USRA Stock Car body rules

Both bumpers are required. Rule 1.8 allows stock-appearing plastic nose and tail pieces, and rule 15.15 conflicts with that; see Body and panels. (Rules 1.15, 1.8, 15.15, Diagram A)

Nose

• Rule 1.8 Nose width: 74 in max, as installed. (Rule 1.8)
• Rule 1.8 Skirting. You can add skirting (a strip along the bottom edge) of up to 3 in to the nose and tail pieces. (Rule 1.8)
• Rule 1.8, Diagram K Ground clearance. The nose, skirting included, must stay at least 8 in off the ground. (Rule 1.8, Diagram K)
• Rule 1.2 With the fabricated 1988 Monte Carlo panels, the only nose and tail allowed are the 1988 Monte Carlo pieces (see Doors and sides). (Rule 1.2)

Bumpers

• Rule 1.15 Edges. No sharp edges on either bumper. (Rule 1.15)
• Rule 1.15 Tubular bumpers. Allowed front, rear or both. Bend them to fit, round the ends and cover them with the molded plastic nose or tail. (Rule 1.15)
• Diagram G Diagram G says a bumper that isn't inside the nose or tail piece must be capped to the body. (Diagram G)

• Rule 1.15 Mounting. Mount each bumper frame end to frame end. (Rule 1.15)
• Rule 1.15 Height. The center of the frame and bumper sits between 16 and 21 in off the ground. (Rule 1.15)
• Rule 1.15 No part of either bumper can be lower than 12 in off the ground. (Rule 1.15)
• Rule 14.3.4 No ballast on the rear bumper. (Rule 14.3.4)

Bars ahead of the radiator

• Rule 2.11 Radiator bars. You can run up to 2 bars in front of the radiator to protect it. They go behind the front bumper, inside the body, and no wider than the stock frame horns (the front ends of the frame rails, ahead of the radiator). (Rule 2.11)
• Rule 2.11 You can tie the front frame horns together. (Rule 2.11)
• Rule 2.11 Every front and rear bar stays inside the body. No adjustable bars on the frame or the cage. (Rule 2.11)
• Rule 2.14 Tow hooks. A tow hook is required at the front and at the rear. (Rule 2.14)

Run a stock steel hood or an aluminum one. You can gut it (remove the inner structure and trim and keep the outer skin). (Rule 1.3, Diagram F)

Hood

• Rule 1.3 One piece. The hood is one piece and separate from the fenders. No one-piece or tilt front ends (hood and fenders built as one unit). (Rule 1.3)
• Rule 1.3 Sealing. Seal the hood to the cowl (the panel between the hood and the windshield). (Rule 1.3)
• Rules 1.9, 1.3 No spoilers or hood scoops, except the air filter shield or scoop described below. (Rules 1.9, 1.3)

Air cleaner and scoops

• Rule 1.3 Hood hole. You can cut a hole in the hood, only to clear the air cleaner, and no bigger than the air cleaner's diameter. (Rule 1.3)
• Rule 1.3 Air cleaner height: 4 in max above the hood. (Rule 1.3)
• Rule 1.3 Air filter shield. On top of the hood, on the front side of the filter, you can add a shield or scoop up to 4 in tall that wraps no more than 180 degrees around the filter. (Rule 1.3)
• Rule 13.6 Under the hood, no shield of any kind can wall off the carburetor or air cleaner. (Rule 13.6)

Engine placement

• Rules 3.7, 3.5 Location. The motor sits in the stock location (where the factory put it). You can't alter the frame or crossmembers to move it. (Rules 3.7, 3.5)
• Rules 3.7, 3.5 Chevy in a metric frame. On a GM 1978-1987 metric frame (GM's mid-size rear-drive perimeter frame), or the Speedway replacement frame built to that pattern, with a Chevy motor, the fuel pump stays ahead of the crossmember, 1.75 in from the crossmember to the center of the pump. (Rules 3.7, 3.5)

• Rule 3.7 Ford. With a Ford engine, the rear of the block sits no more than 22.5 in behind the front of the crossmember. (Rule 3.7)
• Rule 3.7 Chrysler. With a Chrysler block, no more than 21.75 in. (Rule 3.7)

Fenders, doors and quarter panels (the body sides behind the doors) are steel, apart from a few aluminum and fabricated panels allowed by name. (Rules 1.2, 1.1)

