why is a knocking sounds from my rear brake when I hit the brake. The car go slower the sound is slower and faster is faster. I went to few mechanice shop to fix it then clean it machine the the drums, they put grease, but still have the knocking sound.
I try to exchange the right drum to the left and the left to the right. to see if is the drum problem. But still have the knocking sound on the right side. Can you please tell me what to do next?

Year make model would help!

It could be a wheel and not brakes at all. Rotate wheels and see if sound follows is one way to test,

T
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Tom Greenleaf - MetroWest, Boston

I have a 2000 honda odyssey.
I will try to rotate the wheels and see if still have the problem.
I really need this to fix.

Not common but the problem could be a wheel - noise should follow it and that would rule that out,

T
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Tom Greenleaf - MetroWest, Boston