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Caliper & Rotor Upgrade (BBK)

Caliper & Rotor Upgrade (BBK)

Learn and Shop: Big Brake Kits

A kit with increases the rotor size of a vehicle's braking system is generally called a Big-Brake Kit, or BBK to short. Normally the caliper is changed with these kits as well. The new rotors will be either 1- or 2- piece rotors, and may come in a variety of finishes. The calipers will usually be of a radial mounting (but standard mount are possible), and have four, six, or more pistons. Learn more about rotor and caliper features in their respective categories.

Performance Increase

Braking systems work very well to slow and stop vehicles. Many people feel that big-brake kits are employed to stop vehicles better than the do normally. While it is true that braking performance is increased with comprehensive upgrades, this is usually a function of the brake pads. However, the degree of braking force a vehicle is capable of is ultimately limited by the tires. As long as the wheels can be locked up, additional braking power will not slow the vehicle better.

Big-brake kits are improvements over stock because they cope with heat much better than standard systems. As such they offer improved high-speed or repeated braking. Most standard brake systems can handle emergency stops from 80 mph fairly well. However they cannot be asked to do this braking run repeatedly without time to cool off. If a standard braking system is asked to bring a vehicle to a stop from 100 mph, it may not be capable of doing it confidently. Big-braking kits are better at handling these tasks. They can handle repeated stops from higher speeds where standard braking kits cannot.

BBK Rotor Function

Rotors are the primary devices for absorbing and dissipating heat in braking systems. Big-brake kits feature larger rotors which have more mass, and therefore have a greater ability to hold heat. They also have larger surface area which better enables them to dissipate heat through vents and normal convection. Many big-brake kits feature 2-piece rotors which have aluminum rotor hats. Aluminum transfers heat very quickly, and provide and even more enhanced means of drawing heat from the rotor rings and dissipating through the wheels.

BBK Pad and Caliper Features

The calipers in big-brake kits may simply be standard rotors mounted with special brackets to accommodate the larger rotors. They may alternatively be OE calipers from a different vehicle model fitted with a bracket as a relative upgrade for a different vehicle. Or, they could be completely new aftermarket calipers of specific construction for performance. No matter what the caliper, it in most all cases will be a different FMSI specification than those standard for the vehicle. The pad compounds will typically be aggressive, due to the level of performance expected from BBKs, and the rotor's ability to cope with increased heat generation.

Sizing and Fitment

Increased sizing of the rotors and the larger, wider calipers that big-brake kits employ often limits the sizing of the wheels that can be used. Clearly, larger brakes will require wheels with larger barrels and spokes that clear the calipers. Many brake kit manufactures will produce templates that can be printed and cut out then compared with the user's wheels to get an idea if they will have clearance for the brake kit. While rudimentary and not available from all brake suppliers, it is a reasonable tool for testing.

Brake rotors are measured by their overall diameter and width in either inches or millimeters (mm). Other variables are whether rotors are 1- or 2- piece, what finish the rotors have (drills, slots, or both), what color the calipers are, sometimes the piston-count in the calipers, whether or not brake lines are included, and other unpredictable factors. Inside of wheels, BBKs are one of the most significant aesthetic enhancements that can be made to the rolling-stock, and can come with a myriad of technical or visual features.

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