Here’s a shot of a pair of front pads (Hawk DT-10s) used on Sunday at TGPR.
Tapered Brake Pads
The pair are clamped together toward one end and you can see the gap at the other. They still have a good amount of material left, about 50%, and you can see that one is significantly thicker than the other. Anybody know what causes that?
Investigation with a micrometer shows that they are thickest in the center and worn down toward each leading and trailing end.. about .030″ max difference. They’re also tapered from top to bottom in the middle… about .015″
They weren’t working too well.
Saving Time - An Autocrosser's Blog 
How many pistons in the caliper in question?
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Two.
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On my 2000 Boxster S my outer front pads wear more and my theory is that they do not get as much cooling from airflow. I swap them every few events to help them.wear more evenly. I use EBC Red brake pads and have GT3 front brake cooling ducts.
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Interesting. Street-driven, track or some of both?
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Mostly the street driving I do is on the way to/from HPDE (typically 360 miles street driving round trip with maybe 160-200 track miles maybe 4-5 times a year) and to/from autocross (150 miles round trip, maybe 8-10 times a year) and very occasional street runs. I put on my first set of EBC red last October and did 6 track days with them, then before my most recent event checked all my pads, noticed the uneven wear, and swapped them based on some guidance from a friend with a track boxster. The difference wasn’t major (a few mm) but it was definitely apparent. After my first track session they were fully bedded in their new positions based on rotor appearance.
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C5 caliper flex. Common issue unfortunately. Stiffer calipers will fix this.
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That’s been my assumption also, made worse at tracks that create more heat. NCM & Barber no problem. TGPR always an issue.
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The caliper is twisting on the pins. Since the pistons are not pushing right in the middle of the pad, the caliper is trying to rotate.
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