Date: Thu, 23 Aug 2001 08:38:37 -0700
Reply-To: Todd Last <Rubatoguy@MINDSPRING.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Todd Last <Rubatoguy@MINDSPRING.COM>
Subject: Re: Reducing brake fade on '88 Westy?
Content-Type: text/plain; charset=us-ascii
Great post - I'd add one thing. Which brake fluid you use *does* make a
difference. The DOT specifications only set a MINIMUM boiling point standard, so
you can avoid Colby's second situation to some degree by using a high-quality
fluid. I'd also say that the DOT 5.1 fluids (not to be confused with DOT 5)
which are glycol-based and have a higher boiling-point than DOT 4 fluids, would
be a good candidate as well. A general rule is that the higher-quality fluids
tend to reject moisture better and will have a higher "wet" boiling point.
A last point is to avoid brake fluid in plastic containers - or to at least
never leave brake fluid in plastic containers sitting on your shelf as I've been
told that moisture can permeate the plastic over time and contaminate the brake
fluid. Fresh is best - it is not a good idea to use that half-empty container
that has been sitting in your garage for the last 3 years.
However the *most important* thing is to regularly flush the system with new
fluid. Having old fluid (that has acquired moisture over time) can cut the
boiling point of the fluid in half. Which means, major fade. The VW manual says
to change the brake fluid every two years. I wonder how many list members have
fluid in their vans that is older than that?
Here are the DOT standards:
DOT 2 DOT 3 DOT 4 DOT
5 DOT 5.1
glycol glycol glycol
silicone glycol
Dry Boiling point 374 401 446
500 518
Wet boiling point 284 311
356 375
Here are the boiling points on some popular (high-performance) fluids:
Fluid DRY WET
Castrol LMA DOT 3/4 446 311
Ford Heavy Duty DOT 3 550 290
ATE Super Blue Racing 536 392
ATE TYP 200 536 392
Motul Racing 600 585 421
Castrol SRF 590 518
Performance Friction 550 284
There is a company that sells test strips to determine the moisture content in
your fluid.
See: http://www.phxsyss.com/whystripdip.html
Todd
'88 Westy
by Smolens wrote:
> 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
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