15.6 Roll Cage
(See diagram at end of section)
15.6.1 Purpose
The basic purpose of the roll cage is to protect the occupant in case of a rollover or a
collision. It should be able to withstand the weight of the car landing on the roof. These
rules apply to all classes, unless otherwise superseded by the class rules. Vehicles
homologated by, or built to the specifications of, FIA Group N, FIA Group C, JAF, SCCA,
IMSA, and Grand AM must conform to these rules, or may conform to their respective
current class rules for roll cage requirements for guest groups and special events. Any
vehicle that does not conform to the NASA cage rules, yet conforms to cage rules of
another recognized sanctioning body (SCCA, IMSA, Grand Am, etc.), that wishes
compete in NASA events on a regular basis, should be ordered to make modifications
within a time frame specified by the Race Director and approved by the Regional
Director. Note- It is the responsibility of the driver to furnish a copy of any non-NASA
rules applicable to his/her vehicle.
15.6.2 Intent
Chassis stiffening is a side benefit of a good roll cage system, but it is not the intent of
these rules. Parts of the cage deemed by the Chief Scrutineer, to serve no practical
purpose other than chassis stiffening may be considered in violation of the intent of
these rules (Note: Some class rules allow for chassis stiffening.). The Chief Scrutineer
may order the removal of said parts, or require that the vehicle owner redesign,
reconstruct, and re-certify the roll cage if warranted. The removal or redesign of the
cage, whole or in part, to comply with these rules, does not imply that penalties will not
be issued for violating the intent of these rules.
15.6.3 Installation
The cage may be removable or may be permanently welded, or any combination
thereof, providing that all aspects of the cage meet these rules.
15.6.4 Padding
All roll cage surfaces that may come in contact with the driver should be padded with
high-density padding such as Ethafoam or Ensolite. It is recommended that padding
meeting SFI specification 45.1 be used.
15.6.5 Bends
None of the tubing may show any signs of crimping or wall failure. All bends must be
Mandrel type. The center radius of the bends may not be less than three (3) times the
outside diameter of the roll cage tubing.
15.6.6 Main Hoop
The main roll cage hoop should be as wide as the full width of the interior and must be
as close to the roof as possible without violating CCR section #15.6.20 Inspection. One
continuous length of roll bar tubing shall be used as the main hoop. The main hoop
must consist of not more than four (4) bends maximum, totaling one hundred eighty
(180) degrees +/- ten (10) degrees.
15.6.7 Diagonal Brace
One (1) diagonal brace shall be used in the same plane as the main hoop. The diagonal
should be one continuous path; meaning that it must conform to Diagrams 15.6.7a or
15.6.7b. Note- If the installation method from Diagram 15.6.7b is used, the builder
should pay close attention to alignment. One end of the diagonal brace shall attach to
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the corner, or horizontal part, of the main hoop above the driver’s head, within twelve
(12) inches of the driver’s-side corner. The other end of the diagonal brace shall attach
to the mounting plate (or to the main hoop as close to the mounting plate as practically
possible) diagonally opposed to the driver’s head (passenger floor).
15.6.8 Forward Hoops (Option 1)
The forward hoops shall extend from the main hoop (in a forward direction) to the floor
by following the roof and the “A” pillar of the car. There shall be a bar connecting the
two (2) forward hoops at the top of the windshield mounted as close to the roof as
possible without violating CCR Section #15.6.20 Inspection. The forward hoops shall
incorporate no more than four bends each. Optionally a “15.6.9 Halo Hoop (Option 2)”
or “15.6.10 Front Hoop (Option 3)” construction may also be acceptable.
15.6.9 Halo Hoop (Option 2)
A “halo bar” extends from the main hoop (in a forward direction) following the roof line to
the windshield then following along the top of the windshield, then following the roof line
back to the main hoop, thus creating a “halo” over the driver’s head. A “halo” bar shall
be constructed of one (1) continuous piece of tubing. One (1) down tube following the
“A” pillar must support the “halo” on each side of the car. The down tubes shall
incorporate no more than two (2) bends each.
15.6.10 Front Hoop (Option 3)
A “front hoop” is a bar that extends up from the floor, then follows the “A” pillar up to the
roof, then follows the roof line across the top of the windshield, then back down the other
“A” pillar, and then terminates on the floor. There must be one (1) horizontal bar
(following the roof line) connecting the main hoop and the forward hoop on each side of
the car. The front hoop shall incorporate no more than four (4) bends.
