brakes

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brakes

Post by coreys73chevelle on Sat Jun 12, 2010 7:48 pm

i bleed my brakes and put the car on jacks with the engine OFF and it stops the front good, same with the rear. BUT i start it and have nothing goes to the floor. i can pump them up and they feel firm at idle but as soon as i put it in gear it goes to the floor and the car lurches then dies. whats goin on??? have good vaccum and the vac line for the booster is to the back of the carb and there are no vac leaks
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Re: brakes

Post by bigredlaguna on Sat Jun 12, 2010 10:49 pm

Is your master cylinder new?
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Re: brakes

Post by ant7377 on Sat Jun 12, 2010 10:54 pm

Sounds like Master is no good.
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Re: brakes

Post by coreys73chevelle on Sat Jun 12, 2010 10:58 pm

i think i just need a vacuum canister, cant i use the charchol canister for one? if so how? i know a vacuum canister looks about the same has a line from the intake manifold to the canister then from the canister to the booster
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Re: brakes

Post by bigredlaguna on Sat Jun 12, 2010 11:24 pm

The missing charcoal canister would not cause your brakes to do what you described. If any thing, a vacuum leak would make it harder to push the brake pedal.
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Re: brakes

Post by coreys73chevelle on Sat Jun 12, 2010 11:28 pm

http://www.jegs.com/i/JEGS/555/63010/10002/-1 this is what i think i need i dont have any vacuum leaks
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Re: brakes

Post by bigredlaguna on Sat Jun 12, 2010 11:35 pm

The symptoms you describe are not consistent with not having any vacuum or having low vacuum. It really sounds more like a master cylinder problem.

The pedal sinking to the floor while in gear will not happen if the hydraulic system in the brakes is good.
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Re: brakes

Post by BlackChevelleSS on Sun Jun 13, 2010 1:58 am

If you had a vac leak or low vac then the pedel would be hard to push.

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Re: brakes

Post by lagunainnewark on Sun Jun 13, 2010 7:38 pm

An easy test for the master cylinder is to take vice grips and clamp each rubber hose on at a time while checking the brake pedal between each clamping. If at the end with no change in pedal feel then the master cylinder is bypassing fluid internally. If you can pump the pedal and it improves you have air in the system or the rear shoes are way out of adjustment. Good luck, Ron
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Re: brakes

Post by 77malibu77 on Sun Jun 13, 2010 7:49 pm

since we are talking about brakes, how would i be able to tell if my rear brakes are working?? jack it up and have someone hold down the brakes and then try to move it?
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Re: brakes

Post by coreys73chevelle on Sun Jun 13, 2010 7:52 pm

77malibu77 wrote:since we are talking about brakes, how would i be able to tell if my rear brakes are working?? jack it up and have someone hold down the brakes and then try to move it?

jack it up and take off the tires. see if you can turn the drum or take it off, leave it on there pump the brakes and see if it get harder to take off. or put it on jackstands and start it put it in D and press the brakes the tires should stop also if the drum is off the cylender on top will push out if it leaks replace it
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Re: brakes

Post by novaderrik on Mon Jun 14, 2010 4:33 pm

lagunainnewark wrote:An easy test for the master cylinder is to take vice grips and clamp each rubber hose on at a time while checking the brake pedal between each clamping. If at the end with no change in pedal feel then the master cylinder is bypassing fluid internally. If you can pump the pedal and it improves you have air in the system or the rear shoes are way out of adjustment. Good luck, Ron

this is a good way to make good hoses go bad. they aren't designed to be clamped like that.

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Re: brakes

Post by 74Malibu383 on Mon Jun 14, 2010 4:50 pm

I've listened to your start-up videos. That cam doesn't sound radical enough to need a vacuum canister. I second BigRed's thought about the master cylinder.

I see you have a new power booster on the car.... Did you "bench bleed" the master cylinder before you attached everything? If not, it could just be a matter of air in the system.
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Re: brakes

Post by coreys73chevelle on Mon Jun 14, 2010 5:51 pm

74Malibu383 wrote:I've listened to your start-up videos. That cam doesn't sound radical enough to need a vacuum canister. I second BigRed's thought about the master cylinder.

I see you have a new power booster on the car.... Did you "bench bleed" the master cylinder before you attached everything? If not, it could just be a matter of air in the system.

yes i bench bled the master used 1/2 a quart of dot3
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Re: brakes

Post by coreys73chevelle on Mon Jun 14, 2010 5:56 pm

tried it agian today. brake pressure feels ok with the engine off, but start it up and it is soft and goes to the floor, i take the hose off at the booster and there is plenty of vacuum. when i have the engine off and i press the pedal all the way as far as it will go and let it come up on its own it pops sounds like it coming from the booster? wierd sound but no brake fluid leaks anywhere.
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Re: brakes

Post by 77malibu77 on Mon Jun 14, 2010 6:36 pm

coreys73chevelle wrote:tried it agian today. brake pressure feels ok with the engine off, but start it up and it is soft and goes to the floor, i take the hose off at the booster and there is plenty of vacuum. when i have the engine off and i press the pedal all the way as far as it will go and let it come up on its own it pops sounds like it coming from the booster? wierd sound but no brake fluid leaks anywhere.

i think i had this problem after my brakes went out and i had to swing around the corner with no brakes and no emergency brake at 35 miles an hour whoa nelly was hectic
but what happened was i had a hole in my brake line and i changed it out and it did the same thing you were saying, i just kept bleeding the brakes at least a hundred times and eventually it worked lol, i did it like 10 times then tried it the next day and wasnt happy and kept doing it for like a month, and they work fine now just when i stop the front ones squeak bad (need to re finish the rotors and get different brake pads) and i was just wondering if my rear brakes were working
when i bought my car it said it had a new master cylinder but i think i took the one off my 77 malibu and it worked a lot better and ive had no other problems other than wondering if my rear brakes work
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Re: brakes

Post by 74Malibu383 on Mon Jun 14, 2010 6:41 pm

You did replace all of your lines if I remember correctly. That's a lot of air to bleed out. Could just be a couple bubbles somewhere. What about renting/buying a power bleeder?
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Re: brakes

Post by lagunainnewark on Mon Jun 14, 2010 9:03 pm

If the hoses are so old and aren't flexible enough to take a tight turn or clamping, you should have changed them before now. Ron
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Re: brakes

Post by coreys73chevelle on Mon Jun 14, 2010 9:11 pm

74Malibu383 wrote:You did replace all of your lines if I remember correctly. That's a lot of air to bleed out. Could just be a couple bubbles somewhere. What about renting/buying a power bleeder?

yes brand new stainless steel prebent lines from inlinetube.com im going to bleed em some more
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Re: brakes

Post by 77malibu77 on Mon Jun 14, 2010 9:27 pm

coreys73chevelle wrote:
74Malibu383 wrote:You did replace all of your lines if I remember correctly. That's a lot of air to bleed out. Could just be a couple bubbles somewhere. What about renting/buying a power bleeder?

yes brand new stainless steel prebent lines from inlinetube.com im going to bleed em some more

i bought some from napa auto parts they custom make brake lines and fuel lines and things of that nature and they are easy to bend without breaking and work perfect
id reccommend bleeding the brakes from each wheel i need to do that but i kind of stripped all of those screws so i just bleed mine from the master cylinder hahaha!
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Re: brakes

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