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Larry
All good points, though I've installed that RS2 bracket, and find  "infinite" 
life to be optimistic thinking.  That thing will flex, no  question.  The 
best one I've seen in steel was the one's Dave Jones had  made up in steel for 
the 16in wheel applications.
 
Aluminum finite life can be extensive if it's not 'overmachined' , a lot of  
what I read into your post.  If you look at the size of the blocks Carl and  I 
used, they are massive chunks of aluminum with rounded notches for the hub 
and  the lower mounting tab, otherwise it's a billet block of aluminum pretty 
high up  on the temper list (don't recall the number off the top of my head).  
I've  had an aircraft parts machinist quote the part, and he was impressed at 
the  beef.  In retrospect, I see the problems with the ECS kit, and think thank 
 goodness Carl and I were too dumb to make things look pretty.  That said,  
it's a race part of aluminum, and all car parts should be considered finite 
life  IMO, even steel, especially where exposed to such massive heat cycling as 
on  brakes.  I also believe that someone quoted a high caliper mounting spec  
like 90ft/lbs.  I'd be very careful with this, since once heat cycled the  bolt 
will no longer stretch, and it will then pull out the threads in the  
aluminum, or certainly stress the aluminum.  IIRC porsche spec on that  caliper 
mounting is in the 53lb/ft range.  Regardless, use loctite blue to  prevent galling 
and possible stress points on reinstall.
 
I would also suspect that a less beefy carrier will have flex in it, not a  
good property of aluminum.  There is a lot of flexing forces on/in a Big  Red 
at full grab.
 
Carl and I did enough extras to get ours for free.  Then we both took  an 
exit and let the sharks hit the pool.  Now that we are several years  past, I 
encourage everyone to inspect their parts regularly, and go for A8  rotors as a 
replacement when the hats show signs of failure.  To date, the  blocks seem to 
be holding up fine 12 years post install.  Thankful for  that, can't imagine 
what must be going thru the minds of the boys at ECS.
 
SJ
 
In a message dated 7/20/2007 9:24:55 A.M. Central Daylight Time,  
larrycleung at gmail.com writes:

Steel  can be designed for "infinite life", although such a part is heavier 
than if  it was not designed for it. There are many factors including shape, 
expected  stresses, preloads of bolts, stress factors such as bolt holes, etc. 
used in  designing for such. Stress reliefs include rounding of sharp surfaces, 
round  rather than shaped holes, etc. Doin these adds
to the cost of parts, due to  the added labor to round things, etc. Threads 
are stress risers, in general.  

There is NO WAY (at least within the engineering education I received,  to do 
so for aluminum. You can overdesign to a specific no. of cycles, called  
"finite life", but never
for infinite. This is the reason that airframes on  airplanes are carefully 
tracked for #hrs of operation, and parts that appear  perfectly fine are 
replaced. I have often wondered how
those mfgs of cars  with aluminum suspension components (which includes my 
Saabaru) 
deal with  the potential liability, since most cars last varied periods, 
undergo much  more
varied levels of stress, and cars aren't inspected in the proper  method (dye 
check or
X-ray analysis) for their alloy suspension components.  As far as I know, 
this is the only
way to catch minor cracking prior to the  stress cracks becoming 
catastrophic. This is what we used when I was in the  Nuclear Power industry for ALL sorts 
of alloys, both Aluminum and steel based.  Of course the risk of failure 
there was much more critical than the loss of  control of one persons car, so the 
expenditure was  justifiable.


 



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