Crossmember Bars POLL

[amalventano1 at tds.net (Allyn)]

> It would be easy to do some calculations to find out what kind of load
> over what period of time would make that plate bend, no rigorous
> testing involved.

thats not how metal works. either you take it past its yield strength or you 
dont. either it bends or it doesnt. its that simple. that said, it would 
take a much sharper 'V' in the bar to generate enough side load under 
tension (as the 'V' tries to flatten, spreading the ends apart), to make 
those steel plates bend. the steel span will likely bend first, and even 
then, it is sufficiently long enough not to bend beyond its yield point 
(i.e. it will flex, but return to normal once the stress is relieved).

> Failing doesn't mean only breaking. I was referring to that curve on
> the end plates, that would be the weakest link and the first place the
> bar would bend (if it ever did). If that plate were to bend it would
> cause the bar to put the crossmember into constant tension, not the
> best situation for a cracked piece of metal.

even with the curve, there is still a couple of inches of 1/4" steel plate 
that is in-line with the direction of force. this part of the bar alone is 
many times stronger than the rest of the bar. you're missing an inportant 
point - if you end up putting so much stress on the bar that it ends up 
bending, in turn placing stress on the cross member, that much stress would 
have had to cause the factory piece to severely fail in the first place. 
that is the only way enough movement can occur to bend the bar (which is 
more flexible due to its narrower diameter). if all of this was to occur, 
the bar (bent as it may be) would be the only thing providing any kind of 
support for the front motor mount, and it would be placing no pre-load on 
the cross member at that point, because that member had to fail to allow the 
movement in the first place. it would be a flimsy cracked piece of junk. in 
that situation, i'll take bent metal over cracked metal any day.

> Hell, some of this is trying to help you figure out if it
> even needs improvement, which is still uncertain.
> Nate

it could be argued that everything could use some form of improvement. the 
issue with this bar is that in order to keep it (and its installation) 
simple, compromises must be made. sure you could go nuts and make a 
triangulated mini-subframe down there, but it would be much larger, would 
interfere with the rest of the engine bay, and would likely be way more 
expensive to produce. it could even be made without the curve, but you would 
have to re-route your harness/power steering hoses, which is not what eric 
was going for - he wanted a drop-in installation. in my opinion, this is the 
best/easiest thing out there right now.

Al

Allyn Malventano, ETC(SS), USN
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