Brake Fluids

T

ted schurman

New member
Jun 25, 1998
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With my set of SS brake lines, which I have not installed yet, came two
quarts of DOT 5 Silicone fluid. I did not order it but did pay for it.
When I install the new lines I plan to change out or clean the rest of
the brake items. The silicone fluid has some good features, does not
absorb water and has a wet (not sure I understand that (g) )boiling
point of 500 degrees F. However it does absorb air and in fact the label
recommends boiling the air out of the fluid on the stove before use.

Does any one have any experience with DOT 5 or opinions on its use ?

I have seen that may people have recommended a heavy duty Ford brake
fluid. I saw at the parts store the other day a synthetic brake fluid
by Valvolene for $5.00 a quart. It has a 513 degree dry boiling point
and 333 degree wet. It implied that it was less water absorbent.
Also available is a German brake fluid from ATE which has a 536 degree
dry boiling point and 333 degree wet. It cost about $10 a liter plus
shipping from Zims (1-800-356-2964). Probably available at many other
foreign parts dealers. It is available in either amber or blue color to
assist when changing fluid.

Ted Schurman
73 Glacier VA
 
Sorry that my feeble attempt at humor wasn't clear. My comment about
not understanding the wet boiling point of a fluid that didn't absorb
water was meant to point out the seeming conflict.
The comment about possible freezing of unabsorbed water is important and
was just the kind of imformation I was looking for.
Ted Schurman
73 Glacier VA

>

>
> absorb water and has a wet (not sure I understand that (g) )boiling
> point of 500 degrees F.>>
>
> Brake fluids are polyglycol based fluids together with corrosion inhibitors.
> They have the property of absorbing water. This is actually a good thing
> because if they didn't then water could collect in a line and freeze with the
> result that you would have no brakes. Water is absorbed through the hoses,
> past rubber cups and piston seals. After some time, as more water is
> absorbed, the boiling point of the fluid decreases. The "Wet" boiling point
> is measured with water in the brake fluid. So, a fluid with a "500 deg. "dry"
> b.p. would not be as good as a fluid with a 500 deg. "wet" b.p. The boiling
> point is important because the high temperatures of disk pads and brake shoes
> conduct heat to front calipers and brake pistons. This can get high enough to
> boil the brake fluid where it touches the metal parts. This forms a vapor
> which compresses and the result is no brakes. By going to a higher boiling
> point brake fluid you can help prevent the boiling of the fluid. Back in the
> 60's Ford had a problem with boiling and Dow Chemical developed a 550 deg
> fluid for them. It is still available. This fluid was packaged for other
> companies as well, such as Castrol. You should change out the brake fluid by
> bleeding it through the lines. It takes about two quarts to do the GMC. I
> recently did this using Performance Friction 500+ degree fluid which I
> purchased at AutoZone for about $5 per pint.
>
> Silicone fluid has the advantage of a very high boiling point, but the fact
> that it doesn't absorb water could cause problems in cold weather if there
> were to be water contamination. For that reason I have not switched to
> silicone fluid.
>
> As an Associate Member of the Society of Automotive Engineers in the late 60's
> and 70's I helped develop specifications relating to DOT-3, 4 and 5 brake
> fluids. Not much has really changed in the last 20 years.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
 
>
> Back in the
> 60's Ford had a problem with boiling and Dow Chemical developed a 550 deg
> fluid for them. It is still available. This fluid was packaged for other
> companies as well, such as Castrol. You should change out the brake fluid by
> bleeding it through the lines. It takes about two quarts to do the GMC. I
> recently did this using Performance Friction 500+ degree fluid which I
> purchased at AutoZone for about $5 per pint.

IIRC, the Ford "High Performance" fluid was about $1 a pint less
expensive than the Performance Friction fluid at AutoZone and is
reportedly the same stuff.

> Silicone fluid has the advantage of a very high boiling point, but the fact
> that it doesn't absorb water could cause problems in cold weather if there
> were to be water contamination. For that reason I have not switched to
> silicone fluid.

