Front caliper sticking

[JGood]

I was at Pocono yesterday, and towards the end of the day I heard a loud howling under breaking. Pulled into the garage, saw some smoking from the drivers front. I jacked the car up, and noticed the drivers front was definitely sticking, as I had trouble spinning the wheel. Pulled the front wheels off, and noticed the front passenger side pads still had half life left. The front drivers side OUTSIDE still had half life left, but the INSIDE was down to the backing plate.

They are Girling calipers, and the sliders seemed to move around just fine. The piston wasn't totally frozen. I pushed in it, swapped my spare pads on, pumped the brakes, and the rotor spun pretty freely. I drove home with it with no problems. I didn't check to see if it was frozen again when I got home, I'll check it out tonight.

Any ideas?

If it matters, I'm running HT-10's with OEM Brembo blanks and ATE Super blue fluid.

[ITAracer]

if the bushing for the caliper get bound up, like in high load with loose or worn out rubber ones you could see the inside pad wear fast

[JGood]

if the bushing for the caliper get bound up, like in high load with loose or worn out rubber ones you could see the inside pad wear fast

It's a Girling caliper. Only the ATE's have the bushings.

[Massive Lee]

Either the rubber boots have melted and are keeping the pistons from retracting properly, or the seals themselve have overheated... and melted too. Time for an overhaul of the front calipers.

Lee

[JGood]

Either the rubber boots have melted and are keeping the pistons from retracting properly, or the seals themselve have overheated... and melted too. Time for an overhaul of the front calipers.

Lee

So why would the pad wear to the backing plate on inside and the outside has lots of life left? Shouldn't the sliding function of the caliper make them wear evenly (although obviously much faster since the piston is stuck)?

[Massive Lee]

In theory the pressures are similar on both pads. In the true harsh reality of the track life, the sliding pins can have some friction (they can drag) and the temps not the same on each pad. Do you still have he backing plates/heat shields?

[JGood]

In theory the pressures are similar on both pads. In the true harsh reality of the track life, the sliding pins can have some friction (they can drag) and the temps not the same on each pad. Do you still have he backing plates/heat shields?

Yes I do have the stock backing pates.

This wasn't a slight pad wear difference. The outside pad had at least half life left (the same amount of material the other side of the car had on both inside and outside... as in, it did not have any additional wear even though the caliper was stuck). The inside pad however was literally down to the backing plate... metal on metal contact.

[Wh33lhop]

Your pins got stuck, froze the caliper in place relative to the torque member (caliper bracket) and caused only your inside pad to get worked since that's what the piston directly contacts.

I just got some rebuilt girlings from Kragen for $38 apiece, you can get then with torque members for like $54 from Autozone or go the BMA route. I was going to rebuild my own calipers, then saw the prices for a pre-rebuilt painted caliper and decided to just buy a set.

[JGood]

Your pins got stuck, froze the caliper in place relative to the torque member (caliper bracket) and caused only your inside pad to get worked since that's what the piston directly contacts.

I just got some rebuilt girlings from Kragen for $38 apiece, you can get then with torque members for like $54 from Autozone or go the BMA route. I was going to rebuild my own calipers, then saw the prices for a pre-rebuilt painted caliper and decided to just buy a set.

Did they come with new guide pins and boots? Looking at Pelican, that guide pin kit is $35/side...

[JGood]

I guess it does, at least from BMA. That's a hell of a deal. $94 for a pair, shipped to my door.

[Massive Lee]

Get rebuilt calipers and ditch the heatshields.

[Wh33lhop]

Did they come with new guide pins and boots? Looking at Pelican, that guide pin kit is $35/side...

Yep. Wouldn't have gotten them otherwise.

[JGood]

Get rebuilt calipers and ditch the heatshields.

Really? Any info on this or a link to previous discussions? I thought ideally you'd want the stock shield with a brake duct aimed at the center of the rotor...

[Massive Lee]

Really?

Yes, you want some cooling from air aimed at the center of the rotor/hub.

No, you don't want radiant heat to bounce back onto the face of the rotor, keeping one side much warmer than the other. Heatshields were designed to keep the rotors warm for daily driving.

Lee

[Wh33lhop]

Yes, you want some cooling from air aimed at the center of the rotor/hub.

No, you don't want radiant heat to bounce back onto the face of the rotor, keeping one side much warmer than the other. Heatshields were designed to keep the rotors warm for daily driving.

Lee

Hm, that's a good point. Do you think sliding pin seizing can be attributed to heat shields at all?