HELP ! Stuck Clutch Disc or HTOB Air Trapped??

[kitcarbp]

ROADROD, Your math is right. On my long D.C. area commute home last night (and after reading other Mcleod clutch users posts, it occured to me, that I dont have enough Mcleod 1300 series HTOB movement yet. Although Mcleod states "0.375" Pressure Plate finger travel required" I believe that is for "initial" disc release, not "full" disc release, thus that is why my disc is still dragging on PP and not fully released @ my measured 0.390" HTOB piston movement. I think I get it now.

I also found an email from Mcleod on their web-forum where they expect FULL disc release at 0.500" HTOB piston travel, thus, now I see is the source of my confusion. If I would have been a little smarter, and drilled a hole on the bottom of my OEM bell housing, I would have seen that I dont yet have the desired 0.050" air gap between PP and disc at 0.390" piston travel.

You are spot on about 3/4" master and the bolt on HTOB, I wont over extend it with 1.0 or even 1.1" of travel with my current clutch pedal geometry after looking at it upside down via my mirror under the car last night.

I also realized the kit builder (West Coast) installed the clutch pedal stop after years of selling some cars with 7/8" Masters (For Tilton HTOB) that would in some cases over extend the HTOB (slip-on style) bearing if used on a Mcleod HTOB without a pedal stop. When they started supplying pedal stops on the kits, they also realized 3/4" masters are a better choice for pedal effort and preventing over-travel, they left the pedal stop in place (which I now realize was likely intended for using a 7/8" Master to protect from over-stroking the HTOB and leaking. I will now remove the pedal stop (that will give me another 1/4" of pedal travel and move that HTOB piston travel closer to 0.500" I think.

Thanks to all for your posts, its becoming more clear to me now. I love this Forum and could not do this project without all the help I have received.
I will report back in the next days.
Bill

[kitcarbp]

Ok the update is after removing my clutch pedal stop completely, this gives me the 1.1" of travel now on the clutch Master cylinder (3/4" bore). The HTOB now moves about 0.450" after contacting the PP fingers. It was too late to fire up the car and scare the neighbors last night so I will test if the 0.450 is enough to completely release the clutch disc now.

Bill

[roadrod2000]

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]

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]

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]

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]

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]

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.