Options to stiffen chassis 69 Firebird?

[jlwdvm]

Originally Posted by David Pozzi

The front of the subframe needs support more than the rear subframe does. The stock sub is terrible in torsion ahead of the firewall. The front sheet metal contributes to half the front torsional rigidity. jlwdvm, - If you do a roll bar or cage, I highly recommend adding a diagonal brace to the main hoop. SCCA requires it, and it's a main component of any good roll bar. It can be removable by adding some double shear brackets.

Do you mean: from the point above my head where the rear brace meets the main hoop to where the passenger side brace meets the trunk floor? I have thought about it.

[David Pozzi]

Originally Posted by jlwdvm

Do you mean: from the point above my head where the rear brace meets the main hoop to where the passenger side brace meets the trunk floor? I have thought about it.

From driver's side main hoop just behind the driver's head, to the passenger floor where the main hoop is welded or bolted to the floor. It keeps the main hoop from deforming to the side and is usually required for any track use. It makes it hard to get into the back seat area, but can be made a bolt-in to make it easier to work back there doing upholstery or whatever.
A diagonal on the rear supports will help in torsion but not do much for safety.