Quote:
Originally Posted by feuer
Yes and no. You are better off with rotor that is also 32mm thick but also has 50mm from rotor surface to where the rim mounts to because of spoke clearance. Of course, the rotor will have to clear the control arm ball joints on the other side. Hypothetically this Brembo rotors can be mounted on the thinner e90 rotor too and it will be 5mm inward that will help with rim spoke clearance. True, isn't necessarily that rotor would be different if rims are different and I haven't done any compassion of part numbers but have done custom brake projects in the past and don't remember e39 brakes on e36, e 46 or e90. From memory this rotors have different hub registry, 79mm vs 75mm. Usually people used Euro e36 m3 345mm rotor and not the e39. Probably there is a reason. Double check before you start ordering parts.
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I see what you're saying now. I am losing 4.6mm of spoke clearance based on the hat face to rotor face measurement. I did a comparison between the Cayenne caliper and the StopTech ST60 caliper and both are pretty much bang on at 77mm from rotor centreline to caliper face. With the M5 rotor, this puts the Cayenne caliper face 15.3mm outboard of the rotor hat face. For reference, the ST60 caliper sits 19.9mm outboard of the rotor hat face. Though I'm losing 4.6mm of spoke clearance compared to the E90 325i rotor, I still have 4.1mm more spoke clearance than the StopTech ST60 caliper does. So I'll be OK there. As for the rotor register, the E39 M5 and E90 share the same 79mm front diameter, 75mm is in the rear.
People probably use the Euro E36 M3 rotor because whatever OEM caliper they were using wouldn't suit a 32mm wide rotor; OEM rotor is 28mm I believe.
I wouldn't want to run a caliper designed for a 34mm thick rotor on much less than a 32mm thick rotor. I'll be running 1mm stainless backing plates to help keep the pistons in their designed range of travel and help with heat dissipation. I'm sure I'm being a bit paranoid about it and could run 30mm thick (or less) without any issues, but I'd rather keep it within 2mm of the Cayenne's rotor thickness. Plus thicker rotors make them a better heat sink and everyone's a winner.
Cheers.