Tuesday, 2 June 2020

If the Cap Leaks

Car maintenance meets automotive history. The cap on the brake fluid reservoir on my sports car is leaking a little bit so I wanted to replace it. Caterham don't have them in stock, and they're overpriced so I decided to shop around. The threads for the cap are the old fashioned Girling/Lucas ones and the master cylinder is made by AP Racing. I could easily get a cap that would fit from any racing car supplier - hell you can buy a genuine Girling one from Demon Tweeks! The problem is that mine's a road car and it needs a fluid level warning switch (it doesn't strike me as a bad idea on a racing car even if it's not a legal requirement). The warning switch is integrated into the cap. I refuse to believe that Caterham are making their own reservoir caps, so the question becomes: where did they find a brake fluid reservoir cap that will fit an elderly British car, or a racing car, but has a fluid level float switch built into it?

Half a day of googling later and the answer is obvious: Late model classic mini. When they started making minis they would have been using Girling master cylinders, or something compatible. At some stage the law changed and they had to have a warning light for the fluid level, they didn't change the master cylinder, they just cut a hole in the cap and bodged a crappy float switch into it. The part number is GRK6009 and they're available from all the people that look after old minis. It looks like a rush-job, the design is terrible and the lands for the gasket are tiny. Frankly I'm surprised that it kept the fluid in for this long. I'll probably make my own out of a real cap and a modern float switch when I take the car off the road at the end of the year.

Richard "Yes I do believe that I can make a better job of it that Austin-Rover" B

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