[DeTomaso] roll bar /roll cage question

[cullen mccann]

Question:

I notice with respect to the firewall (or bulkhead is referring to the same
panel correct?) that some/ most cages appear to have the main hoop on the
passenger side/ interior side of the firewall ( like Gary's) and some if
seen have it on the engine bay side. I would think the engine bay side would
be less intrusive on the passenger area, but then obviously if you have door
bars or A-pillar down bars and they tie-in to the main hoop you would have
to penetrate the firewall to anchor to the main hoop, etc. I suppose if the
main hoop is on the engine bay side it probably crowds the fuel tank on the
driver side and electrical system on the passenger. 

Structurally, it seems to me that both solutions would provide adequate
reinforcement, and you can anchor at the inner rockers in either case since
it extends past the firewall towards the motor bay. I do like way Gary ties
so much of the suspension anchor points in, and the roofline near deck lid
hinges...etc. Great for chassis bracing from what I can see, especially
considering the stress points. 

Referring back to the "cardboard box with the lid off" comparison that I
have read about, and combined with Garth's Rodericks compiled "Pantera
upgrade tech summary"  (Thanks Garth, I found that and its really cool,
taught me a lot about the overview of the car) . Also in chassis bracing, I
was also reading up on seam welding. When I think about the bracing, the
seam welding could add some strength, but it would be like putting 3 layers
of packing tape on the edges of the cardboard box. It undoubtedly would
help, but the triangulation of the cage would be leaps and bounds ahead for
providing chassis strength, correct?

So, case-in-point.......given the compromises on either end with regards to
main hoop on the interior vs on the engine bay side, what are the arguments
for either side? Which do you prefer if you had decided you were going to
have a cage?

Thanks for helping out the new guy!

Cullen
rusty 3925 in OK