[s-cars] Woah! pics link

[Tom Green]

There was a German ebay seller that was selling a RS2 brake bracket
copy without the holes drilled.  From a cursory look he appeared to be
a reputable firm.  Those could be a means to retain Porsche rotors/Al
hats using a steel adapter.

The stress involved in a BBK are the same for any material on a ride in
Wild Bill's fire chief wagon.  The computer stress/strain analysis makes
some pretty pictures but assumptions involved require some time in the
materials testing lab ( or Mahoney's front struts)  to verify the  
results.
It is difficult to say at this point who or what induced the stress  
risers  that
have shown up here.

You are never going to be able to use a high strength Al alloy in a high
stress/high corrosive environment without frequent inspection and  
cleaning-
hard to do in this application.  You could accelerate that intergranular
corrosion to failure in a matter of days given the heat and stress  
cycles
it must endure, and a bath of corrosive salts.  You certainly can't  
depend
on the anodized coating to prevent corrosive attack with all the  
fasteners,
wrenches, and monkey-lad torque being applied here.

Tom


-----Original Message-----
> Date: Tue, 17 Jul 2007 23:26:11 -0400
> From: "Mark Strangways" <StrangConst at rogers.com>
> Subject: Re: [s-cars] Woah! pics link
> To: "LL - NY" <larrycleung at gmail.com>,	"bill mahoney"
> 	<airbil at gmail.com>
> Cc: Audi S Car List <s-car-list at audifans.com>
> Message-ID: <002a01c7c8eb$64a652c0$0c00000a at dell9100>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> 	reply-type=original
>
> Well being floating 4 piston calipers I would hope that the  
> hydraulics would
> balance the stresses involved in following a warped rotor.
> It is a poor design that is for sure, I can see where the stress  
> riser might
> be to cause this failure.
>
> I am happy I went with the bira design for my upgrades as the don't  
> seem to
> have the same stress problems
>
> My 2 cents anyways
>
> Mark
> ----- Original Message -----
> From: "LL - NY" <larrycleung at gmail.com>
> To: "bill mahoney" <airbil at gmail.com>
> Cc: "Audi S Car List" <s-car-list at audifans.com>
> Sent: Tuesday, July 17, 2007 9:49 PM
> Subject: Re: [s-cars] Woah! pics link
>
>
>> From what I recall from my engineering days, that kind of
>> failure is caused by bending moments (i.e. torque cause
>> by the caliper following disk flexure). This is truely an
>> alarming form of failure, as this is pretty typical types of
>> loads on a carrier. Glad I'm dispensing with my ECS
>> alloy brakets and going to the steel replacements.
>>
>> LL - NY
>>
>> On 7/16/07, bill mahoney <airbil at gmail.com> wrote:
>>>
>>> http://forums.audiworld.com/s4s6/msgs/180531.phtml
>>>
>>> Verge of catostophic failure I'd say.
>>> Not good.  Not good at all.
>>> Bill~little woah~M
>>>