DO know how to send them to an email. Steve
Patrick JUL 29, 08:00 PM
Steve, you've now duplicated three different posts in this thread so far.

[This message has been edited by Patrick (edited 07-29-2022).]