Wilwood Brakes - Dem's Da Brakes Part 2

Rotors And Calipers-There's More To Them Than Meets The Eye.

Mike Harrington Aug 1, 2008 0 Comment(s)
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We went to the CPP showroom and saw several types of floating calipers ranging from large, single, to dual piston, and of course, let's not forget the array of colors.

In the exciting May 2008 issue of Super Chevy magazine, we left off covering the fundamentals of braking and brake systems. As we mentioned, hydraulic drum brakes have been in use in most OE vehicles since the early 1930s. It wasn't until the 1950s and 1960s that the American OE manufacturers started offering disc brakes on their vehicles.

Disc brakes are commonly compared to a 10-speed bicycle's brakes. Pulling on a bike's brake handle is comparable to applying force to a vehicle's brake pedal. The pads on a 10-speed bicycle clamp down on the spinning wheel's rim and slow the bicycle down through the use of friction. Of course, a 25-pound bicycle and a 3,000-plus-pound car are very different, but the theory is still the same. Kinetic energy is transformed into thermal energy via friction. All vehicle braking systems work in this manner.

Welcome To The World Of Brake CalipersChoosing the right brake caliper for your needs can seem a bit confusing given the fact there are so many different types available to the average hot rodder. No matter the choice, all calipers are designed to function the same way: They convert the hydraulic pressure from the master cylinder into a mechanical clamping force.

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Some fixed-brake calipers can employ a radical amount of pistons, such as this Stainless Steel Brakes Company eight-piston caliper. (Photo courtesy of SSBC)

A floating caliper system is by far the most typical disc brake caliper found on vehicles. A floating caliper is usually equipped with one or two hydraulic pistons that apply pressure to the pad. The pistons are found on the caliper's inboard side, while the outboard side floats axially on a sliding bracket in relation to the rotor's position. When pressure is applied, the inboard pistons push the brake pad against the disc while the outboard pad clamps against the outside of the rotor.

If the intended vehicle is going to stay a street-driven vehicle, a floating caliper system would be a great upgrade. A floating caliper system is a more cost-effective route (due to its weight, size, and manufacturing costs) when considering a brake system upgrade. For vehicle owners who split their driving time between the track and the street or just for bragging rights, a rigid fixed-caliper system is the preferred choice. Either route-fixed or floating-will stop a vehicle equally well.

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A two-piece Wilwood rotor and six-piston fixed caliper.

Fixed brake calipers are easily identifiable from that of a floating caliper due to their size and unique shape. A fixed caliper is mounted to a rigid bracket that attaches directly to the spindle. A fixed caliper also houses the pistons on opposing sides of the caliper. Typically, pistons on fixed calipers will vary in size from the front to the back, such as 1.00 inch, 1.15 inch, and 1.30 inch. The reasoning behind this is based on pad wear. The smaller 1.00-inch piston is the leading piston (the point where the rotor enters the caliper), followed by the succeeding sized pistons. Theoretically, longitudinal pad wear (a subject we have no time or space to explore in this article) or tapered pads are the reason for the staggered piston sizes.

Fixed calipers are made of an aluminum alloy just like most floating calipers, but are constructed in two different ways: two-piece forged or one-piece billet blocks. Due to their construction, one-piece billet calipers run higher in production costs. Despite the costs, there is no denying the performance benefits of a fixed caliper on a road course.




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