Long story short, I'm racing with pedal mod and brake load cell mod and wanna recalibrate brake pedal so i really need to step on it for making the wheels getting locked.

My problem now is that I cant figure out on how to proper calibrate the brake axis.

It's not that selfexplained while you're in there in Axis/FF in lfs menus.

When in the axis/ff menu click "recalibrate axis" then move pedals and wheel lock to lock or full travel then back again, then click "lock"

all done

Good luck

SD.

I think that he'd rather adjust brake pedal sensitivity so that it would be less sensitive on the top and become more sensitive when depressed beyond certain limit.

If this is what's on your mind, you can try apps like DXTweak, LFS itself does not provide any curvature or sensitivity settings for pedal axes at all.

I think the load cell mod does that itself?

If you need to or want to only use say half pedal travel, you can repeat the calibration but start with the pedal you only want to use half of, in the fully depressed position, then while calibrating just lift it half way then push it back to the floor, after you click the lock button you will be able to depress and release and see the axis indicator will only start giving brake or gas at the half way point.

I sometimes use this method to set up my throttle when I have that lazy right foot resulting in dogey downchanges under braking

SD.