[76vettester]

Hello,i have a 76 corvette that the front brake lock up after driving it for a while,and when i let the car sit and cool down they release.I have new calipers all round,brake booster and master cylinder.Ive bled the brake and all checks ok.I thought it mite be air in the lines but after bleeding them i took it out again and the samething happened but after letting it cool down the brake light came on and it feels like i have no brakes.Can anyone tell me whats going on? Ive been restoring the car for almost 3 years and im just getting around to driving it.

[T-bucket23]

Originally Posted by 76vettester

Hello,i have a 76 corvette that the front brake lock up after driving it for a while,and when i let the car sit and cool down they release.I have new calipers all round,brake booster and master cylinder.Ive bled the brake and all checks ok.I thought it mite be air in the lines but after bleeding them i took it out again and the samething happened but after letting it cool down the brake light came on and it feels like i have no brakes.Can anyone tell me whats going on? Ive been restoring the car for almost 3 years and im just getting around to driving it.

You brake rod is probably a bit to long and keeping the fluid from bleeding back quickly enough. you can prove that this is the case by cracking the lines at the master when the brakes are locked and see if they release

Chet

[76vettester]

If that is the case what do i need to resolve this? I cant recall if theirs any sort of adjustment i can make? Thanks for the input,

[F&J]

Originally Posted by 76vettester

If that is the case what do i need to resolve this? I cant recall if theirs any sort of adjustment i can make? Thanks for the input,

If it's like car & pickups of similar age...there is an adjustable rod between the master and booster.

I have GM manuals here but never looked up the recommended way to do the adjustment.

The way I do it is I hold the unfastened master up against the booster while someone works the pedal a slight amount. I back the rod off at first to make sure there is freeplay, then adjust it out to take up most of the play.

On the 63-72 chevy trucks, you can work the booster from the engine compartment; so I could do it myself and get a better feel for the actual play. No idea on Vette setup, probably need a helper in the car.

[76vettester]

This is not the original booster and master cylinder its an after market i purchased a while back,and i don't recall if the inner rod is adjustable.

[barnym17]

Are the flex lines to the calipers original? If so I would replace them, they have a habit of small peices of the inner liner flaking and acting like a one way check valve holding the brakes on.

[76vettester]

Rubber lines are new,brakes bleed fine.Like i said when i drive the car and i guess apply the brakes a few times they don't want to release.I just read pirate jacks brakes tech support article on booster push rod adjustment (its where i purchased the combined set) but no info on how to actually adjust the booster push rod.Looks like i will have to pull it apart and check it out.

[vsmidge68]

had this happen on a vette once before.. we used silicon brake fluid.. swelled to much when hot..changed to dot 3 been fine for years now..hope this helps.

[Henry the 32nd]

The rod from the pedal to the booster is adjustable problem may be in that area. When booster builds pressure it applies pressure at master, causing brakes to lock. Adjust for more clearance between prdel at rod

[76vettester]

I haven't been able to look at the problem since last tread but im going to try today.I think im going to start with the line coming off the master cylinder to verify if it is the problem.Thanks for the replies

[76vettester]

Well i got to do some trouble shooting and found the booster rod is too long.I backed off the mc from the booster and the brakes released.The rod to the peddle was adjusted to max and no adjustment can be made from booster to mc,so what i did was shimmed the mc away from the booster with a couple of washers.It looks like its working for now.

[Henry the 32nd]

Something must be still wrong. Do you have the rod mounted in the correct hole on pedel? Is it the correct rod?

[76vettester]

Only one mount hole on the brake pedel for the bracket that attaches to the rod.