I have read comments on the Roadfly E24 board from those who have done this brake upgrade, and it is viable. Not sure about the size of the front protective plates on the wheel assemblies of the E34, but on the E24 they must be removed, as the larger rotors will not fit. I myself have upgraded my rears to the E34 M5 brakes, and am quite pleased. I did leave the stock front brakes (same as the M5 & 6) as they were. Here is a link to a very thoughtful document detailing the options for upgrading your brakes. It is a bit old, so the pricing detailed is significantly different now (for the better). Enjoy!DaveW said:Anyone done this - have any thoughts, views or comments?
I'm considering this as the best route for a reliable source of cheaper mainstream brake parts for the Bi-Turbo. I have to replace the discs as it is and for a couple of hundred pounds more can install the front brakes from the 840ci.
M Brake upgrade options