I have a 1971 Chevelle which had Power drums..I converted the brakes over to power disk..I bought new rotors/pads/lines/changed the mc over to power disc I did use my old booster ..I also used a used prop valve.I bleed the system..seems as though the front brakes isn't working..I did the test where with the car running..hold down the brake pedal and turn off the engine..pedal is still hard and didnt move when I turned of the motor..any thoughts on this problem

You need to pump the pedal a few times with the engine off to use up the stored vacumm in the brake booster.Then apply the brakes and restart the motor.If the booster is working the pedal should drop noticably.
Is the motor making enough vacumm at idle to operate the power booster?

A few causes of a hard pedal, vaccum leak at booster (ruptured diaphram), vaccum line not connected, or that plastic check valve at front of Booster restricted or faulty

I did the test for the power booster..with the car off pump the brake severeal times and then start the car..with pressure on the brake pedal when I started the cat it lowered..so I assume the booster is good..it apears the front brakes arent working..Could it be the prop valve?Any test for it

Anyone?..Someone said to reset the prop valve?..that maybe it was triped shut fluid to the front brakes..How do yuo do this?

Originally posted by Shannon Custalow:
I did the test for the power booster..with the car off pump the brake severeal times and then start the car..with pressure on the brake pedal when I started the car it lowered..so I assume the booster is good..it apears the front brakes arent working..Could it be the prop valve?Any test for it

You might want to verify the calipers are on the correct side, they will bolt up to the wrong side, don't ask how I know :D , if you do they won't bleed properly. Make sure the bleeder screw is on the top. Just a thought.
Steve

Yes both calipers are on the correct side..bleeder screw pointing up..Thanks for the info..anyone else have any other idea's?


Originally posted by Steve1972:
You might want to verify the calipers are on the correct side, they will bolt up to the wrong side, don't ask how I know :D , if you do they won't bleed properly. Make sure the bleeder screw is on the top. Just a thought.
Steve

Shannon,
With the engine off have helper pump up the brakes then open one of the front bleed screws.Do you get a good flow and pressure out of the bleeder or is it just dribbling out.
To check to see if the prop valve needs to be reset,jack up the front wheels, have helper pump and hold the brake pedal,then try to spin the front wheels. If you can spin them the valve needs resetting.

Shannon, having the same issue with my brakes - brakes work but it feels like manual brakes - did you solve it? Also did you find out how to reset the proportioning valve? If so let me know.

Thks

Rich

One of the 1st clues that the valve needs to be reset is the brake warning light will be on steady.This is the same warning light as the parking brake.Part of the function of the valve is to detect a leak and shut down either the front or rear brakes,wherever the leak is.This also trips the warning light.Bleeding the brakes (owner induced leak) can also cause this to happen.You also will lose brake pressure to the either the front or rear brakes.
If this is what you got try this.If you lost the front brakes for instance.
With the engine off, have a helper pump up the brake pedal to prime it, and then let off the pedal,then start the engine(if power brakes) now open the rear bleeder a couple of turns, you want a large leak.Now have the helper slam the brake pedal to the floor and HOLD it there,NO pumping.Shut the bleeder.This usually causes the valve to reset by causing a leak (bleeder screw) in the good side.
I've done this dozens of times,mostly on 70's and 80's era cars,it works.Just never had to put it in print.To cut down on the mess use some clear hose and a jar.I also keep a spray bottle of car wash soap and water and pre-spray the area if I think it will get messy.

Thks John - as of now I will assume it's the booster as the light is not on. I'll trouble shoot it first hopefully this weekend. By the way where in NJ are you any where close to Eatontown? .

Rich

Rich,
I'm in Lyndhurst,up near Giants stadium.You ever go to the car show at the Whiskey cafe?

John,

Had been there once without the car, great car show, maybe one day I'll cruise up with one of the velles.

I spoke with the guy who rebuilt the booster yesterday, he said for me to send it back to him but first he wants me to disconect the vacum and see if there is any difference, also told me to try and listen under the dash to see if I here any vacumm hissing sound while the pedal is depressed. I'll play with it over the weekend and see.

Thks

Rich

Rich;

No I am still having trouble..I did though do the booster test,with the engine off pump the brakes then holding the brake pedal down start the car..if the pedal goes down some then the booster is ok..mine did..My brake light is not on so I assume this means the prop valve is ok?..I am at a lose right now..I would still like to know how to reset it..

Originally posted by richr:
Shannon, having the same issue with my brakes - brakes work but it feels like manual brakes - did you solve it? Also did you find out how to reset the proportioning valve? If so let me know.

Thks

Rich

Shannon,
Have you ever put a vacumm gauge on it.Whats your vacumm reading at idle?
Rich,let me know how it goes.If your ever stuck I could stop by and lend a hand.