steering wheel shakes while braking

I noticed lately on my E300D that when I was in a harsh braking under high speed, my steering wheel shaked and I could feel it came from right front rotor. Under normal speed, say below 40mph, it's smooth. I tend to believe this is some sorta bushing shot (in early stage), not rotor being warped, but don't know which one.

On my 300SDL, I know there is a guide rod bushing which could cause similar problem and I changed that before. On E300D, it seems there isn't a guide rod, but I am sure there has to be something similar to hold the position of hub when immense force pushes hubs toward the back of the car. Are bushings there? Any graphic/screen shots are appreciated.