I just bought a 2006 350z and i noticed a shaking wil braking, so i went ahead and cut the rotors ..but the pads look new, so i did not replace them.
I put the rotors back on and BOOM the car still shakes while braking...can anyone help me on this.

 

that is your problem right there.

 

get new rotors

 

Alignment.

 

So your telling me cause i went and got the rotors cut at a midas...thats my problem???
I had the rotors measured and they fall in specs.

 

ALIGNMENT???...the car does not pull..it just shakes from the brake pedal while braking.

 

It could have to do with slight alignment issues. It might not be noticed in pulling, but in braking. Does it always shudder, or only on uneven surfaces or while turning?

In the past I've had cars with slight alignment issues where braking resulted in a shudder.

 

It shakes anytime you brake...the faster you go the faster the shake and the slower ...the slower the shake. Only when braking.

 

The FSM has a rotor maximum runout specification [usually less than 0.001"] as mounted. Do your rotor as mounted comply?