Foreword.
I'm expecting the following replies to his thread:
a) no replies despite couple thousands views
b) wheel cylinders are cheapo, why bother?
c) you are not allowed to rebuild an aluminum wheel cylinder (and you should change your brake fluid every year using fluid from Dollar Tree store!)
Need for repair:
While doing my rear shoes I inspected the wheel cylinder for leaks by pulling up protective boots. There was some small sweating under boot on the passenger side of the car, along with increased leading shoe wear compared to the driver's side. To be honest, I've changed brake fluid only twice over 12 year period, so I was expecting some sort of this failure down the road (most cars will leak form rear cylinders at this age regardless of the amount fluid changes)
Since cylinders are aluminum [they should not be rebuild!] no kit is available.
What I did:
Made a shoe spreader/holder to make a job easier (BUT, if your shoes are less than 3.5 mm thick, the spreader may not be needed)
Went to the junk yard to practice!
What I've found:
Most of the leaks are caused by dirty fluid "green film" deposit in the bore and hardened seal cups
In other words, in most cases (see below) a good wash with water and soap plus some backing soda and new piston cup seals should take care of the problem.
Important! If cylinder bore has finger-detectable wear marks or heavy corrosion (is not feeling smooth) replace it with a new one
Here is the process (the car is standing on the jack stand, the rear wheel and brake drum are removed and parking brake is released):
1) install the brake shoe spreader and expand the shoes until the distance between the ends of the pistons is about 72.5...73 mm
2) doing one side at the time push on the piston toward the middle of the cylinder until shoe is completely out of the slot; then rotate the piston so the slot is perpendicular to the shoe (small Allen wrench or bent screwdriver)
3) repeat this procedure to another piston
4) crack the line fitting loose (10 mm flare wrench)
5) crack the bleeder screw loose 8 mm socket or box end wrench
6) remove two cylinder mounting screws (10mm socket)
7) fully remove brake line fitting
8) pull the cylinder forward and cap the open brake line end
9) dismantle and clean cylinder; replace the cup seals on the pistons. To facilitate cup seal replacement, clamp the slotted end of the piston in a vise. Use not metallic tool to take the seal out. Smearing some Napa brake grease on the piston helps with seal installation
10) remove bleeder screw and inspect; if its sealing tip needs conditioning, clamp the screw into the electric drill chuck and grind it on the 500 sandpaper (positioned on the flat surface) using low pressure and speed.
11) lubricate seals with brake fluid and assemble cylinder; apply some brake lube to the threads of the bleeder screw
12) orient the slots perpendicular to the shoes squeeze the pistons and install the cylinder, leave the bleeder screw open
rotate and reengage pistons with shoes, remove brake shoe spreader
13) as soon as brake fluid shows out of the bleed screw, tighten it. In most case additional bleeding is not required. Install drum and wheel, test for leaks and road test the car.
Notes: the gap between the brake cylinder and its mounting plate is factory sealed with Permatex #1 compound; use piston seal cups (11/16 bore!) from the brake cylinder kit for 2000 Mitsubishi mirage 1.6. Re-use dust boots

components before cleaning

This ugly film is easy to wash out

brake shoe spreader, 30mm wide

Tools

ready for new sealing cups

 

Whether or not I will ever do this, its still cool to see someone take the time to figure this stuff out and then post about it.
Much appreciated!!

 

Nicely done, doc. Your posts are always informative and, therefore, valuable. Thanks.