Brake Fluid Leak Behind Master Cylinder

[Marko R1]

Hi guys,

I've noticed a small leak under the bonnet due to the wet patch on my garage floor.

I can see a run down the face of the black vacuum cylinder right underneath where the master cylinder is mounted...what is the fix for this? Is there a brake seal kit or do I need to replace vacuum cylinder?

[GTSBoy]

Master cylinder either needs a kit put through it or outright replacement. If kitting it, take it off, take it to brake shop, get them to put a stainless sleeve in it and run the kit through it. Will be more successful than slapping a kit into an old rotten piston bore.

[Marko R1]

Ok thanks, I'll remove the master cylinder. Is the correct term for the large black dome 'vacuum cylinder'?

Also, who would u recommend I take the master cylinder to in syd?

[GTSBoy]

The black thingo is called the "booster". Commonly called the brake booster or the master booster. It is a vacuum cylinder by function, just not by name.

As to Sydney brake shops...I have no idea. In Adelaide I would take it to Power Brakes (if I didn't have a bro-in-law who was a mechanic and so in reality what I would actually do is take it there and get him to organise the M/C being kitted). Hopefully you'll get a tip from a Sydneysider. Or you could scout around for a brake specialist in Sydney who has been in business for 50 years (like Power Brakes have in Adelaide) and use them on the basis that they must know what they're doing to still be in business!

[Marko R1]

GTSBoy - are u familiar with this brand?

http://holfordmotors.com/store/HFM-46010-30p02-1

what are your thoughts mate?

[GTSBoy]

Well, the Holford BM57 has been mentioned in about 20 threads recently as the best option for a massive MC diameter upgrade.

[Marko R1]

In that case I should grab it for $150, includes shipping to Sydney

[GTSBoy]

Beware. You only need the BM57 if you need a bigger cylinder. Generally because of much bigger caliper volume. Do some reading on what happens to pedal pressures and travel when changing MC and/or caliper piston sizes before acting on that impulse!

[Duncan]

Beware. You only need the BM57 if you need a bigger cylinder. Generally because of much bigger caliper volume. Do some reading on what happens to pedal pressures and travel when changing MC and/or caliper piston sizes before acting on that impulse!

Exactly, you don't want to change the master cylinder size unless you are looking for a different result....just relace or rebuild the standard one.