[Tigers] brake fluid - Types

Rense, Mark (GE Indust, ConsInd) mark.rense at ge.com
Mon Jun 15 09:33:31 MDT 2009


Interesting. Folks, the wonderful world of cut and paste into a plain
text editor seemed to have replaced the "degree" symbol with a zero. Not
kewl.

Here is what they should be. Also, I misspelled one term, glycol-based
brake fluid is hyGroscopic. Too early on a Monday.

Brake Fluid Rating  	Dry boiling point		Wet boiling
point
DOT 3 			205C (401F) 		140C (284F)
DOT 4 			230C (446F) 		155C (311F)
DOT 5 			260C (500F) 		180C (356F)
DOT 5.1 			270C (518F) 		191C (376F)

And as for you Dr. Mayf, tungsten doesn't melt until over 3420C (3693K),
so there!

Here is a chart just for you:

Brake Fluid Rating  	Dry boiling point		Wet boiling
point
DOT 3 			478K 		 			413K
DOT 4 			503K		 			428K
DOT 5 			533K 					453K
DOT 5.1 			543K
464K

Bugz

-----Original Message-----
From: drmayf [mailto:drmayf at mayfco.com]
Sent: Monday, June 15, 2009 10:01 AM
To: Rense, Mark (GE Indust, ConsInd)
Cc: tigers at autox.team.net
Subject: Re: [Tigers] brake fluid - Types

Bugz... did you miss some decimal points in the boiling points table
below?  Hard for me to believe those temperatures. I mean DOT 5.1 boils
at 5180 degrees F? And so on...

I think that may be higher than melting tungsten or other exotic metal
alloys...

mayf, just funning ya

Rense, Mark (GE Indust, ConsInd) wrote:

>The main difference between DOT 3 and DOT 4 (both glycol-based) is the
>boiling point. The DOT 4 has a higher boiling point for both wet and
dry measurements.
>This is important to us because our clutch and master cylinder
>reservoirs are not sealed and therefore allow the passage of moisture,
>and since glycol-based fluid is hydroscopic, the DOT 4 rating will
>allow more moisture content while still providing adequate service.
>
>You CANNOT mix DOT 3 or 4 with DOT 5, as DOT 5 is silicon based.
>However, you can mix with the new DOT 5.1 fluid. The recommended fluid
>for most British cars old and new is Castrol GT/LMA, which is rated as
>a DOT 3/4. If you rebuild your hydraulics with all new synthetic rubber

>parts, you can use the silicon-based DOT 5, the advantage here is that
>when (notice I didn't say
>"if") it leaks, it does not affect the paint. The disadvantage of DOT 5

>is that it does not absorb water at all, so the water pools in the
>cylinders and causes corrosion.
>
>In any case, flushing your brake fluid every other year is a Best
Practice.
>
>Brake Fluid Rating  	Dry boiling point		Wet boiling
point
>DOT 3 			2050C (4010F) 		1400C (2840F)
>DOT 4 			2300C (4460F) 		1550C (3110F)
>DOT 5 			2600C (5000F) 		1800C (3560F)
>DOT 5.1 			2700C (5180F) 		1910C ( 3760F)
>
>Bugz


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