Warped rotors or just build up

[2017RoushStage3]

I have had the car for a week and the brakes are roaring. Noticed the rotors have these black spots all the way around. Is it just build up or did I warp my rotors?
2017 Roush Stage 3 with brembos. 16k miles.

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[CJJon]

Looks like it's time for new rotors.

 

[Norm Peterson]

Agreed.

From the shadowing, it looks like there's a pretty substantial ridge at the OD of the rotor where the pads never touch.


Norm

 

[2017RoushStage3]

Well good news...wire wheel and brake parts cleaner and bed in procedure seems to have cleaned them up

 

[20ducks]

FYI: It is extremely rare that one can warp a rotor in most vehicles. The bed-in procedure you used is the most recommended for what is described as a "warped" rotor. Glad to see you have remedied the situation.

 

[CJJon]

FYI: It is extremely rare that one can warp a rotor in most vehicles. The bed-in procedure you used is the most recommended for what is described as a "warped" rotor. Glad to see you have remedied the situation.

Uhhh, wut?

Of course they do...you just need to understand the term as it is applied to rotors. Warped refers to the flatness of the surface of the rotor (not like the rotor itself becomes wobbly-warped). The rotor surface has slightly varying surface hardness and will wear differently. Those were the discolored areas on the rotor face. The lumpy surface is what causes the pedal to pulse in badly warped rotors.

A simple re-bedding isn't going to fix things. Replacement or proper re-surfacing at a shop.

 

[20ducks]

I am not going to argue with you.

 

[CJJon]

I am not going to argue with you.

Nothing to argue about.

 

[Norm Peterson]

In many, perhaps most cases, the wobbly surface comes from unevenness of pad deposits. This probably didn't occur as often with pads that worked via abrasion (semi-metallic) as it does now with pads that work via adherence. Yesteryear vs today.

If you've managed to hot-spot the rotors themselves, then you can have unevenness of the metal surface itself. In that case, the hardened spots will be difficult if not impossible to machine flat and not end up with the shuddering returning (the hard spots that still remain won't wear as fast as the unhardened regions).


Norm

 

[20ducks]

Thank you, Norm.

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