ptwohey

I willl appreciate everyone's help to locate a thread about pedal height on a '72 automatic with PB.
My pedal is only 2" off the floor and the booster rod is holding it there. I cannot get full travel on my master cylinder.

My '71 4 speed has twice as much room.

All help is welcome. Thanks.

Durango_Boy

Check, and make sure of what hole the pin is in. There are two holes, a lower and an upper. The lower is probably where you have it pinned now, and the upper is where a power booster rod would pin, and that would give you a few extra inches.

If you're already in the upper hole, then you may have to start looking at the booster. Is it a stock booster or was it replaced at some point?

ptwohey

Durango, I will check that out. I did remove the booster and see a stamp REMF in yellow so I guess the previous owner changed it. He did say he had brake trouble and he is not a mechanic but had a friend work on them...oh no!

Thanks, I give you the progress report tomorrow.

BBShark

Bad information, the booster clevis goes in the LOWER hole, not the upper. Check your booster, you should have 5 3/4 inches from the firewall mounting face of the booster to the clevis hole center. Make sure you have the correct booster, should look like this:

Durango_Boy

How is that bad info? Power on bottom and manual on top. How is that wrong?

SIXFOOTER

LOL, there ya go, thinking again...what I tell you about that?

Durango_Boy

Probably the same thing you said about listening, but I wasn't paying attention.

SIXFOOTER

LOL, Yep

ptwohey

OK, so now that we have our holes figured out, I measured the distance from the mounting plate to the center of the clevis pin and I come up short...story of my life!
It measures only 5 1/4" so that could be why the pedal is so close to the floor. I will use a splicer nut and a stud on the clevis to get to the 5 3/4" and all should be fine.

Thanks for everyone's help!

Durango_Boy

So you're thinking the guy that replaced the booster did not use a Corvette correct unit? Is that .5" going to make enough of a difference for your pedal position preference?

BBShark

The brake pedal is a lever. It has a ratio of travel at the pedal to travel at the clevis. In the case of a C3, the PB lever ratio is 3.38:1. So a .5 inch difference at the clevis will make 1.7 at the pedal.

Durango_Boy

I understand that and agree. I was just asking, as he is used to a brake pedal that's 4" form the floor. I think that should be considered when lengthening it so it's not done two or even three times.

BBShark

The clevis is threaded so it is easily adjustable, the first time.

ptwohey

I spent yesterday changing the starter in this car to a cast iron bell after the "delco rebuilt" snapped the aluminum that was on it, then I attacked the brakes again.

I called "Booster Dewey" who was very helpful and pulled an original off his shelf to give dimensions. My clevis, which can only screw on to the rod end and lock, is non-adjustable but the correct length. The rod adjustment is on the master end of things. He also gave me an extended length of just under 6" so compared to the 5 3/4" mentioned in the thread, mine is not correct. Without opening mine to compare it with correct internals, he could not determine why the lengths are different and that the rebuilder use incorrect parts.

I went out shopping last night and found the connector nut I wanted. It is 1 1/4" long so I have plenty of stock to cut to the proper length. I will get really technical later today and raise the pedal to the desired height and use a coat hanger as a gauge between the booster firewall mount and the lower clevis pin hole. With that engineered length, I will modify the clevis to the longer length and try it out. My technigue will be a screw on modification so it can be undone if all fails.

Durango_Boy

Very well thought out. Looks like you have covered all your bases and you will end up with what you're looking for out of pedal height.

Also, while you are down there, this is a good time to check the brake pedal return spring. I have owned three C3s, and two of them didn't even have one in place. The one that did was broken. Just a thought.

BBShark

The 6 inch dimension is correct, if you want the pedal against the rubber stop in the support bracket. I think the pedal seems kind of high (compared to the gas pedal) at the 6 inch length. I think the AIM recommends a gap between the rubber stop and the pedal arm also.

I would not bother with replacing the return spring on your car. Most, if not all, PB cars do not have a return spring. As you are probably aware there is a large return spring in the booster. Sorry for the "misinformation". Hope it didn't cause you too much trouble. Sounds like you went to an expert (Booster Dewey) however. Sometimes you get good information on here, often not.

BBShark

I am not going to check my AIM. Go to the parts list for the power brake option (if you know how). The spring PN#3921686 DOES NOT APPEAR ON THAT LIST! The spring bushing PN#3908768 DOES NOT APPEAR ON THAT LIST! However, I am sure that pedal assemblies with a return spring were installed on PB cars. Why, CAUSE IT DOSEN'T MATTER BECAUSE THE BOOSTER HAS A RETURN SPRING!!!!!!!!!!!!!!!!

I made that comment trying to save the original poster the unnecessary trouble of fixing something that was not broken. I made my first correction to your INCORRECT statement about the hole the clevis goes into to try (again) to save the original poster from tying to spend hours trying to fix something (again) that was not broken. Then you told me that I was wrong????????? Then you told me that you were wrong but somehow your hands typed the wrong thing but you really were THINKING the right thing (so I guess therefore you are not wrong like usual ). To make things even worse you made that ridiculous statement to cover yourself after stating that you didn't see how a .5 inch difference was going to be enough!!!!

In this thread I have tried to save the original poster from implementing the BAD INFORMATION that you have provided. I have done this without insult, in a matter of fact manner. You on the other hand WILL NOT STOP with the most ridiculous series of postings (in one thread) I have seen on any forum. At least your bad information was not dangerous this time!

I don't post to this forum that much but I have tried in two postings in the last few days (wheel studs) and this one to correct the WRONG information you give to people. Why is it OK for you to post bad information and send someone (who does not know that you are the prime source for inaccurate, incorrect and sometime dangerous information) down to there garage to try to implement your fix?

noonie

Any repairs to brakes is very serious and has no room for error.

IrishMac

Enough!!!

The Forum should be a place where we treat one another with civility so that it remains a fun and friendly place to hang around with other Corvette enthusiasts. Hostility to others is rude and inappropriate.

Personal attacks cannot be tolerated. Attack ideas, not fellow Forum members.

Durango_Boy

Sorry Bill. I know this is getting old.