308 uneven brake temps/pulling

Its difficult to diagnose from here...........but maybe you should remove the caliper and then the piston and inspect/clean. You may have crap/gunk behind the piston which is not allowing the piston to release properly once you are off the brake pedal. That will cause the brakes/wheel to overheat and also it would be the 1st to pull/lock up,as the piston doesnt have to travel as far onto the disc if it has crap behind it. It is a little harder to determine a fautly brake hose thats internally collapsed. Remove the hose from the car and have a feel of it. It should be nice and hard,but still flexiable, not soft and jelly like. Even blow some compressed air through it if you can to make sure its not blocked/collapsed. But i think your problem lies in the caliper.

 

If none of the above work it could possibly be your proportioning valve. They don't go out too often but it does happen. Unlikely solution but you never know.

 

If the caliper isn't parallel with the rotor, it'll cock the pistion & cause it to tend to bind & stick. Also, lots of wear in the caliper's piston hole can leave room for the piston to cock & bind.

 

When you first bled out the system, did you notice "dirty" brake fluid from the front cylinders? By "dirty" I mean a muddy black color. Is so, that's a strong indication that the rubber brake lines are starting to break down.

 

Brownish usually comes from rust. Time to check the callipers. In some cases, it can be caused by corosion in the metal brake lines, in which case, the lines should be replaced. To avoid this, change the brake fluid every few years.

 

Did you replace the pads and bleed the system because of this problem, or did it start happening after the new pads and fluid?

Were the rotors machined during the pad replacement? How did they look?

Does it pull to the right under hard braking, or every day driving, or both?

My car did the same thing (only under very heavy braking) before and after a caliper rebuild, pads, turned rotors, and new flexible brake lines. I drove the car for a couple hundred miles, bled the system again (including cracking open the lines at the master- messy) and all is well so far.

To check if the rotors are even with the caliper, I used a digital caliper and took some measurements between the lip surrounding the caliper piston and the face of the rotor- top/bottom and iside/outside of the rotor. Honestly, I'm not sure this is the best place to measure- maybe someone else has a better method.

 

Jack up the front after a drive, when one rotor is hotter than the other. See if one wheel is harder to turn than the other. Crack the bleeder on the stiff wheel. If this frees the wheel it's the hose, if it doesn't it's the caliper or the pads getting out of line(a problem I've never seen). Did the pads all slide in with equal ease when you replaced them? Did they come out with equal ease? If you have a bad hose it should have become evident when you pushed the pistons back to put in new pads.
Cheers, Tom

 

I'm wondering if you've got a problem with the caliper that's NOT overheating. This would result in the other caliper doing more of the work of stopping the car, hence overheating.

Disassemble the caliper to see if there are marks from the piston scraping the side of the cylinder walls. If the piston is cocking, then there should be a noticable mark on the cylinder wall where the end of the piston is jaming into the wall.

If you have internal & external micrometers, you can measure the piston & cylinders to verify that they're round. The cylinder-piston clearance should be constant, so you don't actually need specs.

Callper-rotor parallelism being off will produce uneven pad wear, one edge of the pad will have much more wear than the other edge. You can detect this by measuring the pad thickness at each edge. If it's bad enough, you'll see that the pad is becoming tapered. Locating a machined surface on the caliper & measuring from it to the rotor surface as JWise described is the measurement technique. Sometimes you can mount a dial caliper on the rotor & swing it between points on the caliper surface.