[DeTomaso] Master Clutch Cylinder

[Tomas Gunnarsson]

I seriously doubt that the problem is that one uses DOT 4 instead of DOT 3. I've not run anything but DOT 4 in any of my cars for the last 20+ years, in the Pantera for 12 years now. I don't even think DOT 3 can be found on the common market (read: gas station etc) over here.

Tomas

----- Original Message ----- 
From: "Trevor Fougere" <trevor at fougere.com>
To: <detomaso at realbig.com>
Sent: Thursday, July 17, 2008 8:00 AM
Subject: [DeTomaso] Master Clutch Cylinder


> 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
> 
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