Brake Pad Frictional Formulation

Brakes work on the crude principle of friction between two surfaces. To give a uniform measure of the frictional characteristics of a Brake Pad the SAE J866A test procedure is used to give a two character code e.g EE FF GG HH.

HH or GG

• HH Pads These have the highest coefficient of Friction and are ideal for high-performance motorcycles and race track use. Some modern performance motorcycles specify HH as standard. HH Pads can sometimes prove grabby, scary in the wet and ineffective in every day use when they fail to reach a good operating temperature.
• GG Pads This grade of Pad is a great all rounder and will perform well in most conditions. GG are softer than HH pads and bed in quicker on worn discs.
• Mixing HH and GG Pads Many manufacturers specify HH for the front of performance Motorcycles with GG in the rear. This is because GG pads can give you more feel and control of the back brake. It is not considered safe to use HH in the rear with GG pads in the front.

Obviously Pads are only as good as the condition of the whole braking system. When first used, brake pads can sometimes give poor braking, as residual moisture from the manufacturing process works its way out and the pads bed in. It is best to bed in pads with gentle use and very heavy initial use can result in glazing, a condition where the resins in the pad crystalize with resulting poor performance and squeal.