WRX FHI 4 Pot Calipers

[churchx]

Do you really trust your calculations and precision level of your butt dyno THAT much more then that of car manufacturers and brake vendors testing? I'm sure that your calculations may miss several variables that can still affect brake torque (for example does your spreadsheet cover also brake pad geometrical shape, and at what actual radius from center is center of it's friction material area? Or width of leading edges? Or effect of mid grooves in some of pad designs?), and one's butt dyno "feel/detection" precision/brake press precision & repeatability is also far from what can be tested on proper brake testing rigs with precise hydraulic pressure and torque measurement, or at very least real skidpad tests. And how many various brake usage scenarios you have tested? Just track? Just on dry? How about in wet? How on ice/snow? (for example, the less grip, the less front-biased brake bias should be. Opposite to more grip, eg. with grippier tires. I'm sure, that nannies that are designed to help at different weather/different grip levels, expect close to stock brake bias). Do you really still think that you can trust yourself or spreadsheet with just subset of possible variables (of most probably just ratio of front/rear brake cylinders, piston diameters, brake pad area and brake rotor diameter, no?) so much more then car or brake vendor that has all those testing means & data? Have you actually _measured_ mass & grip transfer with different suspension setups? Are you sure in your view enough to advise someone else on modifications of which car or brake vendors advise against for something as important as brakes and use on track? Not daily driving but actually pushing on track?

[jamal]

My numbers for effective radius came out of the service manual so hopefully they are fairly close. In other cases, I did go so far as to take measurements on drawings of calipers and pads (and also have compared my math to the given ER for some setups).

The assumption is that the same pads are used front and rear, and weight transfer is based on deceleration rate, so stuff like grooves in the pads or what surface you're on is irrelevant.

But on that note, with the stiffer 4-pots, the "apparent" change in bias might actually be less than calculated.

I should probably make a new thread about this since we're getting a little off topic.

[dsc_pat]

I like how some think the OE bias is some magical deeply developed scientific absolute number, while it is actually more of an economy and part mix-matching from other comparable supply-chain car models. It is hard to admit some are arguing over something nobody knows the truth, but this is what the internet is all about these days amiright.