Clutch pedal stop

[Tony Radford]

I am considering replacing the lower clutch master cylinder bolt with either a longer bolt run from the outside in and installing a rubber cap (with same thread) or perhaps a piece of all-thread rod. It looks like that bolt location would provide a good place for a stop. Has anyone done this? It would prevent having to remove / modify the pedal. Is there a better way?

[RJacobsen]

Tony, I don't know if there is room enough but you might consider using a coupling nut on the inside of the lower bolt. you could then install another bolt and jam nut into that coupling nut and have a 1/2 to 3/4 inch or more of adjustment.

[weaver]

I don't guess it can hurt but I don't see the need for a pedal stop with a slave cylinder. The car the slave cylinder came on from the factory did not have one.

Alan

[Mike Del]

If you are using a slave cylinder you shouldn't need a stop. I had a slave cylinder setup for 13 years on my first Unique Cobra and put some 60K miles with no problems. Your master and slave should be matched though. ie:don't use a slave that was designed for a 3/4 master with a 7/8 or 1" master.

[Jim Harding]

The car the slave cylinder came on from the factory did not have one.
Alan

Alan, if this is the same slave that I just purchased, what vehicle did it come factory installed on. I tried to cross reference the part number that was on the box lid, but could not find it listed any where. I was more interested in finding the specs for this slave, like size (3/4, 7/8, 1") and travel.

[Tony Radford]

My reason for the stop is that I think I'm overdriving the master and causing premature death. I did take a piece of 5/16" all thread and replaced the lower master bolt. I put the hex coupling on the end and covered that with a small nylon cap for an additional 3/4" or so of adjustment. I can now adjust for the max travel of the master piston. Does anyone know what that travel is? On the drawing, it looks like 1.4" is max travel, but the dimension isn't totally clear to me.

Alan, I had the pedal set so far off the floor that I could feel what I believe was the master cylinder piston sticking in the bore. I suppose the required travel for that Ram clutch may exceed the max travel of the master. I may be making this unnecessarily complicated, but I've got a box full of destroyed masters. And they are a pain to change by myself.

[Tony Radford]

Well, I called Wilwood and my interpretation was correct - 1.4" max. I guess I'll use as much of that as I can and hope for the best.

[diegokid]

I'm new to hyd. slaves for clutches. You said you had a box full of dead ones, are they rebuildable?

[Tony Radford]

Jim, there are several makes for this slave. The cheapest I've found is the Raybestos SC 33721. They're $26 at Rockauto.com. They charged me $6.73 for shipping to Atlanta for a total of $32.72.

Diegokid, they're not rebuildable. There isn't much to them and if everything is set up right, they probably last quite some time. I had a serious alignment issue between the slave and clutch fork. I've corrected that and have moved on to the master.

[diegokid]

Looks like some of the joys I'll get to learn here in the near future.

[Naumoff]

Here is what I installed first then Rod gave a great ideal with a rod coupling so adjusting was made easy.


http://www.uniquecobra.com/uploaded/Naumoff/Clutch%20pedal%20stop%20002.jpg

http://www.uniquecobra.com/forums/showthread.php?t=6653&highlight=Clutch+pedal+stop

This set up is easy and it works

[Aggressor]

I'm using the above Namoff setup. The install and adjustment is quick and easy. What advantage is had with a rod coupling?

Also, I installed my stop to protect my McLeod hydralyic throwout from overextension as recommended by McLeod.

-Geary

[Tony Radford]

All done and no two was about it. The M/C doesn't have enough travel. It does look like there is additional travel available in the slave. I'm skeptical that the larger Wilwood will fit in the foot box hole. But assuming it would, will there be significantly greater pedal pressure going to the larger master? It's already NASCAR grade.

[brfutbrian]

tony , the 1"m/c should bolt right in. theres alot of dimensional specs on wilwood`s website(wilwood.com). check it out to be certain as to fit. im using a wilwood 7/8" m/c (260-3376) in my car ( my slave doesnt bottom out) and theres not much increase in pedal pressure. i cant imagine a 1" m/c would be be much more than i have. get wilwood products directly from wilwood. theres a phone number on the website. great prices and fast shipping. im with alan and mike, no need for a stop with an external slave. later , brian

[Tony Radford]

Brian, the drawings are what raised my concern. The 1304 has a dimension of 1.37" in diameter as opposed to the 6766 that has a diameter of 1.55". The small one fits pretty tight when the boot is installed. I suppose if it fit in your pedal bracket hole, then it should fit in mine. There's only one outline drawing for all three bores, so I'm assuming the 1" is no larger than yours. If I'm going to invest the money and time, I'll go all the way.

[Naumoff]

Here is what I have now for a pedal stop.
I turned the original bolt on the bottom around and fed it in from outside.
installed a rod coupling, bolt and lock nut.
This makes it easier to fine tune the pedal stop.

http://i229.photobucket.com/albums/ee99/Naumoff_photos/Chocolatemilk002.jpg

[RJacobsen]

Tony, Nice work, just the way I envisioned it.

[Naumoff]

Thanks Rod.

I am glad you like it.:)

[Jim Harding]

The M/C doesn't have enough travel.

