Another brake question
Thread Starter
Instructor
Joined: Sep 2018
Posts: 165
Likes: 64
From: Lakeville MN
Another brake question
Ok so I’ve done a ton of research on this and I’m not totally sure what to make of this problem. I have a 1979 vette, recently the brake pedal went mushy and the dash brake light came on and stayed on. I found that both front calipers were old and leaking fluid so I replaced all four calipers front rotors and new pads all around. At first I wasn’t able to gravity bleed the back brakes so I replaced all the bleeder valves with speed bleeders and that did the trick. I bench bled the master cylinder and bled all four wheels. Now the brakes work great, nice firm brake pedal, great stopping power but the dash brake light stays on, I’m pretty sure it’s got to be the proportioning valve/combination valve/distribution block...whatever you want to call it. From my understanding of how that valve works, how can the brakes work so well but the light stays on? I’ve tried stomping on the brake pedal to recenter it, didn’t work. Should I replace the valve? Live with the ugly red brake light on all the time? Has anyone ever replace it? Looks easy enough (btw, the master cylinder is new also)
Last edited by Gralls4771; Nov 5, 2018 at 03:51 PM.
Race Director
Joined: Oct 2008
Posts: 19,135
Likes: 1,667
From: Long Island
The valve detects an imbalance in the brake system front to back. Sometimes the valve will stick and a light tapping on it can help.
I would suggest there is still air in the system somewhere, either front or back. It doesn't take much, on my 71 it was the LR that gave me fits.
I would bleed the brakes using the brake pedal as the pump. Then see if the light goes out.
I would suggest there is still air in the system somewhere, either front or back. It doesn't take much, on my 71 it was the LR that gave me fits.
I would bleed the brakes using the brake pedal as the pump. Then see if the light goes out.
Thread Starter
Instructor
Joined: Sep 2018
Posts: 165
Likes: 64
From: Lakeville MN
It’s not the parking brake, tried that. I’m going to throw a new proportioning valve at it and re bleed the system and see what happens, at least then 95% of the brake system will be brand new.
Safety Car
Joined: Sep 2007
Posts: 4,452
Likes: 327
From: Indy Indiana
get you a infrared heat gun for 20 bucks on ebay/harbor freight, go for a drive and exercise your brakes. check your rotor heat.
if all are near the same temp then your proportioning valve/block is doing its job and you have a ground issue on the wire or inside the valve.
if one or more rotors is significantly cooler than the others then you probably still have air in your system at your coolest rotor. bleed accordingly.
i think that block can be rebuilt?
if all are near the same temp then your proportioning valve/block is doing its job and you have a ground issue on the wire or inside the valve.
if one or more rotors is significantly cooler than the others then you probably still have air in your system at your coolest rotor. bleed accordingly.
i think that block can be rebuilt?
Thread Starter
Instructor
Joined: Sep 2018
Posts: 165
Likes: 64
From: Lakeville MN
Well good news, the brake light went out, not really sure what I did.....engine running, stomping the brake, holding the brake down, cycling the parking brake on and off, light goes out, problem solved. Thanks for the ideas!
