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      10-18-2021, 10:17 AM   #1
Dartanium
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3.0si brake upgrade BBK

Hello,

It's been a journey to finally settle on my current parts and part of the brake upgrade is for performance and the other part is for pure aesthetics so we can get that out of the way.

After reading C's 3.0 to 3.0Si brake guide, I realized current brakes might not be under-powered (I noticed full endless mx72 pads, new rotors are more than capable) as I anticipate but part of me just wanted some new calipers since I finally found a set of 17x8.5 Et38 BBS CH in silver to give the car a bit of personality and a set of new brakes will polish it off just right. My target tire size is 235/40/17 square in RE71RS for a bit of lively rear end. But since it's a brakes thread let me get into it, Questions: will AP cp9440+cp5317 a four piston front with two piston rear both using 330mm rotors be out of brake bias? If someone can share the piston area of OEM car (or brake piston sizes), then I can crunch some piston area numbers to get a rough estimate

The goal is to get hold of decent set of calipers under 17inch wheels and retain similar OEM brake bias

4 piston:cp9440 piston size, Ø36.0mm x 2 - Ø41.3mm x 2. 47.12cm²*piston area
4piston:cp9449 piston size Ø28.6mm x 2 - Ø34mm x 2. 2 30.9cm² Piston Area
2 piston: Cp5317 piston size Ø38.1mm Pistons.22.8cm^
Or 41.3mm Pistons. 26.8cm^2

Calculating true brake bias numbers are difficult since you have to throw in the effects of piston area, pad area, coefficient of pads, rotor diameter to analyze true torque values, so maybe some brake experts or someone who have some insights, please share, thank you.
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      11-10-2021, 04:36 AM   #2
Dartanium
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long story short, I went with 9440 and 5317, it should;ve kept brake bias similar to OEM, but slightly shifted to the rear
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