Overzealous stopping

FlDart360 said
Ok this has happened more than once so I think it is time to sort this out. Yesterday on my Weakley drive around the block to make sure everything still works my left front wheel locked briefly as I tapped the brakes backing down the driveway and then once more as I approached my first stop sign. The rest of the 4 mile journey was uneventful, stopping was normal with no brake pull or fade. The details: 1971 Swinger with disk brakes from what I believe was another mid 70's A Body. They are single piston.
The whole setup is manual and I still have drum brakes in the back. On occasion the right front has squealed under light braking but never under heavy. The pads have very little wear on them and other than a visual inspection this is the one part of the car I have not completely disassembled at one time or another. Could this be a caliper piston sticking or a problem with the pins that attach the caliper? Heck I probably should find an exploded
view picture to verify they were even installed correctly. Thanks for the help.

Could be a few things. Sticky pistons, worn caliper guides (sliders or pins depending on the style), trash in the brake fluid (rust) or brake lines getting pinched when you steer or the suspension moves.

The sliders or pins can be inspected pretty easily by removing the calipers, no need to even unhook any lines for that. Any damage, pits or burrs could cause some rough movement that could cause erratic applications. Are your calipers to the front of the car or the rear? Since you have a disk conversion, you may have the wrong length lines or poor routing. Is the sticking related to turning the wheel at all? This can also be inspected, but you may need a helper to turn the wheels back and forth and see if the lines pull tight or get pinched. If they’re getting pinched there may also be damage to the outside of the lines. Also easy do to, for both you’d need to raise the front end and pulls the wheels to see everything. You can flush the brake fluid and look at that. If there’s nothing obvious on the inspection of the sliding surfaces and the lines then do the brake fluid. If that’s nasty then run it for a bit with the new brake fluid and see if it recurs. Brake fluid is supposed to be flushed every few years, BTW. If it does recur then it may be time to rebuild the calipers. It may also be the lines themselves, rubber lines can collapse internally. Although usually when that happens they stay on and drag.

Since it’s happened on both sides, I would suspect something that hits both sides- like poorly routed lines, or rust in the fluid. The other stuff requires separate problems on both sides. But that is still possible.

volunteer said
Shouldn't have 'pins' since the '73 - '76 A-body calipers were of the sliding type, with a springy plate on each one. Possibly a slight issue with the caliper seal or M/C? Smarter minds than mine will zero-in.

Shouldn’t be single piston calipers is it was stock either. The pin style calipers came on B/E and F/M/J bodies. And since the brakes have been sourced from a later mopar, they could very well be pin types.