>
> 1- I saw mention of 'dreaded DOT 3' brake fluid. What kind should
> be used and what is wrong with DOT 3.
>
> Use only Castrol GT "LMA" brake fluid. Not only is this
> rated at DOT 4, but it is compatible with British rubber
> seals in your hydraulic system. Standard US-spec DOT 3
> fluid will dissolve your brake and clutch seals in fairly
> short order.
I think this is a misconception. I've tried soaking british seals in
DOT 3 to see what happens, and its uninteresting. No sign that DOT 3
is a solvent for british rubber seals. As further proof of this, my
little sister used to have a Pontiac Fiero that happened to use a
Lucas/Girling clutch master cylinder. Even though that master cylinder
used british seals, Pontiac recomended DOT 3 fluid. Of course, the
reason that I found out that the car used a Lucas/Girling master cylinder
was because it needed to be rebuilt on her less than 5 year old car.
Of course, this was no longer surprising after I found out this master
cylinder was of british origin :-) .
> LMA also stands for "low moisture activity,"
> meaning that it is non-hygroscopic to a high degree. This
> helps keep the boiling point fairly low, and also helps
> keep from rusting your brakes from the inside out.
I've always heard that "LMA" stands for "low moisture _absorbption_". Anyway,
I think this is the real reason DOT 4 is recommended. There's something
about the metal used in british hydraulic components that makes them very
prone to rust. I've rebuilt Japenese, American, and Italian hydraulic
components, and have never seen the kind of rust that you almost always run
into when rebuilding british hydraulic components. If they rust that easily
with the miniscule amount of water that DOT 4 absorbs, I imagine that using
DOT 3 would rust the cylinder walls in very short order. I suspect the
failure mode of the seals would then be physical damage against the rough
walls of the cylinder.
Joe
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