[aerobod]

Originally Posted by Polo08816

Are they necessary though? Are the single piece plain steel rotors failing at the track?

Not sure about the C8, but the C5 Z06 steel rotors cracked a lot under hard use. My son only got 3 track days out of one set on his car before significant cracks appeared.

[two_three_two]

Originally Posted by xtougher

Yeah, mostly curious. I was told that even with my previous car, which was a 2016 340i.

Even called some random shops around me and even they said they would change rotors with the pads...couldn't tell if that was just an upsell tactic, or a general rule these days.

on our commuter mk7 jetta, i have no problem doing just pads. on anything i put through its paces in a pointed fashion, track or not, i usually do pads and rotors together. there's something to be said about having an appliance type vehicle on the side. it sees valvoline for 3 oil changes in a row (~20k miles) and then it sees my real mechanic on the fourth for a pat down. no issues in almost 100k miles...

[DSTR]

Originally Posted by two_three_two

on our commuter mk7 jetta, i have no problem doing just pads. on anything i put through its paces in a pointed fashion, track or not, i usually do pads and rotors together. there's something to be said about having an appliance type vehicle on the side. it sees valvoline for 3 oil changes in a row (~20k miles) and then it sees my real mechanic on the fourth for a pat down. no issues in almost 100k miles...

Savvy!

[RockCrusher]

Originally Posted by xtougher

Yeah, mostly curious. I was told that even with my previous car, which was a 2016 340i.

Even called some random shops around me and even they said they would change rotors with the pads...couldn't tell if that was just an upsell tactic, or a general rule these days.

Not quite fair to the shops but in some way it is a cover their ass rule.

With new pads mated with new rotors the two items have the necessary degree of pad/rotor material and flatness and the rotor surfaces are parallel and braking will be optimum. Brake life will be optimum. And the chance of a customer having to bring back the car due to some brake issue is greatly reduced. Almost nil really.

[M_Power Rob]

Originally Posted by RockCrusher

Not quite fair to the shops but in some way it is a cover their ass rule.

With new pads mated with new rotors the two items have the necessary degree of pad/rotor material and flatness and the rotor surfaces are parallel and braking will be optimum. Brake life will be optimum. And the chance of a customer having to bring back the car due to some brake issue is greatly reduced. Almost nil really.

Too mant miles/damage (grooves & lip) to the rotors will not only have potentially inconsistent stopping/bite but it will take time to seat in and match the grooves and you will lose a lot of brake pad life.

[xtougher]

Originally Posted by RockCrusher

Not quite fair to the shops but in some way it is a cover their ass rule.

With new pads mated with new rotors the two items have the necessary degree of pad/rotor material and flatness and the rotor surfaces are parallel and braking will be optimum. Brake life will be optimum. And the chance of a customer having to bring back the car due to some brake issue is greatly reduced. Almost nil really.

Originally Posted by M_Power Rob

Too mant miles/damage (grooves & lip) to the rotors will not only have potentially inconsistent stopping/bite but it will take time to seat in and match the grooves and you will lose a lot of brake pad life.

Makes sense. Maybe not a pure "upsell" but a combination of manufacturers maybe making rotors "built to last" a long time ago, and at some point, shifting to different materials/specs which help cause the overall life of rotors to decrease in general...and then add that to the actual risk/inconsistency of the stopping, and then the desire to CYA.

Thanks for the thoughts!

[RockCrusher]

Originally Posted by xtougher

Makes sense. Maybe not a pure "upsell" but a combination of manufacturers maybe making rotors "built to last" a long time ago, and at some point, shifting to different materials/specs which help cause the overall life of rotors to decrease in general...and then add that to the actual risk/inconsistency of the stopping, and then the desire to CYA.

Thanks for the thoughts!

At some point brake rotors went from having a lot of wear tolerance to not much.

I can't recall the rotor details of my first cars but with my 2002 Boxster the rotors had 2mm of wear. 1mm per surface. When the pads were worn out the rotors were also worn out.

This lack of excessive rotor thickness has been the norm for those cars I have owned since then.

Lighter rotors require less energy to spin up as the car accelerates, and less braking force to slow. And lighter rotors mean less unsprung weight.

The only thing that could be better would be the BMW M Carbon Ceramic brakes.

[M_Power Rob]

Originally Posted by RockCrusher

At some point brake rotors went from having a lot of wear tolerance to not much.

I can't recall the rotor details of my first cars but with my 2002 Boxster the rotors had 2mm of wear. 1mm per surface. When the pads were worn out the rotors were also worn out.

This lack of excessive rotor thickness has been the norm for those cars I have owned since then.

Lighter rotors require less energy to spin up as the car accelerates, and less braking force to slow. And lighter rotors mean less unsprung weight.

The only thing that could be better would be the BMW M Carbon Ceramic brakes.

That a significant reason to go with Girodisc, plus they are stronger and cheaper than OEM M rotors. Also, all future changes are even cheaper as all you need to do is replace the ring.

[xtougher]

Originally Posted by RockCrusher

At some point brake rotors went from having a lot of wear tolerance to not much.

I can't recall the rotor details of my first cars but with my 2002 Boxster the rotors had 2mm of wear. 1mm per surface. When the pads were worn out the rotors were also worn out.

This lack of excessive rotor thickness has been the norm for those cars I have owned since then.

Lighter rotors require less energy to spin up as the car accelerates, and less braking force to slow. And lighter rotors mean less unsprung weight.

The only thing that could be better would be the BMW M Carbon Ceramic brakes.

Makes a lot of sense to me!