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Old 10-27-2009, 12:03 PM
Apogee Apogee is offline
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Quote:
Originally Posted by BRIAN View Post
Just remember that OEM single piston calipers will need more pressure at the pedal than say wilwood 4 pistons.

There is a great 5 page write up ON HOTRODHEAVEN.COM

Either way just make sure you ge the right sized master it is the key to the whole set up.
Buyer beware...we've had several customer purchase master cylinders from H-R-H and they have always supplied oversized master cylinders for late-model, C5/C6 big-brake conversions.

You can't say that an OEM single-piston caliper will need more pressure than a 4-piston Wilwood without stating what the piston diameters/areas are for each specific caliper. There are several piston sizes for the OEM cast iron calipers, however they are 2-15/16" diameter for the '69 Camaro application and most other early muscle cars. That piston diameter equates to a 6.77 sq inch piston area and is typically matched with a 1-1/8" bore MC in a boosted application and 1" bore MC in a manual application. Don't assume that all vacuum boosters are equivalent...just because a single 7" diaphragm booster will fit does not mean that it will do the job required.

A C5/C6 2-piston caliper has double the pistons (40.5mm) and not even 2/3 of the overall piston area at 4.00 sq inches. The Wilwood Superlite 6-piston calipers are very similar at 4.04 sq inches. We would run a 15/16" to 1" bore MC in a boosted application and a 7/8" to 15/16" bore MC in a manual application assuming a matched rear disc application. Just for reference, the 4-piston SL calipers range from 2.22 to 5.18 sq inches with all of the various piston sizes and staggers.

Based on the areas stated above, the single piston caliper will need less pressure and more volume than any of the "big-brake" options, and this is true for the majority of the aftermarket big-brake kits on the market today. CPP's kits may be the exception that proves the rule since they use big truck calipers with their kits specifically so that their customers can retain their facotry MC/booster arrangements to save on cost.

"BIG-BRAKES" does not mean big caliper pistons. The rotor is what takes the heat and abuse, so bigger rotors (and pads to a certain extent) are what allow you to brake harder and longer. While smaller caliper pistons reduce the effective brake torque of the system, they give better driver feedback and are more responsive making threshold and trail braking that much easier. Assuming the brakes can achieve lockup with reasonable levels of pedal effort, any brake torque in excess of that is unusable. Once the tires are at their limits, you're done...I don't care how big or small your brakes are.

Tobin
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Last edited by Apogee; 10-27-2009 at 12:07 PM.
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