I have an old bike that I'm fixing, and I can't get the rear caliper brake to center after I tighten the brake's mounting bolt.

The front brake has the wrench flats for a cone wrench (or similar), so that's how I got that one centered. Here's the front with my wrench hanging off it:

front brake.jpg


The rear brake has no such flats, so I'm not sure how to keep it in proper place. This is what it looks like:

rear brake 2.jpg

rear brake 3.jpg


I've tried holding the brake all the way to one side (or the other) while tightening the bolt that mounts the brake to the frame, but it always wants to lean back towards one side after I squeeze the brakes a few times. Without my wrench flats, I'm lost.

Another thing I've tried is giving the brake's spring a good whack from on top, at the spot where it does a double loop; my tools were a flat-headed screwdriver and a mallet. It doesn't seem to accomplish anything. I'm probably doing it wrong; I have always sucked at this method. I'm supposed to bang down on the side that needs to move CLOSER to the center, i.e. the side with the extra clearance, right? I've been hitting this thing pretty hard without anything happening.

Can you guys give any advice on this? It's driving me crazy!