Once the brake master and slave cylinders were out of the car I opened them up to see if they could be rebuilt using just new seals and o-rings etc. A rebuild kit like this is a pretty inexpensive way to do this. However, if the cylinders inside the master or slave are pitted, scored or enlarged then you have two more expensive choices. First, you can purchase a rebuilt brake master or slave cylinder that has been bored out and resleeved or you can purchase brand new units. I was hoping I could get away with a simple replacement of seals, o-rings, springs etc. and save some money.
The first unit I took apart was the master cylinder. I could see it was leaking fluid onto the brake pedal before I removed it – so I knew that at the very least the seals had to be in bad shape. First, I took off the rubber boot. To remove the piston shaft from the cylinder you have to depress the spring and cupped washer on the spring and remove a spirolox circlip at the top of the shaft. To hold the spring and cup down I simply used a piece of flexible wire wrapped around the top of the spring and the cup and secured to the two bolt mounting holes on the cylinder. I then unwound the spirolox circlip off the shaft and pulled the cup and spring off the shaft. I then removed the standard circlip from the mouth of the cylinder. Bingo – I could disassemble the master cylinder and see what kind of condition it was in.
S far so good. The brake master cylinder shaft looked fairly decent. However, the inside of the cylinder was quite dirty and brown – a sign that the fluid had absorbed water and there might be some corrosion. I proceeded to clean out the cylinder with a clean rag and see what I was facing inside the cylinder. It soon became apparent that I was not going to get away with a simple rebuild of the existing unit. There was a very large area of corrosion and scoring right near the outer end of the cylinder wall. That was where the brake fluid was coming from that was running onto the brake pedal. Darn! No cheap fix here! The cylinder would have to be resleeved or replaced.