With the car able to start, we need to make sure that it will stop. When the car came in, the shared brake fluid reservoir was dry. The first troubleshooting step was to put brake fluid in and try to bleed the brakes, but we weren’t able to get any fluid to come through the line. The most likely cause, then, was a failure of the master cylinder, so off it came. Once the pistons were out, it was pretty obvious that the seals were well past their prime.
For $143.60, Lenny from AutoItalia sent me the rebuild kits for the clutch and brake master cylinders as well as a new hose for the clutch.
Once the cylinder was disassembled, I used a hone to clean it up, dropped the whole thing in some Evaporust in the ultrasonic cleaner, and got it looking pretty good.
Once the new seals were installed and the pistons were back in the cylinder, it was time to bench bleed.
There are a total of four ports on the master cylinder – three for brake circuits and one for the brake switch. Each of them have M10x1.0 threads. I used a Dorman bench bleeding kit for two of the fittings and then a couple bolts to block off the others. Once the first two were bled, I swapped the plastic fittings and the bolts and bled the other two and after very little effort, I had no air bubbles.
With that bled, I got it bolted back onto the booster and hooked up the brake lines. The next step is to vacuum bleed the brakes to see if the caliper seals are also in need of replacement.
The clutch master cylinder also got a rebuild kit installed. I followed the same basic process of tearing it down, hitting it with the hone, and cleaning it up in the ultrasonic cleaner. Bench bleeding it was a little easier since it only has the one port. The most difficult part was coming up with a reservoir for it, since it shares with the brake master cylinder.
Both the clutch slave that was installed on the car and the one that was supposed to be a “good spare” were frozen up. I was able to knock the installed one loose, but it’s leaking enough that it also needs a rebuild kit. Once that comes in, I’ll get the slave rebuilt, bleed the whole system on the bench, and then install it in the car.