Vibration Issues | Very odd

[thmotorsports]

Today, X5 (04" w/49K) stood in my driveway for 1 day, I took it on a trip. On the highway, when light braking, the entire wheel shakes and the pedal kind of vibrates. The first thing I thought is: Warped rotors. I was wrong, its not the rotors at all after checking, they are perfect. So then I went to see if it was a balancing problem with the wheels/tires. All tires perfectly balanced, tire pressure perfect and at 80mph she is steady as a rock on the freeway.

So now, I have ruled out the two things that cause vibration in steering wheels and worsen braking. Ive had this problem before when the inside of the rims iced over and the car shook when braking, but that was again from improper balancing and would do it all the time. I am so damn lost. The service tech at a local BMW dealership suggested it was a frozen caliper or piston, but then it would drag which it does not. The caliper may be frozen and not coming down... but I dont understand how this happens overnight. My last idea is that a hardline is broken, but fluid in the master cylinder is full, flushed, and the car stops in a perfect linear motion.

What do the techies think?


Eddie