Whoa up cowboy!

The 'wet' boiling point of Dot 3 is 284 F and the 'dry' boiling point is 401
F.

The wet boiling point of Dot 4 is 311 F and the dry boiling point is 446 F.

'Dry brake fluid is fresh fluid and 'wet' fluid is defined as having a water
content of 3.7% by volume.

Jake

On Fri, Jun 25, 2010 at 2:13 PM, Scott Daniel - Turbovans <
scottdaniel@turbovans.com> wrote:

> I was surprised how low the boiling point of brake fluid is.
> Dot 3 is only 273F I think,
> which isn't that far above the boiling point of water , as a handy
> reference.
>
> Vanagons use Dot 4 Brake Fluid of course...
> forget what the boiling point of that is, but it's somewhat higher ..
> and it's not anything like 400 degrees I don't think.
>
> shoot the temps of front rotors sometime after heavy brake use ....they can
> get way up there.
>
> and yes, it's mandatory to change brake fluid every two years on all cars.
> When it's old and thin and black ...
> it's probably 70 % water I bet.
>
> 'just sitting'......... brake fluid absorbs moisture out of the air. It
> attracts water practically.
> In a high humidity environment, it should be changed once a year.
> You may notice some  Owner's Manuals say 'add brake fluid from a sealed
> container.'
>
> and that is a great idea on the blue and gold fluids ..so you can tell when
> the old is out and new is in.
> 'usually' products made for racing might be better at racing applications
> than for daily and regular road use, so check on that I'd say.
>
> I just believe in a high quality Dot 4 brake fluid, and change it twice a
> year, including clutch hydraulics.
>
> Scott
> www.turbovans.com
>
>  ----- Original Message -----
>   From: Don Hanson
>  To: Scott Daniel - Turbovans
>  Cc: vanagon@gerry.vanagon.com
>  Sent: Friday, June 25, 2010 1:50 PM
>  Subject: Re: Brake question......
>
>
>  Right on, Scott.
>
>    A loaded Westie, maybe an automatic without much engine braking, going
> down a long steep grade...that is "Brake Fade...waiting to happen"  if you
> apply the brake the whole time to control your downhill speed.  If you apply
> continuous braking all the way down a long hill, the pads and rotors get
> real hot and transmit that heat into the caliper and through that to the
> fluid.  Real hot brake pads are also less effective, requiring more braking
> as the heat builds, so you have to push harder, creating even more heat...a
> vicious cycle..
>
>   The most effective way to descend in a heavy vehicle with small brakes is
> to apply them firmly and slow the vehicle below it's 'perfect speed', then
> get off the brakes and let it build back up to speed (allowing the brakes to
> cool off some)  Watch the truckers go downhill.
>
>    Brake fade is mostly caused by the moisture in your brake fluid turning
> to steam.  Brake fluid has a very very high boiling point but it also loves
> moisture...So over time your brake fluid will absorb a small amount of
> moisture...a drop or two in the whole vehicle's brake system is all it takes
> to create a lot of steam....Water expands  and creates a lot of steam which
> is 'compressable' unlike brake fluid...So at 212f...which is nothing when
> you are talking brake temps...your brake system can boil the moisture in old
> stale brake fluid and give you  the classic "Soft Pedal" of brake
> fade....You push and push harder but all you are doing is compressing the
> steam that's been created by Hot Brakes...
>
>    Changing brake fluid regularly is good.  Once you experience Brake
> Fade...you will become a believer...if you live.
>  In my road racing car I changed brake fluid every race weekend, at least.
>  Sometimes I would change between sessions , if I'd really cooked the
> brakes.  I use ATE Super Blue and ATE Gold, alternating the two so I can see
> when I get Fresh new fluid out of my bleeder valves..Cheap insurance and not
> difficult with a Power Bleeder set up.
>    Don Hanson
>
>
>
>  On Fri, Jun 25, 2010 at 12:48 PM, Scott Daniel - Turbovans <
> scottdaniel@turbovans.com> wrote:
>
>    hi.
>    no , that is not classic brake fad.
>
>    Brake fad is when you have decent pedal, but brake pads and calipers
> have
>    gotten so hot from continued or hard downhill use, that the brake fluid
>    starts to boil...
>    then you have essentially no brakes, are barely any.
>
>    btw ...
>    continued light use ..or steady light use, as in a long decent is not
> the
>    right thing to do at all.
>    that just builds up heat.
>    Instead...use the brakes hard enough to drop some speed, then don't use
>    them ...
>    given them some cooling time...then use again a little harder, then let
> cool
>    etc...
>
>
>    And brake in new pads properly too.   Another subject.
>    Scott
>    www.turbovans.com
>
>    ----- Original Message -----
>    From: "Paul" <wognacious@GMAIL.COM>
>    To: <vanagon@GERRY.VANAGON.COM>
>    Sent: Thursday, June 24, 2010 11:54 PM
>    Subject: Brake question......
>
>
>
>      Is this what I've heard described as "brake fade?" I'll be going down
> a
>      hill
>      and the pedal feels normal, if there is such a thing, and once in a
> while
>      it
>      feels like the pedal all of a sudden will go right down to the floor
>      board.
>      I
>

--
Jake

1984 Vanagon GL 1.9 WBX 'The Grey Van'
1986 Westy Weekender/2.5 SOHC Suby 'Dixie'

Crescent Beach, BC

www.thebassspa.com
www.crescentbeachguitar.com
http://subyjake.googlepages.com/mydixiedarlin%27