M4 F8x brakes to M3 F9x

[Expressivedrives]

Hi. I believe, this is covered here already, but here I share my solution to make M3 F9x stock brakes batter. Last year I wore new Ferodo DS2500 front brake pads during one trackday -- ca 150 laps, 2,5 km each. Destroyed also front disks. Had to trailer my car to the workshop. Don't get it wrong, M3 OEM brakes are very good in an average punishment, but I just needed more. So, I investigated several options on decided to go to very economic route. Used E8x calipers are relatively cheap. I purchased used 4-pot Brembo M4 F8x front calipers (ca 550 US a set, used) and 2-pot rear Brembo-made M-calipers (ca 450 US a set, used), purchased new front 380 mm and rear 370 mm M4 F8x discs.

There are no adapters available to install front E8x calipers to F9x (rear calipers are direct bolt-on), so I swapped E8x M4 knuckles to my F92 M3 (used, 200 US each). They are same size, but two small differences:

1. wheel speed sensors are mounted in 90 degree angle. There are two solutions. To alter F9x M3 wheel sensor and use additional metal bracket to hold it correctly in the place. Second option is to to buy F8x wheel sensors and to solder to F9x connector (F9x and F8x have different connectors). I modded F9x sensors.

2. four hub / wheel bearing bolts are different (spherical-head, not flat-head)

Also, rear calipers require two additional washers to center disc-caliper. Thats is it! I changed brake fluid and put fresh DS2500 pads, had two track days and what can I say. First, brake pad wear is much less. I believe it's due to lower temperatures. Brake feel is fetter, but not dramatically.

Front:


rear: