When I hit the brakes to slow down, especially at slower speeds, there's a loud shimmying noise from the front rotors, that feels like the pads are slipping all over the rotors. Besides the disturbing noise, it detracts from the braking power.

I have replaced the upper and lower control arms, center link, and idler arm, and tightened up the steering box, to no avail. The front suspension has since been aligned. Also, there are no leaks in the power steering/brake booster system.

The front bearings grind when I spin the wheels by hand. And, the rotors and pads are cheap. And, when I replaced those, I didn't return the little allen-bolt to the rotor, since someone told me those are just used to keep the rotors on the axle on the assembly line. These may be the problem?...

My repairs have tightened up the steering a bit, but have made no difference to this braking problem. Any ideas, or solutions, would make a huge difference, and would be much appreciated!

Thanks, iain