Wednesday, September 30, 2009

Master Cylinder Rebuild

Dateline – Sep 26 – Last weekend I noticed that my brake fluid was getting low, so I started to look around and found lots and lots of brake fluid on the inside fender below the brake master cylinder, merrily eating away at the original Jaguar paint. You guessed it! Leaking master cylinder! I ordered a rebuild kit form Terry’s Jaguar (again, very fast service) and today I did the rebuild.

The first thing was to get the master cylinder off the car. Not too bad. Things came apart easily and I soon had the cylinder on the workbench. Then the fun started. I pulled the feeds off the top of the cylinder and found a yucky, Vaseline like substance inside. Brake fluid and water mixed! NICE!

Then I discovered that there is no way to get the center plunger out without taking the “tipping valve” out of the top. This required a ½ inch Allen wrench. Who has a ½ Allen wrench? So a trip to Harbor Freight and now I own a ½ inch, ½ inch drive socket wrench mounted Allen wrench (along with 11 other sizes!). Good thing to, because it took that and a hammer to get the plug holding the tipping valve to unscrew!

After getting the guts out, I found what I most dreaded…RUST! Bad rust! The bottom of the cylinder was extremely pitted. This was not good! I got my trusty cylinder hone out (it saw a lot of use on the Spitfire) and honed out the cylinder the best I could. It is still pitted, but it would take machine equipment to get that out! I cleaned everything up, replace all the rubber with new stuff, put it back together again and hoped for the best.

I put the cylinder back on the car and tried to get the brakes to work, but could not pump up the fronts. So I had to take the cylinder back off, prime it with brake fluid, and then put it back on without all the fluid leaking out! I was up to my elbows in brake fluid and had it running all over the inside of the engine bay! What a mess, but I finally got everything installed.

Now for bleeding. This is when the inside mounted rear brakes become a real pain! You just can not get to the bleed nipples! Plus I had to replace one of the bleed nipples that had been flattened by the exhaust pipe that rubbed up against it (prior engine installation). Thanks again to Terry’s I was able to get the bleed valve. I’ve read about people building remote bleeding nipples for these cars since it is so hard to bleed them. I’m going to do this when I have the rear end out this winter! I’m not doing this again! The front brakes are easy, since you just need to take the wheels off and do a normal bleeding process.

Once everything was bled, I took the car out for a test and guess what, the pull to the right that I used to have under hard braking is gone! Even though I bled the brakes twice, I must have still had some air or something on the left hand side! I’ve also noticed a roughness to the brake peddle, which I know is the hard rubber plunger seal sliding over the pits in the cylinder. I suspect that this is going to weep brake fluid over time and I will end up getting a new $370.00 brake master cylinder at some point. But I’m keeping my eye on it, and hope it will last until next year.