Hello, how are you today.
In this Tech-Session I want to give you some information about Setting Up Race Car Brake Proportioning and Balance with a bonus section about Forced Brake Cooling .
Setting Up Race Car Brake Proportioning and Balance
To achieve the perfect brake balance is difficult and requires plenty of attention and understanding of what conditions will impact the end results. Gaining that perfect balance between the front and rear brakes under hard braking can be a major problem. Each wheel should have the correct braking force applied to it that will allow that wheel to transmit that force directly to the track surface without lock up or break away.
If too much braking effort is applied to one pair of wheels, the other pair will not be doing enough work, and the result will be the most heavily biased set of wheels will lock up. If the front wheels lock up you will experience heavy under steer until the brakes are unlocked. If the rear wheels lock up the car will most likely break away and spin out. The optimum and most stable braking condition is to have the front wheels lock up just an instant before the rear wheels.
The front braking bias in most race cars is 55% to 80% of total braking. This can be adjusted with the obp bias pedal solutions, the obp bias valve or by altering the size of the front brake calipers.
There are many conditions that will vary the front to rear bias required. These conditions include the weather, track shape, track smoothness, tyre selection, tyre compound, vehicle speed capacity, vehicle weight, distribution of weight and of course the personal drivers technique. So you can see there are many factors to take into consideration when setting up the brake bias.
Forced Brake Cooling
As you are aware a build of heat in the brakes is the enemy to efficient brakes, the heat will boil the brake fluid, distort the discs / rotors or cook the pads. Any of these will dramatically reduce your braking capability and increase your lap times. A total no go for any motorsport or race situation.
One way to assist the cooling is to use a forced air brake cooling system, this is vital in most race conditions however when you are undertaking a long endurance race this type of installation is vital.
The best and easiest way to achieve this is to use fire retardant plastic ducting to force the cool air from the high pressure areas from the front of the car. A good place to fit the intake is in the front lights openings or in the front spoiler. Use a minimum of 3″ / 75mm inside diameter cooling ducts to supply the sufficient amount of air to cool the brakes. You can use larger ducting this should reduce the brake temperature even further. However some heat is required in the pads for efficient braking.
The place you need to aim the cool air flow is the centre of the vented disc and the caliper. Always make sure the ducting is secured properly and will not come loose in race conditions.
Thank you for your time.