Have 34 ford coupe with disk brakes all around . Brakes seem to drag until start moving then they release. Put new master on and still seems the same. Any ideas? Thanks
Just have pro portioning valve in line now master cylinder under floor,took out 2lb check valve and nothing changed
Something is holding pressure on the calipers. There has to be somewhere in the line from the caliper to the Master Cylinder that is blocking fluid passage. Is this a new build or was it working and then the issue started? If new, some Master Cylinders have residual valves built in. Is the new MC the same model as the one it replaced? Might need a MC without the built in residual valves and add the 2psi ones back in. Are there any other components in the system?
I had the same problem, and mine would drag after an application, tried a bunch of stuff, and found I needed a little more free play in the pedal. I just backed it off a turn on the adjuster, and it was golden!
Was doing the same thing before replacing master cylinder ,just bought car and found this problem . Nothing else in system thanks Posted using the Full Custom H.A.M.B. App!
Of all the possibilities, the most common would be faulty, sticky calipers or human error in adjustments or travel at the pedal. For a diagnostic test Try cracking the bleeders. If you get fluid and the piston retracts from reliving the pressure you can rule out the calipers and look further into the system. Calipers can get sticky, hoses can collapse inside with no outward visible problems, mechanical adjustments at the pedal, internal master defects.
Good advice above. Does the master match the calipers if they are off a donor car application? I see the incompatiblity of components being the first line of offense with brake problem posts. I would go with pedal free play and cracking the bleeders first. Then pulling off the calipers, check and replace hardware and use the right lube on all sliding pieces. All you need is one corner of the car being off to mess it up.
^_ Same as Vanislander, I had the smallest amount of tension on the adj rod between the pedal & cyl. I wouldn't allow the master cyl to fully bleed off the pressure. Once I took out the tension, all was fine.
I'm having the same problem, I cracked the bleeders and they loosened up. Cracked the line at the M/C and same results. I'm gonna give 'er some more freeplay and see if that works.
Found out the master cylinder has a 10 pd residue valve in it and was told to take that out and that should fix problem , we'll see and I'll let you guys know. Thanks for all your help.c
CPP was called and they sail to ck . Master cylinder for residue valve and to take it out and that should salve problem
I had a 50 Ford coupe that would drag the brakes after a few minutes of driving. One day while I was at the firehouse a fellow stopped by and told me I left the lights on in my Ford. When I checked on it just the brake lights were on. The system had developed enough pressure to activate the brake lights from just sitting there, parked. The brake system had just been overhauled including a new master cylinder. The culprit, there is a tiny vent hole at the bottom of the reservoir in the master cylinder that lets fluid return to the cylinder. The hole was never drilled though in the casting. drilled it clear and the problem was fixed. I know you have a more modern system but do not overlook flaws in the master cylinder.
The Jalopy Journal
