Nissan Spec-V: Part 4: Triangulating the Cage
8/1/2006
In our last installment we laid the foundation for our roll cage, concentrating on improving roll over protection. We touched on the fact that the cage’s other primary function is to improve chassis stiffness. The stiffer the chassis, the more sensitive the car will be to changes in the suspension. A stiff chassis allows the suspension to not only absorb bumps but also improve both ride quality and traction.
This week we added more tubes to our cage. The tubes tie the suspension mounting points to the main structure of the cage to give the chassis some added stiffness. In effect, we are triangulating the structure. Why triangles? The triangle is the strongest, stiffest and most minimal of all structures. It’s an elegant form to use because it gives the most strength for the least amount of weight.
Richie Watanabe of Technosquare cuts out the top of the stock shock towers and welds in a new top section. This allowed us to add a camber caster adjustment plate made by Ground Control. This allows us to adjust the camber and caster, critical adjustments for a racecar’s handling. 
We connected the shock tower to the main portion of the cage using tubes. We fully triangulated it on two different axes to prevent torsion and bending. The tubes pass through the stock cowl reinforcement and the firewall to the cross-tube and the forward leg of the cage.
The full extent of the triangulation is show here from a top plain view.
This view shows the tubes going downward to the lower part of the front cage legs.
The triangulation is visible from inside the engine compartment.
Since the cowl is one of the strongest parts of the stock chassis, the tubes were welded to a doubler plate to reinforce the thin sheet metal, and then spot-welded to the cowl. This effectively stiffens the chassis by tying the cage into the main structure.