[DeTomaso] Master Clutch Cylinder

[Trevor Fougere]

Well...on the plus side I've run 5,000 miles on it after replacing the DOT 4
that had been in there for the previous 5,000.
 
This change over was after a debate, of sorts, with the Pantera Community
insisting on DOT 3 or DOT 3/4.  Versus
DOT 4 arguments.
 
The fact is the seals in my 3rd Master Clutch Cylinder are disintegrating.
At least they didn't disintegrate immediately upon 
installation like the 2nd one, or soon after I purchased the car as with the
1st MCC.
 
Frankly, the whole subject confuses me. The following Wikipedia entry seems
to imply that DOT 4 would be better.
 
Trevor
 
 
 
According to Wikipedia: http://en.wikipedia.org/wiki/DOT_3 
 
DOT 3 is one of several designations of automotive break fluid, denoting a
particular mixture of chemicals imparting specified ranges of boiling point.

In the United States, all brake fluids must meet federal standard #116.
Under this standard there are three DOT minimal specifications for brake
fluid. They are DOT 3, DOT 4 and DOT 5.1

DOT 3, like DOT 4 and DOT 5.1, is a polyethylene glycol based fluid
(contrasted with DOT 5, which is silicone based). Fluids such as DOT 3 are
hygroscopic and will absorb water from the atmosphere. This degrades the
fluid's performance, and if allowed to accumulate over a period of time, can
drastically reduce its boiling point. In a passenger car this is not much of
an issue, but can be of serious concern in racecars or motorcycles.

As of 2006 most cars produced in the U.S. use DOT 3 brake fluid.

Girling brakes, which were widely used in British cars in the mid-20th
century, use nitrile seals, which are degraded by DOT-3 brake fluid. Many
owners of British cars had no problems with their brakes as long as their
brakes were serviced by a British-car dealer who used the
Girling-recommended "Castrol Golden Amber" brake fluid, but at some
indeterminate time after allowing a non-specialist mechanic to top up oil
and "all fluids," felt their brake pedal go to the floor without stopping
the car. The problem: the generalist mechanic used DOT-3 brake fluid in all
cars and rarely sees a British car (twice). The solution-after body
repair-is to drain the brake system and rebuild all cylinders with new
nitrile seals, then fill the system with the Girling-recommended fluid.

Boiling points

Minimal boiling points for these specifications are as follows:

(C-Centigrade, F-Fahrenheit)

Dot 3    205C (401F) Dry, 140C(284F) Wet

Dot 4    230C(446F) Dry, 155C(311F) Wet

Dot 5    260C(500F) Dry, 180C(356F) Wet

Dot 5.1    270C(518F) Dry, 191C(375F) Wet