TOM305T/A

Hi guys, looking for a little assistance. on my GTA my brake pedal was very hard and didnt stop the car most of the time. i placed a new booster on and brakes seems better. i went for inspection they said back brakes arent working. i checked and wasnt getting any fluid to the rear brakes. i checked pressure at master cylinder. plenty of pressure, when i opened the rear line, no pressure at all. i replaced master have good pressure now leaving front and back when line is opened. (after i bled master) still no fluid in rear, changed all hoses..now i have brakes in the rear but brake pedal is alot harder. stops but pedal is still a little still hard. bled at all 4 corners no air, all new hoses master and even rear calipers. thanks in advance

Tootie Pang

iTrader: (2)

What pads/shoes are you using?

3.4 grape

iTrader: (1)

What about the check valve for the brake booster? Are you getting proper vacuum to it?

QwkTrip

iTrader: (22)

If the pedal is hard then I would suppose it comes down to three things:

1. Lack of power assist. Make sure the vacuum tube is there, in good condition, vacuum present, and that the check valve isn't stuck closed.

2. Obstruction in the brake lines. If fluid can't move then the pedal isn't going to move.

3. Restricted movement of brake calipers. If the brake calipers can't move, or are already locked up against the brake disc, then the pedal isn't going to move.

I'm not sure what the pedal would feel like if the balance bar in the prop valve were off center. There is a procedure to reset that.

TOM305T/A

I believe they were dealer brakes, my friend use to work at dealership and they were throwing away boxes of brakes and he picked me up a few. they seem to be working fine before the booster originally went

TOM305T/A

i used new check valve, went to old check valve and even bought a new one.. still the same. it has good vacuum, the idle changes when unplugged from the booster but i didnt check to make sure it was getting proper vacuum. whats the best way to check that.

TOM305T/A

seems like if brakes are pushed slower they stop better. even when brake pedal is hard, i can still look up tires. so its better than before when brake booster was bad. new hoses, calibers, rear brake lines, no air. and not calibers sticking

QwkTrip

iTrader: (22)

Well, you're calling it a hard pedal but maybe the brakes are just working normal for the first time ever?

A hard pedal is what the brakes feel like after pumping them a couple times when the engine is off.

QwkTrip

iTrader: (22)

How much of the pedal throw are you using? And did you check bore diameter the master cylinder before you installed it? A bore that is too large would increase pedal effort.

TOM305T/A

thats exactly how it feels maybe its a bad booster i think i got a ac delco from rockauto

TOM305T/A

i didnt check bore diameter, the master cylinder is also a ac delco from rockauto

QwkTrip

iTrader: (22)

How much pedal travel are you getting?

Make darn sure you have vacuum to the booster. Also make sure you don't have some kind of problem with the pedal that causes it to have restricted movement.

You're getting closer with every thing you fixed or determined isn't the issue. Won't be long now before you find the last problem.

TOM305T/A

sometimes its like he car is off and u pump the brakes sometimes its gives me regular brake travel. no restrictions with the pedal, i do have vacuum

antoine

What year is your car if it's an 88 down rear calipers

TOM305T/A

its a 87 i have already installed new rear calibers

ploegi

How old are the brake hoses? Does it feel like any of your brakes are dragging?

TOM305T/A

the brake hoses are new. no dragging. 60% of the time the brakes are fine its the other 40 i worry about

firefox7518

You maybe have vacuum in the booster but maybe it's filled up with brake fluid from the master! I had that on one of my cars :-( Took me ages to find the issue... just a hint as it sounded like my issue where I sometimes had brake assist from the booster and sometimes not....

TOM305T/A

how did brake fluid get in there. its a new booster. btw