Knocking Sound When I Apply The Brakes

I took my 2000 Honda Civic LX to the shop on Friday to get the exhaust system replaced and have the rear brakes looked at (they’d been making a squeaking noise before the exhaust went). They replaced the exhaust system & the rear brake shoes, but on my way home I had to pump the brakes to get them to grip, which was NOT safe.

I had to take it somewhere else yesterday since the first place is closed Saturdays… The 2nd shop replaced the rear wheel cylinders and the rear brake drums and bled the brake lines. Everything seemed fine after that.

…Until tonight, when I ran a few errands. On my way back from my last stop, I noticed a knocking noise from the rear passenger side whenever (and only when) I apply the brakes. The knocking is faster when the car is still going fairly fast, and it slows as the car slows.

I am getting REALLY frustrated and don’t know who or what to blame. Is this something to worry about, or just some crud from the road that got stuck on my wheel?
I took it back to the second shop and they said that the new drums must have been slightly out of round from being stacked in storage. The flat spot going past the curvature of the brake shoe is what makes the knocking sound. They machined them to round them again and put them back on, which cured the problem (and they didn’t try to charge me, which was good). They said if the noise does happen to come back (heat can warp drums) that they may have to try a different brand of drums, but so far, so good! *knock on wood*

Answers for The Question

  1. Will S
  2. marvin_g_33334
  3. Bob H