sticking right side caliper

So about a year ago out of the blue my passenger front caliper started sticking , I replaced the rotors pads and calipers and the problem seemed solved . Then about a month ago it did it again and had to hit it with a hammer constantly to make it home . So I welded the grooves on the sliders and filed them smooth . Problem seemed solved for a few days and a couple of long distance trips , then again it started doing it ! So researched some more and changed out my rubber brake lines and ended up twisting the hard line and replaced that !! Problem seemed solved ? Then once again again !!!!! This time almost glowing red by the time I got home . So I bought new pads , rotor , caliper , and hub bearings but I'm worried about wrecking these if it does it again ( I have a feeling it will ) so does anyone have any other ideas of what could be going on ? There was the slightest hint of movement on with the unit bearing that's why I'm replacing it this time , could that have been the issue? Thanks for any help cheers Adam

I'd take the caliper bolts out and roll them on a mirror. If you put a light behind the bolts and then roll them on a mirror, any bent spots show up quick.

What year XJ? ABS?

On some years there is a plastic insert in the caliper sliders, it can get wrinkled and cause the calipers not to slide well.

Push the pistons all the way in with the caliper still mounted. You can do this by carefully prying, being careful not to damage the pad. If prying doesn't work, loosen the bleeder and try again. Then try to move the caliper on the slider bolts. It will take some force to move them, but they will (must) move. A bent mounting (slider) bolt will jam the caliper. A tip off is severe uneven wear, one pad wearing significantly more than the other. I use a rubber friendly (read the label) silicone lube on my slider bolts.

Another reason to push the caliper piston all the way in, is you can feel if moisture has gotten behind the rubber seal and rusted the piston cylinder wall. Rust on the cylinder wall behind the dust cover (seal) can cause the piston to jam. The pads (caliper) have to relax a tiny bit when the brakes are released, if the piston jams, it can keep some pressure on pads and cause things to heat up.

Polluted brake fluid can do the same thing, if it has much moisture in it, the moisture can turn to steam. That is why they always recommend using a new closed container of brake fluid, brake fluid sucks up moisture like a sponge..

First, PLEASE post up year, etc.

Second, I agree with 8Mud.

Third, NAPA has plenty of brake hardware including caliper bushing kits--can't give you the part numbers because I don't know what year XJ you have.

I appreciate the advice guys , its a 93 sport model . I replaced the caliper tonight and as I was bleeding I found a small leak where the master cylinder connects to the booster . It probably happened while bleeding since I've never noticed it before ? It basically bubbles out when the brake pedal is released . Also noticed every time I took off the cover to check level the gasket on the lid seemed as though it was sucked down , not sure if that's normal ? Thanks again

Also , last year when I replaced the caliper it came with new pins , but I will check them out on a mirror ya never know , it would be wicked if that's all it was !