Front disc brakes not releasing

38 Conv

38 Conv

Well-known member
Got a 55 Ford F-100 with front brake conversion and they will not release all the way-- got all NEW lines-- hoses-- correct valves power booster frame mount and front caliber pads will not release after stepping on pedal and let off go out try to spin wheel dragging real hard to spin-- go in thru inspection hole with small flat screw driver slid between pad a piston will release and wheel spins smooth and easy just a little drag the way it should-- so something wrong it will not let piston release all the way back in-- Thanks
 
Check the part number on the master cylinder to see if its a disc/ drum, or a drum/ drum. Drums should have 10 PSI on them at rest, discs only 2. Mix this up, and you have the result.
 
MC is bought from CPP it is a 1980 Corvette and 7 " booster complete frame mount made for a 1955 Ford F-100 by CPP and it is plumed correct with correct valves and all NEW system--
 
Most likely, the rod from the pedal to the master needs to be shortened up. When the fluid warms, it expands and you wind up with locked up brakes.
 
I don't think this applies to the front brake problem, but just in passing. You got disc's on the rear? That Corvette cylinder is a disc/disc, not disc/drum. Don't know if that will make a difference when the front problems solved.
 
After doing all the adjustments, valves still did not work, decided it had to be in calibers so took the inside pad out and removed the anti- squeal plate behind pad which was very thin and reinstalled pads and all is working PERFECT the way it should--- So I am thinking the pads were not built correct and the entire system is NEW-- Thanks
 
These are GM style calipers? My guess is that something else was wrong and the reassembly itself took care of it, not the thin-plate removal. I could see if the plate was hanging up on the caliper adapter on the spindles.
 
just a thought I did the front brakes on my 2011 f 150 recently and found out the hard way the pads are different for the front side and rear side although they fit one side was dragging they were packaged as matching sets
 
boboss396-- they are 1971-76 Chevy Impala calibers and did have them apart 5 different times and same problem till I took the anti-sequel plate off and works SUPER ever since-- I think the pads were made wrong-- should of went to a Chevy dealer got OEM pads see if that would of worked
 
It still strikes me as odd, I've probably done well over 1000 GM disc brake jobs when I was fixing cars, never saw a bad set of pads, but anything is possible.
 
VERY Confused HERE also but they are working just great since anti-squeal pad was taken off---
 
Just going on a hunch here, but I think you may be using a Speedway Motors kit with the 5 1/2" bolt circle rotors. Those rotors are shown as 1.200 nominal thickness and the GM calipers you are using are for a rotor with a thickness of 1.050. I wonder if the extra rotor thickness is just great enough for interference even if the caliper pistons are retracted completely; when the anti-squeal pads were removed it may have helped the clearance issue. Could you mic your rotors for curiosities sake?
 
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Fordors said:
Just going on a hunch here, but I think you may be using a Speedway Motors kit with the 5 1/2" bolt circle rotors. Those rotors are shown as 1.200 nominal thickness and the GM calipers you are using are for a rotor with a thickness of 1.050. I wonder if the extra rotor thickness is just great enough for interference even if the caliper pistons are retracted completely; when the anti-squeal pads were removed it may have helped the clearance issue. Could you mic your rotors for curiosities sake?
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It has to be something like that and Speedway and a lot of others sell kits that fit "most", but not all. Or the wrong pads got tossed into the kit. I always like to have something that I can get parts for anywhere.
 
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