Project: OLC2: Safety First - Building a NASA Rally Spec Cage

One of the driving forces behind building the OLC2 (vs upgrading the '67) was the desire to make the transition from a street car that is driven on the track to a true track capable car that happens to be street legal. In the four years since the OneLapCamaro was finished we have been fortunate to have been able to participate in a variety of unique and challenging events... but there were several which necessitated more safety equipment than we had in the '67. Hopefully the OLC2 will address those needs with a comprehensive roll cage, fire system, and full selection of safety equipment.

When it came time to build a roll cage the question we had to answer was"what rule set should it be built to?"

The Tire Rack One Lap of America has no rules but some of the other events that we want to run - The Silver State Classic Challenge, Targa Newfoundland, and the Chihuahua Express - have explicit but not necessarily consistent guidelines. Ultimately we chose to build the cage to the most stringent - and logical - rule set we could find: NASA Rally Sport. It meets or exceeds most all road course rule sets and essentially follows FIA guidelines. Going this route means that the OLC2 will not only have a cage that we can be confident in but also that we will (we should) qualify for a Log Book as an Open 2WD Heavy car under Rally Sport rules.

The NASA Rally Sport roll cage rules break the construction in to seven required elements with options for each provided within the rule set. Follow along with our design...

Required Element 1 - Main Roll Cage Structure & Backstays

Design 253-3: One piece main hoop, two forward bars tied across the top of the windshield and two straight rear backstays.

while not part of Element 1 we added a bar behind the dash that will tie forward and support the pedal block.

the front bars in to the engine compartment are also not part of Element 1 but we wanted to position them as our work on the front continued. These bars may cause some issues with RS compliance as some groups prefer to see more crumple zone in front of the suspension but we should be OK.

With the main cage framework in place we mocked up some of the future elements

Required Element 2 - Roof Bars
Required Element 3 - Backstay Diagonals

The design for Element 2 and Element 3 ultimately tie in to one another. We chose 253-14 for the roof bars which dictates 253-22 for the backstay diagonals. Essentially these two elements consist of two "V" shapes which meet at the top of the rear main hoop.

This first attempt at the backstay diagonals was quickly scrapped as the diagonals did not end in the proper position. In me mean time work commenced on the next element

Required Element 4 - Main Hoop Diagonal Members

Design 253-7 - an X across the hoop with a separate harness bar that will be behind the X

Backstay diagonals are now in the proper position terminating within 3" of the backstays

Required Element 5 - Sill bars

Required Element 7 - Door Bars

This design ultimately results in three door bars - one horizontal bar parallel to the sill and two bars making an X across the door entry. This design is a variation of 253-9 which uses two shallow U shaped bars which meet in the middle.