my brakes have been dragging and i took the mc off last night and the piston was seized(not moving). I got another and put it on and just pumped the pedal without bleeding and i had tons of pedal after a few minutes of driving and braking the brakes were dragging i would loosen the the lines and let the pressure out and then i would gain back pedal and be dragging again. i never messed with the poshrod i just looked at it. i pulled the whole rod out of the booster and i'm not sure if you are supposed to be able to do that. Either my pushrod needs adjusted or the booster is acting up and its pretty new. its seems like the pushrod doesn't relaese the piston all the way or something.

Any suggestions?

 

did I miss the part where you bleed the master cylinder and the brake system and then you still had problems. If not that's what has to be done; if you expect it to work

 

You need to try adjusting the rod so that it is shorter. A couple of turns at a time until it is right.
When you are putting the master cylinder back on, does it feel like the rod has pressure on the M/C when you push it up to the booster. It should be almost flush with the booster before the rod touches 1/16".
Jimmy

 

yes i bleed the mc before i put it on. Before i did bleed the system but i didn't have to this time cause i have a problem and the brakes work to good. they drag.

And lxman1 i don't feel any pressure on the mc when i put it up there on the booster but the pushrod is sticking out about as far as the studs for mounting the mc. I wll adjust but don't know if that will help. I will have to try it anyway.

 

If I remember correctly, didn't all of this start after the m/c change? If so, it may be bad. I have seen them not allow the fluid back into the m/c causing the brakes to drag.
If there wasn't any pressure on the m/c when reinstalling it, then don't mess with the rod. Get another m/c and try that.
Jimmy

 

this is my 4th mc in the last couple months the first 2 had fluid go to the back compartment and the last 2 have been associated with dragging. i want to find something other then cardone junk but thats all i can find. maybe i should go the a ford dealer and order one or something. The guys at the parts store said i was like the only one the have problems with the mcs and hes thinks it something else. I'd like to get something of another brand. is this a bad proportioning valve that couls be the blame of something?

 

Have you thought about replacing your flex hoses, if they are collapsed on the inside that will cause your brakes to drag also.

Another thought, does your pedal move freely when mc is off, does it travel all the way back to the top.

 

The only thing I can think of other than the master cylinder that can build pressure like that would be the rear shoes self adjusting too tight or simply being too tight to start with. The front pucks should self adjust.

 

Wait, am I reading this right? Are you saying that you bled the MC but did not have to bleed the brakes at the caliper and wheel cylinders because they are dragging?

If that is how I interpret that you still have to bleed the entire braking system.

the front pucks get there adjustment from the slide of the caliper, now if the calipers are all rusted up that will also allow the piston's to not retract into the caliper bore.

FYI, i sold cardone MC's for many years and did'nt have alot of reject's, of course that was 15 yrs ago and they might be makin everything in china by now LOL

 

i ended up getting all the wheels bleed and that doesn't work. I have to get out and open up the lines to the master cylinder to let the pressure out and then they work for about 5 or so stops and they are dragging again. Could the booster be bad and not allow the pushrod to release or has it all been a bad proportioning valve. why is pressure building up?

 

If pressure is building up in the M/C then something is not retracting as it should. If you can continually get the brake system to lock up, I would say that it is something other than the M/C since you have replaced it several times.

If the booster has a bad diaphragm, this will create the same situation. When you have released the pressure on the hydraulic system, start the truck WITHOUT your foot on the brake pedal and watch the pedal. If it travels towards the floor or modulates when you goose the throttle, you have a bad booster. Usually, the passage between the front of the booster and the pedal side gets blocked with soemthing.

Also, watch the pedal when you step on it. You should see it return after you release it with the engine running. If it lags or seems to not want to return to where it was, the booster has gotten crap in it.

Was there any debris in the booster area when you removed the first M/C? If so, it might have gotten stuck in the booster vacuum ports.

I have a 1970 Boss 302 Mustang that had the same problem. Brakes came on full until you let the car sit for a while. The brake pedal would move while applying and letting go of the throttle with no foot on it.

I say it is the booster. Let the truck sit a while after the brakes lock up and see if the pressure releases. If so, most likely the booster....


John Neary

 

there was no debris. The booster is fairly new I know that means nothing but i would mention it anyway. The pedal releases and all. I don't think that it is any wheel cylinders or calipers are acting up.

 

All,
Stop right there!
This is not a MC problem.
This is a caliper and/or flex line problem. The MC does not have the ability to stop fluid from returning. It is way too simple to adjust the rod correctly. He has tried four MCs so far. Enough, this must be the calipers and/or the flex lines. I have seen these failures over and over again. They are as common as rain in Florida. Stop wasting your time and money and simply replace the calipers and flex lines. I hope you haven't warped your rotors from dragging the pads and overheating the rotors. if the pedal pulses after your repair, you'll know.
Consider it,
KingFisher

 

by flex hoses you mean the rubber hose to the splitter in the back or the hoses to the front calipers. I have been told about the hose in the back collasping but i'm not sure which one you are talking about. And yeah i kinda have ruined the rotors. it was dark but the looked bad and my pads are worn more so i will be replacing something soon.