2003 G35 sedan. When I brake about 40-50% of the way I get this loud clicking sound. This is a sound clip of it, http://johnberry258.tumblr.com/post/63712128911. I cant figure out what it is, and I tried pulling the hand brake but it wont do it then. It also feels like my rotors are warped from 50-35 mph, I thought it was the front brakes so I replaced the rotors with drilled and slotted one, new pads, and cleaned everything up with a wire brush, and it also didnt shake at all when using just the hand brake. What could this be from? Any help is much appreciated

Sounds like an infamous axle click....

Thats what I thought initially but it only does it while braking

Well, the hand brake is actually a small drum brake inside the rotor, so you won't hear the same noises or feel vibrations from a warped rotor anyway. After listening to that sound clip, it does not sound like the axle click. It sounds more like something is rubbing. Check clearance of the dust shield all the way around the rotors and bend them back a bit if needed.

Have you inspected the rear brakes yet? You replaced front stuff already. I'd start with cleaning everything up, greasing all the pins and shims on the back of the pads, and inspect bushings.

I have the same exact problem but on my passenger front brake. I was inspecting it yesterday and took the wheel off and rotated the hub while I had a friend apply pressure to the brake. It seemed to be coming from the thin metal brackets attached to the caliper. Interested in what solution you come up with. I just put some PB blaster to lube them a little but I'll report back when I drive the car to see if that helped.