Single Pivot Brake Caliper Overhaul

My new-to-me Miyata has sticky brake calipers that don't move freely.  These Dia-Compe single pivot calipers are very common on older bikes, and I'll show you how to take them apart to clean and grease the moving parts.

Before getting started, grind down a cheap 10mm wrench so that the open end is thin enough to fit the inner locknut without touching the outer nut. Alternately, you can buy Park Tool CBW-1, which is rather inexpensive. You won't be able to retighten the locknuts afterwards without a thin 10mm wrench, so don't try to do this without that special tool.

First I loosen the two locknuts with my thin 10mm wrench on the inner nut, and a normal 10mm wrench on the outer nut:

A thin washer will be next. Slide that off, and you can remove the brake arms after you unhook the spring from the back side:

 

Keep everything in order. There should also be a plastic washer between the two brake arms, and another washer on the back.

Here's the order for reassembly (left to right):
Acorn nut
Small locknut
Washer
Long brake arm
Plastic washer
Short brake arm
Washer
Spring








Clean all of these parts, and add grease to the washers and the pivot bolt before reassembly:

  

The reassembled brake pivot needs to be adjusted like a wheel bearing. You want the brake arms to pivot freely, but you also don't want them to wobble around because the brake will feel sloppy. I will screw the small locknut on until it is snug, then back off a little bit and check. Then I will screw the outer acorn nut back on:

 

The most important step is to tighten the locknuts against each other to secure the caliper. Again, you'll need that special thin 10mm wrench for this step. Put the thin 10mm on the inner locknut, and tighten the outer acorn nut against it to secure the adjustment (like a wheel bearing, but less torque).

Finally, you can hook the spring back into the nubs behind the brake arms, and then you're done: