Front breaks lock up, back ones don't?
Instructor
Joined: Jun 2001
Posts: 116
Likes: 0
From: Brighton MI
Re: Front breaks lock up, back ones don't? (Road Racer)
When you bench bled the master cylinder, how did you clamp it in the vice? If you did it anywhere other than the ears that you put the bolts through to mount it, you may have destroyed your seals. I wrecked one master by clamping it in the vice wrong. Really easy to do. I started putting them on the car to bench bleed.
Good luck
Good luck
Thread Starter
Burning Brakes
Joined: Jun 2002
Posts: 809
Likes: 0
From: Derry NH
Re: Front breaks lock up, back ones don't? (AV76)
I clamped it in a vise. There is really only one spot to grab the master cylinder, on the bolt hole area is the only place to grab without doing damage.
This is not the first master cylinder that I have bench bled. :flag
This is not the first master cylinder that I have bench bled. :flag
Abby Normal
Joined: Dec 2001
Posts: 53,466
Likes: 92
From: Press "2" for English
Re: Front breaks lock up, back ones don't? (Road Racer)
first thought i had is, did you have rear rotors turned? i have heard they must be turned as an assembly. if they were turned separately, they may have too much run-out and cause the back calipers to suck air. backs won't do anything but fronts lock up and pedal goes to the floor, the more i think about it the more i need the answer to that question. if that isn't the case, then i would suspect the proportioning valve or the flexable lines.
not a big fan of the silicone fluid. i always heard it was intended primarily for cars that saw little road use like show cars. i run blue oval DOT 3 but i beat the daylights out of my brakes.
not a big fan of the silicone fluid. i always heard it was intended primarily for cars that saw little road use like show cars. i run blue oval DOT 3 but i beat the daylights out of my brakes.
Thread Starter
Burning Brakes
Joined: Jun 2002
Posts: 809
Likes: 0
From: Derry NH
Re: Front breaks lock up, back ones don't? (clutchdust)
Before installing the new rear calipers that I bought, I bought a proportioning valve (switch) and replaced it hoping that would be my problem and I could return my calipers. I bled the system with a hand held vaccume pump. I pumped till I filled the jar three times, each wheel and I felt a good pedal, although I still got some air through. I put my tires back on and went to test my breaks, they went right to the floor with the engine running. So I put the car back up on stands and started the bleeding process again. My question is, why do I keep getting air bubbles? dose bleeding take so much pumping? I will continue the bleeding tomorrow morning. The pump is connected correctly with no air leaks I even wraped teflon tape around the bleeder nipple thread to secure the seal. Has any one used these pumps? Do I need to pump each break 30-50 times? What the heck? :confused:
Instructor
Joined: Jun 2001
Posts: 116
Likes: 0
From: Brighton MI
Re: Front breaks lock up, back ones don't? (Road Racer)
I have heard that when you bleed brakes with a vaccum pump it is possible to pull air in through the seals on the calipers. Not sure if there's any truth to that, just trying to throw around some ideas. Try a different method for bleeding. I have had good results using a pressure bleeder.
Thread Starter
Burning Brakes
Joined: Jun 2002
Posts: 809
Likes: 0
From: Derry NH
Re: Front breaks lock up, back ones don't? (AV76)
OK! I bled the heck out of the breaks and still no good pedal. So I replaced the left caliper I could not remove the right one because one of the bolts is pretty much frozen on. I broke a wrench trying to take it off, I used my air gun set at 4 (max) it would not budge, so I left it alone. I also found out that the rear calipers have two bleeder nipples. My Haynes book said that the two bleeder nipples started on the 78 models. So I bled like the book said left inner left outer, right inner right outer. I took the master cylinder off and bench bled it again. I now have some pedal, the car stops pretty good. I wish my pedal was harder but its good enough. I guess the master cylinder still had some air in the rear reservor along with some air trapped in my rear calipers because I did not know about the two bleeders on each caliper. So my break system is mostly new except the lines which are in good shape and the right rear caliper which I could not get off. Thanks for all your help! I used everyones suggestions.
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Advanced
Joined: Sep 2002
Posts: 62
Likes: 0
From: Houston Texas
Re: Front breaks lock up, back ones don't? ('79ProwlerOrange)
Wait a minute 79prowerorange, are you saying that AutoZone does not make good calipers for our vettes? If you are then I would have to say that you are the exception, because I have replaced all four brake calipers with the AutoZone ones and I have not had a single problem(5 years with over 40k miles) with either one and if I do its lifetime replacement warranty helps and to answer the intial problem in question you may have forgotten to place the brass washer on the brake line to the caliper itself.
Scott
Scott
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Safety Car
Joined: Feb 2002
Posts: 3,556
Likes: 0
From: Seattle WA
Re: Front breaks lock up, back ones don't? (SBcoupeC3)
i dont know about vettes, but i had bought brake componentes for my TA and my blazer and all wer total crap. on both vehicles i had to replace the brakes within a year. i order from VB&P for the vette. havent driven it for a year straight, so i dont know about their products. seem good so far!
i stick to NAPA and CarQuest for the daily drivers. :cheers:
i stick to NAPA and CarQuest for the daily drivers. :cheers:
Abby Normal
Joined: Dec 2001
Posts: 53,466
Likes: 92
From: Press "2" for English
Re: Front breaks lock up, back ones don't? (Road Racer)
road racer, on the front brakes there is a copper compression washer that fits between the brake line fitting and the caliper. you should have one there, if you don't 99 times out of 100 it will leak from there. most likely, you do, it's just stuck to the fitting that screws into the caliper. you should use a new one every time you break the seal though.