15.6.11 Rear Braces
The main hoop must have two (2) braces extending to the rear. The braces shall be
attached as near as possible to the top of the main hoop, and no more than six (6)
inches below the top. The braces must not contain any bends*. There must be at
least 30 degrees between the plane of the main hoop and the plane of the rear braces.
The main hoop rear braces shall be installed to form no more than a one hundred five
(105) degree angle or no less than a seventy-five (75) degree angle with the main hoop
when viewed from the top. The main hoop braces may be mounted at the rear shock
mounts or suspension pickup points (providing that the braces remain in compliance with
all other sections of the CCR). They may go through any rear bulkhead(s) provided the
bulkhead(s) is sealed around the cage braces. *There may be certain exceptions
allowed for cars that cannot possible meet this “no bend” requirement. One exception is
listed [Ref15.6.11.A)]. Other exceptions may be made (not guaranteed) if all of the
required bars meet the specifications for a vehicle in the next heavier weight
classification and the alternative design is submitted to the NASA National Office for
special allowance.

15.6.11.A Rear Braces - Exceptions
On cars where the rear window/bulkhead prohibits the installation of rear braces
(Porsche 914, Pontiac Fiero, etc.) the main hoop must be attached to the body by plates
welded to the cage and bolted to the stock shoulder harness mounting location. There
must also be a diagonal bar connecting the top of the main hoop to the lower front
passenger side mounting point (“Petty bar”). Some cars built for racing in other
recognized sanctioning bodies may be granted a waiver of this rule, however they must
show proof of compliance with the current published rules for their class.
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15.6.12 Door Bars / Side Impact Protection
At least one (1) door bar on driver side and one (1) on the passenger side must be used.
At least two (2) door bars on the driver side and one (1) door bar on the passenger side
must be installed in all vehicles that obtain a new logbook after January 1st, 2007.
All vehicles, regardless of date of manufacture or date of logbook issuance will be
required to have at least two (2) door bars on the driver side and one (1) door bar on the
passenger side starting January 1st, 2011.
Unless superseded by class rules, modifications to any non-chassis structure (such as
door panels, inner door sheet metal, windows, door internals, etc.) may be made to
accommodate any allowed door bar configuration. However, removal of material and /
or modifications is limited to 1) the least amount to accommodate the door bar(s), and 2)
can serve no other function. Holes in the door jam (B-pillar) may be permitted to
accommodate door bars; however the structure should not be “notched” so as to weaken
it.
15.6.13 Mounting Points
The roll cage shall be mounted to the floor area of the car in six, seven, or eight points.
The cage shall not go through the firewall. The seventh and eighth points must attach to
the firewall or front fender wells. All cage attachment points must be mounted to plates
or a mounting box (plinth). Each required cage bar shall terminate on a plate with a 360
degree weld to the mounting plate, except as specified in Section 15.6.14.B. There shall
be only one (1) mounting “point” per plate. This point is defined as where the “required
tube” mounts. All additional tubes mounted to that plate must be mounted as close to
the required tube as possible [Ref: (15.6.14.B)]. It is recommended that plinth boxes use
a bottom support plate in cases where the edges of the box may punch through the
sheet metal.
15.6.14 Mounting Plates
Each mounting plate shall be no greater than one hundred (100) square inches and no
greater than twelve (12) inches or less than two (2) inches on a side. Welded mounting
plates shall be at least 0.080-inch thick. Plates may extend onto vertical sections of the
structure. Any mounting plate may be multi-angled, but shall not exceed one hundred
(100) square inches total including vertical sections. Each mounting plate should have
an area of not less than nine (9) square inches.
15.6.14.A Mounting Plates – Bolt-In Cage
The attaching points of a bolt-in cage to the body must use reinforcing plates to
sandwich the body. At least three (3) bolts are required for each bolt-in plate and the
plate must be at least 3/16 inch thick. All hardware must be SAE Grade 5 or better with
5/16” diameter minimum. All nuts must be held securely by a locking system such as
safety wire, lock washer, Nylox, or jam-nuts.
