So here's the scoop, I've got a reoccurring vibration while braking in my 2011 JCW R55.
initially thought it to be a run of the mill rotor issue, so I replaced front and rear with OEM pads and oe supplier (textar) rotors since i'd just picked up the car figured why not?
and the vibration went away for a time. then comes back, check the runout of rotors, out of spec. suspecting quality control issue, replaced with genuine Mini rotors.
vibration goes away for a longer time. now back at full force.

no lights on dash, but harsh shaking in steering wheel consistent with vehicle/wheel speed about 90% of the time.
Had it up on a lift, and couldn't find any obvious culprits, and braking system passes all actuation tests.

when the calipers were off for pad replacement, all pistons slid back in without issue.

anyone else run into this kind of issue? I actually might resort to taking it to a dealer at this point...

 

Given what you've already replaced, I would put money on bad wheel hubs/bearings. Jack the car up and try moving the tire left/right with your hands. A bad hub/bearing will ID itself with excess play (it shouldn't move at all).

 

i was kinda thinking that too, but the problem only presents itself during braking, though the car has 146k on it so it wouldn't surprise me since the rear bearings already took a dump.

last night i got it to happen very rhythmically at low speed, almost feels like the clunking of an axle joint. still the weird part being that after new rotors were installed, it went away.

... more on this as it develops

 

Are you properly cleaning the hub faces of rust build up when you put the new rotor on? That can cause run out that isn't the fault of the rotor.