Re: Battle of the DOTs

[chymar01@xxxxxxxxxxx]

I can buy it at my local parts stores and motorcycle shops. It's very common now, didn't used to be. 

Here's a good article: 

http://www.moparaction.com/Tech/quest/BINDER_JUICE.html 

Tech Question 


Gary Boak, Chilliwack, BC, Canada, 1969 Dart Swinger 340 

I notice in the April 04 issue you say that DOT 5 brake fluid can be used without flushing the system. Everything I have heard and read states that Dot 5 does not mix with anything except DOT 5. When switching to DOT 5 are you not supposed to use new rubber? 

Gary- 

Another old wive's (or Mopar Muscle) tale. First, realize that DOT specs don't specify the composition of the fluid, the rating relates only to the boiling point. So, therefore, it would be possible to have DOT 3 fluid that's silicone, and DOT 5 that's not (and this latter combination does exist.) These specs are covered in detail in Federal Motor Vehicle Safety Standard section number 571.116, which is part of the Code of Federal Regulations, #49, Chapter V, see for yourself at: Code of Federal Regulations, #49, Chapter V 

Here's an excerpt from the law on boiling points: 

Equilibrium reflux boiling point (ERBP). When brake fluid is tested according to S6.1, the ERBP shall not be less than the following value for the grade indicated: 

(a) DOT 3: 205 ÌŠC. (401 ÌŠF.). 

(b) DOT 4: 230 ÌŠC. (446 ÌŠF.). 

(c) DOT 5: 260 ÌŠC. (500 ÌŠF.). 

A recent change to the law specifies that non-silicone DOT fluid be labeled DOT 5.1. All DOT 5 fluid must be purple in color, all other grades must be clear to amber. 

The baziilion pages of the specs relate mostly to boiling points, viscosity, and the fluid's effects on rubber (swelling), as well as testing procedures. But there's also much written about compatibility. What has probably caused the confusion is that DOT 5 fluids are tested differently than other types, but these tests apply equally to silicone and non-silicone fluids. Subchapter S6.5.4 addresses miscibilty, specifying that the fluid being tested must mix with a standard type fluid, and this miscibilty test DOES apply to DOT 5 fluids, and can't gel, swell cups, etc. when mixed. So there! 

The Society of Automotive Engineers (SAE) also has detailed specs: J1703 and J1705. 

It's true that much has be written saying that silicone based fluids cannot or should no be mixed with other types, this is that old myth-perpetuating deal. Nowhere can I find a scientific study or analysis to back this story up - do a Google search yourself if you don't trust me.. There's only been two studies on this that I'm aware of: Dow-Corning, the leader in silicone brake fluids (possibly the only true USA manufacturer), did a detailed study almost 30 years ago, wherein a system was haphazardly swapped from DOT 3 to silicone, with the intent of leaving a significant portion of the fluid UNchanged. The system passed all DOT tests easily. The second test is less scientific, but, to me, more significant: Yours truly has been using DOT 5 silicone in every car I've owned or serviced since approx. 1978. I have never flushed a system! I have, in some cases, bled out most of the old stuff, in other cases, I've just topped up a DOT 3-filled system with silicone. Cars serviced by me in this fashion have stopped will from speeds over 160 MPH. I've never had a stuck caliper (or wheel cylinder) pistion since making this change universal in my fleet - even in cars stored for long periods. I've also never damaged pain from a brake fluid spill. Come to my garage - you will find 4 or 5 bottles of DOT 5 silicone, and zero of DOT 3 or 4. 

On your Dart, do what I do (and say): bleed out as much of the old garbage as you can, until you see purple at each bleeder screw. And don't worry about it! 

End of story. 

