My dad's '98 Ranger (4x2, 2.3L) rear wheels have been locking up when moderate pressure is applied to the brakes, even on dry pavement. The brakes have less than 10k miles on them and I took the truck back and even to a 2nd mechanic to be told there's nothing wrong with them. The only explanation they could think of was the truck was sitting for an extended period, which the truck does.

Jump ahead a month and I was driving the truck every other day a few miles for a few weeks and the brake lock-up problem has gone away....until I was leaving a parking spot and put it into first gear. There was a large 'bang!' from the rear of the truck like I had just blown a tire and there was the feeling like I had a blown tire (thud, thud, thud), but when I checked, none of the tires were flat and the rear wheels were locking up even worse than first time.

Any ideas?

 

Tough to say without seeing it in person but it sounds like you have a busted differential.

 

Welcome to the forum

1998 Rangers had 2.5l engines, or 3.0l/4.0l, so is it a 1998?

Do you ever use the Parking Brake(e-brake)?

Parking Brake adjusts the rear brakes, people with Automatics often never use the Parking Brake, just use Park.

Hold the Parking brake Release handle out and Pump the parking brake pedal a few times it should get higher and higher if rear brakes were out of adjustment.

Possibly a differential issue but on a 2WD I would expect Open axles so only one wheel would lock up.

It should also have Rear ABS(anti-lock brake system) so could be a problem there, when you turn on the key does the ABS light come on and then go off?