In addition to the non-absorption of water and possible incompatibility
with some brake system components, I understand that silicon fluid also
tends to become "aerated" making it hard to bleed and sometimes
resulting in a spongy pedal feel.

I'll stick with the Ford fluid, but I'm sure there's some silicon fluid
devotees out there that'll disagree.

Patrick
- --
Patrick Flowers
Mailto:patri63

The GMC Motorhome Page
http://www.gmcmotorhome.com
 
I doubt if this is applicable, but I routinely see Silicone based fluids
used as a Dielectic insulating medium in large electrical transformers. The
acceptance limits (IEEE) for moisture content are approximately twice
those of mineral oil based fluids. In addition, Silicone resists
decomposition to a higher degree than Mineral oil. Like I said I don't know
how much this helps, but take it FWIW.

Dave

- -----Original Message-----
From: Ted Schurman
To: gmcmotorhome
Date: Friday, February 05, 1999 8:18 AM
Subject: GMC: Brake Fluids

>With my set of SS brake lines, which I have not installed yet, came two
>quarts of DOT 5 Silicone fluid. I did not order it but did pay for it.
>When I install the new lines I plan to change out or clean the rest of
>the brake items. The silicone fluid has some good features, does not
>absorb water and has a wet (not sure I understand that (g) )boiling
>point of 500 degrees F. However it does absorb air and in fact the label
>recommends boiling the air out of the fluid on the stove before use.
>
>Does any one have any experience with DOT 5 or opinions on its use ?
>
>I have seen that may people have recommended a heavy duty Ford brake
>fluid. I saw at the parts store the other day a synthetic brake fluid
>by Valvolene for $5.00 a quart. It has a 513 degree dry boiling point
>and 333 degree wet. It implied that it was less water absorbent.
>Also available is a German brake fluid from ATE which has a 536 degree
>dry boiling point and 333 degree wet. It cost about $10 a liter plus
>shipping from Zims (1-800-356-2964). Probably available at many other
>foreign parts dealers. It is available in either amber or blue color to
>assist when changing fluid.
>
>Ted Schurman
>73 Glacier VA
>
 
Arch, I as said in my original post, the instructions that came with the
silicone fluid said to boil out the air before use. Do you or your
mechanic friend do that ?

Ted Schurman
73 Glacier VA

>
> Patrick
>
> I wont disagree to hard. I put Sillycone brake fluid in my GMC. You can
> all watch another experiment. I stick with what works for me. When it
> fails me I will change. I have an old farm truck that lost brakes because
> of the problems with regular brake fluid. Six years ago I converted it to
> sillycone brake fluid. It may sit for 6 months with no use.
 
BRAKE FLUID 101

Brake fluid is blended into 2 types which are glycol-based, DOT3 and
DOT4 and one which is silicone based, DOT5. DOT 3&4 are hygroscopic,
that is they readily absorb moisture. Moisture in brake fluid reduces
the boiling point. For example, DOT3 must have a dry (no moisture
absorbed) boiling point of no less than 401 degrees F, and a wet
(moisture absorbed) boiling point of no less than 284 degrees F. Most
new DOT3 brake fluids have a boiling point ranging from 460 to 500
degrees F. As the concentration of moisture increases, it causes a
sharp drop in the fluid's boiling temperature. A moisture content of
1% can reduce the boiling point to 369 degrees F, 2% to 320 degrees
and 3% to 293 degrees. Depending on humidity, most new brake fluid
will absorb up to 2% in one year and after several years it's not
unusual to see as much as 8%.
DOT4 has a minimum required dry boiling point of 466 degrees F and a
wet boiling point of 311 degrees F. Reduced boiling point can cause
the brake fluid to vaporize in high temperature conditions, such as
extended downhill braking or emergency stops. Vaporization creates
pockets of air in the system, which compress when the brakes are
applied. This results in what is known as "brake fade" and in its
extreme, can result in complete loss of breaking power. If brake fluid
is left in an open container for more than just a few hours, it could
absorb enough moisture to render it unsafe for use. DOT5, the silicone
based brake fluid, does not absorb water. It has a required dry
boiling point of 500 degrees F. Because DOT5 does not provide the
lubrication to ABS components like glycol-based brake fluid, it is not
normally used in over the road cars and trucks. Also, because water is
not absorbed in DOT5 brake fluid, water that enters the hydraulic
system will settle at low points where it causes corrosion. DOT5 is
used normally in motorcycles because of the higher temperatures
required of the brake fluid.