Rick 
----- Original Message ----- 
From: "Herb" <zephyr9900@xxxxxxxxxxx> 
To: 1962to1965mopars@xxxxxxxxxx 
Sent: Wednesday, March 11, 2009 9:51:26 PM GMT -05:00 US/Canada Eastern 
Subject: Re: Battle of the DOTs 



I beg to differ with you but 5 is not miscible with 3 or 4! Federal Law can 
say all it wants to it's still chemically not compatible also DOT 5 is not 
an on the shelf item unless you go to a speciality store like speed shops 
and the like and I don't recall seeing it on the shelf their. 


-------Original Message------- 

From: chymar01@xxxxxxxxxxx 
Date: 3/11/2009 6:31:39 PM 
To: 1962to1965mopars@xxxxxxxxxx 
Subject: Re: Battle of the DOTs 


While I understand what the article is saying about attracting the crud in 
the system when DOT 5 is introduced(section #4), the fact remains that the 
fluids themselves are fully miscible. Federal law requires that all brake 
fluids sold in the US must be able to work with each other. That way, if 
someone needs fluid NOW, they can use whatever is on the shelf. 
It is recommended that when switching to DOT 5 that it be done when 
replacing the brake system components all at once. I wouldn't switch 
otherwise. And definitely crack the bleeders at least once a year like it 
says below. 


----- Original Message ----- 
From: "Herb" <zephyr9900@xxxxxxxxxxx> 
To: "1962 to 1965 Mopars" <1962to1965mopars@xxxxxxxxxx> 
Sent: Wednesday, March 11, 2009 5:54:07 PM GMT -05:00 US/Canada Eastern 
Subject: Battle of the DOTs 



FYI if any one wants to read it! Her it is. 

