Brake Master Cylinder

The brakes on the first few test drives were very very spongy, I had to stomp the pedal to the floor the get the car to stop, especially down my steep driveway. Obviously I want the car to stop as well as it goes so I don't have to rebuild the car everyday after I crash into the back of a late braking truck.

Upon further inspection I found that brake fluid was leaking from the master cylinder into the boot behind the pedal when the system was under pressure, so I knew some seal in there was bad. I ordered a master cylinder rebuild kit and got to work disassembling the cylinder.

Removing it from the car was a lot easier than the clutch master, don't know if it was location or experience but I had it out in under 30 minutes this time. I took it apart a little to just get the thing out of the car. I disassembled the old cylinder preparing to clean and replace the seals inside. It's a relatively simple process of pulling and tapping things out of the bore.

This is the only tricky part, the "Guide Bearing" it's basically hammered tight into the cylinder, so to get it out the only option is to either drill screws into it and try to walk it out (which is what I did obviously) or supposedly you can melt through it with a soldering iron, if you go that route use a respirator. My only lesson I can pass on is when you choose your screws make sure you go for a small diameter coarse thread, and be very careful of your angle, you don't want to scratch the piston if you can avoid it. You aren't worried about salvaging the bearing because a new one is included in the rebuild kit. Once the guide bearing is out the only tricky part is a circlip way down the bore, but with a pair of circlip pliers and a good light source it shouldn't be too tough. Once everything was out I had a bag full of parts.

 Now everything was out, time to start cleaning up the cylinder. I know it's a hydraulic component deep in the bowels of the engine bay that nobody can see and surface peeling or rust makes no difference to it's functionality. I'm just fanatical about making everything shiny and new, sorry.

Now doesn't that look so much better? Once all the gunk and rust was removed I took a bottle of brake cleaner to the whole bore and all the ports, using small wire to clean all the passages too. The aluminum (I'm assuming it's aluminum since it was so soft) was really pitted under the paint, so Instead of clear coating it I decided on a thick valve-cover paint to hide the flaws. Taped up the important parts, primed and painted. While all that was drying I set to work on the internals, the seals, springs, and rings.

The primary piston, pulled from the bore (it takes some force)

close up of the front piston, notice the directionality of the seals, very important

all the circlips, washers and spacers from inside the bore.

The paint dried, I'm very very pleased with the results, my tape job could have been better but the paint did exactly what It was intended to and covered up the pitting nicely.

Just set on top, the gasket between the reservoir cap and cylinder was obliterated in the removal process, and the rebuild kit didn't include one. So I made my own, I had to end up doubling up because one layer was too think.

bought 6 new bolts and locking washers, stainless steel this time.

The exterior done it was time to put the piston assembly back in. This is a difficult process, and I had to literally hammer in the new guide bearing using a deep well socket to go around the piston.

In the process of getting the piston back into the bore I chipped the paint. I'm still cursing myself, I may sand the area and try to repaint it later.

During the reconstruction somehow the primary piston got jammed and wouldn't return, we used a syringe to inject a small amount of brake fluid into each of the valves and both my dad and I pulled on the piston trying to break the seal. 30 minutes of forcing fluid into the system and pulling on the piston we got it to break free. Once it was fully extended we put back on the reservoir bottle and hose, plugged up the valves with random bolts and filled the cylinder. I'm letting it sit still, giving the fluid time to percolate into all the places that it was cleaned from before trying to get it to pump fluid again.