Disks

[Weet-rider]

I always thought it was to increase the surface area, as heat loss through convection is increased in proportion to the surface area, thus reducing the risk of brake fade and keeping the pad gap

and allow steam and gas to escape from between pad/disc.......or I may be talking hot air

[Beerbelly]

I always thought it was to increase the surface area, as heat loss through convection is increased in proportion to the surface area, thus reducing the risk of brake fade and keeping the pad gap

Wouldn't increase surface area if you are drilling holes in it! Would decrease!

[Grobb]

Depends on the thickness of the disk, but generally if you do the calcs, it does increase surface area/vol ratio, because you are removing more volume than area. It is mainly to aid with venting to help reduce fade and wear.

[Beerbelly]

Depends on the thickness of the disk, but generally if you do the calcs, it does increase surface area/vol ratio, because you are removing more volume than area. It is mainly to aid with venting to help reduce fade and wear.

Can't see how that works! I must be thick...

[Grobb]

It doesn't seem obvious I know but you are removing the volume and creating more surface area through the inner bore surface of the holes. It's more about moving air across the pad surface really though. I spent some time years ago doing some consultancy work tuning truck brakes.

[Stewie]

I always thought it was to increase the surface area, as heat loss through convection is increased in proportion to the surface area, thus reducing the risk of brake fade and keeping the pad gap

Wouldn't increase surface area if you are drilling holes in it! Would decrease!

Think of a sliced loaf, before you slice it, it has the surface area of the 6 sides, then slice it into 30 pices, and hey presto you've increased the surface area, the same principal applies .