6 waggin
07-27-2008, 09:59 AM
Here is some additional info to go with the tire thread
Autocrossing and to an extent Road Racing is all about getting the car to transition as fast and stable as possible. It can be getting the car (specifically the cars momentum) to move front to back under acceleration, back to front under braking or side to side under corning. Ideally what you want is a good balance between the front and rear brakes that will both help stop the car the most effiectenly but can also aid in helping to bring the rear of the car around entering turns.
Looking at an OEM type braking system from the factory, cars are heavily biased towards the front brakes for safety. Simply, manufactures do not want the rears to grab as much or more than the front brakes as this will mostly likely cause a spin with the slightest turn of the wheel under hard braking. They do this by making sure that most of the brake pressure goes to the front calipers/pads. Another way they do this is by size of the brakes. The front brakes are always bigger than the rears and/or the rear pads are normally not as aggressive as the fronts.
Knowing this we can use the cars brakes to help "turn" the car especially into tight slow turns by changing how much work the rear brakes do in relation to the fronts.
The most common way race cars do it is with a mechanical knob in the car which the driver can just adjust during a race to allow more or less brake pressure to the rear. Since 99% of us do not have such devices in our cars, we have to use another.
The absolute simplest way to make a brake bias adjustment is to simply change the pads. We will use a stock Miata as an example. The stock Miatas from the factory are notorious for wanting to lock the front and having the rear do almost no work.
One thing that can be done is to put a less grippy pad up front. This will allow you to push harder on the brake pedal before locking the front wheels and generate more braking force out of the rears. The down side is that normally a "lesser" pad than what comes from the factory will usually mean that you will have some heat and fade issues as the brakes heat up.
Another thing that can be done is leave the factory fronts alone and replace the rears with a more grippy pad. One that has more initial bit and higher coefficient of friction than the factory pad. That will generate more work from the rear while using the same amount of pedal pressure in relation to the front.
So when choosing a pad, it is important to knowing your operating temps that you will be running at, understand what you need the pads to do for you, and then choose the correct combination that will get the desired result. Ultimately there is quite a bit of time that you can find with brakes. A good setup will allow you to stay on the gas longer, brake later, turn faster and give you the confidence to push a little harder. It will also take a bit of seat time to get used to what a good brake setup will gain you over OEM pads.
It is probably also worth mentioning that brakes DO NOT STOP a car - the tires do. So if you have upgraded your tires to something more sticky, then you probably need a better set of brakes to cope with the added heat dissipation.
Autocrossing and to an extent Road Racing is all about getting the car to transition as fast and stable as possible. It can be getting the car (specifically the cars momentum) to move front to back under acceleration, back to front under braking or side to side under corning. Ideally what you want is a good balance between the front and rear brakes that will both help stop the car the most effiectenly but can also aid in helping to bring the rear of the car around entering turns.
Looking at an OEM type braking system from the factory, cars are heavily biased towards the front brakes for safety. Simply, manufactures do not want the rears to grab as much or more than the front brakes as this will mostly likely cause a spin with the slightest turn of the wheel under hard braking. They do this by making sure that most of the brake pressure goes to the front calipers/pads. Another way they do this is by size of the brakes. The front brakes are always bigger than the rears and/or the rear pads are normally not as aggressive as the fronts.
Knowing this we can use the cars brakes to help "turn" the car especially into tight slow turns by changing how much work the rear brakes do in relation to the fronts.
The most common way race cars do it is with a mechanical knob in the car which the driver can just adjust during a race to allow more or less brake pressure to the rear. Since 99% of us do not have such devices in our cars, we have to use another.
The absolute simplest way to make a brake bias adjustment is to simply change the pads. We will use a stock Miata as an example. The stock Miatas from the factory are notorious for wanting to lock the front and having the rear do almost no work.
One thing that can be done is to put a less grippy pad up front. This will allow you to push harder on the brake pedal before locking the front wheels and generate more braking force out of the rears. The down side is that normally a "lesser" pad than what comes from the factory will usually mean that you will have some heat and fade issues as the brakes heat up.
Another thing that can be done is leave the factory fronts alone and replace the rears with a more grippy pad. One that has more initial bit and higher coefficient of friction than the factory pad. That will generate more work from the rear while using the same amount of pedal pressure in relation to the front.
So when choosing a pad, it is important to knowing your operating temps that you will be running at, understand what you need the pads to do for you, and then choose the correct combination that will get the desired result. Ultimately there is quite a bit of time that you can find with brakes. A good setup will allow you to stay on the gas longer, brake later, turn faster and give you the confidence to push a little harder. It will also take a bit of seat time to get used to what a good brake setup will gain you over OEM pads.
It is probably also worth mentioning that brakes DO NOT STOP a car - the tires do. So if you have upgraded your tires to something more sticky, then you probably need a better set of brakes to cope with the added heat dissipation.