6 Piston Brembo with sticky piston and uneven pad wear

[Theflyingz]

I went to change my brake pads on my 2018 Mustang GT PP1 and noticed the right front caliper was wearing the pad uneven. There must be a piston that is sticking and causing more pressure to the other pistons. I didn't notice the issue until after the job was completed and I installed new rotors and brake pads. I was looking closer at the pads the following day and noticed when viewing the pads from the side that the wear was very uneven.
The car is still under warranty, but I swapped to stainless brake lines before swapping the brake pads and rotors. All fluid was flushed with Motul RBF 600 fluid. Now I wonder if Ford will honor the warranty about the defective caliper because the brakes were modified. Even if I put all the stock pads and rotors back on the car, it would be a PIA to swap out the stainless lines.
Has anyone had an issue with uneven brake pad wear with the 6 piston Brembos?

 

[JDee]

That's not likely a defective caliper, that's the way pads wear. Especially true in road cars with the amount of stuff they use to kill NVH in everything, there is always some caliper movement with braking force and the force created by the friction tries to cock the pads slightly. There's probably a better technical explanation than that, but that's the way it works. That pad should have been changed much earlier.
This has been a thing since forever with street car based braking systems and as far as I know, it still is.

 

[thelostotter]

My stock pads did the same. The track pads I am running now do it to a much smaller degree. I believe it is related to heat, I can tell the leading edge runs hotter based on how the metal backing plate has turned blue which I think causes accelerated wear on that end.

 

[Dave_W]

No personal experience, but I'd think the 6-pot Brembos would use staggered piston sizes to reduce taper wear on the pads. The "leading" piston should be smaller than the "trailing" piston. That said, I don't think the taper is that bad on the pad pictured. Original pads? How many miles on them?

Do you know if it's the leading or trailing edge of the pad that's more worn? Did the other pad from that caliper show the same taper wear, and on the same end, i.e., were pads worn more on both their trailing edges, both leading edges, or one trailing and one leading? If it's one of each, it could be the caliper is not aligned with the rotor/hub plane.

 

[Theflyingz]

No personal experience, but I'd think the 6-pot Brembos would use staggered piston sizes to reduce taper wear on the pads. The "leading" piston should be smaller than the "trailing" piston. That said, I don't think the taper is that bad on the pad pictured. Original pads? How many miles on them?

Do you know if it's the leading or trailing edge of the pad that's more worn? Did the other pad from that caliper show the same taper wear, and on the same end, i.e., were pads worn more on both their trailing edges, both leading edges, or one trailing and one leading? If it's one of each, it could be the caliper is not aligned with the rotor/hub plane.

These were the stock pads with about 16,500 miles. The leading edge was the side most worn and this was mostly on the outside pad on on passenger side. The inside pad on the passenger side was a little off but not as bad. The driver side had a pretty even wear.
I was a little concerned that the pistons might have been pushed in crooked with the amount of pressure that could be created from an uneven pad. I am generally a person that understands we push our cars harder than most consumers and there can be some parts that don't hold up as well as expected.
It sounds like most people dont think this is too bad, so I will keep an eye on the new pads and see how the wear goes. Thanks

 

[67GTA]

The PP 6 piston Brembos use the same size piston in all 6 positions, which cause the tapered wear. The Shelby Brembos and higher end race calipers use staggered piston sizes to compensate. As mentioned above, you should see this to a lesser degree with race pads. Also, the pads can be swapped side to side at frequent intervals to even out wear - much like rotating tires.