1981 Brake Pedal Too Low!
Thread Starter
Instructor
Joined: Jun 2005
Posts: 135
Likes: 0
1981 Brake Pedal Too Low!
Ok, I've replaced the 4 calipers and Master because my brake pedal went almost to the floor (engine running). Engine off it held nice and firm about 1/2 way down.
I replaced everything because I did not feel safe stopping. I did find slight leakage out of the rear of the old master and thought I found the problem, but no improvement - pedal still very low with lots of $$$ and time invested. Brakes have been bled multiple times and no air.
Any thoughts?
I replaced everything because I did not feel safe stopping. I did find slight leakage out of the rear of the old master and thought I found the problem, but no improvement - pedal still very low with lots of $$$ and time invested. Brakes have been bled multiple times and no air.
Any thoughts?
Thread Starter
Instructor
Joined: Jun 2005
Posts: 135
Likes: 0
Everything looked identical and the master I took off was the original. I wish I had bought a slightly longer push rod, but it shouldn't need that. The brakes used to feel fine. Very frustrating!
Thread Starter
Instructor
Joined: Jun 2005
Posts: 135
Likes: 0
Found this on-line for '68 - '82 C3 Vettes:
13 Lubricate and install the brake pedal rod connection clevis pin and cotter pin securely.
14 Back off the jam nut, and then spin the threaded brake pedal rod (in or out) of the clevis to adjust the brake pedal height as desired (9/16 and 7/16 wrench).
15 Double check for appropriate thread engagement at the clevis (8 thread minimum), then tighten down the brake pedal rod to clevis jam nut (9/16 wrench needed).
Adjust the brake light switch to match the revised pedal height if changed from stock .
13 implies there is an adjustment. i looked under the dash and didn't see anything between the wire bundles and heater flow vents.
13 Lubricate and install the brake pedal rod connection clevis pin and cotter pin securely.
14 Back off the jam nut, and then spin the threaded brake pedal rod (in or out) of the clevis to adjust the brake pedal height as desired (9/16 and 7/16 wrench).
15 Double check for appropriate thread engagement at the clevis (8 thread minimum), then tighten down the brake pedal rod to clevis jam nut (9/16 wrench needed).
Adjust the brake light switch to match the revised pedal height if changed from stock .
13 implies there is an adjustment. i looked under the dash and didn't see anything between the wire bundles and heater flow vents.
Burning Brakes
Joined: May 2008
Posts: 1,116
Likes: 5
From: Middleburg Florida
It's not the booster is it? If the master was leaking from the rear, that would get brake fluid on the diaphragm of the booster, and it might be leaking. If everything else is correct, bled and adjusted correctly, you might look at the booster...
Race Director
Joined: May 2003
Posts: 10,956
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From: California
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Pro
Joined: Jul 2008
Posts: 699
Likes: 3
From: Millersville, MD
You can purchase an inexpensive bench bleed kit for the MC. Works great. Motive Power Bleeder is the way to go as well for bleeding the calipers. I had the same problem last year and narrowed down my issues to an incorrect MC (Different ones for manuals) and rotor replacement.
Racer
Joined: Jun 2006
Posts: 476
Likes: 0
From: Easton PA
you can check your booster by shutting engine off and pulling main vacum ,line off it. it should make a noise like air rushing. master still has to be bench bled even with vacum bleeder i would think, but dont bottom the cylinder out stop just before the bottom.
Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
I am assuming you have power brakes.
I had the exact same issue when I bought my vette.
Problem was the power booster.
Replaced outer seal which was leaking, but still had issue...
Then found problem with the inner seal on the shaft.
But in pulling the booster apart several times, several of the lock tabs fatigued and broke. Ended up replacing the booster.
Has been fine for 15 years now.
I had the exact same issue when I bought my vette.
Problem was the power booster.
Replaced outer seal which was leaking, but still had issue...
Then found problem with the inner seal on the shaft.
But in pulling the booster apart several times, several of the lock tabs fatigued and broke. Ended up replacing the booster.
Has been fine for 15 years now.
