Ok – now that I knew the brake master cylinder was trashed I decided to try my luck with the slave cylinder and the attached vacuum servo and see if that unit was rebuildable. To open this unit up and inspect the seals, rings and cylinder you have to first split the large sheet metal shell of the vacuum servo. Inside that is a a large rubber diaphragm which uses vacuum from the engine intake manifold to provide power assist to the brakes. The two pieces of the shell are held together by a set of pressed in indents one one side and ledges on the other and have to be twisted apart.
Now twisting the vacuum servo apart requires securing the cylinder in a very large vice, attaching a bar to the exposed mounting bolts on the outside of the shell and exerting considerable counter-clockwise torque to get the two halves of the shell to slide. Once the indents are clear of the tabs the units come apart. Once the unit was open I could see a lot of brake fluid inside and on the rubber diaphragm. That told me right away that the slave cylinder was leaking fluid into the vacuum servo. That also meant that the fluid would have traveled through the vacuum hoses and was probably in places like the vacuum tank. I will tackle that issue later. The slave cylinder was certainly leaking – but was it rebuildable? To find out I had to further disassemble the unit.
The next step in disassembly is to take the assembly off the vice, remove the rubber diaphragm and then push on the hard plastic diaphragm support to remove pressue on the spring and shake out the metal split-key that holds the support and shaft. Once that is done you can remove the support and get at the three bolts that secure the vacuum assembly to the slave cylinder. They have locking tabs that have to be bent down to remove the bolts. You can now remove the push-rod and piston assembly and clean and inspect the slave cylinder.
The moment of truth had arrived. Time to see if the slave cylinder was usable or if it was like the brake master cylinder – in need of replacement or resleeving….
Upon inspection, sad to say, the slave cylinder was also corroded and deeply pitted. This makes getting a fluid-tight seal impossible and means the unit must be resleeved or replaced. So much for saving money and using a simple bebuild kit….
Once I knew that both the master and slaver cylinders were corroded and pitted I looked into the cost of rebuilt and resleeved units and brand new units. This was a no brainer. I found that I could purchase brand new units cheaper than I could purchase rebuilt and resleeved units. For the brakes on a car like a Jaguar XKE it makes sense to go with the new – and presumably reliable units. So I ordered the new brake master cylinder and servo-slave unit up.