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Re: Brake Efficiency

To: mgs@autox.team.net
Subject: Re: Brake Efficiency
From: Ajhsys@aol.com
Date: Mon, 8 Nov 1999 10:37:40 EST
In a message dated 11/7/99 12:27:31 PM Eastern Standard Time, 
ccrobins@ktc.com writes:

<<   Someone else advised changing to a brake fluid with a higher boiling
 point to combat fade. >>

My post suggested changing the brake fluid.  I had a similar experience in my 
Mitsubishi Expo, with ABS, 4 wheel disks.  Going down a long mountain with 
some really cool switchbacks, I found that I had barely any brakes.  Didn't 
want to scare my daughter who was with me, so I kept my mouth shut and my 
foot off the pedal until the brakes cooled enough from the air blowing on 
them.  Downshifting helped.

When I got home I changed the brake fluid.  The old fluid was a few years 
old, and it was blood red when it came out.  New Castrol LMA went in.  The 
next year, when I went down the same mountain, no fading AT ALL.  I may be 
mistaken, but I was using the same brand pads and the same rotors, so I 
figured the fluid was the culprit.
 
<<   Hmm, I learned that the cause of brake fade was heating of the
 friction surfaces and resultant warping and lowering of friction
 coefficient in the rubbing parts. Things have to get awfully hot to boil
 the fluid!  I'd think that the brakes would have gone away before the
 fluid boiled.   >>

You may be correct.  I am not well versed in all things automotive.  But, 
brakes do get awfully hot, and fluid that is several years old will 
accumulate water which lowers the boiling point considerably.  Maybe it is a 
combination of both surfaces and fluid overheating.  I do know that when 
brake fluid boils, the steam it creates inside the system is compressible, so 
therefore, no brakes.
 
<<   I'd suggest that the Voyager's brakes were marginal for the load the
 vehicle was carrying and that the driver didn't shift the tranny down on
 the downhills in order to give the brakes a break (pun). >>

I agree with you 100% on the marginal brakes in most American cars.  (But I 
didn't like the pun!)  (Sorry! <LOL>)

Allen Hefner
SCCA Philly Region Rally Steward
'77 Midget
'92 Mitsubishi Expo LRV Sport

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