Thursday, May 24, 2012

Brake Performance - obp Motorsport Tech Session



What makes a good braking system in a race car?
If you have a road car you will want your brakes to be able to slow the car from whatever speed the car is capable of to a dead stop in the shortest distance possible. Further to this, the car must be totally controllable and stable while slowing or stopping. The car must stop in a straight line without any brake fade.
A race car has different criteria when braking, a racing car rarely needs to be slowed to a dead stop in race conditions (However the car must be capable of stopping to a dead stop if needed). A race car used on the circuit must be able to slow from the maximum speed to the slowest speed required in the shortest distance possible, this braking performance needs to be repeatable as many times as required without loss of brake effectiveness, whilst remaining totally controllable at all times in the brake zone. That means being able to change the race line or position on the track while under maximum brakes, with no hint of brake fade. That is a massive ask in race conditions and why a good driver is always aware not to over brake.
The braking capability of a car is measured by the distance it takes to slow from maximum speed and the reason for this is that when you do so, the cars overall braking efficiency is being taken into consideration.
In all instances the race car must be controllable under heavy braking and the brakes must be repeatedly able to take such harsh treatment without brake fade. Fortunately with the advancement in brake pad compounds this is now achievable as long as you use the correct brake fluid, calipers, rotors, brake pads and pedal solution. 
A good brake pad compound to use are the Carbon Metallic type, these are very aggressive pads and require heat in them and the rotors to operate correctly. Due to the very high temperature created under race conditions (Can be above 500 - 600 Degrees C) the disc / rotor material anneals or softens resulting in the contact surface wearing very quickly, also tiny cracks can be created. This is why precise air-cooling of the rotors is vital.
It is essential that you check and inspect rotors and pads after every race meeting or practice just to be sure there are no extra cracks from the last inspection. Spending time and money on the braking system is well worth it. The brakes must match the cars overall performance capability.

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