How to Rebuild Brake Cylinders

Rebuilding your brake system's leaking wheel cylinders can restore them to factory performance. This a low-cost alternative to a replacement cylinder. Never use a brake cylinder hone on an aluminum wheel cylinder; these parts have an anodized finish to prevent corrosion, which would be damaged during the honing process. Instead, use a lightly abrasive hand pad (Scotch-Brite is a good one) and warm soapy water.

Instructions

1

Disassemble the wheel cylinder by removing the dust boots on each end, and pulling the pistons, cup seals and spreader spring out of the cylinder ends.

2

Discard the spreader spring and cup seals, as the rebuild kit comes with replacements.

3

Clean the aluminum cylinder bore with warm soapy water and a lightly abrasive hand pad (not steel wool). Then final clean with a can of brake parts cleaner, and dry with a lint-free cloth.

4

Hone out cast-iron or steel housing to remove any heavy corrosion and accumulated gunk. The result is a smooth bore and a nice cross-hatch pattern. Clean the external housing with brake parts cleaner and a scrub brush to remove brake dust buildup.

5

Scrub the wheel cylinder pistons, which are aluminum, with warm soapy water, then dry. Cleaning these parts thoroughly now will prevent problems later during reassembly and during use.

6

Begin reassembly by placing the spreader spring into the cylinder. Then lubricate the cup seals with clean brake fluid. Install them flat side out and pushed in against the spreader spring. This will keep them from collapsing or turning in the bore.

7

Insert a piston in each side of the cylinder. Install them flat side in against the flat side of the seal.

8

Carefully install one dust boot side by wrapping the large end around the recess in the cylinder housing until it spreads and slips into place. Then install the other end by pushing that side's piston in and using the same wrapping motion until it slips into place.

9

Slide the pistons back and forth in the bore to center them; make sure they are positioned properly.