front brakes dragging, started soon after build complete

[hk9mm]

i recently after something like 4 years of sitting have set out to get my FFR roadster driving again. 75XX serial number. soon after i finished this car the front brakes "seized" up. then other things in life came up and it sat for 4 years.

now ive gotten it running and went through and redid allot of stuff to get it roadworthy, the rear brakes are fine but the fronts drag no matter what ive tried. ive flushed and replaced fluid of course. i cut up my aluminum to get access to my pedal box and tried to adjust the master cylinder threaded rod. ive replaced the front brake lines thinking maybe i had some kinked spots causing this. nothing has work and the brakes are locked. barely able to turn the front passenger with the wheel on for extra torque.

short of buying new calipers idk what to do and im going to try to take the pistons out of one of the front calipers probably tomorrow to see if that can help any taking them out cleaning and replacing. i have read around trying for help and this thread http://www.ffcars.com/forums/17-fact...ng-solved.html the guy mentions that the pistons are plastic(seriously?????) and known to be too tight and squeeze the rotors. i have the brakes that came with the complete kit and they say PBR so know im frustratingly thinking that i must buy new calipers? is this a known issue because it seems like these are defective calipers and not my fault.

can any pros out there lead me in the right direction? i feel like ive eliminated everything but the calipers. could it be possible im not adjusting the balnce bar or the master cylinder pushrod the right way?

[stack]

one of mine was frozen as well. just replaced them with a rebuilt unit from the parts store.

stack

[hk9mm]

one of mine was frozen as well. just replaced them with a rebuilt unit from the parts store.

stack

99 year model mustang gt? that one looks like correct part

[AZPete]

Are both fronts brakes frozen? or just one? If both are acting the same, the cause is something that controls both - the master cylinder.
If just one front is frozen, the cause it likely something with that caliper, brake line or pads.
If you open a bleeder briefly to let out a little fluid, does the wheel become unfrozen? If so, the problem is too much residual pressure in the line, which is a master cyl problem if both fronts are the same. Or, if only one side is frozen, then maybe it's just a block or crimp on the line for that side.
Press the brake pedal a few times - does the freeze up again? If so, fluid is not returning, but maintaining too much line pressure, which is likely a master problem.
I'd check that the master piston is returning all the way when the brake pedal is not pressed, like if the actuator rod is too long. You should have a slight play in the pedal.

[Murd]

I bought the same PBR brakes from a Mustang guy used. Had the same problem soon as I got my brake system together, pistons sticking. Did some inter web research and sounds pretty common. Got a rebuilt set from the parts store and worked perfectly right away.
That would be my suggestion

[Murd]

FYI it was both my fronts and replacing them fixed it.

[Big Blocker]

WOW, I feel really lucky then.

My PBR fronts are 15 years old and never an issue . . . but that doesn't mean I won't go out to the car right now and see if I can spin a wheel.

Doc

[hk9mm]

Are both fronts brakes frozen? or just one? If both are acting the same, the cause is something that controls both - the master cylinder.
If just one front is frozen, the cause it likely something with that caliper, brake line or pads.
If you open a bleeder briefly to let out a little fluid, does the wheel become unfrozen? If so, the problem is too much residual pressure in the line, which is a master cyl problem if both fronts are the same. Or, if only one side is frozen, then maybe it's just a block or crimp on the line for that side.
Press the brake pedal a few times - does the freeze up again? If so, fluid is not returning, but maintaining too much line pressure, which is likely a master problem.
I'd check that the master piston is returning all the way when the brake pedal is not pressed, like if the actuator rod is too long. You should have a slight play in the pedal.

front driver is stuck rly good, the passenger is stuck but not nearly as bad as driver. with no fluid in the system they are both still squezing so at this point im convinced its the "Phenolic" pistons that have swelled and caused this.. seems to be a common issue if they arent used often. im gonna swap them out with some new calipers from the parts store and see if that works. they were 90 dollars total so its worth a shot at this point. i will report back probably tomorrow and see if new calipers resolve this issue.

[hk9mm]

I bought the same PBR brakes from a Mustang guy used. Had the same problem soon as I got my brake system together, pistons sticking. Did some inter web research and sounds pretty common. Got a rebuilt set from the parts store and worked perfectly right away.
That would be my suggestion

rear calipers on mine are not "Phenolic" they are metal so that must be why my rears are fine. im thinking these new calipers im gonna get will resolve my issue and i can get this thing driving good! exciting!

[CraigS]

I remember some parts suppliers specifically stating the piston material in their listings so this must be pretty common.

[hk9mm]

new calipers fixed problem, spindle will spin freely now after depressing brake. car drives fine now. brakes nice and good.

