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He Brakes to a final stop (Long, but the last one w/new info)
Allow me to attempt to wrap up this virtual masturbation on brakes and brake
systems.
FWIW, the Alcon B-type caliper is EXTREMELY similar to the Porsche S4
caliper except is uses a slightly smaller pad and although one piston is
smaller and the other larger, the total area of the pistons is virtually
identical...9.8 sq. inch for the Alcon and 9.89 sq. inches for the
Porsche/Brembo.
Any internationally known brake manufacturer...Brembo, Alcon, AP, Wilwood,
etc. can boast of successes in major auto racing. This shouldn't be
surprising to anyone. It called marketing and has nothing to do with the
quality, reliability or anything else as it relates to the products you and
I use.
All these manufacturers also make top notch, quality brake calipers and/or
rotors and related components.
Someone, now I don't recall who, mentioned the MMC (Metal Matrix Composite)
rotors. These are also known as the CoolTech rotors. The CoolTech rotors
have a critical limitation especially as it relates to Audis. The MMC rotors
(and Alcon for that matter) are only good for about 850 degrees. If you are
tracking a 3500 lb. car aggressively, your rotors will reach temperatures of
1100 degrees. At that temp you will blown the MMC and Alcon rotors apart.
Even the carbon/carbon rotors don't go much over 1100 degrees.
Following is a brake temp recommendation table:
Calipers Temp (in F) Status
Porsche/Brembo 338 cool
392 IDEAL
428 OK
500 Melt Down
Rotors
Porsche/Brembo 800 cool
/Zimmerman 1040 IDEAL
1130 Hot
This brings us to the topic of brake fluid. In private testing, (has nothing
to do with the boiling points the manufacturers claim) the dry boiling
points and costs are:
Brand Cost/Quantity Dry Boiling Point
Castrol LMA
Ford HD $2.89/pint 561F
ATE Super Blue $9.95/liter 564F
Castrol SRF $69.95/liter >600F*
* The device used to measure the dry boiling points does not provide greater
than 600F.
Notice that if you are boiling your brake fluid, you may have also started
to melt components (dust shields, piston seals, etc.) in the caliper.
Probably time for a caliper rebuild.
Lastly, with all this talk about big calipers and even bigger rotors, no one
has addressed the issue of tires and contact patch. Remember your brakes are
only as effective as the maximum co-efficient of friction your tires can
maintain. If you can exceed the limits of your tires, bigger brakes will not
stop you faster or in a shorter distance. Bigger brakes will, however
dissipate larger thermal loads.
I would be surprised if anyone on this list, other than pure race cars, that
needs BRs on there car. Yes, I have them. Do I need them? No! Even on the
track? No again. Do I like the way they look? without a doubt. Would I spend
the $$ again to have the looks of the BR? Yes. But the BR did not reduce my
lap times. Learning how to use the brakes less and carry more speed through
corners dropped my lap times.
If you are tracking a car and burning up your brakes, you need to learn how
to conserve the car and drive accordingly. If you're standing on the brakes,
you're not going faster. Sometimes you have to go slow to go fast.
Well, I'm done with the brake thing. I will be happy to answer anyone's
questions either via phone (your dime) or offline of the list.
Thanks for listening. Hope the info was helpful.
MGW
Michael G. Wachholz
1993 Black/Cashmere 968 w/Big Reds
131K miles and still counting
Nord Stern PCA Region
* 190 Gleason Lake Road
* Wayzata, MN 55391
* 612.475.1156 vox
* 612.475.3267 fax
* <mailto:mwachholz@usinternet.com>
* http://www.usinternet.com/users/mwachholz/mgwhome.htm
> -----Original Message-----
> From: owner-quattro@audifans.com [mailto:owner-quattro@audifans.com]On
> Behalf Of Todd Candey
> Sent: Friday, May 14, 1999 9:59 AM
> To: Greg Amy
> Cc: AUDI S Cars Discussion List; 'quattro@audifans.com';
> 'QSHIPQ@aol.com'
> Subject: Re: Breaks in brakes
>
> Can I bring a handfull of cars all with Alcon B-Types on 13"
> rotors which all
> stop from 60-0 in under 60 feet???
>
> Todd