Which brake fluid?
Bob Owen has produced an excellent article which sets out
the facts with a dispassionate assessment of the issues so fellow
members can understand the DOT categories, the DOT fluid performance
tests and the benefits and disadvantages of each fluid. He has also
highlighted some concerns - key variables where there is uncertainty.
In essence they are the lack of information on the composition of
the replacement rubber seals and the effect of various formulations
of glycol fluid available in the market on those different types of
rubber seal - and the effect of silicone fluid on them too. They are
being examined and a further report will follow. (Jan
the topic of silicone brake fluid as a replacement for glycol is raised
amongst classic car enthusiasts you soon see that some of the key
issues and even some of the facts needed to make a balanced assessment
are either not available or not sufficiently clear. So in the end
each classic car owner has to make their own decision whether to change
to silicone or stay with the original fluid, glycol. That decision
is based on either their own view or, where they do not feel qualified
or able to form a view, they will usually rely on the recommendation
of the specialist who services their car.
of fluid is a topic that does attract firm views from some quarters
and in a few cases the assertions of the merits of silicone as a replacement
brake fluid are made with a zeal that worries those who would prefer
to see the issues more calmly presented and assessed. Well, when the
topic reached this stage in a bulletin board thread on the V8 Register's
website last November, it was felt an impartial article setting out
information derived from original sources rather than hearsay would
provide fellow members with the facts and other information as a basis
upon which to make their own decision on "which brake fluid to
use?" Bob Owen was approached by the chairman of the V8 Register
to do the research and prepare the article as he had
a number of useful workshop notes and, whilst not a brake expert,
he has a good understanding of physics from his electrical engineering
training and has had a love of all things mechanical since he
was a boy with a father who ran an agricultural engineering business.
Equally Bob can claim to be impartial as he has some personal
experience of both types of fluid having a 1974 MGBGTV8 using
standard DOT4 glycol and a 1949 MG TC converted to DOT5 silicone
fluid some five years ago.
Bob says "this article is an attempt to provide all the information
you need to enable you to make your own choice of fluid".
As the article is lengthy, some six pages, it has been published
on the V8 website and available as a download at:
Please note the content of this article is subject to the important
caution and caveats set out at the end of the six page article
a copy of the brake fluids paper. More