Date: Fri, 25 Jun 2010 20:08:10 -0700
Reply-To: Jake de Villiers <crescentbeachguitar@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Jake de Villiers <crescentbeachguitar@GMAIL.COM>
Subject: Re: Brake question......
In-Reply-To: <090a01cb14ab$3d5dc630$6401a8c0@PROSPERITY>
Content-Type: text/plain; charset=ISO-8859-1
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
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