OK gang, I've got something serious to discuss today.
The roll bar rules we have currently, suck.
As far as I can tell, we have:
- a ruleset for Stock
- a ruleset for Street Prepared (and thus SM by inheritence)
- a ruleset for Showroom Stock road racing
- a ruleset for whatever the SP equivelent is for road racing (Touring?)
- a ruleset for the NHRA
It would be a Very Good Thing if the rules for roll bars/cages could be
unified in such a way that there was a clear and obvious progression and
cross-legality between roll structures. To wit:
1) Stock class and Showroom Stock road racing should share the same rules
2) SP, SM, and Touring should share the same rules
3) An NHRA legal bar/cage should be legal in SP and SM, and it would be
nice if it could be made legal in Stock class too.
Here's the major bullet points:
- Roll structures should be considered safety equipment. While it is true
that there may be some performance-enhansing chassis stiffening going on
(and the rules should be worded to restrict this performance enhansing
aspect as much as possible without compromising safety - a roll structure
should not be a "must have" performance-enhancing item for autocross) the
main point of a roll structure is to protect the driver in case of the
shiny side going down.
- The likelyhood of an event ocurring at an autocross that would require a
roll structure to defend against is fairly low. However, many autocross
cars see double or triple duty as drag cars and track day cars. (I see few
autocross/road race cars outside of Prepared) The NHRA requires a roll bar
at 11.99 or faster. Most track day (Solo 1) sanctioning bodies require some
sort of roll structure. Nobody's car should be made illegal for Solo
competition because they added a piece of safety equipment.
- While there is a performance aspect to the installation of a roll
structure, there's also the weight consideration. Any roll structure is
going to add roughly 70 lbs to a car. With this in mind, minor interior
trim removal etc. to accomodate the bar is a non-issue performance wise.
Here are the NHRA regs for roll structures, edited for applicability (ie,
no dragsters, sub-9 second cars, etc)
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4.10 ROLL BARS
All roll bars must be within 6-inches (15.2 cm) of the rear, or side, of
the driver's head, extend in height at least 3-inches (7.6 cm) above the
driver's helmet with driver in normal driving position, and be at least as
wide as the driver's shoulders or within 1-inch (2.5 cm) of the driver's
door. Roll bar must be adequately supported or cross-braced to prevent
forward or lateral collapse of roll bar. Rear braces must be of the same
diameter and wall thickness as the roll bar and intersect with the roll bar
at a point not more than 5-inches (12.7 cm) from the top of the roll bar.
Sidebar must be included on driver's side. The side bar must pass the
driver at a point midway
between the shoulder and elbow. All vehicles with OEM frame must have roll
bar attached to frame; installation of frame connectors on unibody cars
does not constitute a frame and therefore it is not necessary to have the
roll bar attached to the frame. Unibody cars with stock floor and firewall
(wheel tubs permitted) may attach roll bar with 6-inch (15.2 cm) x 6-inch
(15.2 cm) x .125-inch (3.2 mm) steel plates on top and bottom of floor
bolted together with at least four 3/8-inch (9.53 mm) bolts and nuts, or
weld main hoop to rocker sill area with .125-inch (3.2 mm) reinforcing
plates. All 4130 chrome moly welding must be done by approved TIG Heliarc
process;
mild steel (or ST51) welding must be approved MIG wire feed or approved TIG
heliarc process. Welding must be free of slag and porosity. Any grinding of
welds prohibited. See illustration (Drawing 12).
Roll bar must be padded anywhere driver's helmet may contact it while in
driving position. Adequate padding must have minimum 1/4-inch (6.35 mm)
compression or meet SFI Spec 45.1.
4.11 ROLL CAGE
All cage structures must be designed in an attempt to protect the driver
from any angle, 360-degrees. All 4130 chrome-moly tube welding must be done
by approved TIG heliarc process; mild steel tube welding must be approved
MIG wire feed or TIG heliarc process. Welding must be free of slag and
porosity. any grinding of welds prohibited. Additionally, roll cage must be
padded any where the driver's helmet may contact it while in the driving
position. TAD, TAFC, Pro Stock, Funny Car & Top Fuel padding must meet SFI
Spec 45.1.
Open Bodied cars
When driver is in driving position in an open bodied car, roll cage must be
at least 3-inches (76 mm) in front of helmet.
Full Bodied Cars
On full bodied car, with driver in driving position, helmet must be in
front of main hoop. If helmet is behind or under main hoop, additional
tubing same size and thickness as roll cage must be added to protect
driver. Main hoop may be laid back or forward but driver must be
encapsulated within the required roll cage components.
All cage structures must have in their construction cross bar for seat
bracing and as the shoulder harness attachment point; cross bar must be
installed no more than 4-inches (102 mm) below, and not above, the driver's
shoulders or to side bar. All required rear braces must be installed at a
minimum angle of 30-degrees from vertical, and must be welded in. Side bar
must pass the driver at a point midway between the shoulder and elbow.
Swing out side bar permitted on O.E.M. full bodied car 7.50 (*4.50) E.T.
and slower. The following requirements (a through d) will be enforced on
cars certified after 1/1/98, on all cars 1/1/99.
a. 1 5/8-inch (41.2 mm) O.D. x .083-inch (2.1 mm) (CM) or .118-inch (3.0
mm) (MS) minimum. Bolts / pins must be 3/8-inch (9.5 mm) diameter steel,
minimum and in double shear at both ends.
b. Male or female clevis(es) permitted. Male clevis must use two minimum
1/8-inch (3.2 mm) thick brackets (CM or MS) welded to each roll cage
upright; female must use minimum 1/4-inch (5.4 mm) thick bracket (CM or MS)
welded to each roll cage upright. Pins must be within 8-inches (204 mm) of
the vertical portion of both the forward and main hoops. A half cup backing
device must be welded to the vertical portion of the main hoop (inward
side) or the upper end of the swing out bar (outward side), minimum
.118-inch (3.0 mm) wall (CM or MS) extending at least 1 5/8-inch (41.2 mm)
past the center of the pins. A clevis assembly utilizing a minimum
.350-inch (8.90 mm) thick male component and two minimum .175-inch (4.45
mm) thick female components may use a 1/2-inch (12.7 mm) diameter grade 5
bolt, and does not require a half cup backing device.
c. Sliding sleeves of 1 3/8-inch (35 mm) x .083-inch (2.1 mm) CM or .118
(3.0 mm) MS, with minimum 2-inch (51 mm) engagement, are permitted in lieu
of the upper pin/cup.
d. All bolt/pin holes in the swing out bar must have at least one hole
diameter of material around the outside of the hole.
----------------------------------------------------
Based on this, and my (admittedly sketchy) understanding of the road racing
GCR, it seems that the following criteria should be acceptable:
1) For Stock class, any bar of up to 6 mounting points (main hoop, two
rearward main hoop supports, two forward main hoop supports, which may or
may not have an additional front hoop which may tie into the rear hoop but
not connect to the chassis at any other point) bolted in using sandwich
plates.
2) For Street Prepared and Street Modified, as per Stock Class but with
welding of the attachment points permitted
Comments? Can anybody see any contradiction between what the NHRA wants and
what the GCR requires?
DG
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