In less than 4 years we have new wheel cylinders full of moisture, which means rust, which means leaking brake fluid!.
Is there something I can do to stop this!!!

When they're not used too often the machined surfaces inside the wheel cylinders where air from outside can contact them get a little surface rust on them. Then when you go to used them the seal will try to clean the rust away each time it moves over it. This eventually takes a small amount of rubber off the seal for each time the seal has to do this.

You could try putting brake assembly rubber grease (PBR or otherwise) inside the boot of the wheel cylinder on assembly, it will protect from corrosion where it makes contact with the machined surfaces inside, but it won't absolutely keep the water out.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Stainless steel is the answer worth every cent

Can you get S/S wheel cylinders, that would be worth having!

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

Most specialist brake places can re-sleeve cylinders in stainless.

The last ones I had done cost a bit more than a new cylinder - but it was a long time ago

Cheers, Ian

Oh I got ya, I was expecting a complete S/S cylinder...

Yeah, sleeved in stainless is the way to go.

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SooperDooperMiniCooperExpertEngineering

All garage work involves equal measures of enthusiasm, ingenuity and a fair degree of irresponsibility.

In the old days they used to sleeve cylinders with brass, that was very good too. And probably less likely for the pistons to jam in it.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

I have a bloody good wife!!, BUT, BUT BUT, I think I would get a funny look if I gave her 60 wheel cylinders to be sleeved. ...I think I had better try the PBR grease

If water can get in then brake fluid can get out so if the brakes work then the fluid isn't leaking into the system.

Most water in brake systems comes from condensation of water vapor in the top of the reservoir and usually takes some years to contaminate the whole system.

That's why the recommended replacement period for mineral brake fluid is 2 years.

Pete

Why don't you give Silicon Fluid a try? You must however, innitially clean your lines and componets of existing brake fluid.Which means dismantling and re-assembling all wheel cyl.,master and proportioning valve(rubber grease is OK to use in assembly). Whilst all components are off the vehicle, ,use your compressor to flush the system with Methylated Spirit then Silicon Fluid. To my knowledge,this fluid does not attract moisture.I have been using this fluid for 30 years. No rust in components,but,it does tend to use up seals faster.

Silicone Dot 5 brake fluid. It is great stuff. A bit more expensive that conventional brake fluid but does a great job especially on cars that don't get used regularly. Silicone brake fluid is also good as it does not Bubble paintwork.

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