1980 450sl Knocking when brakes applied

[AaronPayne]

Hey folks, I am getting this loud knocking, and shuddering sound when applying the breaks from forward driving. It is a very fast knock like a machine gun and feels like it is only in front passenger side of the vehicle. I need to test it again while rolling in neutral to see if it only happens in drive but does this sound familiar to anyone? I do not get this pulse by applying the breaks when the car is stationary so I am not thinking it could be a vacuum issue with the brake system, it is only when the car is moving forward. The faster the car goes the faster and louder the knocking sound is. Any ideas?

[optimusprime]

You need to jack it up from the front and spin the wheel .Sounds to me like wheel bearings .Also backing plate on the disc pads might have parted company with the pad material , so are in 2 parts

[Diseasel300]

Wheel bearings, worn/trashed suspension components, etc will cause knocking.

Before getting carried away, CHECK YOUR LUGNUTS!!!! I had exactly what you describe and it was from a tire shop not torquing down the lug nuts!

[AaronPayne]

Thanks for the input. I will check those items today and try to get a video of it if it continues.