Battle of the DOTs 
DOT 3-4 Verses DOT 5. Which brake fluid should I use? 
"With regards to the DOT 3-4 verses DOT 5 brake fluid controversy, here is 
an article sent to me by Mr. Steve Wall. It is one of the most professional 
treatments I have seen on the subject". 
[I had to condense this article from 6 pages to 1 due to space limitations. 
Brake Fluid Facts 
by Steve Wall 
As a former materials engineering supervisor at a major automotive brake 
system supplier, I feel both qualified and obligated to inject some material 
science facts into the murky debate about DOT 5 verses DOT 3-4 brake fluids. 
The important technical issues governing the use of a particular 
specification brake fluid are as follows: 
1. Fluid compatibility with the brake system rubber, plastic and metal 
components. 
2. Water absorption and corrosion. 
3. Fluid boiling point and other physical characteristics. 
4. Brake system contamination and sludging. 
Additionally, some technical comments will be made about the new brake fluid 
formulations appearing on the scene. 
First of all, it's important to understand the chemical nature of brake 
fluid. DOT 3 brake fluids are mixtures of glycols and glycol ethers. DOT 4 
contains borate esters in addition to what is contained in DOT 3. These 
brake fluids are somewhat similar to automotive anti-freeze (ethylene 
glycol) and are not, as Dr. Curve implies, a petroleum fluid. DOT 5 is 
silicone chemistry. 
Fluid Compatibility 
Brake system materials must be compatible with the system fluid. 
Compatibility is determined by chemistry, and no amount of advertising, 
wishful thinking or rationalizing can change the science of chemical 
compatibility. Both DOT 3-4 and DOT 5 fluids are compatible with most brake 
system materials except in the case some silicone rubber external components 
such as caliper piston boots, which are attacked by silicon fluids and 
greases. 
Water absorption and corrosion 
The big bugaboo with DOT 3-4 fluids always cited by silicone fluid advocates 
is water absorption. DOT 3-4 glycol based fluids, just like ethylene glycol 
antifreezes, are readily miscible with water. Long term brake system water 
content tends to reach a maximum of about 3%, which is readily handled by 
the corrosion inhibitors in the brake fluid formulation. Since the 
inhibitors are gradually depleted as they do their job, glycol brake fluid, 
just like anti-freeze, needs to be changed periodically. Follow BMW's 
recommendations. DOT 5 fluids, not being water miscible, must rely on the 
silicone (with some corrosion inhibitors) as a barrier film to control 
corrosion. Water is not absorbed by silicone as in the case of DOT 3-4 
fluids, and will remain as a separate globule sinking to the lowest point in 
the brake system, since it is more dense. 
Fluid boiling point 
DOT 4 glycol based fluid has a higher boiling point (446F) than DOT 3 (401F) 
and both fluids will exhibit a reduced boiling point as water content 
increases. DOT 5 in its pure state offers a higher boiling point (500F) 
however if water got into the system, and a big globule found its way into a 
caliper, the water would start to boil at 212F causing a vapor lock 
condition [possible brake failure -Ed.]. By contrast, DOT 3 fluid with 3% 
water content would still exhibit a boiling point of 300F. Silicone fluids 
also exhibit a 3 times greater propensity to dissolve air and other gasses 
which can lead to a "spongy pedal" and reduced braking at high altitudes. 
DOT 3 and DOT 4 fluids are mutually compatible, the major disadvantage of 
such a mix being a lowered boiling point. In an emergency, it'll do. 
Silicone fluid will not mix, but will float on top. From a lubricity 
standpoint, neither fluids are outstanding, though silicones will exhibit a 
more stable viscosity index in extreme temperatures, which is why the US 
Army likes silicone fluids. Since few of us ride at temperatures very much 
below freezing, let alone at 40 below zero, silicone's low temperature 
advantage won't be apparent. Neither fluids will reduce stopping distances. 
With the advent of ABS systems, the limitations of existing brake fluids 
have been recognized and the brake fluid manufacturers have been working on 
formulations with enhanced properties. However, the chosen direction has not 
been silicone. The only major user of silicone is the US Army. It has 
recently asked the SAE about a procedure for converting from silicon back to 
DOT 3-4. If they ever decide to switch, silicone brake fluid will go the way 
of leaded gas. 
Brake system contamination 
The single most common brake system failure caused by a contaminant is 
swelling of the rubber components (piston seals etc.) due to the 
introduction of petroleum based products (motor oil, power steering fluid, 
mineral oil etc.) A small amount is enough to do major damage. Flushing with 
mineral spirits is enough to cause a complete system failure in a short time 
I suspect this is what has happened when some BMW owners changed to DOT 5 
(and then assumed that silicone caused the problem). Flushing with alcohol 
also causes problems. BMW brake systems should be flushed only with DOT 3 or 
4. 
If silicone is introduced into an older brake system, the silicone will 
latch unto the sludge generated by gradual component deterioration and 
create a gelatin like goop which will attract more crud and eventually plug 
up metering orifices or cause pistons to stick. If you have already changed 
to DOT 5, don't compound your initial mistake and change back. Silicone is 
very tenacious stuff and you will never get it all out of your system. Just 
change the fluid regularly. For those who race using silicone fluid, I 
recommend that you crack the bleed screws before each racing session to 
insure that there is no water in the calipers. 
New developments 
Since DOT 4 fluids were developed, it was recognized that borate ester based 
fluids offered the potential for boiling points beyond the 446F requirement, 
thus came the Super DOT 4 fluids - some covered by the DOT 5.1 designation - 
which exhibit a minimum dry boiling point of 500F (same as silicone, but 
different chemistry). 
Additionally, a new fluid type based on silicon ester chemistry (not the 
same as silicon) has been developed that exhibits a minimum dry boiling 
point of 590F. It is miscible with DOT 3-4 fluids but has yet to see 
commercial usage. 

    
Herb 

1959 Coronet 326 Poly 
1963 Fury 2D/HT 6.1 
1963 Sport Fury Convertible 361 
1970 Challenger RT 440 
1999 Durango SLT 5.9 
2006 300-C Heritage 5.7 
2008 SRT-8 Magnum 6.1 
St. Louis, MO. 


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