06 Hyundai Santa Fe brake problem

SWMBO's co-worker brought over his wife's 2006 Santa Fe(V6/FWD/Auto about 120kmi) this afternoon for some assistance diagnosing an intermittent brake problem.

About 5 or 6 times over the last few months sometime while his wife is driving the brakes will lock up. The first few times it happened she would continue to give it gas & eventually made it to her destination.

Once it locked up leaving a parking lot(after having been parked for about 1/2-hour) and wouldn't move at all. He went to assist her and confirmed the RF wheel was locked up after jacking it up. Eventually it slowly freed and she was able to drive it home.

Once it locked up and was undriveable, so she called for a tow. By the time the flatbed arrived it had released.

Most recently it started happening a couple blocks from home. When she stopped 1/2-block away it popped free and drove fine after that. Every time it occurred has been locally, at speeds varying from parking lot speeds to almost highway speeds.

Of course it was behaving fine when he drove it over today(about 2-3 miles). I checked the brake rotor temps as soon as he pulled up, and all-4 were right around 106-degrees. The pads are almost down to the wear bars on all-4 corners, and the front rotors were visibly worn too. I also discovered one of the LR guide pins had worn flat and was causing the pads to wear at an angle.

I told him to order all-4 hoses, F/R pads, front rotors, and guide pins & boots for all-4 corners as well. Is there anything else I'm overlooking, or are there any weird failure(ABS module, etc.) that are common on these?

I would consider front calipers.

I would also flush the brake fluid out of the system and replace with new.

In reply to dean1484:

I'm definitely going to flush the entire system when I put it back together. I also considered calipers, but they seem fine & the piston boots are intact?

Depends on price I guess. If the are cheap I would do it.

If you're r/ring the lines, it wouldn't hurt to blow the pistons most of/all the way out to make sure they are clean and smooth.

Clean and grease the surfaces that the pads meet the calipers and caliper holder - sometimes they get grooved or dirty/rusty and can capture pads and prevent them from retracting properly.

That and the new (and greased) caliper sliders should cover your bases.

Apart from that, it could be a sticky residual pressure valve or something in the abs...

In reply to jfryjfry:

Thanks! The pads were pretty stiff in their stainless retainers on the caliper bracket, so I lubed them while I had them out. If the new pads are this stiff I'll file their ends down a bit.

My gut feeling is he'll still need to have the ABS module replaced eventually, but at least this will rule out the simple/easy/cheap stuff first.

My experience says Jounce hose first, ABS internal seal second. If everything was releasing pressure properly, there's no reasonable way that crud on the pad slides could cause that much off-brake drag.

In reply to AngryCorvair:

Thanks, I'll tell him to prepare for its eventual return and expect a tow to the dealership/indie shop to fix it.