Serious Brake problems

[GiDvEtTe84]

I have an 84. This only happens when its cold (about 50 degrees F and under) My brakes seem very hard, especially if I apply them quickly. It feels as if the booster is not working. My booster and check valve are rebuilt/new and the master cylinder is only a couple of years old as well. It seems like there is good vaccum to the booster but its hard to tell. The line from the intake to the booster does not seem the have any leaks and my engine does not run with a high idle like I would have a Vac leak. I really need to get this figured out because its nearing winter time. I would also like to ask if anyone has a diagram of the 84's vac lines. Thanks.

 

[Tuna]

What kind of pads do you have on the car?

Some of the 'high performance' pads don't work well until they are warmed up. Is this what you are noticing?

 

[JonM]

Sounds like you do have a leak someplace in the vacuum system...could be the booster leaking again. This is one of the reasons I would never go with rebuilt when it comes to brakes or related components. The vacuum diagram should be on the cowl above the radiator. Gid…are you able to get into the CROSSFIRE forum…I have been unable for a couple days.

 

[GiDvEtTe84]

Thanks for the help. Ken is having trouble with his new DSL since he moved. He is waiting on a cable modem so he can ditch the DSL. Just sit tight. Thanks man.

 

[GiDvEtTe84]

Oh yeah, I have regular rebuilt pads. The pads arent giving me problems. Its just the hardness of the brakes. Someone mentioned the master cylinder before too. I suppose it could be that. Its only a couple years old.

 

[jsinga]

If it goes away when things warm up it sounds like it's the brake pad compound. Will the brakes come up if you make a few quick hard stops before the engine warms all the way up? If it does that's a sure test to see if it's the pads.

JS

 

[GiDvEtTe84]

No they dont work even though i pump them or anything. It will stop but i have to stand up on the pedal. It feels hard like the booster isnt working. Everything is fine all summer. Like today, its 75 in the morning and 84 in the afternoon. No problems at all.

 

[vettenick]

Disconnect and plug the vacuum supply to the booster and drive the car. If it feels the same, your booster is not doing it's job.

 

[86PACER]

I HAD THE SAME PROBLEM. I THEN BEGAN TO HEAR "HISSING" WHEN I HAD TO STAND ON THE BRAKE PEDAL. IT TURNED OUT TO BE THE BRAKE BOOSTER.:duh

 

[GiDvEtTe84]

Just to update you guys from last year:

I changed the booster and my brakes still do the same thing. I also ran new hoses. Thanks.

 

[vettenick]

Jack the car up, have someone step on the brake pedal, and see if you can rotate each wheel by hand. This will indicate if there's no braking at one or more wheels. If it's just one or two wheels, then back track the lines until you determine why you don't have pressure. If it's all four wheels, then I'd look at the master/booster set up. By the way, are you sure all of the air is out of the system? When you let up on the brake pedal, is the master cylinder/booster rod fully retracting? Take a look under the dash. Make sure there's nothing in the way of the brake pedal and rod. Also, make sure that vacuum is getting to the booster. Remember that check valve should allow vacuum to the booster. It should allow vacuum in one direction. If it allows vacuum in both directions then it's bad. Remember to check it when it's cold. Take it off, put it in the freezer for an hour, then check it. Forgive me...I'm just thinking aloud.

 

[GiDvEtTe84]

Thanks. I have bled the system. The booster is new but the MC is a couple of years old. It seems like a vaccum problem. I have not changed the little filter on the line. I have stuck that thing into the freezer and blew through it and it does not restrict at all. Bleh.

 

[vettenick]

Did you put the filter or the check valve that's on the booster in the freezer?

 

[GiDvEtTe84]

I put the filter in the freezer. Checks out ok. The valve is brand new. I havent broke the seal between it and the booster.

 

[vettenick]

At this point I wouldn't overlook anything. I would take that valve off and check it when cold too. It seems that you've checked everything else.