Mark in Baltimore

I was changing my rotors out yesterday and noticed that my right front pads were worn down far more than my left front ones. At my last track event, I experienced some serious rake fade, even with a fresh bleed and Castrol SRF. Any ideas on what may be causing this? It could possibly be a LF caliper that isn't working as it should, thus forcing the RF to work harder. Or maybe the RF pistons are sticking?


Thanks in advance for any thoughts.

Joe Weinstein

Just 2 cents worth, but maybe the pad material is unintendedly different? (quality
control/labelling/installation mixup). I would try swapping the lefts and rights and
see if you regain balance (really imposing more wear on the rights) or whether
the worn ones continue to keep their lead in wear (pad material problem).
Do the rotors look about the same? Do you have ABS? You don't have the
steering wheel (and driver weight) on the right do you?

renvagn

Mark, I have heard of the inside sometime wearing slightly faster than the outside warranting a right left swap. But if yours are significantly disproportionate, I would have the caliper looked at.

Greg Fishman

What about wheel bearings? Could worn bearings cause this?

Mark in Baltimore

All of the other front pads have about 7.8mm of pad material. The inside pad on the right front caliper has 4.2mm left. It's the difference between a pad that has eight more sessions and a pad that needs to be replaced immediately.

Joe - t's possible that Hawk put the wrong compound in but...I don't know. I have ABS but my steering wheel is on the left side and I only weigh 180 lbs, anyway.

renvgn - Thanks. I've got the wheels off right now.

FYI, here are the rotor thickness measurements:

outside left front-8.7mm
inside left front-7.9mm

outside right front-8.8mm
inside right front-8.1mm (this is the side in question)

agio

Do you have PSM? If so, there is supposed to be brake "compensation" for stability management. If you have PSM and you invoke it regularly, that could be one of the reasons. But, take the car to see a very qualified mechanic and get the story.

Mark in Baltimore

agio - No PSM on my car.

Flying Finn

Mark,

One of these would be my guess. First you can just apply hard brake pressure and then turn the front wheels and see if they are stuck. If not, try to move pistons and see if one (or two) are sticking, either LF ro RF, not necessary piston sticking so that it's dragging, as you said, it can be LF sticking so that not enough pressure get applied and this making RF to work harder.

Mark in Baltimore

Petu,

The pistons are moving freely, no dragging or hangup.

John H

Sounds like you might need to rebuild your calipers. I'll bet they are not retracting everytime like they should. Also, or in the meantime, while you've got the pads out, try cleaning the caliper where the ends of the pads sit. Take a file to the edges and that will help the pads slide back off the rotors as long as the pistons are actually retracting.

Matt Romanowski

If it is only one pad, then you have a sticky piston (or two). Push the pistons all the way back into the calipers and put the pads back in against the rotor. Have someone press the pedal slowly and watch them come out. Make sure everything is moving freely.

Matt

Flying Finn

If the pistons are moving freely, whatta hell could it be? I'm still betting something sticky with one of the pistons...

If not, are all the seals good, dry (no leaky fluids)?

Mark in Baltimore

John - Yeah, I figured I might have to rebuild the calipers. What part of the calipers am I filing down?? Are you talking about the circumferentiual edges of the pad material itself?

Matt - I tried moving the pistons, and all seems well.

Petu - No fluid leak. Seals seem fine. I know, I'm perplexed. I wish I could get more local help but no seems too concerned that I'm wearing out one of my pads more than the others and that I've experienced terrible brake fade with this condition.

Larry Herman

Here's a shot in the dark for you. Is the vent line open on the master cylinder? If all the pistons are moving freely, then a slight buildup of pressure in th system could cause the "most free" piston to press against the pad and constantly hold it against the rotor. It would wear faster & possibly overheat too.

Mark in Baltimore

Thanks, Larry. I'll check it out. It's an interesting premise.