I am having problems getting pressure back on the brake pedal after bleeding the brakes.  Can this be caused by a bad proportioning valve and if so what do i need to do from here.  Thanks for all the help. I am stranded and need a life vest!

From my experience it tends to be air in the lines. These cars are a b!*ch to bleed properly. You need to also bleed them weird, which the order is: drivers back, pass back, drivers front, pass front. Sarge812007-11-09 19:23:19

Did you have a good pedal before? Did you replace anything, like pads, or calipers?
If so, then you prolly do have some air in the system.

The p-valve can flop to one end if the brakes are not bled properly. If it does, you will only have brakes on one end or the other...front or rear. It will normally re-set itself if you do hit the pedal fairly hard, quickly. Does your "Brake" light come on? If it comes on when you press the pedal, but then goes back off, there is air in the system, or the master may be bad, or have air in it.


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Joel Adams
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I did have low pedal before but that was because I found out my right front caliper was leaking.  I replaced both front calipers and hoses on it and put new pads on the front.  I did not bleed the brakes in the sequence as described above.  The proportioning valve does appear to be leaking so I will try to bleed the brakes again in the proper manner.  Thank you for all of your help, I appreciate it!

For what it's worth I recently replaced a trailing arm assembly and when replacing the caliper, (with my son in the car as the brake pedal management assistant), I first tried to pump up the brakes and open the valve to let the air out and basically got nowhere. What worked for me was to open the valve on the downward movement of the pedal then close the valve for the upward pedal travel. Took a few strokes and trips to the master cylinder to add fluid but now the pedal is solid and the brakes are good.

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"Pumping" the brake pedal really only aerates the brake fluid...not a good thing when trying to bleed them!
With the pedal up, open the bleeder screw, then press the pedal down. Once it is all the way down, close the bleeder, and release the pedal slowly.(same method as described above). This works the best, is you have to manually bleed them with the pedal.
Tapping on the caliper with a plastic, or rubber mallet will also help dislodge any air bubbles stuck to the calipers, especially on the rears.
Of course, a pressure bleeder is the absolute best way, but not everyone has one. They are getting cheaper now, tho, so they are a bit more affordable, and well worth the investment for anyone with a Corvette with discs.

I have to say, my sequence for bleeding is not the same as Josh's...the normal procedure is:
RR-LR-RF-LF...you want to bleed the furtherest caliper from the master first. This lessens the chance of having trapped air in the crossover line, that may wind up just floating from one side to the other, and never really getting out.

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Joel Adams
C3VR Lifetime Member #56    
My Link


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"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

I used the same sequence Joel recommended and it worked fine.  I had the wife pump the brakes and I did the bleed screw management.  You need to close the valve before you let the pedal up to keep air out of the system.  I have a pressure bleeder, but have done just as well with the 4.99 brake bleed kit at autozone.  Little tygon plastic hose and bottle with a  magnet that make it easy.  I like the clear tubing as I can see the color of fluid and check for bubbles/debris in the system.

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C3: 1979 Corvette Coupe, Auto, L-48, Red/Doeskin (my wife's fave);

[QUOTE=Adams' Apple]I have to say, my sequence for bleeding is not the same as Josh's...the normal procedure is:
RR-LR-RF-LF...you want to bleed the furtherest caliper from the master first. This lessens the chance of having trapped air in the crossover line, that may wind up just floating from one side to the other, and never really getting out.[/QUOTE] defsegx2007-11-09 10:28:00

[QUOTE=defsegx]Ah. See I got my bleed order from another poster here who said the service manual said the rd, rp, fd, fp order. I'd probably listen to Adams', he knows a lot more about these things than I do [/QUOTE]

Well now...I don't know about that...

Perhaps the person that posted the other method is from Australia, or somewhere else that drives on the wrong side of the roads...

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Joel Adams
C3VR Lifetime Member #56    
My Link


(click for Texas-sized view!)             NCRS

"Money can't buy happiness -- but somehow it's more comforting to cry in a CORVETTE than in a Kia"

79rebuild2007-11-09 15:00:35

yup - replaced the rubber with SS. The primary hard lines were in good shape, but I may replace with SS just for appearance - but the steel ones are still good.  It really helped the feel to go with SS flex lines instead of rubber and it gives you a lot of confidence not having 30 year old rubber holding your brake system together.

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C3: 1979 Corvette Coupe, Auto, L-48, Red/Doeskin (my wife's fave);

The filter that was in the vacuum line does not affect the brake operation at all if it's working properly. kstyer2007-11-12 18:39:56