Do you even know how
AO Gold Member
Join Date: Sep 2007
Location: South Africa
County: Western Cape
Nick, there are a number of reasons why brake discs get drilled and grooved: Grooving is usually for degassing and deglasing brake pads which allows them to seat better when hot. Ithis can be felt when pushing on under conditions that would normally induce brake fade due to overheating of pads. Brakes are drilled for weight reduction mainly (even though they may claim cooling, it actually does not really affect cooling that much). A lower mass means that the brake disc heats up faster during racing applications, but it also retains less heat and cools quicker (not because of the holes, but because of the reduced mass!).
Quick running through tight country lanes can cause excessive brake overheating, and driving through puddles with hot brakes can cause discs to warp and as an advantage, drilled discs will be a little cooler and may withstand warping because of this.
On the contrary, they may crack as the holes themselves are not stress releived and cause cracks when overheated.