Re: He Brakes to a final stop (Long, but the last one w/new info)

[Todd Candey <tcandey@wans.net>]

Michael G. Wachholz wrote:

> Allow me to attempt to wrap up this virtual masturbation on brakes and brake
> systems.

Virtual Masterbation?interesting concept.

> 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.
>

Wrong.The only similarity the Alcon bears to the porsche caliper is the number
of pistons. period.
For starters, the Alcon calipers are machined from billet. The billets are cast
from a proprietary aluminum alloy, under pressure. the process is called
Squeezeform. It's patented. By Alcon.
The Brembo calipers are cast. The piston bores and fluid passages are machined
out of this casting.

The Alcons have a bridge bolt for increased caliper stiffness. The Brembos do
not.
The Alcons have roughly 4.5 times the clamping force of the Brembos. 7,200psi
vs. 28,300psi.
The alloy used by alcon is formulated to dissipate heat better than standard
cast aluminum.

The Alcon B-Type and the porsche 993 and 993tt and 928gts calipers all use the
same pad. The 928s4 caliper is actually smaller than the above.

> 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.

If a manufacturer is boasting successes, you're right, it is called marketing.
It's how you make your products sell and your company grow. What you need to
look at here is how many successes are they boasting, and what is the type of
race vehicle is the product being used in?  That's what will help you form an
honest opinion.

> 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.

No, MMC is a combination of a raw material and a process that results in a
product.CoolTech is a brand name. They make/sell MMC 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.

Wrong, at least on the Alcons.The Alcons do not have a problem with heat
dissipation. Nor do they have a problem with high heat ranges.
We have measured temps on the outside of the B-Type caliper bodies in excess of
550degress and temps on the backing plates in excess of 900degrees. This
indicates a surface temp on the rotor of over 1100degrees. We've no problems
with the alcon rotors whatsoever, and neither have we with the coleman rotors
for that matter.

> 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

Actually, really doesn't sound that good...

> 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.

Actually, I agree completely on the subject of fluid boiling.This is where the
heat dissipation of the caliper, and it's ability to NOT transfer heat to the
fluid passages comes into play.
As far as time for a rebuild, I guess that would truly depend on at what temp
the seals start to degrade.

> 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.

Agreed, the contact patch is the limiting factor. Better modulation and higher
clamping force will allow you to place that contact patch at it's limit more
controllably.

> 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 better brakes did not help your 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.
>

You bet.Take care Michael

> 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