Hopefully someone can help me out quick. Its the night before the Southwest Nationals here in Okc. My 37 Dodge sedans front brakes are locking up. I have a Mustang II frontend under the car and has a power brake system on the firewall. Could it be the booster going bad?
Do they lock up when hot, then return to normal when they cool down ? If so more then likely your pedal is not returning enough, to allow the pressure to blead off. Is there freeplay in the pedal, when hot ? and there should be free play when cooled off. If this is what it does shorten the push rod, make it ajustable. There was a post like this not to long ago, it was the push rod length. it was to long. I had this same problem with ths Divco, the brakes would start to drag. The hotter the rotors got the more it would lock up. They got so hot, the seals burnt out and ate the outer bearing. .
I will have to check to see if there is free play after it has cooled off. I know when it was hot there was no free play, the brake pedal was hard you could not even puch it down.
Check the free play as divco said. Also if your brake lite switch is depressed by the pedal arm it may be set to close. Both are common probs Should have said if the brake switch is above the pedal it may need some more clearance.
Look at the path of the fluid to the piston bore. The piston needs to return enought to allow the pressure to bleed off. If the piston has restricted return travel, the pressure will build as the rotor and the caliper get hot. As when you do a brake job, and push the piston back in to the caliper, in order to get the new/thicker pads to fit. The fluid returns back to the reservoir / fluid level goes up.
Is it a newly installed system? If so they're probably right unless you were sold a bad master cyl. On an older set up the master would be a prime suspect.
OK heres what I have tried. Tried to pull the shaft from the but its fixed to the inside and can not be removed. The other end has no adjustment either but has a hole on the end of the shaft that attaches to a pin on the side of the brake pedal. So I unbolted the booster and put about 5/16 thick washer on each of the four bolts. So I reinstalled the booster and pulled up the the brake pedal then pressed it in. At that point I felt the shaft thud as it was it was entering the booster. When I released the pedal the shaft came back but not to its original location, so I pulled up on the pedal and I felt the same thud again. I pressed and depressed a few times and heard samething over and over. So anyone one have any ideas.
does your brake pedal have a return spring.that thud could be your freeplay .try it.what type of brake fliud did you use.silicon fluid can cause these issues or any other contamination.
The Jalopy Journal
