Mixing/changing Brake fluid

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Mon 26 Jun 2006 15:39
Mixing/changing Brake fluid - pvmw

I have a '30s car fitted with pre-war hydraulic brakes (originally from a Triumph Gloria). The restorer of the car (pre my ownership) used silicon brake fluid, which is a pain - its very expensive and not easy to find when you need it.

I asked around - including a couple of manufacturers - and was assured that modern DOT4 fluids are compatible with silicon, so I used some (months ago). I'm now getting sticking brakes and feedback that they aren't compatible after all.

I'm resigned/prepared to strip the system and replace the seals, which I've already managed to find - and I'm not not too concerned as after 50k miles of thrashing I'm happy to give the brakes as once-over anyway - but I've been told that its not possible to revert to DOT4 fluid.

I can't really believe this. If I thoroughly flush out the system (possibly using a sovent such as acetone, any comments??), change all seals in slave and master cylinder and then re-assemble I can't really believe there will be enough resuidual silicon in the system to cause problems.

Any comments, anyone????

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Mon 26 Jun 2006 16:36
Mixing/changing Brake fluid - Hamsafar
Silicone is VERY and TOTALLY incompatible with glycol ester fluids. You will need to strip and flush the system so that there is no silicone left. No need to use solvent, that's more likely to strip the lubricating fluid from seals.

Why didn't you like silicone? it's pretty much a lifetime fill.
It's popular amongst classic vehicle, airport emergency vehicles and the military because it doesn't need changing and it doesn't absorb moisture during storage.
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Mon 26 Jun 2006 16:47
Mixing/changing Brake fluid - jc2
The fact that it doesn't absorb moisture is one of the concerns;you'll always get moisture in the system and with silicone ,it'll be in globules not just reducing the boiling point as is in normal brake fluid.
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