My Brakes Seized up on the Trail

Hey everyone, I took my jeep out on a trail for the first time today with a buddy of mine. We got about a mile down the road and realized that when I tried to shift into second gear it would stall because the jeep would suddenly come to a stop before I could even shift. We got out and realized that all the brakes were seized up, even the brake light was on. I did a disc brake conversion on all four wheels so it isn't stock but the MC is stock. The rotors were super hot. I crawled under and loosened one of the bleeder nuts and everything let go. It shot a bit of fluid out. Luckily we were on a pretty flat ground otherwise the jeep would have rolled over me underneath it (I've never claimed to be smart). my rig doesn't have a master cylinder heatshield in between the exhaust, do you think this could have been a contributing factor? I loosened the cap on the MC so it couldn't build up pressure in the system on the way back and I didn't have any problems. Anyone had a similar problem? Any suggestions? I can either get a heat shield or wrap the exhaust?...

ndnchf wrote: is your brake pedal adjusted from proper free play? If not, the internal port in the MC may not be uncovered by the piston. This allows pressure to be equalized or relieved in the system. Heat wrap would be a good idea if you don't have a heat shield.

X2. Free play is important and needs to be checked.

I haven't adjusted them at all, so that's most likely the culprit. I'll do some reading. Thanks!

X5 on the lack of free play being the culprit, minus one on the lack of a heat shield being the culprit.

Bruce W wrote:   if you did not remove the residual pressure check valve, the disc brakes will not release completely. If you do remove it, the rear wheel cylinders will leak.  BW

Stev wrote: Something else to consider: If this system has rubber flex lines hoses, they can also act like check valves when they get old.  The hoses can collapse once you take you foot off of the break - trapping the fluid in the wheel cylinders / pistons - keeping the breaks engaged.

Yes they will! This caused my old 9" brake set-up to lock up the rear brakes after every application of the brakes. I thought I was not adjusting the brakes right but it turned out to be the frame-to-axle brake hose collapsing. During my recent 11" conversion I changed out all the hoses.

I shortened the rod and adjusted it so there was a very slight amount of movement before the rod begins to move the piston and confirmed that the piston now rests on the snap ring. I've driven it around the neighborhood a couple of miles and no sign of the brakes retaining any pressure. Thanks guys! I would have chased the exhaust heat issue had it not been for your suggestions.

Help ! I'm having the same problem with my brakes. Front disc brake conversion with 11" rear drum brakes, Dual reservoir MC, New brake lines , new rubber hoses. The front Disc Brakes seized up & won't release. If I loosen up the bleeder valve they release. I have shortened the brake rod & adjusted the free play. It still seizes up. Where should I look next?

Basically either your piston is not returning to the rest position or you still have some sort of residual pressure valve present. Is your MC new?