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Quick- help me diagnose a brake problem on my DD

N

nitroheadz28

New member
Heres the deal, was returning from school last night. About a mile from my house, I was coming up on a light and the brake pedal started sinking to the floor. When I hit the brakes, its firm as soon as I tap it and will slowly sink to the floor. If I pump the pedal as I'm braking the pressure will return after I let off and the pedal will once again sink.

At first I thought I had a leak in the flex lines, I topped off my MC (was half full)- to my surprise it was still 100% full today after driving 50 miles with this issue.

I've had an MC go out on another car, and it felt entirely different. As of now I suspect either blown seals in the MC or issues with my booster. What do you guys think?

I'd like to run my car at the track next wednesday so hopefully I can get her up and running asap!
 


Yes sir, everything else has tons of meat on it. Calipers/ lines appear to be dry, I will jack the car up tomorrow and confirm this.
 
Eh, I've had my MC go out on my Fiero and have zero braking power. The difference is that it was 5 speed, and had a working e-brake (albeit very weak). I really needed the car for class today, my commute is 90% highway so I just kept downshifting to slow down- not my first rodeo :). It would have been more reassuring if this car had a working e-brake, but thats on the to do list.

I'm thinking of what else to order along with an MC, SS flex lines. I'd consider using 12" rotors off an Impala and the Intrigue brackets, but not sure if they'll fit under my 16"s.

Thanks again!
 


I still have braking power, I don't put others on the road in danger. Regardless I have driven cars with broken steering racks/ no brakes/ ect. its not my first rodeo lol. I know where you're going with this and like I said, the car was necessary today and still safe enough to drive. I won't need it until the week after next so I have time to make repairs.
 
nitroheadz28 said:
I'm thinking of what else to order along with an MC, SS flex lines. I'd consider using 12" rotors off an Impala and the Intrigue brackets, but not sure if they'll fit under my 16"s
Click to expand...

they'll fit. lots of us ran that setup.

and i would agree that this seems like a MC problem.
 
Bleed your brakes and see if any have air in them. If one does then somewhere in that line there is a leak.
 
I ordered an MC this morning. I was going to get SS flex lines as well but decided to hold off on it for now, I don't want to load too much cash into this car as its just a beater. I guess I'll see in a few days when it gets here and I install it, at least I got a pressure bleeder so it'll make bleeding brakes that much easier.
 
Grrrrrrr. I bench bled the new MC last night, swapped them today w/o any issues. Then I go to the RR caliper and pb blast it, let it sit for a few and then begin trying to crack it gently to the left and right- SNAP.

I figure I might as well check the rest of the bleeders, I go to the LR and do the same- SNAP. The 2 fronts are fine, calipers look newer.

1 caliper has enough of the bleeder sticking out to weld a nut on, the other is flush- they're both rusty as hell so I'll just replace them. Man this car is rusty :(
 


jeez I thought mine was the rustiest grand prix and i just bled my brakes the other day with no problem. Sorry about your luck. Hope you get it going soon.
 
Thanks me too. This one is pretty bad, its got huge holes in the rockers. The subframe and suspension look alright, but you know that a good half of those bolts are just rusted in place- the rear trailing arm mounts look iffy. I'm going back and forth on whether I should get rid of this car or not, it does run like a raped ape apart from the crappy mileage.

I'll see if I can get the bleeders out with an EZ out tomorrow (highly doubt it but worth a shot), if not I'll be looking for an Fbody or some other brake upgrade.
 
That's the only part of doing brakes that I dislike..trying to bleed with ancient bleeders. I've had good luck with reverse drill bit looking extractors. Then I often buy the one man bleeders for the extra $2
 
Ah damn thats no bueno. The stock calipers are pretty damn expensive new, around $80 each (ouch). If I'm going to have to spend money, I sure as hell would rather upgrade..

Not sure what to do, I haven't found the damn EZ out bits yet either :mad:

It seems that the gxp brake setup isn't too common. I found one setup for sale but its $500, a bit more than I want to spend. Blah!
 
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just got a pair of Raybestos "pro" reman calipers with brackets for $46 each (and no core charge) shipped from Amazon. the paint is drying on them as I type.
 
Got a link for em?

I was pricing em out everywhere today, I actually found a type of Raybestos calipers on Amazon for like $52 but there was no specification for which side- only "rear" and they aren't identical considering the bleeder placement.

What I did find on ebay is a place not too far from my school that has Centric reman calipers for $46, I messaged them about picking them up but I don't know how good Centric is.. Waiting on their response anyway, but I'd prefer Raybestos- not to mention all of the ones I've seen come loaded. Time to do more searching!

Edit- I found em! But alas, out of stock :(
 
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Yeah Centric did turn out to be good. Got the calipers last week, installed them. I had a problem with bleeding though. The drivers side rear didn't want to bleed, there must be an obstruction in the line. I bled it like 75% and go frustrated with it, I still have a low pedal. I'll give it another shot this weekend, this time I'll do a 2 man pump bleed and no a pressure bleeder to see if I can force out whatever is stopping the fluid.
 
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