That link took an 1.5hr up biggrin

This from 2006 was pertinent however:

"Quote:
Originally posted by JanusCole
I was just re-reading this idea and I think it is brilliant. And I don't see why it could not be done in an aesthetically pleasing way. For instance, why not coat the entire inner tub from the rear package shelf to the pedal cluster with a strong structural epoxy - the same stuff they use to assemble airplanes. Then lay a dozen or so layers of carbon fiber on top - essentially creating a carbon fiber monocoque using the original unibody tub as a mold. Then you can cover it all with carpeting and the thing should be TOTALLY stiff...

Is this too simple? Am I missing something obvious?
Kind-of. Just because Carbon fiber makes strong tubs in F1 doesn't mean that it's a wonder material. Carbon fiber is quite strong in some situations (and directions), and not very strong in others. The reason that F1 tubs are so strong has to do with the following:

1) The tubs have very few if any openings in them excepting those required by the rules (such as the cockpit) and by serviceability requirements (such as access ports to the pedals). A convertable or Targa 911 tub is a completely different design.

2) As I said, CF is very strong in some dimensions, and not in others. Just slapping CF down like shredded Fiberglass will not by definition make a strong tub. In reality the tubs come out strong because some clever engineers have figured out subtle ways to align the individual plys, and combine them in certain ways to manage some very specific load paths, both from the suspension as well as in accident situations.

3) In many cases a honeycomb matrix is put between the CF layers in certain areas to increase the cross-sectional area and thus increase the regidity of the tub.

So the short form answer is that slapping CF down on the shell of a 911 will most likely not make it a whole lot stronger.

That being said, you did prompt a recollection of an old Formula Ford trick -- which is to squirt some two-part expanding foam into any enclosed cavities in the chassis. This trick was used to good affect in some spec classes (Formula Opel/Vauxhall comes to mind) where the spec chassis was somewhat less stiff then desired. Just as adding honeycomb can increase the stiffness of CF or FG panel, so can adding foam to an enclosed space. The downsides are:

1) A slight increase in weight.
2) Once it's in there, it's never coming out
3) Many of these foams turn into noxious gasses if heated or burned, so consider carefully where you decide to put them.

A clear opportunity for this trick would be in the rockers and frame rails of open 911's.
__________________
John
'69 911E

"It's a poor craftsman who blames their tools" -- Unknown
"Any suspension -- no matter how poorly designed -- can be made to work reasonably well if you just stop it from moving." -- Colin Chapman
Last edited by jluetjen; 06-21-2006 at 07:28 PM.."

Last edited by jcc; 01/16/19 01:37 AM.
Reality check, that half the population is smarter then 50% of the people and it's a constantly contested fact.