sticking caliper?
 

I'm about to put new front rotors on and change brake fluid. I'm noticing that the front left wheel does not spin as freely as any of the other wheels. It barely spins at all, I can turn it by hand and there's moderate resistance, while the other 3 will spin a bit on their own with the same amount of effort. I don't notice the car particularly pulling to the left, or any smell, and the pads don't seem to be really any more warn - in fact, compared to the right front pads, the wear looks nearly identical - outside pad is evenly warn across the same amount, inside pads both are more worn in the front than the back, but are equal on both sides. So pad wear appears similar. Wheels turn equally freely with the pads out.

What else should I be looking for to diagnose this? It's possible the situation could have been like this since last fall when I put on a new pad wear sensor ( they both got the newer style that monitor both sides), and I've put less than 1K miles, if the caliper was really sticking, I'd think there would be a noticeable difference in pad wear. Or is it just that the left caliper takes a few more revolutions of the wheel to retract, and it's nothing to worry about (that seems unlikely).

Why are you replacing the rotors...............are they warped? That might explain it.

Hows the wheel brgs?

Hi Chris,

Is there any noise accompanying the 'sticky' rotation?

I had same problem on both front wheels, and it was corroded dustshield rubbing against the hub. Once i replaced these the hubs span freely and noiselessly. The flaking/swollen metal against the hub created rubbing/grinding sound.

But both dustshields were same highly corroded condition (RHS shown in pic), whereas in your case only 1 wheel has the problem and I can't see how one dustshield would be in begtter condition than the other.

Have you checked bearing tightness? Maybe front left is too tight (thrust washed should just move with pressure from screwdriver blade) and the bearings are binding on axle?

With pads out is problem still there? If so then you can eliminate caliper.

Keep us posted - should be fairly simple to pinpoint the problem.

could be the "rod" that the calipers rotate on so the pads wear unevenly. If you have this symptom (of one pad worn more than the other) then try tapping the caliper lightly with a large hammer until it rotates freely.

Marton

Sorry Chris, just reread your post and you said that problem only there with pads in place, so please dismiss my dustshield suggestion!

thats one rusted dust shield

The UK is one rainy country, and we get a lot of salt on the roads in winter!

Rotors are at min thickness. There may be some warping or pad material buildup on at least one rotor, there is a very slight pulsing in the brakes. THe other 3 brakes turn very smoothly, but the front left is difficult enough to turn that I can't really tell if there's variability in the resistance due to uneven pressure.

Marton - I've got the pads out, so I'll give your advice a try when I get the new stuff in - I'll clamp down good with the brake pedal and then see if tapping the calipers does anything.

How free should the wheels turn anyway? THey spin extremely freely with no brake pads in, how much should they still spin with the pads in? Compared to my bimmer, they spin much less.

In case anybody was curious - when I got new rotors, the problem went away. Both front wheels now spin about equally.

It is common for the pistons to stick a little more when they 'all the way out' from pad/ rotor wear. Pushing the pistons back in may have solved the problem

Ah, makes sense.

Quote: Originally Posted by fabric
Rotors are at min thickness. There may be some warping or pad material buildup on at least one rotor, there is a very slight pulsing in the brakes.


Could be a combo with the full retraction for new pads, but my vote is on r&r of the warped rotor, the one that caused the "slight pulsation" you mentioned.

Pretty sure slight pulsation is in the rear, as that still exists. I"m hoping that's just from barely driving the car. I have the 33 bar rear regulator on now, we'll see if a bit more use on the rear rotors will wear off some pad material buildup that seems to have builtup on them.