[dubzz24]

Hello all, hopefully someone can provide some advice on this - I searched the forum and my vibration issue is a bit different than most others.

The car is a new to me 2011 335i x-drive 6spd, and I took it to the drag strip to get some baseline runs before I start modding it. The first couple runs I braked gently at the end and took a further exit, but then on my last pass I braked pretty hard to take the first exit off the track. This is the first time I've really hit the brakes hard in this car, and from high speed (100~ MPH). I could feel a really heavy "womp womp womp" rotational kind of vibration from the front of the car, similar to a warped rotor, except I could not feel any vibration at all though the brake pedal or the steering wheel, just through the chassis.

After that on the drive back to the pits I could still feel/hear a tiny vibration while driving but I think I could only feel the vibration because the track was super smooth. That was the last run of the night. On the drive home on normal roads and highway I didn't feel or hear any vibration, nothing under heavy acceleration or normal braking, but if I hit a really smooth spot of fresh asphalt I could hear it just a tiny bit. If I slam my brakes hard I can still feel it through the chassis, but again not through the pedal and wheel.

The vibration I can feel slightly on really smooth roads reminds me of when you have super high performance tires and the first couple minutes driving on a cold morning you can hear and feel the tires a little bit as they warm up and round out the flat spots. Hopefully that makes sense lol.

A bit more about the car:
-only 30k miles on it
-brand new tires (Falken ze950as) less than 2k miles ago.

So since I can feel/hear it ever so slightly on smooth roads when cruising, and not through the wheel or pedal I'm thinking I can rule out a braking issue. I've had bad CV's on FWD cars before and the vibration on those was usually most pronounced on acceleration or turning so I'm not sure that's the problem, although this is my first AWD car. I've heard that control arm or thrust bushings can cause vibration (my old 135i it had bad thrust bushings but no vibration though so I guess that's not always the case).

Has anyone had a similar problem? Any insight on what to check for first? Any help would be appreciated!

[dubzz24]

Well, I jacked up the car to check out the CVs and control arm and thrust arm bushings, which all checked out ok. I gave the front tires a spin and low and behold, a melted piece of someones tire and glued itself to my front drivers side tire. A whole bunch of scraping and rubbing goof-off on it and finally got it all off. Took the car for a spin and problem solved. I guess the weight and suspension shift under heavy braking explains why it was only really there when braking heavily.