Date: Thu, 23 Aug 2001 04:16:03 -0700
Reply-To: Coby Smolens <cobys5@HOME.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Coby Smolens <cobys5@HOME.COM>
Subject: Re: Reducing brake fade on '88 Westy?
In-Reply-To: <3B835EBD.8734.F4D4048@localhost>
Content-Type: text/plain; charset="iso-8859-1"
There are two recognizable stages of failure during long, steep, downhills
in heavy vans:
The first, nerve-wracking enough all by itself, happens when the friction
surface of your normally nice, cool, dry brake pads and shoes heats to the
point where it begins to ablate (melt- the term is normally used to describe
what happens to the heat shielding tiles on the nose of an atmospheric
reentry vehicle). Thereafter instead of a friction surface, you have a
lubricant - just what you always wanted on your brakes! This is experienced
as the need to apply increased pressure on the pedal to maintain a safe
descent speed.
The second stage has very little competition as a source of death-defying
thrills, and occurs as a result of all that (nightmarish) increased
pressure, when the brake fluid (even DOT 4) begins to boil and fill up your
brake hoses and lines and wheel cylinders and calipers and master cylinder
with vapor instead of fluid, at which point your foot starts to squish
sickeningly towards the floor.
Prevention: Have the rotors measured, replace them if they are less than
14mm (86-) or less than 12mm (-85). Ditto drums < 252.75mm. (I know what it
says in the book, but that stuff is for nice, polite round-town drivers.)
Use GOOD quality shoes and pads (Pagid, Jurid, PBR, ATE re some names to
look for. Metallics tend to heat up slower, but chew up rotors quicker.
Flush fluid regularly (every two years). Use DOT 4 fluid.
NOTE: There are some up and coming performers in the brake pad business
which may be available for the Vanagon at some point - probably by special
order, (a'la Syncro Bilsteins) - I'm referring to carbon
fiber/Kevlar/trimetallics. I don't know enough about these yet, but I intend
to find out and will keep the list posted. These hi-tech pads and linings
are being used on race tracks and are reputed to be super rotor-friendly as
well as practically unfazed by heat and complete strangers to disk brake
squeal. You can do a quick Google search for "carbo fiber brake pad" to see
what I mean.
Front brakes do the majority of the braking, so rotor/pad health is crucial
to good brake performance. The thinner the rotor the faster it heats up, and
the quicker it'll warp.
Crickey - I just looked at my watch. Good night!
Coby Smolens
Valley Wagonworks
VW Bus and Vanagon Specialists
"Intimately acquainted with VW Vans since 1959"
1535 SF Drake Blvd, San Anselmo, CA 94960
415-457-5628
-----Original Message-----
From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM]On Behalf
Of Shawn Wright
Sent: Wednesday, August 22, 2001 7:27 AM
To: vanagon@GERRY.VANAGON.COM
Subject: Reducing brake fade on '88 Westy?
Once again I encountered fairly serious brake fade driving behind
some slowpokes coming down various passes on the Crowsnest Hwy. I
flushed the system 2 years ago with fresh DOT4 fluid, so I suppose
it's time to do this again. But since the van has only gone ~10k km
since the last fluid change, I'm not convinced this will help all
that much.
I know I do have slightly warped front rotors - could this lead to
more heat build-up? I'll need to pull them and either have them
turned, or replaced I guess. Cross drilled rotors seem pretty
expensive - what other options do I have for improved braking at low
cost? Are there specific brands of pads to look for that offer better
fade resistance?
Thanks.
Shawn Wright, I.T. Manager
Shawnigan Lake School
swright@SLS.bc.ca
http://Zuiko.sls.bc.ca/swright
http://www.sls.bc.ca