15.6.14.B Tube / Mounting Plate Specifications
Any number of tubes may attach to a plate so long as they are touching each other at
the plate. There may be a small gap between tubes to allow welding 360 degrees
around each tube. If there is no gap between the tubes, they must be welded around
the base as much as possible to form a single figure-eight weld, AND the tubes must be
welded to each other two (2) inches up from the base plate.
15.6.15 Welds
All welding must be of the highest quality with full penetration and shall conform to the
American Welding Society D1.1, 1994 Edition, Structural Welding Code, Chapter 10,
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Tubular Structures and Standards for the material used. Arc welding should be used
whenever possible. It is strongly recommended that the welder inspect all welds using
Magnaflux™, x-ray, or other effective methods. All tubes must be welded 360-degrees
around the circumference of the tube.
15.6.16 Tube Structure Design / Body
Tubes may touch the body in any place (not to violate CCR section #15.6.20 Inspection),
but shall not be attached anywhere except as permitted by CCR Section #15.6.11.A
Rear Braces - Exceptions. No deformation of the interior body panels is permitted,
except that the horizontal part of the sheet metal (next to the driver’s and/or passenger’s
head) between the top of the “B” pillar and the top of the “A” pillar, may be pushed in to
accommodate the roll cage. The intent of this allowed deformation is strictly to allow for
more headroom for the driver and/or passenger.
15.6.17 Additional Reinforcement
Any number of additional reinforcing bars are permitted within the structure of the cage
provided that they are installed strictly for safety and do not violate CCR Section #15.6.2
Intent. This rule does not permit reinforcements in classes with spec cages.
All required bars must be made of the same material and meet with at least the minimum
specifications for size and thickness.
15.6.18 Roll Cage Tubing Sizes
For the purposes of determining roll bar tubing sizes, vehicle weight is as raced, but
without fuel and driver. Note: There is an allowance of minus 0.010 inches on all tubing
thicknesses. Minimum tubing size for the roll cage is:
Up to 1500 lbs.
1.375” x 0.095” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM
1501 - 2500 lbs.
1.500” x 0.095” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM
1.500” x 0.120” ERW* (No issuance of log books for cars with ERW cages 04/30/03)
*Note- Specifications listed for reference for inspection of grandfathered vehicles.
2501 - 3000 lbs.
1.500” x 0.120” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM
1.750” x 0.095” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM
1.750” x 0.120” ERW* (No issuance of log books for cars with ERW cages 04/30/03)
*Note- Specifications listed for reference for inspection of grandfathered vehicles.
3001 - 4000 lbs.
1.750” x .120” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM
No ERW allowed.
Over 4000 lbs.
2.000” x 0.120” Seamless Alloy (4130), Seamless mild steel (CDS Mechanical) or DOM
No ERW allowed.
15.6.19 Bending Allowances
If the maximum number of bends permitted for any one bar is exceeded, all required
components shall be made from the tubing size listed for the next heavier category and
must be approved by a NASA race tech shop or scrutineer.
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15.6.20 Inspection
A 3/16-inch inspection hole must be drilled in each of the required bars in a non-critical
area for the purpose of determining wall thickness. All welds, except those mounted to
plates on the floor, must be accessible for inspection (360 degrees).
15.6.21 Head Support-Rear
This section applies to seats without an integral headrest. A head restraint must be
used to help prevent whiplash. The head restraint should have a minimum area of thirtysix
(36) square inches and be padded with a non-resilient material such as Ethafoam or
Ensolite with a minimum thickness of one (1) inch. It is recommended that padding
meeting SFI specification 45.2 be used.
15.6.22 Seat Back Support
A seatback support must be made to hold the seat from going back in the event of a
crash. A plate should be used to distribute the load. No bolts, corners, or sharp objects
should be placed in such a manner that could lead to a possible puncture of the driver in
a high impact crash. Proper design and installation is crucial to safety and it is
recommended that the driver employ the services of a professional race car builder for
this, as well as all other vehicle safety items. An exception may be made for those seats
homologated to, and mounted in accordance with, FIA 8855-1999 or 8862-2009
standards. Those seats that qualify for the aforementioned exception must conform to
the entire FIA 8855-1999 or 8862-2009 set of regulations, as applicable. This includes a
mandatory seat replacement, or use of a seat back brace, for any seat more than five (5)
years old (8899-1999) or more than ten (10) years old (8862-2009). Please reference
the FIA regulations. http://www.fia.com/