El Camino Central Forum banner

1 - 9 of 9 Posts

·
Registered
Joined
·
58 Posts
Discussion Starter #1
Hello all!

I have a question about my 1984 brake booster. From reading here I believe my brake booster has gone bad. I have a lot of fading when depressing the brake, and I have already replaced the master cylinder, front brake tubes, pads, rotors and hubs. ( The rotors were seized to the hubs).

The question I have is that when I am at a red light with the car in drive, waiting for the light to turn green, the car likes to "lurk", or "jump" forward slightly. I have been told that this could be because of a vacuum leak inside of the the brake booster. And, because the booster is going bad, it would also not depress the pads hard enough to stop the lunging.

Any thoughts, ideas, or confirmations?

-Shuuz
 

·
Registered
Joined
·
1,818 Posts
Yep.... I think you've already diagnosed it.

A method to test if it's got a leak, get a hand vacuum pump - like a mighty vac - and use it to pull a vacuum on the booster. I had to get tubing adapters from the parts store to make it work. Once the vacuum is pulled, just let it sit. It should not drop at all unless you press the pedal. If it does drop, (or in the case of my original booster - it couldn't even draw a vacuum at all) then it's failed and definitely needs replacement.


The other possibility is that you simply have vacuum leaks elsewhere and it's not able to pull enough from the booster. Using that mighty vac "teed" into the line, you'll be able to see if you're getting enough at idle to make it work. I had enough leaks at first that I was only getting 11-13 inches of vacuum. Once I replaced the carb, I was up to 19-20 inches (ideal).
 

·
Premium Member
Joined
·
843 Posts
Rotors were seized to the hubs?
What type of front brakes are you running?
 

·
Past Texas Director
Joined
·
6,185 Posts
Definitely sounds like you're in need of a new brake booster.
You can pop off the vacuum hose that hooks to the booster, and shove a same size diameter bolt in the end of that vacuum hose, and drive it as if it has manual *as in NON POWER BRAKES until you get a new booster put on. (do it SOON though! I do not suggest driving with the vacuum hose plugged like that except in case of getting the car safely home.) Once that booster takes a final crap on you, you won't stop, so keep that in mind! Be careful and get a new one put on! Good luck to you!
 

·
Registered
Joined
·
58 Posts
Discussion Starter #5
I know they are disk brakes on the front, However, I do not know how to mechanically describe them! Sorry rnhart3! I know I took a blow torch and got em red hot. Still no dice!
 

·
Premium Member
Joined
·
5,785 Posts
The hub and rotor are one piece if stock. Hope you get it figured out but watch out for us old timers poking at you a little - as in this is not a Honda, its an OLD chevy.
 

·
Registered
Joined
·
58 Posts
Discussion Starter #7
Ahh I See!

Well, if I remember correctly it was the "spindle" that it was fused to :p
 

·
Registered
Joined
·
2,102 Posts
you can test the booster by pumping the pedal several times with the engine off to remove all stored vacuum then starting the engine with your foot on the brake, the pedal should drop away from your foot slightly. also after idleing for a couple minutes turn it off and let it sit for 20 min. pull the vacuum check valve out of it and you should hear a rush of vacuum when you pull it out. from inside the car you should hear a slight sound when you press the pedal that stops when the pedal stabilizes,if the niose continues when the pedal is down the booster is leaking from the actuater valve. dont forget to check the vacuum supply hose for obstruction and colapsing. also check the check valve for function.you should be able to blow through it from the booster end but not the engine end
 

·
Registered
Joined
·
55 Posts
Brake light will not go out

I am having a problem with my 1987 elky. The brake light on the dash will not go out. I bleed the brakes several times 32 oz fluid. still a light found the left rear wheel cylinder leaking replaced it bleed that side and still have a brake light on. I read this post and pumped the brake with eng off, started car and the pedal went to floor what does the indicate?
 
1 - 9 of 9 Posts
Top