Thread: front calipers wont retract

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I have gone around and around with this brake system for a week now. I solved the front calipers not wanting to retract by simply removing the guts from the front residual valve but now I can't solve the issue of a low pedal.

I bench bled my M/C, adjusted the rear brakes and made sure I have about a 1/4" freeplay before I can feel the booster rod hitting the M/C. I bled the brake system several times and I am not getting any air out of the system.

When I think the pedal feels good, I start the car the vacuum makes the pedal feel much much worse. Everything in the system is brand new and I am thinking this issue might be caused from running no front residual pressure valve. Could this be so?

I've had problems with various projects with a low mounted master cylinder.... Are you bleeding the system with a pressure bleeder or with the pedal??? I had one very persistant car, a dang Fairmont with a floor mounted M/C in a drag car....Had to use a pressure bleeder after many of the same battles you desciribe to get things correct....

Also, you have a proportioning valve,,,,did the little valve in it possibly get stuck in one position or the other instead of staying centered?????

One thing I found on my truck was the position calipers are mounted in does not put the bleed screw at the top. So when bleeding them they always had air left in them. It took a while to figure that one out.....

My calipers are in the correct position ( bleeder up). I have bled the system using a hand vacuum pump and also with the pedal. The system has the symptom of trapped air but I have bled about 3/4" the M/C volume from each wheel when I bleed. I would think this would be enough to get the air out. I can try a pressure bleeder but I am wondering if not running a front residualy pressure valve could cause this symptom.

I checked the proporting valve using a test light on the brake plug and it didn't light up so I must assume the piston is still centered.

Yup, that would indicate the valve is still centered..... Did you see anything inside the front residual valve that looked like it could cause a malfunction when you had it apart??? If you have access to a pressure bleeder I think it would certainly be worth a try..... Have you ever put a gauge on the brake lines to see what pressure the M/C puts out? What bore size is the M/C????

Only other thing I could think of to try is to test the Booster with a vacuum gauge and make sure it is holding pressure???? Even though it is new, that doesn't always mean much these days..........

Brakes are a simple, simple hydraulic deal---you are over looking something or you have a bad master cylinder, proportuning vavle--start over

hi guys. had avery sim problem and i had to change the flex hoses to the calipers. seems that they would fold internaly and the brake fluid could not return to the master and releace the calipers. just a thought . dave

mrrilla,

when you say that the calipers "do not retract" do you mean that the brakes are locked up OR do you mean that the pads drag on the rotors? Disc brakes are designed to NOT retract enough to create a large gap between the pad and rotor....if the calipers retracted the pads that much, when you put the brakes on the next time you would have a LOT of pedal travel....hmmmm