Nano

iTrader: (1)

only when I change pads. With brand new pads there is some vibration, but it goes away after some miles (2-3 laps). After that they are smooth as silk

C Ray Z

iTrader: (2)

I had this before I went to brake ducts under high speed breaking from +105 down to 45mph. I believe it is the smearing of the brake pad material due to over heating. This can also occur if the pads are not bedded correctly. But even with proper bedding I was getting the vibration. That is now gone. N tech use to sell this duct system but no longer seems to have a site open. You can also make a set. Search for picturs of the ones built by different members here.

ATL_Red_G35

iTrader: (8)

so for street driving, you don't see this kind of vibration right? Only extreme braking on the track?

C Ray Z

iTrader: (2)

That is corect. If it is doing this on the street under light breaking, then you probably have a warped rotor.