You can see where frost can produce an ice plug in your system when
using silicone fluids.

This should generate some comments?
Herm

>
>

>
> >
>
> One thing in favor of the Silicone brake fluids, in addition to the
high
> boiling point, is that it is not as hygroscopic (water absorbing) as
regular
> brake fluids. This means that it is not as spongelike in sucking
water
> through hoses and seals. Like everything else in life there are
pros and cons
> to everything. We all have to make up our own minds based upon
various input.
> The contributors to this list help to provide a wide range of useful
input to
> us. Thanks to all.
>
> Emery Stora
> 77 Kingsley
> Santa Fe, NM
>

_________________________________________________________
DO YOU YAHOO!?
Get your free @yahoo.com address at http://mail.yahoo.com
 
Arch, here is the exact quote from the instructions.
Wish I had a scanner .

"Since Silicone Brake Fluid tends to retain air, which will not escape
until the fluid has been heated (as under heavy use), we recommend the
following additional procedure be followed, prior to installation:

a. Pour fluid into a pot and heat on a stove until bubbling stops,
indicating that most of the entrained air has been driven-off (fluid
will not be damaged since boiling point is 500 degree F).

b. Let fluid cool slowly; do not agitate prior to use or more air will
be entrained.

By your answer, it is clear that you do not follow this procedure.

Ted Schurman
73 Glacier VA


>
> Ted
>
> I saw that in your post. I must admit I did not understand it, so I
> let it be. I could see heating it to drive off any moisture but I must
> admit I dont understand boiling off the air. Think I will wander around
> the net for a while and see what I can find.
>
> Take Care
> Arch 76 GB IL
>
> In a message dated 2/6/99 5:20:24 PM Central Standard Time, tedsch

>
> >
> > Arch, I as said in my original post, the instructions that came with the
> > silicone fluid said to boil out the air before use. Do you or your
> > mechanic friend do that ?
> >
 
Since silicon brake fluid is not hydroscopic, and cannot absorb water, how
would the water get into the lines in the first place so it could settle in
a low spot? Is someone going to purposely put some into the system?

sounds like another myth to destroy!

>BRAKE FLUID 101
>
>Brake fluid is blended into 2 types which are glycol-based, DOT3 and
>DOT4 and one which is silicone based, DOT5. DOT 3&4 are hygroscopic,
>that is they readily absorb moisture. Moisture in brake fluid reduces
>the boiling point. For example, DOT3 must have a dry (no moisture
>absorbed) boiling point of no less than 401 degrees F, and a wet
>(moisture absorbed) boiling point of no less than 284 degrees F. Most
>new DOT3 brake fluids have a boiling point ranging from 460 to 500
>degrees F. As the concentration of moisture increases, it causes a
>sharp drop in the fluid's boiling temperature. A moisture content of
>1% can reduce the boiling point to 369 degrees F, 2% to 320 degrees
>and 3% to 293 degrees. Depending on humidity, most new brake fluid
>will absorb up to 2% in one year and after several years it's not
>unusual to see as much as 8%.
>DOT4 has a minimum required dry boiling point of 466 degrees F and a
>wet boiling point of 311 degrees F. Reduced boiling point can cause
>the brake fluid to vaporize in high temperature conditions, such as
>extended downhill braking or emergency stops. Vaporization creates
>pockets of air in the system, which compress when the brakes are
>applied. This results in what is known as "brake fade" and in its
>extreme, can result in complete loss of breaking power. If brake fluid
>is left in an open container for more than just a few hours, it could
>absorb enough moisture to render it unsafe for use. DOT5, the silicone
>based brake fluid, does not absorb water. It has a required dry
>boiling point of 500 degrees F. Because DOT5 does not provide the
>lubrication to ABS components like glycol-based brake fluid, it is not
>normally used in over the road cars and trucks. Also, because water is
>not absorbed in DOT5 brake fluid, water that enters the hydraulic
>system will settle at low points where it causes corrosion. DOT5 is
>used normally in motorcycles because of the higher temperatures
>required of the brake fluid.
>
>You can see where frost can produce an ice plug in your system when
>using silicone fluids.
>
>This should generate some comments?
>Herm

