mine was vibrating when i bought the car but i replaced the rotors for some drilled and slotted and then it went away plus the it looks good

 

either a bad compression rod or a failing caliper seems likely

 

well, i replaced my rear rotors, which were really bad, and now she's back to perfect,
thanks for all the input

 

In my case the viabation was my rotors (wraped) I just got them resurfaced

 

It can also be bushings on the front that are bad and causing it.

 

I've got the same issue, I have turned the front rotors, have brand new yellowstuff pads, and when I brake I get a front end shimmy, and it's worse if I'm going downhill to the left or right. I guess I'm just going to take it in for an alignment and see whats up. Car doesn't feel safe to me right now with the braking shimmy, and I hate driving slow!!!