Tony, when I read this, I thought I'd make some measurements on my car. Pushing the clutch pedal to the floor results in a M/C stroke of 1 1/16 inches. No where near the 1.43" max as stated by Wilwood. I then measured the stroke at the slave cylinder and again pressing the clutch to the floor gave exactly one inch of stroke. Each measurement was made a few times and repeatability was met. Free play at the clutch fork is set at 1/8", so the clutch fork moves 7/8 of an inch to completely disengage the clutch (diaphragm type).
These measurements on my car probably won't agree with what someone might measure on their particular car. For example, thick insulation and carpet in my car probably restricts the total master cylinder stroke.
I guess these results indicate that my floor is an OK pedal stop!!:rolleyes:

[Tony Radford]

Jim, I did a similar thing on the pedal stop. I ran a piece of all thread and put a hex coupler on the inside end with a plastic boot over the coupler. I measured 1.4" between the pedal bar and the stop. It wasn't enough. I just ran the stop down another 1/4" or so an it feels acceptable (at least until I destroy another master). I'll upgrade to the larger one after this one is compromised. Still, getting the slave lined up yields a feeling of accomplishment. If I add up all of the micro-accomplishments I've made to my car over the last 5 years or so, they add up to a significant feeling of success. Kind of a Donald Trump thing.

By the way, how did you get down into the footbox to make your measurements? By the time I got inside with my two wrenches, a flashlight, tapemeasure and specs, I felt like John Glen on his third orbit.

[Tony Radford]

double post

[Naumoff]

Tony, when I read this, I thought I'd make some measurements on my car. Pushing the clutch pedal to the floor results in a M/C stroke of 1 1/16 inches. No where near the 1.43" max as stated by Wilwood. I then measured the stroke at the slave cylinder and again pressing the clutch to the floor gave exactly one inch of stroke. Each measurement was made a few times and repeatability was met. Free play at the clutch fork is set at 1/8", so the clutch fork moves 7/8 of an inch to completely disengage the clutch (diaphragm type).
These measurements on my car probably won't agree with what someone might measure on their particular car. For example, thick insulation and carpet in my car probably restricts the total master cylinder stroke.
I guess these results indicate that my floor is an OK pedal stop!!:rolleyes:


I think this is something everyone should check on their car.
Every car is a little different in its set up and it could be hit or miss without checking to make sure your set up is within the specs of your M/C and slave.

Jim it looks like you are set and don't have to worry.:cool:

[Jim Harding]

By the way, how did you get down into the footbox to make your measurements? By the time I got inside with my two wrenches, a flashlight, tapemeasure and specs, I felt like John Glen on his third orbit.

Well I cheated..... I attached a string to the M/C push rod and attached a pen to the other end of the string. I then clamped a pad/clip board to the door sill and keeping the pen in line with the push rod, made a mark on the pad. I pushed the pedal to the floor and made another mark on the pad and measured between the marks. Did this several times and got marks within a 1/16". I did try the method you did and got so cramped up in there that I couldn't get good readings. :D

[Jim Harding]

Jim it looks like you are set and don't have to worry.:cool:

Yep, took her for a short spin around the neighborhood and everything felt real good. Reallty didn't have time to do much more.... honey do's to be done before she'll let me watch the race. Gotta run... she just saw me goofing off here....:mad:

[rdorman]

The primary purpose of the pedal stop is to allow sufficient travel without clutch drag and to prevent overtravel. It is set by measuring the air gap to between the disc and the flywheel. It is a tuning tool that allows faster more consistant shifting. Check with your manufacturer. Here are some general recomendations from McLeod.

"First of all, be sure all mounting fasteners are torqued correctly, this is very important. The actual adjustment will vary depending on the type of pressure plate being used. With the clutch pedal completely depressed, a diaphragm should have .030-.040 air gap between the disc and the flywheel. For a Borg & Beck the air gap should be .040-.050 and for a Long-Style pressure plate it should be .050-.060. On linkage, with the pedal released, an air gap of .250" should exist between the throwout bearing face and Pressure Plate fingers. On cable and hydraulic applications, the throwout bearing face should rest lightly on the pressure plate fingers"

[Naumoff]

Thanks Rick.

Good Info.

This is the one reason I hate the blow proof bell housings. They need to have an access panel on the bottom so the the gap can be checked.
It is impossible to check it through the fork opening. This is why I said it is hit or miss depending on your set up.

[rdorman]

Darn near impossible isn't it Tony. Of course, a small slot in the bottom will go nicely :) Normally, I just adjust it out the point where the throwout is lightly resting on the fingers, adjust the stop in until the car will go into all gears when running and then play with it to see what I like best.

[will butterworth]

how in the world did you get such a good picture down in that footbox?Will-alabama

[Naumoff]

Will,
I use the close-up setting on my camera.

Rick, They have a big hole on the side I don't see why they can't put one on the bottom. :p

[rdorman]

Will,
I use the close-up setting on my camera.

Rick, They have a big hole on the side I don't see why they can't put one on the bottom. :p

LOL! I am the type that if I need a hole, I make one! Ask question later!

[Naumoff]

LOL! I am the type that if I need a hole, I make one! Ask question later!
SSSHH. I wasn't going to say anything. I am just bitching about it.:)