• From: NH
  • Registered: 2010-01-20
  • Posts: 3,299

Topic: Sudden Brake Pad Wear Rate Change

We've had the same set of ST-43 pads on our Saab for 5 races now, and they have been amazing. Up until NJ that had all worn perfectly evenly. Meaning the fronts are always equal and the rears are always equal. Now after NJ our driver's front is about 2mm thinner than passenger side. I'm trying to talk myself through why so that we can fix it before CT in a week and a half. The only thing that changed with the car is that the driver's front wheel bearing went out at NJ. I drove the last 2 hours on sunday with it absolutely howling, and I'm sure it was doing the same the stint before me. The simplest explanation to me is that the bearing added heat to that corner and caused the pad to wear more. Slightly more complicated explanation is that the heat started screwing with the caliper slides causing a bit more binding.

Am I missing anything crazy here? Is there anything else I should be looking for? I did have a side thought of "oh, clearly the other 3 are binding and not applying as much pressure, that's why this one is lower", but that just seems like too much would need to coincidentally go wrong to be the case.


The driver's front pads still have enough life that I'm not worried about CT, but they will probably be the last race we run on those pads before buying new ones. I really want to replace the entire caliper and bracket, but don't think we'll get to before CT. I think I'll settle for replacing the guide pins and sleeves just to be sure there isn't any binding.

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  • Registered: 2014-11-04
  • Posts: 274

Re: Sudden Brake Pad Wear Rate Change

Is it possible that the play and vibration was causing the rotor to chatter against the pads when you weren't braking? I would check the caliper for damage or wear, but I wouldn't assume that it's bad off hand.

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  • From: San Diego
  • Registered: 2015-05-03
  • Posts: 147

Re: Sudden Brake Pad Wear Rate Change

Are you cleaning and regreasing the sliding pins before each race? My first assumption would be the low pad  caliper is dragging/binding and just needs cleaning/regreasing.

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  • Registered: 2018-05-22
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Re: Sudden Brake Pad Wear Rate Change

Other possible causes:

1. Rubber lines leading to the caliper can swell and start closing over time. The pressure on the brake pedal is sufficient to open the passage and push the brake fluid into the caliper, but when the brake is released the rubber line closes again, leaving the brake pads pressed against the rotor.

2. The pistons are not retracting in the caliper properly and the caliper needs a rebuild. This involves popping out the pistons (usually done carefully with air pressure), and installing a new seal kit.

  • From: NH
  • Registered: 2010-01-20
  • Posts: 3,299

Re: Sudden Brake Pad Wear Rate Change

All things to consider. Though I do tend to lean towards simple explanations are often the correct ones. And the only change was that wheel bearing.

I'll be cleaning/greasing all the slide pins no matter what. Good to consider that the lines might be going bad.

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  • Registered: 2011-10-14
  • Posts: 4,167

Re: Sudden Brake Pad Wear Rate Change

You still have the GM brake-bias traction control by chance?

  • From: NH
  • Registered: 2010-01-20
  • Posts: 3,299

Re: Sudden Brake Pad Wear Rate Change

OnkelUdo wrote:

You still have the GM brake-bias traction control by chance?

The ABS and traction control systems are fully functional and used. But it seems to use engine limiting over brake bias for traction control. And it's never resulted in uneven wear before. Not saying it can't be related, only adding data points.

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  • From: WPB Fl.
  • Registered: 2010-10-27
  • Posts: 1,571

Re: Sudden Brake Pad Wear Rate Change

Was the bad bearing loose and wobbly?

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  • Spank
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  • From: Escondido, CA
  • Registered: 2009-06-10
  • Posts: 5,863

Re: Sudden Brake Pad Wear Rate Change

I'm with others: the loose wheel bearings would cause the rotor to cock sideways in relationship tot he calipers, spreading the caliper slights and also putting pressure against the pads.

Had this happen on the moke more times than I'd care to think and each time we were chasing what we thought was a brake issue that turned out to be wheel bearings.

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  • From: NH
  • Registered: 2010-01-20
  • Posts: 3,299

Re: Sudden Brake Pad Wear Rate Change

Team Infinniti wrote:

Was the bad bearing loose and wobbly?

It wasn't horribly bad yet, but it sure wasn't great. I was babying it through all right hand corners to try to get to the end without a failure.


I think we've settled on replacing the caliper and bracket on that corner just to be safe, and checking that all the other slides are greased properly. We'll replace the rest of the calipers before NH likely since they are original to the car.

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  • From: Elverson, PA
  • Registered: 2017-08-15
  • Posts: 1,124

Re: Sudden Brake Pad Wear Rate Change

For me, spot on timing, directly on point. Thank you!

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  • Registered: 2010-03-08
  • Posts: 419

Re: Sudden Brake Pad Wear Rate Change

It is also possible that a binding caliper could have cooked and killed the wheel bearing.  That used to happen all the time when we were running Spec Miata until I identified and binned the bad caliper.

  • Registered: 2013-11-15
  • Posts: 670

Re: Sudden Brake Pad Wear Rate Change

Spank wrote:

I'm with others: the loose wheel bearings would cause the rotor to cock sideways in relationship tot he calipers, spreading the caliper slights and also putting pressure against the pads.

Had this happen on the moke more times than I'd care to think and each time we were chasing what we thought was a brake issue that turned out to be wheel bearings.

I remember that with the moke, I had to pump the brakes too.

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