[Dasky_spas]

The m850 has the odd sizing in the rear, at 398x28 while the M cars using 380x28. I purchased custom floating rotors but it turns out they won't be about to make the rear 398 sizing as requested. I either get a refund or pursue putting the M sized 380mm rotors in. I'm ok with this as it'll help further reduce a good amount of rotating weight but I cannot understand if they will fit in current form. The M8 and m850 both have the same rear caliper, same pad, same caliper carrier but 18mm delta diameter.

Does anyone know if there's a way to make this work?

[Dr Thrillride]

Originally Posted by Dasky_spas

The m850 has the odd sizing in the rear, at 398x28 while the M cars using 380x28. I purchased custom floating rotors but it turns out they won't be about to make the rear 398 sizing as requested. I either get a refund or pursue putting the M sized 380mm rotors in. I'm ok with this as it'll help further reduce a good amount of rotating weight but I cannot understand if they will fit in current form. The M8 and m850 both have the same rear caliper, same pad, same caliper carrier but 18mm delta diameter.

Does anyone know if there's a way to make this work?

Mate, hope someone knows. You're so deep into the detail with your build.

[Dasky_spas]

Well at this point, I'm going to keep digging down. The value of the car is already so low, so it's a money passion pit at this point. But yea, otherwise I'll just buy a used f90 rotor and test it.

[__AD__]

Originally Posted by Dasky_spas

Well at this point, I'm going to keep digging down. The value of the car is already so low, so it's a money passion pit at this point. But yea, otherwise I'll just buy a used f90 rotor and test it.

The wheel carriers that hold the caliper carriers are probably the difference. They are unique to each model and probably push out that extra 18mm on the m850i rear to support the bigger rotor diameter.

[Dasky_spas]

Ya indeed that is correct. The knuckle in the rear is unique to the 8 series it seems.