On Wed, 24 Aug 1994, Frank Marrone wrote:
> What is the straight, modern day, scoop on break fluid in brit
> car systems. I thought that anything but LMA or Silicon was
> a no-no because brit cars use natural rubber brake parts and other
> types of fluid would eat the natural rubber seals. Recently I have
> had this belief contradicted. Help staighten me out on this.
Conventional wisdom has it that standard DOT-3 brake fluid rots the
rubber parts in BritCar brakes. Con Wiz is wrong. As far as I can tell,
this dates back to the days before the DOT standards for brake fluid
existed, when mineral oil fluids (like hydraulic fluid) was sometimes
used in brake systems. This stuff would definitely destroy natural
rubber componants!
Most owner's manuals for very old BritCars said someting along the lines
of "Use only genuine Girling (or Lockheed, depending on the maker of the
brakes) fluid". At the time that was a sensible precaution because the
makers knew their own fluid was okay, but couldn't guarantee anything
else. Later on, BritCar makers started adding on "In the North American
market fluid meeting DOT-3 standards may be substituted if genuine
Girling (or Lockheed) fluid is not available" (or something to that
effect). This would seem to be official recognition of the fact that DOT-3
fluid wouldn't harm the system.
What do owner's manuals for comparatively recent BritCars say? I
wouldn't know, since most of my BritCars have dated from the 30's, 40's,
and early 50's. My TR4 (1962) is the youngest one I've ever had.
For what it's worth, until very recent years, I always used DOT-3 fluid
in every BritCar I owned. I never had any problem with it other than the
moisture absorption you'll see in _any_ car using DOT-3. For the past
ten years or so I've been using Castrol GT/LMA or silicone fluid, but
that's because of the moisture thing, not because of rubber rot.
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Chip Old 1948 M.G. TC TC6710 NEMGTR #2271
feold@umd5.umd.edu 1962 Triumph TR4 CT3154LO (daily transportation)
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