Author Topic: Why STi brakes on an FR-S/BRZ is a bad idea  (Read 3584 times)

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Offline Jimmy@Vex

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Why STi brakes on an FR-S/BRZ is a bad idea
« on: January 20, 2015, 11:54:37 PM »
A lot of people are presenting this idea to us, as they've seen it on MotoIQ and several 86 forums. The calipers bolt up and fit fine, but there are several compromises when doing this setup that very few are aware of. A lot of R&D goes into designing a proper functioning braking system with ABS, and there is no "cheap" way around it.

STI calipers are made to be mounted in the trailing position (behind the axle). If mounted in front of the axle, by exchanging positions of the plugs and bleed screws on the caliper, it is not possible to bleed all the air out of the system because the fluid crossover in the caliper is the highest point and will trap air. This leads to poor brake performance and a poor pedal feel. If the calipers are mounted in front of the axle by putting the left hand STI caliper on the right side of the BRZ/FRS and vice versa, then the staggered pistons are in the wrong order, which leads to rapid and significant taper wear on the pad, which causes a number of other problems with the brake system.

Secondly, the piston sizes of the STI calipers are not appropriate for the BRZ/FRS, they are too large (25% increase in front). This leads to a number of non-desireable side effects, including long brake pedal travel, greatly increased front brake bias, and ABS problems.

Please be aware of these issues before considering a cheap brake upgrade, for arguably the most important part of your car.

If anyone would like more info, or would like help to set up a braking system for specific feedback, I'd be more than happy to give you free advice or to help tailor a system to your needs.

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Offline cmyles

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Re: Why STi brakes on an FR-S/BRZ is a bad idea
« Reply #1 on: January 21, 2015, 07:10:36 AM »
Thanks for the information Jimmy!

A lot goes into designing a braking system. It's a little different swapping them onto a GD WRX chassis, but an entirely designed system isn't the best option.
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Offline 05LGT

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Re: Why STi brakes on an FR-S/BRZ is a bad idea
« Reply #2 on: January 22, 2015, 07:02:33 AM »
I don't name things I know I'm going to sell eventually. Hence why I'd never name any kids I had.

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Offline jellynuts

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Re: Why STi brakes on an FR-S/BRZ is a bad idea
« Reply #3 on: January 22, 2015, 07:22:22 AM »
I love learning new things, thanks Jimmy. Also, LGT, great idea for a non-existent but desperately needed like button :p
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