Interesting marks on brake discs

[Sailor]

I tried braking hard from 60 down to not very much but still rolling. After 4 or 5 goes at it, the brakes felt smoother - at least, I convinced myself they did. The marks were less obvious just after the exercise, which was encouraging.
There's been no juddering since, but the marks have come back again.

[Doggo]

Result! (Hopefully).

[Merlin]

The 2nd and last paragraph. This is happening to your discs because of the pad compound.

When applying the brakes on your car, the caliper squeezes two brake pads to the spinning rotor, creating friction against the rotating mass of your tires and slowing you down. There are two types of friction at play here, abrasive friction and adherent fiction. Abrasive friction literally breaks the bonds of the crystalline structure of the pad and even the cast iron of the disc, creating heat. Mohs Law tells us that the harder material (ideally the disc) wears away at the softer material of the pad as the two materials rub together. Picture a sanding pad against a board. Same concept.

Adherent friction is where some of the pad material literally adheres to the opposing surface as they scrape by each other, creating a thin and (ideally) even layer of pad material on the face of the rotor. That material can continually break its bonds and transfer from surface to surface back and forth between the disc and the pad, continually breaking and reforming like they were bouncing across political parties between elections (heyoo!).

Good performing pads need to strike a balance between these two types of friction. A primarily abrasive pad will have a quick wear rate and will fade at high temperatures as its structure weakens and gives, no longer stiff enough to be abrasive. A primarily adherent pad will result in too much build up, as it is not abrasive enough to scrape the disc clean and uniform, and requires much higher temperatures to be effective. Between these two is where the balance needs to strike for good street pads — something that can handle being ridden all the way down a long hill without fading to nothing once you reach the bottom, and something that can still stop your car effectively on a cold morning. This is why a racing pad that requires high heat to work effectively and can be so dangerous on the street.

http://www.ludegeneration.co.uk/chassis ... 15300.html


If this is a problem changing to pads that have a different compound should solve it.