While awaiting the new brake master and servo cylinders – required because the original units both had corrosion and scoring in the barrels – I took the time to really clean-up and detail the firewall area on the driver’s side of the car. I will show how that went next. In any case, once the new units arrived I fitted them in place and replaced all of the rubber brake and vacuum hoses in the car. I also tidied up the reservoirs.
One thing that you should check while replacing hoses and brake master cylinders is the vacuum bottle. This metal bottle is located on the firewall on the passenger’s side and maintain some vacuum so that in case the engine dies you can still get some power assisted braking to slow you down and get you off the road (remember that the power brake boost is supplied by engine vacuum). If you have leaking in the brake vacuum servo you will have brake fluid in your vacuum lines and it will find its way to the vacuum tank. By the way, these can mask a leaky brake system because you will be losing fluid and not see where it is going – the fluid gets ‘stored’ in the vacuum bottle.
Now, to get to the vacuum bottle and get it off the firewall you have to remove the air cleaner. I was lucky because I already had removed the air cleaner and carbs anyway. You have to remove the vacuum line and the bottle unbolts relatively easily from the firewall . Once it was off I took off the vacuum valve and then tipped it over a waste storage container – out came loads of brake fluid. This was from the blown vacuum operated brake master cylinder set-up. Clearly the previous owner must have had to top the brakes up from time to time, but had not fixed the root cause of the fluid loss. I sanded down the bottle and repainted it gloss black as original. While this was out I also cleaned and detailed the firewall and replaced the original starter with a high torque gear reduction starter – more on that later. So, I ended up with a new brake master and power system and very clean firewall area – although it cost me a little more than anticipated. That is the Jaguar way I suppose…