Manufacturers perform rigorous...
Manufacturers perform rigorous brake testing on brake dynamometers to find the limitations of their products. Photo: StopTech
We began this series by covering brake rotors in Part I. Now that you have a better idea of what you may want for your rotor design and why, it's time to discuss performance calipers, pads, and fluid. Once again, we've teamed up with some of the biggest names in the performance after-market and asked them to share their knowledge regarding what to consider when upgrading your brake system.
There is a stigma that factory brake systems are inadequate, and you have to go with something bigger and better. While this may be true in some cases, it's not for all. Many Pontiac owners with factory-disc brakes may have all the braking power they want, or they may desire a few subtle upgrades.
If you're simply after a better appearance, take the calipers off and paint them with specialized brake-caliper paint that will stand up to the heat and elements. If you're seeking improved stopping power, run a more aggressive pad. If you want more reliable operation, keep the fluid clean.
However, if you're looking to step up to the next level in braking, determine your budget and use the information in this series to your advantage to seek out a company that can provide the matched components you want.
Here is a typical OEM-style...
Here is a typical OEM-style floating caliper, as shown on our '05 GTO. Notice the discoloration of the red paint from the extreme temperatures the caliper was subjected to during our outing at Sebring International Raceway ("Open Track Packin'," Dec. '10).
The caliper is the muscle behind the braking system; it sits over the rotor like a clamp. As hydraulic pressure is sent to the piston, it applies pressure to the pad, creating braking force. As more force is applied to the back of the pad, the caliper itself will want to expand. This expansion must be controlled and limited to maintain proper braking performance.
There are two kinds of calipers: floating and fixed. Both are designed to perform the same task, but which is right for you?
Floating calipers (also called sliding calipers): In a floating caliper, the caliper body is usually made of cast iron because it's subjected to forces that a fixed system is not. Cast iron is strong, cheap, and has known thermal properties. Floating calipers are the most common type of calipers and are used for most OE applications. In this system, one or more pistons mounted on the inboard side of the caliper push against the back of the brake pad. The caliper attaches to a bracket that allows it to "float" or slide freely so that when the brake pressure is applied, the caliper body actually moves, creating friction with both pads on both sides of the rotor.
Here is a two-piston floating...
Here is a two-piston floating caliper. The red part is the actual caliper; the blue part is the caliper bracket. The caliper bracket is fixed and stays attached to the spindle. A: This is where the caliper bolt allows it to slide in and out of the bracket. B: This is where the brake line attaches to the caliper and supplies fluid to the piston, which is on the inboard side of the unit. C: This is the brake bleeder fitting. Photo: StopTech
A downside to floating calipers is that they tend to be heavier than fixed calipers (despite the fact that fixed calipers have more pistons) and can produce uneven pad wear. Since the caliper and its brackets are quite heavy, unsprung weight is increased.
When cool air is drawn through the rotor "eye" of a ventilated disc, it exits from the openings on the outside of the rotor, blowing additional heat onto the caliper. If floating calipers are used regularly in racing conditions, they may begin to deform from the stress of applying brake pressure (the caliper tries to expand) while being softened from heat. This is easy to identify when you remove your pads because they will show irregular wear-less material at the top than at the bottom of the pad.
On the plus side, floating calipers can be very powerful and provide excellent stopping power on the street. Since these are probably what your Pontiac already has (both factory-disc-brake-equipped vintage Pontiacs and late-models use floating calipers), they become very attractive to the budget-minded aficionado. If you don't plan on aggressive braking, such as road racing or high-speed autocross, your floating calipers are probably up to the task of excellent braking, they just may not have the eye-catching appeal of a fixed caliper.
Here is a Brembo four-piston,...
Here is a Brembo four-piston, monoblock fixed caliper. It's called a mono-block because it's formed from a single block of aluminum and isn't comprised of multiple pieces like other fixed calipers. Photo: Brembo
According to Emanuele Bruletti,...
According to Emanuele Bruletti, chief engineer for Brembo North America, the shape of the caliper is the source of its strength. Brembo analyzes the stresses received by the caliper and increases strength where needed by adding material. Notice that the pads can be easily changed by pulling them out from the top-another consideration when choosing a braking system if you will be doing your own maintenance or trackside pad changes. Photo: Brembo
This is an StopTech STR40...
This is an StopTech STR40 anodized aluminum caliper. Notice that strong, thick bolts on the perimeter of the caliper hold it together. This is to prevent the design from flexing. Major race teams use this caliper, and StopTech even makes a version with dust boots for the street that you can get in assorted colors. Photo: StopTech