HELP ! Stuck Clutch Disc or HTOB Air Trapped??

roadrod2000 · #1 (**permalink**) 10-28-2010, 08:36 AM

Bill,
If it come down to splitting hairs (and it might) your next choice for MC is not 7/8, I know that Tilton has sizes in between 3/4 and 7/8, not sure about Willwood. The jump to 7/8 is pretty substancial, in terms of volumn of fluid, and may have more pedal effort required than you would want. If the 3/4 MC won't do the job take time to calculate the the exact size you need with the info that you have.
Rod

patrickt · #2 (**permalink**) 10-28-2010, 10:52 AM

Quote:

Originally Posted by roadrod2000

The jump to 7/8 is pretty substancial, in terms of volumn of fluid, and may have more pedal effort required than you would want.

Not really. My Tilton 7/8 really doesn't have any more noticable pedal effort than any other big clutch car I've driven. Pics of it are in this recent thread (where I had to remove it) So, Should I Replace This Part or Not?

mpanten · #3 (**permalink**) 10-28-2010, 11:45 AM

Quote:

Originally Posted by patrickt

Not really. My Tilton 7/8 really doesn't have any more noticable pedal effort than any other big clutch car I've driven. Pics of it are in this recent thread (where I had to remove it) So, Should I Replace This Part or Not?

Agreed,

I use a 1 inch master and it's not a problem. I would just change the master and be done with it. As far as the bleeding goes have you tries pushing the air up through the master rather than pulling it. All you need is an oil can and some hose. Works fantastic

mpanten · #4 (**permalink**) 10-28-2010, 11:47 AM

Quote:

Originally Posted by patrickt

Not really. My Tilton 7/8 really doesn't have any more noticable pedal effort than any other big clutch car I've driven. Pics of it are in this recent thread (where I had to remove it) So, Should I Replace This Part or Not?

Agreed,

I use a 1 inch master and it's not a problem. I would just change the master and be done with it. As far as the bleeding goes have you tries pushing the air up through the master rather than pulling it? All you need is an oil can and some hose. Works fantastic.

kitcarbp · #5 (**permalink**) 10-29-2010, 11:58 AM

Guys I discovered another issue that I need to remedy, @ .450" of HTOB travel and 1.1 inch of MC stroke, my clutch pedal is now bottomed out against the firewall. (still need to check if clutch disc completely releases tonight)

The way the builder set up my clutch pedal, at the top of travel the clutch pedal pad sits about 2.25 inches BELOW the height of the BRAKE PEDAL pad. I dont like this. My preference is (when both pedals are released) the clutch pedal pad should be the same height or a little (1/4") above the brake pedal.

I too have looked at the 13/16" Wilwood MC, that would be just enough to get the full 0.500" HTOB travel and a tad more if needed with 1.1" mc stroke. If my math is right the 3/4 MC gives a slug of fluid volume 0.485 cubic inches compared to the 13/16" bore MC that gives me a slug of 0.570 cubic inches. Pedal force will go up if I jump up to a 13/16" mc but not too much. I dont think the 7/8" MC is needed in my application.

Patrickt, Mine is a concentric slave, I have no clutch fork, pedal effort relates to combo of the master/slave cylinder diameters, a 7/8" MC on my MCleod concentric HTOB set-up would increase the pedal effort way higher than I want. The sweet spot for my set-up just may be the 13/16" MC. we'll see
Thanks for the inputs.
More later.

patrickt · #6 (**permalink**) 10-29-2010, 12:29 PM

Quote:

Originally Posted by kitcarbp

Patrickt, Mine is a concentric slave, I have no clutch fork, pedal effort relates to combo of the master/slave cylinder diameters, a 7/8" MC on my MCleod concentric HTOB set-up would increase the pedal effort way higher than I want. The sweet spot for my set-up just may be the 13/16" MC. .

Sounds good. Keep us posted as it's an interesting thread. Although I would have thought that a 7/8 MC would feel the same on a HTOB as it does on an old fashioned set up.

kitcarbp · #7 (**permalink**) 11-01-2010, 06:09 AM

Ok, After removing the "RETURN" stop on my clutch pedal ( allowing pedal pad to be higher and more even with brake pedal pad when released) I was able now adjust the pedal linkage to get 1.1xx" (give or take) stroke on the 3/4" Master Cylinder, which is the advertised maximum stroke. This now moves the HTOB enough to be able to shift gears, finally ! BUT, the disc still drags with clutch pedal to the floor in gear and I am not yet getting 100% clean disc disengagement, which tells me the air gap between disc and pressure plate is not yet @ 0.050". I need to now measure HTOB travel again. Boy I wish I had a lift ! I am now leaning toward getting a 13/16" master so my clutch pedal travel is not so far.

Patrickt- Found the rubber grease you mentioned. Its assembly lube used when rebuilding hydraulic cylinders so you dont scuff the rubber piston seals etc during assembly. Pegasus Racing sells i for $9 /tube. WIll add this to the tool box wiht my next order !

patrickt · #8 (**permalink**) 11-01-2010, 10:00 AM

Quote:

Originally Posted by kitcarbp

Patrickt- Found the rubber grease you mentioned. Its assembly lube used when rebuilding hydraulic cylinders so you dont scuff the rubber piston seals etc during assembly. Pegasus Racing sells i for $9 /tube. WIll add this to the tool box wiht my next order !

Yep, that looks like the stuff. I went to Pegasus and found a nice pic of it and it says it's made from castor oil. Here's a pic for the viewing audience.