[CapriCrunch]

I have 370mm rotors and I’m not sure whether I’m supposed to purchase 370mm calipers or 380mm.
I bought a sport brake kit but didn’t realize I would have to upgrade my brakes for them to fit.

[johnung]

If you are talking about front rotors that are 370mm in diameter, they should be 30mm thick. The 4-piston Brembo front calipers that have raised lettering on the back that says “370/380” is dependent on the car.

The F30 hubs take 370mm rotors with those calipers. But the same caliper when bolted onto an F80 hub will fit a 380mm rotor. The front brake caliper mounting points on those cars differ slightly with the F80 being 5mm further from the center of the hub.

[CapriCrunch]

The rotors I have are 340mm. I tried putting on the new rotors that are 370mm but the caliper did not fit around the rotor.
But if I’m understanding correctly the 370/380 caliper can be used for the 370mm rotors ?

[Dagstar]

You either need to buy 340mm rotors for your current m sport calipers or 370/380 marked calipers for the 370mm rotors.

Front rotors:
M Sport calipers=340mm
M Performance calipers=370/380mm

Keep in mind I've even seen some sellers confused by advertising m sport brakes as m performance and vice versa. Only way to be sure is to look at the number on the back of the calipers.

[CapriCrunch]

Thank you