I was checking the car out after a track day and noticed that the rear pads were worn to the point that they should be changed (the Pagids start at 10mm new and were down to about 3mm). The fronts were about 6.5mm so I am leaving them for another DE or two, since it took them 4 DE's to wear 3.5mm, which is really good.

When I removed the driver side brake pads, both inside and outside pads were evenly worn front to back. However, on the passenger side, the outside pad was worn to under 3mm in the front and close 9mm at the rear. This is the 5th set of brake pads (3 OEM's and second Pagid) and the first time I have seen uneven wear.

I am wondering if perhaps I installed them "incorrectly" or if they somehow got hung up on the guide pin or if one of one of the pistons is hung up and not putting pressure on the brake pad. In any case, I will keep a closer eye on them, but was wondering if anybody else has seen this?

 

This has happened to me once too (with Pagids on my BBK). I was asking myself the same questions and take extra care of everything when swapping pads... but so did I before. I keep an eye on my pads more frequently during track weekends now to try to prevent it from happening again.

 

Thank goodness that the brake pressure is still applied mechanically,therefore you can trouble shoot. One of the pistons must be wonky.

 

Was the most likely explanation. We cleaned up, we checked the fluid, proper functioning of the pistons (we played with them, making sure none was stuck), installed new pads...and the problem disappeared forever.

 

Thanks guys. I'll watch it more closely and report back if it happens again.

 

The torque vectoring might have something to do with it.

 

Hi Stalker, I am sure the torque vectoring in creases the wear on the rear pads, but would not explain uneven wear on one pad.

 

You are probably right, especially that much wear.

 

More wear on the leading edge of a pad is common.
Thats why piston sizes are staggered to compensate for it (but that does not always fully eliminate it).
I tend to rotate track pads because of that uneven leading edge wear.
Now in a car with torqe vectoring and stability control the brakes are being applied while the rotors are leaning over, in the calipers, due to bearing flex. That can cause more uneven wear.
How many track days did you run on those pads?
Were your hard turns consistently in any particular direction?

 

Hi Lunarx, I had about 4 track days on those pads, two of them very hard days. What is unusual to me is that the other 7 pads all wore uniformly, as have the previous 4 sets of pads on the car. It really looked like either the rear piston was not working correctly or it was hung up on the guide pin somehow so it could not slide correctly. There was 6+mm more wear on the front edge than the rear edge of the pad. 1 or 2mm would not have surprised me.

With regards to the turns, they were probably fairly even across the 4 days at 4 tracks. Two were clockwise, two were counter clockwise. I have never rotated pads before, nor needed to, but I will certainly watch them more carefully. I am hoping it was a weird anomaly but I will have the caliper(s) checked out if it happens again. I might have to put OEM brake pads back on for the trip to the dealer...

Thanks again, always appreciate your input!

 

John's 991, I also would also suspect "normal" uneven wear to be the same per axle.
You could check for a sticky piston fairly easily.
Just wood block the other pistons (so they dont over extend) and compress different pistons to see if they compress easily and if other pistons extend similarly, in reaction to the fluid displacement.

What tracks have you been running?
LS is primarily Left turns and one of the hardest on brakes.

 

Question... I normally think also that wear would be similar on the same axel.. But I wonder if that applies with torque vectoring, if for some reasons you tended to overall make more turn movements To the right vs the left..

I understand that it probably averages out, but doesn't most racing tend to be overall. in one direction... And even in everyday driving it seems like we have a tendency to make slightly more right turns than left ( opposite maybe in uk and left side countries)..

Maybe that's not enough to matter, it just seems torque vectoring might through a little additional factor into the mix at least on the rear axel.. Seems folks have had some other strange brake wear issues ( also with PCCB overheating) that seem to point to the potential for torque vectoring to have some involvement..

 

Lunarx, good idea. I will check the pistons if I start to see uneven wear on this set of pads. I was at Laguna, Sonoma and Thill twice. Agreed that Laguna is the hardest on brakes, but you can give them a good work out at the other two as well. One of the trips to Thill I was on the track for 2:50, which was a blast. My last DE was at Sonoma and I was driving pretty hard, so threshold braking going into 4, 7 and 11.

As these are the same tracks I usually drive, plus Buttonwillow, I will see if it does it again then check the pistons. Hopefully it was an anomaly but worth keeping an eye on. At least the brakes worked well and were not pulling or anything.