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Not enough vacuum for brakes?

R

Runicdionysus

New member
Turbo kit all put together and running good. Had to get the smaller brake booster from zzp to fit the 3" DP of course. but now the brakes are ROCK HARD. It stops, but with an insane amount of effort. First though was to bleed the brakes, no change. Couldn't figure anything else out so I took it to the performance shop we have here in Albuquerque to let them tinker with it. After a few weeks they're now telling me that I don't have enough vacuum at idle for the brakes and said I need to install an electric vacuum pump. they told me that when they add more vacuum with a pump the brakes come back and work normally. Anyone had this problem before? Is their another way to fix it besides spending $400 on a pump?
Thanks.
 


whats your set up intake wise? if you pull the vac line off the booster is there vacuum?

maybe you got a beat booster?
 
Something not right. I run the smaller brake booster and it stops me just fine at the track with traps at 135mph.... on stock brakes too.

Either vac leak, or using a hose that is collapsing? or the checkvalve is bad?

Either way something is not right in your setup.
 
Me thinks you didnt bleed the master correct, my truck did the same thing, after correct bleeding it was fixed.
 


Would something like this keep the brakes from holding when trying to brake boost? When i try to build boost i just roll through the brakes.And they do not stop very good when hard braking. They are corvette callipers and rotors so I would think they would hold good. Thanks for any advise
 
got the calipers on with the bleeders up?

mushy pedal is a bad master, a leak, or needs to be bleed, hard pedal is the booster not working. or not getting vacuum.

turn the car off pump the pedal, it gets hard, thats what no vacuum to the booster feels like.
 
I have an st5 cam and it only pulls 14 inhg at idle and mine stops fine too with a small booster and f body brakes. The first small booster I had was **** and the brakes were insanely hard
 
The front 2 calipers have the bleeder facing down the rears are up. The pedal is defanatly not hard. It is kinda soft now that I really pay attention. Do I need to swap the calipers and then bleed them? I don't see that I have a leak anywhere. Thanks for the help
 
yup. you messed up the install. flip each caliper to the other side of the car, bleeders up, re bleed, you'll be good as new.

pretty common f up. just need to keep in mind if the bleeder is not up, air cant get out.
 


Finally getting back to this post months later... I had some family stuff come up and had to put the GP on hold for a quite a while. I've figured out with 98% certainty it's the booster. Just getting back into it now. Now when Depressing the brake pedal you can hear an air leak type of noise and the RPMs jump up. Figure the diaphragm in the booster is ripped or damaged and is causing a vac leak. I'll be ordered another one from ZZP soon and see if that correct the problem.
 
if you pump the brakes you will hear a hiss, and the rpms will go up,,,why you ask? cause your took vacuum from the engine to re fill the booster.
 
Scottydoggs said:
if you pump the brakes you will hear a hiss, and the rpms will go up,,,why you ask? cause your took vacuum from the engine to re fill the booster.
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oh well i feel dumb :th_laugh-lol3::th_laugh-lol3: I didn't ever recall that happening before the turbo. Maybe I'm just looking for something to be wrong. I figure it would be best to get another booster anyway since that is most likely the issue.
 


fix the calipers and re bleed then, make sure the master is done properly, you cant just add fluid and be on your mary way
 
Runicdionysus said:
I didn't even touch the calipers. Just removed the master, removed the old big booster, put in the new booster and then reinstalled the master.
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if you have not flipped your calipers over yet,,,,,why are you posting about the booster again? fix the calipers, life will be good again.
 
Scottydoggs said:
if you have not flipped your calipers over yet,,,,,why are you posting about the booster again? fix the calipers, life will be good again.
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I'm sorry I'm confused. After installing a smaller brake booster it is necessary to flip the brake calipers over and bleed them? What exactly does flipping them over mean? is it literally unbolting them and turning them upside down? lol
 
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