deward

I need help with my wife's street rod. She has a 1949 Chevy pick-up with a 1978 Monte Carlo stub, and power disc brakes on the front and drum rears. The brakes front or rear will not lock up in a panic stop. Could this be caused by the booster or master cylinder? All the running gear on her truck is from a 1978 monte Carlo including the brake system. I need help guys! My wife wants to go cruise aand she wants to go now! Any help or suggestions are greatly appreciated. Thanks in advance for your help.

mopar1968

What kind of combination valve are you using, with out one the master cylinder will bypass under hard braking :!:


''JUST MY TWO CENT'S WORTH''

deward

The valve is the stock unit fron the 78 Donor Monte Carlo. Everthing seems to work normal except for the fact the brakes will not lock up. I guess I'll replace the master and see if that solves the problem. If my wife keeps harping about getting her truck fixed, maybe I'll just up the insurance and tell her to drive it. LOL

CamBirdRacing

Will not stop as good with the brakes locked up. Just the opposite of a burnout. Car will not move is the tires are spinning.

gearhead1011

I don't think a master cylinder is the cause. Usually if there's a problem with that you will have a low pedal or one that creeps. Start by checking the booster and vacuum to it. Here's a quick check for the booster. With the engine not running pump the pedal a couple of times to bleed off the vacuum. Then with medium pressure on the brake pedal start the engine. You should feel the pedal pressure change as vacuum comes up. Release the pedal, shut the engine off and wait a minute then pump the brake again, as the vacuum bleeds off the pedal should get harder. One big problem you have with a street rod and a vacuum brake booster is the big rumpity rump cams that are so often used will cause low manifold vacuum. The other thing that is often overlooked is the material in the brake pads. The harder metallic pads have a lower frictional coefficient and will require more pedal pressure to stop. Sometimes the pads will get contaminated and create problems. Just a little bit of brake fluid on them will make a big difference in how well it will stop.

deward

First I want you guys to know that I really appreciate your feed back. Thanks for your help.
I'll check the booster like you recommended and let you know what I find. I need to get this truck fixed soon or look for another place to live. The wife wants her own vehicle to drive to the local cruise and shows.
Since the pads are fairly cheap, I'm going to go ahead and replace them.
On the bright side I guess it good to have a wife thats into the Street rod scene as much as me, maybe more.