After smelling burning for a few days randomly, I've narrowed it down to the rear driver side wheel. After a bout on hte highway, I stopped, and it is HOT! I pulled the wheel but the hub spins easily 1/16th of a turn or so, as it's in park, so the brakes are not dragging. Any idea what else this could be? Or are they dragging at random? The rotor is perfect, no rust and no groves, so hte pads are doing their job.

Edit: 1/16th of a turn is way exaderation, but it can move. Also there's no sounds at all.

 

Sounds like a sticking caliper. Those are the exact symptoms I had, random smells, HOT wheel, and when I took it apart, didn't seem stuck at the moment, but it sure had been hot.

 

Axle bearing or caliper

 

Replace the caliper.

 

Yeah, seems like it. started the truck with the rear tire in the air and trans in neutral and pumped the brakes, then went back and tried to spin it and there was resistance. No good there. I'll pull it this weekend and rebuild the caliper.

 

if the pads are worn, the caliper pistons can hang up in their bores when they are fully extended. If so, grease the pistons and replace the pads. If pads are good, its probably the caliper. the ex also uses an integral drum as a parking brake too, if you can't find anything wrong with the caliper assembly.

If it was the bearing it would smell like burning grease and the hub would be hotter from the inside out. Caliper will be hotter from rotor (outside) going in.

 

Yes, I would expect the brakes first and like mentioned check them out. There should be a little bit of drag but the hub should still turn quite free. Rusty pins is where I would start looking, then look at caliper (had to replace my drivers rear as well the first day I got the X), finally if all the brakes are working good you can move onto bearings which can be pricy once a bearing fails and starts dumping metal in the rear end.

 

Oh yeah! The ebrake! inside of the rotor is a drummed ebrake. The linings like to separate from the metal and cause weird problems. It is a stupid design that lots of auto makers use.

 

On my 2003, I had to replace the calipers at around 88k miles. They were both sticking.

 

It was the right rear sticking for me at 55,000 miles. I replaced both rear calipers and rubber brake hoses. If it is the caliper is causing the problem, as I understand it, it could be the pins or the pistons that stick. It could also be the rubber brake hose. The hose may look fine on the outside, but the inside lining could fail to the point where it does not allow the brake fluid to leave the piston, and return to the reservoir when the driver lets up off the brake pedal. So while I had the brake system cracked open replacing the calipers, I took the extra ten minutes and replaced the brake hoses. I also took the opportunity to flush and refill the entire system with new brake fluid. If you do replace the brake line, be careful not to damage the metal brake line that the hose connects to. When I purchased the new calipers, pads, and hoses, I also bought the metal brake lines, just to have it on hand in case I did crack the old line. I managed to get the passenger side hose removed without damaging the metal line, but I was not so lucky on the drivers side. I was glad I had the new one on hand. The new lines come straight. Bending the required radius's to make it fit added an additional 20 minutes to the job.

To be honest, I do not remember if I replaced the rotors as well. Maybe someone will chime in and render an expert opinion on the merits of changing the rotors after they have been heated excessively by a stuck caliper.

 

they just get heated a lot when a caliper sticks so they are probably warped.. if you can't feel it I wouldn't worry about it.

 

I went back and looked at my maintenance log book, and sure enough, I did replace the rotors when I replaced the calipers.

This post in now way constitutes an expert opinion.

 

Also check the brake rotor backing plate for rust. It could be the park brake dragging on the drum part fo the rotor causing the heat. The backing plate has a pin through it that is part of the pivot point for the park shoes. If the backing plate or the pin rusts out, the shoe can flop around, drag or get stuck.

 

I have heard that its recommended to check and change the shoes if necessary when swapping rear rotors, and I've also heard the shoes are only available from ford, but I've never looked into buying any.