Posted by Pete Sturgess on 8/29/2009, 12:05 pm, in reply to "Re: Silicone fluid? Caliper strip"
87.112.24.119
The only benefit of silicone fluid is it doesn't damage the paintwork, unless operation at -40C is important to you :-)
Drawbacks are not widely published but I've had some serious problems developing calipers for a US military machine.
It doesn't absorb water but any water that gets in will fall to the lowest point, usually the caliper, then it'll boil. Alternatively it will collect in a pipe and rust through.
Its compressibility is much worse than DOT4 especially when hot, giving longer lever travel.
It is prone to collecting micro-bubbles of air, giving a spongy feel.
It's a terrible lubricant causing fretting between pistons and bores.
Don't mix it with DOT4. It doesn't damage seals like LHM but the purple dye comes out and forms a sludge which looks a bit like rubber seal debris, this then sticks everything up and causes valves to leak etc.
For the US military we had to use a certified supplier, stockists in the UK claimed it was used by US Military but they couldn't prove where they got it from. By the way H-D doesn’t use it anymore as far as I know.
It's only OE user is the US military so they can deploy to hot or cold climates without having to change all the fluids.
Pete Sturgess
1979 T140E
Engineering Inspiration
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