Monday, November 24, 2014

Watch This Video And Carefully Rethink Your Roll Cage

This is one of the most horrifying crashes I have seen to date, simply because it hits so close to home. This could've been any of the Miatas that I've seen racing at Chumpcar and LeMons. It begs so many questions -

Is it too dangerous to race an open-top car?

How high should the roll cage be?

Should every race car have an arm restraint?

Shouldn't every race car have a window net?

How about padding on the cage?

There's a lot that goes into a properly built roll cage and you should take a few minutes to understand it better. The Chumpcar roll cage rules (starting on p. 50 of their rule book) are an excellent starting point. Since I know that most of you will be too lazy to drag your asses over to another link, I am pasting the Chumpcar rules below:

Roll Cages
A. At minimum, all roll-cages must include:
1. Full rear, main-hoop with either: (i) front-hoop appropriately braced to each other along the
roofline; or, (ii) halo-hoop appropriately attached to two front vertical legs; or (iii) front vertical
bars bent rearwards at the roofline, connecting to the rear main hoop and cross-braced
horizontally along the upper windscreen line;
a. On all closed cars, the main hoop must be as close as possible to the roof (in height) and “B”
pillars (in width).
b. The main hoop (behind the driver) must be the full width of the cockpit for all cars. It must
be one continuous length of tubing with smooth bends and no evidence of mandrel crimping
or wall failure.
c. A 3/16” inspection hole must be drilled in the main hoop, such that a Tech Inspector has
access to measure the wall thickness of the main hoop without obstruction.
2. Two driver-side door bars that will prevent cockpit intrusion (NASCAR-style or X-design is
a. The spacing between the fore and aft terminal ends of all door bars (including X-design)
must include a separation of no less than six inches of open space when measured at the
centerline of each bar. Triangulated bars that meet or join at the front hoop are allowed so
long as the spacing of the upper and lower bars (attached to the main hoop) is a minimum of
six inches when measured at the centerline of the tubing bar.
b. The upper door bar shall not be placed higher than the top of the door or window sill.
c. If the distance, measured at any point between the highest portion of the door sill or floor
pan (whichever is higher) and the lowest edge of lower door bar is greater than ten inched
(10”), a floor or lower-sill intrusion bar, mounted as low as possible on each side of the rollcage,
at or just above the door sill, joining the front hoop and the main hoop.
d. A minimum of one (1) door bar shall be required on the passenger side. This bar can be a
floor- or sill- or mid-level door bar.
3. Appropriate main-hoop rear-supports (backstays) with no bends, located as close to 45 degrees
from horizontal as practical;
4. One main-hoop diagonal support bar; installed in the same plane as the main hoop, with one end
terminating in general proximity to the main hoop bend above the driver’s head and the other
end terminating in general proximity to the lower end of the opposite side of main hoop. The
diagonal support bar may be of one (1) or two (2) piece construction and it may intersect with
or cross-through the horizontal support bar (used for seat belt harness attachment and/or seat
5. Complete 360-degree welds at all welded joints. All welds to be sufficient in heat, penetration,
bead and consistency.
6. Each major load-bearing member must be formed from its own single, continuous tube.
7. Shoulder-harness bars strongly encouraged (over floor-mounted harnesses), and virtually
necessary for proper shoulder-harness mounting in some applications; dash bars are not
required but very strongly encouraged.
Your roll-cage GENERALLY better have the same main bars in the same main places as shown in
the picture below or you’re going home.

8. Roll-cage Steel Tubing and Hardware (Vehicle Weight Without Driver):
a. Minimum tubing size for cars weighing UNDER 2,500 pounds, as raced, must use a
minimum tubing size of 1.50” x .095.
b. Minimum tubing size for cars weighing OVER 2,500 pounds, as raced, must use a minimum
tubing size of 1.75" x .095 or 1.50” x .120".
c. For purposes of determining tubing sizes, the vehicle weight is as raced without fuel and
9. Properly-bent, racecar-grade and -quality tubing is mandatory: no stretched or crushed bends
allowed. DOM mild steel is very strongly recommended over ERW (seamed) tubing.
10. The radius of all bends in the roll cage (measured at centerline of tubing) must not be less than
three times the diameter of the tubing.
11. All attachment points on the vehicle must be selected and reinforced as necessary so that, in an
accident, the roll-cage will not punch through, tear, or grossly distort any roll-cage attachment
point. Heavily rusted floor pans must be replaced or reinforced with sheet steel plate.
INSPECTION. Spreader plates, gussets, and/or other reinforcing hardware are generally
required to meet this goal. Minimum 1/8” (0.125”) thick steel backing plates – not washers –
must be present on the reverse or underside of any bolt-in cage location.
12. All mounting hardware is to be Grade 8 bolt hardware or better (no Grade 3 or 5
hardware will be allowed).
a. Minimum bolt size is 3/8” diameter. Fine or coarse thread is open.
b. All nuts should be self-locking (nylok / ovalated) or cotter-pinned or drilled and safetywired.
13. No waivers or “repair by next event” allowances will be granted on any roll-cage issue.
Make sure it’s 100% right the first time.
14. All roll-cages / seats / drivers must be fit such that when the driver is securely belted in-place,
the top of the driver’s helmet does not extend above the centerline of the main hoop. This
applies to ALL drivers on the team. Any driver found in violation of this rule will be blackflagged
and the car withdrawn from competition until repairs or modifications have been made
and the car completes a re-tech inspection.
15. All roll cage tubing must be padded with high density roll bar padding wherever a driver’s
extremity may contact the tube.
16. Cars may compete with bolt-in cages. Roll-cage design and construction must maintain typical
SCCA/NASA standards. (Hardware per Item 12 – above.)
In order to prevent massively expensive roll-cages that start to look and act like a tube-frame
chassis, ChumpCar has defined the “maximum, value-free” roll-cage. The “maximum, valuefree”
roll-cage includes all pads, points, tubes and triangulations necessary to maintain an
extremely high degree of safety, while keeping costs in-check and keeping competition wellbalanced.
Teams MAY exceed the design and application of the “maximum, value-free” roll-cage;
however, additional value will be assessed by the Tech Inspector, based on the perceived
performance enhancement of the roll-cage. As per Section 3.2 of ChumpCar’s Basic
Competition Rules:

3.2.2 The maximum, value-free roll-cage design: Will NOT feature more than 2 tubes inside the front engine or storage compartment
and each tube MUST terminate prior to the centerline of the front axle. Is limited to eight (8) body and/or frame mounting points – welded and/or bolted. The total number of mounting points does NOT include a sub-frame to
support a seat mount, provided that the seat sub-frame does not exceed two
(2) chassis contact pads. The total number of mounting points does NOT include welded tabs
connecting any hoop to the body; however, a “tab” is defined as being not
greater than 3/16” thick steel plate, no longer than six inches (6”), and a
maximum of two (2) tabs may be placed within any 36” of tube. Will NOT have more than four (4) tubes installed behind the main hoop and two (2)
of these must include the main-hoop rear-support (backstay) bars. Will NOT have any tubes or bars extend below the factory floor-pan.

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