Date: Thu, 17 May 2007 06:43:40 -0700
Reply-To: Don Hanson <dhanson@GORGE.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Don Hanson <dhanson@GORGE.NET>
Subject: Re: Brakes...no van content.
Content-Type: text/plain; charset="Windows-1252"
----- Original Message -----
From: "John Rodgers" <inua@charter.net>
To: "Don Hanson" <dhanson@GORGE.NET>
Cc: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, May 17, 2007 2:58 AM
Subject: Re: Brakes...no van content.
Don,
Thanks for posting this.
I have warped front rotors twice due to heat build-up when going down
steep grades. This is good stuff to know.
Regards,
John Rodgers
88 GL Driver
To add a little van specific info: If you do have problems like John
mentions, here are some suggestions.
Get more air circulation onto your brake rotors somehow. Many racers use
brake ducts to direct cool air right onto the rotors somehow. My Porsche
928 GT came stock with some air dams built onto the lower A-arms..These
scoop-like air deflectors gathered air from under the car and deflected it
into and onto the brake rotors. For a street car, this worked very well.
When the car was converted to racetrack only use, we removed the parking
light lenses and installed some big air intakes there, with brake ducts
going directly to the inside of the wheels...for even better brake cooling.
That one change decreased my lap times by over 3 seconds at 2:00min.
tracks.. Something like those a-arm air dams would work on a van with brake
overheating problems.
Do..apply your brakes and then get off the pedal. I was taught this by
canny experienced racers. If you need to slow, brake hard and then release
as soon as you've slowed adequately. Repeat.. This causes less build-up of
heat. If you "ride the brakes" by braking continuously, with a moderate
input to the pedal (and hence, to the pad and rotor) you are continuously
adding heat, without allowing any air in to cool the components...
Don't set your e-brake when your rotors are really hot..If you come down a
big pass and pull right off the road, use park or a gear to hold your
vehicle in place, at least till the brakes have a chance to cool down...If
you do just set the brake and walk off, the spot where your brakes are in
contact with the rotors will hold the heat while the rest of the system
cools more quickly..Warpage will result.
A huge portion of total braking force is supplied by your front wheels.
(seen the trick motorcycle riders doing "Stoppies"? with the rear of their
bikes way up in the air under hard braking?) Especially in a high vehicle
like a Vanagon. As you apply braking force, the center of gravity (may not
be the proper term, but you get the idea) shifts dramatically to the front .
That's why it's a bad idea to brake while engaged in cornering..As you go
round the corner, each end of the vehicle is stuck to the earth by it's
tires and the weight/friction of those 4 little tire contact patches. If
you brake during the act of cornering, you cause the center of gravity to
shift onto the front tires, leaving the rear tires (nearly) weightless...not
good for going round corners.
If you are looking to improve braking by modifying your brakes..1st might
be get more air onto them and use appropriate compounds. Make sure your
fluid is fresh and moisture free, and that the system is bled properly.
Then, an increase in the diameter of the front rotors, or more pad area..
.
Don Hanson
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