[hk9mm]

hopefully they only started swelling due to sitting without use and that these new one will last good with periodic use

[AZPete]

Glad you got it solved. I just assumed you had fluid in the system when I offered suggestions - oops. The plastic pistons clearly accounts for the problem.

[hk9mm]

Glad you got it solved. I just assumed you had fluid in the system when I offered suggestions - oops. The plastic pistons clearly accounts for the problem.

no worries. when there was fluid in the system the front drivers side was very locked and the front passengers was locked but not so much. at various points such as when replacing the front brake lines when there was no fluid in the system they would be just as locked as when there was. the fact that it was both like you mentioned made me not suspect the calipers as well but after eliminating every other apparent possible cause and realizing replacements would be so cheap i found the culprit haha.

thanks everyone for the help. use it or you lose it hahah

[JJ in Cbus]

Through 200 miles of go karting I never had an issue with the front calipers. When I drove for my inspection it had been the furthest that I had driven at one time. The front passenger caliper was hanging up just enough to get hot, and the hotter it got the worse it hung up. By the time I got home it was smoking. I thought it might have been the flex line so I replaced it first. Nope, as soon as the caliper would heat up, it would start dragging again. I wound up replacing the caliper and all has been great since.

[JRD56]

I too had this issue with my 2000 GT calipers (PBR). Replaced them with rebuilt units from the parts store and all is fine. I have a friend who works at a Ford dealership and specializes brakes. He says this is a common problem with that style of caliper.

[emac]

Add another PBR caliper issue to the list. My R side locked up. In its defense, it has been sitting a long time and its been a while since I flushed the system. I had to drive on it longer than I wanted so I might just replace the pads and rotor as well. It was driving odd and I thought it was just flat spots on the tires. After a few miles, and a couple of hard braking to try and get some heat in tires, my daughter said "I smell something funny". I guess the lesson is to drive it often and bleed it often.

[emac]

Update.... in case anyone reads this thread. I decided to mess with my frozen PBR caliper. I put a C clamp on it and compressed both pistons. Pressed the brake to expand the pistons. I did that a few times, put it all back together and bled/flushed the entire brake system with fresh fluid. Fingers crossed but it seems to be back to normal. for how long, who knows.

[emac]

Update.... in case anyone reads this thread. I decided to mess with my frozen PBR caliper. I put a C clamp on it and compressed both pistons. Pressed the brake to expand the pistons. I did that a few times, put it all back together and bled/flushed the entire brake system with fresh fluid. Fingers crossed but it seems to be back to normal. for how long, who knows.

UPDATE....that didnt work and the caliper locked up again. I removed the caliper and the pistons were very very hard to remove. I got a remanufactured caliper from autozone for $50. No doubt the phenolic (plastic) pistons swell and bind. My calipers were clean and new looking but, my car does sit a lot.

[Mustang5L5]

Those calipers are notorious for seizing when the vehicle sits for a while. Can't tell you the number of calipers I've replaced on Mustangs due to this issue. Usually when someone complains of a dragging front brake with that 99-04 style of PBR, I just recommend it be replaced vs trying to mess with it.

[1930Harley]

I had a brake light switch adjusted to tight and it wouldn't let the pedal return all the way and the brakes seized up.

[GoDadGo]

I'm resurrecting this thread and will be changing the calipers today while the body is off.
Heading to the auto parts store when they open at 7:30 AM.
Don't you just love it when a plan comes together?

[Tocoti]

Hi,
I had the same problem yesterday on the MK4 I'm going to the parts store today. So I ask for calipers for a 99- 04 ?

[GoDadGo]

Hi,
I had the same problem yesterday on the MK4 I'm going to the parts store today. So I ask for calipers for a 99- 04 ?

I asked for a 2000 Mustang GT with the 2 Piston Calipers.

They seem to be identical;however, I won't get to that project until this afternoon.

[Tocoti]

Thanks, The vent on the master cylinder was also clogged so the heat from the bad caliper caused enough expansion to put pressure on the rest of the brakes. I removed the master cylinder cap and all but the R front released.

[Tocoti]

Calipers installed. The banjo bolt had a 7/16 instead of the 1/2 in. Probably because people have over tightened it with the 1/2. There was a warning note that said that if you strip the threads you don't get your 40$ core each back.

[GoDadGo]

Tociti,

Mine fit too. Now I just need to gravity bleed before the final pump it, pump it, pump it process is done.

Steve

[JJ in Cbus]

Started reading this thread and thought, this looks a bit familiar, and then I saw my post and looked at the date...

FWIW: Update Report, since swapping out the offending front caliper all has been well with the braking system.

[emac]

You know your getting old when you search something in google trying to remember how you fixed something and come across a thread that you posted years ago!