What's up with OEM rear brake pads?

[Bull Run]

Upgraded brake pads today and noticed that OEM rear pads are designed in such a way where they won't make a full contact with rotors until they're worn down. Doesn't this leave some braking power on the table?

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[Norm Peterson]

Not really. The amount of friction you get from "X" amount of caliper piston force is independent of the pad surface area, or at least close.

Maybe it has something to do with pad surface temperatures or how much of the caliper piston sits out past the caliper bore.


Norm

 

[Bull Run]

Not really. The amount of friction you get from "X" amount of caliper piston force is independent of the pad surface area, or at least close.

Maybe it has something to do with pad surface temperatures or how much of the caliper piston sits out past the caliper bore.


Norm

So what do you think the effect will be when the OEM pad wears down and makes full-width contact? Similar braking effort as larger friction surface area but the same amount of pressure that's spread further out?

 

[Norm Peterson]

The same amount of force is being applied, just that it gets spread out over 2 or 3 more square inches. The force on each square inch drops but the total force on the pad friction area remains constant.

Another possible reason for that non-uniform thickness could be to reduce brake noise, something that typically accompanies pads with higher friction coefficients.


Norm

 

[melwff]

are you sure you bought the correct pads for a PP equipped vehicle?

 

[Bull Run]

are you sure you bought the correct pads for a PP equipped vehicle?

The pad on the right was purchased from www.opmustang.com and they don't even carry rear pads for non-pp EBs or V6s. The SKU is GP1793R8 and I didn't have any issues putting them in.

 

[melwff]

there maybe other reasons for the difference in design, such as noise. You selected the R8 design pad, is the car driven other than purely on the street?

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[GuardEcoBeast]

Brake noise would be the main reason.

 

[Bull Run]

there maybe other reasons for the difference in design, such as noise. You selected the R8 design pad, is the car driven other than purely on the street?

Will start doing some tracking in the future. I don't drive in freezing conditions and R10/R8 seem to do well on the street as long as you don't mind some squeal, and I can switch to more aggressive pads at the track, if needed, without needing to sand the rotors. I wonder if their GS-1 pads are shaped like OEM or R series pads...

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