C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

1990 Brake problem

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Old Jun 26, 2011 | 03:34 PM
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Default 1990 Brake problem

I have a brake problem , almost acts as if my power brake booster is not working , I have replaced it 3 times, the first 2 where like the original , plastic both cracked by the vacuum connection the last one I installed is made of metal , I am not loosing any fluid, but the brakes are not good to the point my wife won't drive the car and I find I have to really use a lot of pressure on the peddle to achieve that the car stops. My thoughts are the calipers need to be rebuilt or replaced yet I am not loosing brake fluid , any thoughts would be appreciated !
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Old Jun 26, 2011 | 04:08 PM
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Originally Posted by Joe
I have a brake problem , almost acts as if my power brake booster is not working , I have replaced it 3 times, the first 2 where like the original , plastic both cracked by the vacuum connection the last one I installed is made of metal , I am not loosing any fluid, but the brakes are not good to the point my wife won't drive the car and I find I have to really use a lot of pressure on the peddle to achieve that the car stops. My thoughts are the calipers need to be rebuilt or replaced yet I am not loosing brake fluid , any thoughts would be appreciated !
Did you check the vacuum line for cracks and split end on connectors??
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Old Jun 26, 2011 | 05:05 PM
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Well I have had this problem for a couple of months and I am trying to back track what I might of done to cause a problem , I replaced the fuel injectors but some where in testing them I did have a fire , the AC control stopped working and I found a vacum line under the distribuator that had burnt so I cut it , cleaned it up and hooked it back together with some shrink tube , was thinking the shrink tube might be colapsing but the AC is working fine and also there seems to be lots of vacum at the end of the booster line !

Then around the same time I preasure washed the front brakes , as I hade both wheels off to polish them !?!?
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Old Jun 26, 2011 | 08:45 PM
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From: levittown pa. usa Even a bad day with my `Vette, is better than a good day at work
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I feel for ya bro`. I just replaced the booster on my `90. What a PITA that was with arthritis in my back & shoulders working against me Now I have to take almost everything apart again because I did not tighten the right side nut enough, & when I step on the brake the booster moves to the left. DANG!!
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Old Jun 26, 2011 | 09:19 PM
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Yup sorry to hear about your arthritis but am glad someone else knows what it is like , I have 2 kinds of arthritis , fibromyalgia , both my knees are wore out and I feel like every dollar I earned I had to earn it twice , seeing I got married at 16 in 1966 and we are still trying to make it work might have something to do with being wore out !
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Old Jun 26, 2011 | 09:40 PM
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You could have a bad booster or check valve.
Another possibility is the output rod on the booster is not adjusted out far enough. If it is not set properly, it doesn't reach inside the master cylinder far enough to push on the piston. Does your pedal feel like it's using too much travel? That is a symptom of a miss adjusted output rod.
When you pressure washed the brakes, did you use any detergent? That could have contaminated the pads and rotors. Or even the high water pressure could have moved oil and grease onto the pads.
If you're truly getting good vacuum to the booster (I don't know the inches, maybe 20?), my first suspicion would be the booster or valve.
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Old Jun 26, 2011 | 10:24 PM
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From: summerfield ( Villages ) FL.
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I have a good pedal , very little travel , firm , does not go down after I hold it for a min. or 2 but when trying to stop it is as nothing is grabbing , heart is in your throat then the car will finally stop if you really press hard but still does not lock up the wheels or even comes close , I guess I will try new pads first maybe I got something on them but seems strange both sides as the car is not grabbing to one side or the other.
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Old Jun 27, 2011 | 12:00 AM
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There should be a significant difference in pedal feel between engine running and engine off. If you think you have oil and grease on the fronts why not scuff the pads and rotrs with 400 grit sand paper and wash everything with brake clean. Even if it does not make them perfect it might tell you if you are the right track.
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Old Jun 27, 2011 | 05:41 AM
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Originally Posted by Joe
I have a brake problem , almost acts as if my power brake booster is not working , I have replaced it 3 times, the first 2 where like the original , plastic both cracked by the vacuum connection the last one I installed is made of metal , I am not loosing any fluid, but the brakes are not good to the point my wife won't drive the car and I find I have to really use a lot of pressure on the peddle to achieve that the car stops. My thoughts are the calipers need to be rebuilt or replaced yet I am not loosing brake fluid , any thoughts would be appreciated !
My 90 does this too brake pedal stays up after pumping the brakes, then immediately falls down a far way. But on mine seems like it has little to no front braking action. Wondering if seized pistons from sitting so long is the problem. Yours sounds like that check valve is bleeding vacuum down. I don't loose fluid either.
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Old Jun 27, 2011 | 08:28 AM
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I don't have to pump mine to have a good peddle, that is usually a sign the master cylinder is bad , another is to hold your foot on the peddle and push hard for a min. or 2 and if the peddle goes to the floor the master sylinder is bad , I don't have this problem but yes it is as the front brakes are bareley working.
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Old Nov 27, 2017 | 09:00 PM
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Did you ever figure out your problem
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Old Nov 27, 2017 | 09:45 PM
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I would be interested in knowing as having the same problem.
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Old Nov 27, 2017 | 10:02 PM
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I am on my 2nd booster in 3 years the first just cracked right down the middle and the latest Cardone model is plastic but the brakes work way better that the 1st one ever did. You may have received a bad or a poorly working booster.
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Old Nov 29, 2017 | 12:47 AM
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lost interest , might order a new pair of drilled slotted rotors and new pads if that don't work at least I know what is not wrong
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