I seriously need some help here. I have been trying to get my car to brake well since last summer and I just cant seem to figure out what is wrong. So far I have bought a new booser, added a vacuume canister, put in all new brake fluid and I still cant stop very well. I just got done checking out the front calipers and they both look like they are in pretty good condition. Good pads and grease on the sliders. What else could it be. The pedal goes down about half way but is very firm at that point. Could the master cylinder be the cause?

 

Have you bled them? Bench bled the master?

Bleeding brakes is absolutly nessecary.

 

I made absolutly sure that when I put new brake fluid in that I bled all 4 calipers perfectly. I have never bled the master before so im not sure how to do it. But I thought that air in the line just gives you a soft petal. I could be wrong. The petal is firm but doest brake hard.

 

That's funny, I have the exact same problem. Very frustrated. I have added new fluid, changed the brake booster vacume valve, replaced master cylinder, and was about to go buy a new booster. When I push on the pedal it feels like the booster is working for a few inches, then its hard as a rock and my braking sucks!

 

Well if you replaced the master cylinder and that didnt help then were down to either clogged brake lines or shot calipers. Anybody else have any ideas/opinions?

 

if you have drums, check to see if there adjusted correctly, if they are to far in, youll get a poor pedel feel.

 

4 wheel disk
The fronts work really bad but the rears barely work at all

 

I have rear drum and front disk. I adjusted the rear drums. I know the lines aren't clogged because I changed all the fluid. I raised the rear end and got the tires moving pretty fast then hit the brakes really hard. Both the rear tires locked up at the same time.
I want to believe its the booster check valve. When I suck on the booster side of the valve it takes a second before it closes and restricts air flow. If I suck and blow gently the valve never locks closed...Isn't it supposed to be only a one way valve? It seems that if air can go both ways for a second then my booster is equalizing with my engine all the time. That means under acceleration I won't have any vacume assist at all..? Am I understanding this right?
With that said, I went to the auto parts store and bought a new check valve. I opened the box right in front of him and started sucking and blowing on the part...same problem. I asked him what the problem was and he didn't know.

 

Could be the brake hoses also

 

im leaning toward the front calipers are shot. on my 88 four wheel disk 9 bolt rear brakes worked like new would lock them up in a second then had to sell my car then years later finally got her back brakes sucked bad put in the LS1 rear thought this would give me better brakes nope didn't then put in a 1LE proportioning valve when i took out the old one it fell apart the valve inside for the rears was shot so thought this was it nope same deal backs where a little better so now im waiting on the rest of my LS1 front brake kit from ed miller. one thing i have noticed is that since i got my car back the front brake pads last for ever! and there cheap ones.

 

Ok Since this isnt going to be as simple as I hoped im going to just replace everything from the rubber lines forward and pray thats where the problem is.

Any suggestions on upgraded calipers without haveing to buy to much extra crap. I dont feel like replacing spindles. Im going to buy earls stainless lines and hawks hp pads. Im just going to ruff up the disks with some heavy grit sandpaper since they are not warped. Any opinions on the calipers are welcome.

 

Well I think I found the problem with mine... I don't think that I'm pulling enough vacume to help my booster. I didn't think that I had a very extreme cam, but i guess I do. I am ordering a Vacume Resevior from Summit. I think that might be the problem with yours as well, assuming you have a 383. I will let you know in a few days when it arives.

 

I already added a vaccume canister last year. It did help a bit but the brakes are still weak. Even if it wasnt the problem it did help and I think it was a great investment for 30$ or 40$.

And yes by the way I am running a pretty aggressive cammed 383 but with the canister I have lots of vaccume.

 

Any progress? I'm curiouse to know what the problem is.

 

Nope not yet. It got cold again so I covered her back up. Once it gets warm again im just gonna start replacing stuff until it gets better. I wish i could just upgrade but im stuck with these GTA rims and I dont think theres any upgrades that will fit under there. I do kinda like the rims though.

 

Welcome to my world!! I have the exact same symptoms as 383GTABoy. My 1991 1LE with cam and mods etc stops horribly. Im pulling 13"-14" if I remember correctly on a cam thats not radical. I changed:

check valve--> nothing
rubber brake lines to stainless braided---> nothing
Bled and re-bled--> nothing
vacuum can--> nothing
new rear calipers--> some improvement
new master--> nothing

Im looking into a new prop valve ((a tech at work thinks this is the issue)), some better pads like HAWKS and maybe new front calipers. I used to be able to literally lock the fronts up and screech the tires if I stabbed the brakes. Now it just comes to a pathetic stop.