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      09-29-2020, 02:47 PM   #8
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Drives: E92 M3,G20,F22 240iX,F82 M4
Join Date: Jun 2009
Location: Mid-Atlantic

iTrader: (11)

Originally Posted by Captain Caveman View Post
Thanks for providing the info - that's very useful and refreshing to see so much detail - nice one!

I've done the maths, and it seems your kits has about 9% smaller piston area than a stock E92 M3, meaning 9% firmer pedal, 9% less travel/modulation, and 9% less torque and a slightly more rearward bias:

Essex Racing AP kit
Front 27/31.8/38.1mm = 2506 x 2
Rear 28.6/34mm = 1550 x 2
Total 4056 x 2 (9.4% firmer pedal / less torque) 61.7% front bias

Obvisouly I've no doubt that you went through very deliberate and considered R&D when choosing the piston area for our cars, so I am curious as to your rationale for deciding on a not insignificant reduction in piston area and the consequential impact on torque and pedal feel/travel.

I've heard it said before that AP calipers tend to have smaller piston area than stock as a general rule, so there must be a reason. Be great if you could share your wisdom?


To calculate brake torque you also must include the radius of the rotor. The mean diameter of the AP 372 mm rotor is 345 mm whereas the stock 360 mm rotor has a mean diameter of 326 mm - the AP mean radius is ~6% larger than the stock mean radius.
Appreciate 0