>>
>>

>>
>> >
>>
>> One thing in favor of the Silicone brake fluids, in addition to the
>high
>> boiling point, is that it is not as hygroscopic (water absorbing) as
>regular
>> brake fluids. This means that it is not as spongelike in sucking
>water
>> through hoses and seals. Like everything else in life there are
>pros and cons
>> to everything. We all have to make up our own minds based upon
>various input.
>> The contributors to this list help to provide a wide range of useful
>input to
>> us. Thanks to all.
>>
>> Emery Stora
>> 77 Kingsley
>> Santa Fe, NM
>>
>
>_________________________________________________________
>DO YOU YAHOO!?
>Get your free @yahoo.com address at http://mail.yahoo.com
>
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach
 
Some interesting reading for those that do not think there are civil
penalties involved in violating govt standards. I have not had the time to
really read it and understand it. There is also informtion on the site
about brake fluid standards and which ones passed.
http://www.nhtsa.dot.gov/cars/testing/procedures/Civpentb.o97.html

>

>
>would the water get into the lines in the first place >>
>
>1. From condensation in the master cylinder.
>2. From water splashing on the pistons that move in and out of the seals.
>3. From absorption from the hoses. Even if the silicon doesn't absorb
>water, the rubber parts do and they are in physical contact with the fluid.
>
>Emery Stora
>77 Kingsley
>Santa Fe, NM
>
>
Tom & Marg Warner
Vernon Center NY
1976 palmbeach
 
Speaking of Myths ....

Silicone based fluids are LESS hygroscopic than Parrifinic based fluids, as
apposed to the Mythical Non-Hygroscopic.

There is a world of difference between "LESS" and "NON"

Without Completely sealing your brake system. ( A highly dangerous venture
I might add)
there will always be a tendency for moisture to be introduced to some degree
or another. Brake systems are thermal cycled routinely, as a part of their
operation. This provided a mechanism for the introduction of moist air,
which in turn can be introduced into the fluid. The advantage of Si based
fluids is that they resist this tendency to a greater extant than other
types of fluids.

Hopefully this helps quell some of the misinformation circulating here.

Dave

- -----Original Message-----
From: Thomas G. Warner
To: gmcmotorhome
Date: Sunday, February 07, 1999 06:28 AM
Subject: Re: GMC: Brake Fluids

>Since silicon brake fluid is not hydroscopic, and cannot absorb water, how
>would the water get into the lines in the first place so it could settle in
>a low spot? Is someone going to purposely put some into the system?
>
>sounds like another myth to destroy!
>
>
>

>>BRAKE FLUID 101
>>
>>Brake fluid is blended into 2 types which are glycol-based, DOT3 and

Massive Snip

>>
>>This should generate some comments?
>>Herm

>>>
>>>

>>>
>>> >
>>>
>>> One thing in favor of the Silicone brake fluids, in addition to the
>>high
>>> boiling point, is that it is not as hygroscopic (water absorbing) as
>>regular

Snip

>>> us. Thanks to all.
>>>
>>> Emery Stora
>>> 77 Kingsley
>>> Santa Fe, NM
>>>
>>
>>_________________________________________________________
>>DO YOU YAHOO!?
>>Get your free @yahoo.com address at http://mail.yahoo.com
>>
>Tom & Marg Warner
>Vernon Center NY
>1976 palmbeach
>>
 
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