Golden
Cruiser DOT 3 Brake Fluids
DOT 3 fluids are usually glycol ether based, but as stated
earlier, that is not because they are required to be. The brake fluid industry
has determined by consensus that glycol ether fluids are the most economical
way to meet the requirements
By definition, DOT 3 fluids must have a minimum dry boiling point
(measured with 0 percent water by volume) of 205°C and a minimum wet boiling
point (measured with 3.7 percent water by volume) of 140°C. The specification
says little more as far as the performance enthusiast is concerned.
Golden
Cruiser DOT 4 Brake Fluids
DOT 4 fluids are also glycol ether based, but have
a measure of borate esters added for improved properties including increased
dry and wet boiling points. A seldom talked about characteristic is that
because of this chemistry, the DOT 4 fluid will have a more stable and higher
boiling point during the early portion of its life, but ironically once the
fluid does actually begin to absorb water its boiling point will typically fall
off more rapidly than a typical DOT 3. By FMVSS116 standards, DOT 4 fluids must
have a minimum dry boiling point of 230°C and a minimum wet boiling point of
155°C.
DOT 4 is the grade applicable to most race
engineered brake fluid in the world today, especially with regard to viscosity
limit. Note that although the DOT 4 designation has a minimum dry and wet
boiling point, a DOT 4 racing brake fluid may have a dry boiling point over
600F. Its viscosity is challenged, however, to be under the viscosity limit of
1,800 mm2/sec. Some claimed racing brake fluids exceed this important limit.
Caution should be exercised if these fluids are used in race cars with ABS
systems.
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