Doors and quarter panels

• Rule 1.1 Shape. Fenders, doors and quarter panels keep the OEM (original factory) shape and arc. No flat-sided bodies. (Rule 1.1)
• Rule 1.1 Front fenders. Keep the OEM size and body curve. (Rule 1.1)
• Rule 1.1 Steel Chrysler 300 and steel Camaro fenders are allowed on G-body cars (GM's 1978-88 rear-drive mid-size cars, such as the Monte Carlo, Cutlass Supreme, Regal and Grand Prix). (Rule 1.1)
• Rules 1.1, 1.2 Aluminum parts. Five Star Bodies aluminum lower front fenders (#601-23A) and Five Star Bodies aluminum doors (#601-21A) are allowed. (Rules 1.1, 1.2)
• Rules 1.1, 1.2 Fabricated fenders aren't allowed, except the 1988 Monte Carlo option. (Rules 1.1, 1.2)
• Rule 1.2 1988 Monte Carlo option. You can run fabricated front fenders, doors and lower quarter panels made as 1988 Monte Carlo parts. They must meet the body diagram measurements for this option, and the nose and tail that go with them are under Nose and bumpers. (Rule 1.2)

• Rule 13.8.4 Exhaust. No exhaust out through the body panels or fenders. (Rule 13.8.4)

Skirts and ground clearance

• Rule 1.8, Diagram B Skirts. You can add skirts along the bottom of the doors and quarter panels. The body, skirts included, stays at least 4 in off the ground. (Rule 1.8, Diagram B)

Rub rails

• Rule 1.5 Rub rails. Steel rub rails (strips along the body side that take contact) are allowed, no bigger than 1 in by 2 in, mounted flush with the body. They can run from fender well to fender well and along the rear quarter panel. (Rule 1.5)

Door bars and door plate

• Rule 2.13 Door plate. Weld a steel plate, at least 18-gauge (0.049 in), solidly to the outside of the driver-side door bars (the horizontal cage tubes beside the driver). It must stay visible for inspection. (Rule 2.13)
• Rule 2.13 The plate covers from the top door bar down to the rocker panel (the sill under the doors), and from the rear down post (the rear down bar of the cage) to 6 in ahead of the seat. (Rule 2.13)

Keep the roof at stock dimensions and slope, the window openings at stock dimensions and every pillar stock, steel and in its stock location. All the glass comes out. (Rules 1.2, 1.7, 1.12, Diagram D)

Roof

• Rule 1.2 G-body cars can run an aftermarket fiberglass OEM replacement roof (a copy made to the factory pattern). (Rule 1.2)

Pillars and windshield

• Rule 1.2 Pillars. You can move the driver-side B-pillar (the roof pillar at the back of the door) to get the driver in and out. (Rule 1.2)
• Diagram E B-pillar trim. Diagram E says B-pillars can be trimmed, to no less than 2 in. (Diagram E)

• Rule 1.6, Diagram J Windshield bars. At least 3 windshield bars in front of the driver. (Rule 1.6, Diagram J)

Windows and visors

• Rule 1.7, Diagram D Sun visor. You can add a metal sun visor of up to 7 in at the top of the windshield opening. No visors in the door openings or side windows. (Rule 1.7, Diagram D)
• Rule 1.7 Opera windows. You can cover the rear opera window (the small rear side window on some coupes) with clear Lexan (polycarbonate sheet) only, the same on both sides. (Rule 1.7)

Window net

• Rule 15.13 A full-size window net is required in the driver's window opening on the left side, with its mounts welded to the roll cage. (Rule 15.13)

The trunk lid and quarter panels slope down to the back of the car. (Rule 1.10)

Trunk lid

• Rules 1.10, 1.9 Trunk lid. No concave trunk lids, and no spoilers on the trunk lid or anywhere else on the car. (Rules 1.10, 1.9)

Tail piece

• Rules 1.8, 15.15, Diagram A Tail piece. Rule 1.8 allows a stock-appearing plastic tail piece, and rule 15.15 conflicts with that; see Body and panels. Tail skirting is under Nose and bumpers. (Rules 1.8, 15.15, Diagram A)
• Rule 1.8, Diagram B Tail height. The back of the tail piece and the rear of the deck lid (the trunk lid) can be no more than 20 in above the center of the bumper and frame rails. (Rule 1.8, Diagram B)

Fuel cell and rear firewall

• Rule 7.4.2 Fuel cell. Fasten the cell securely inside the trunk, above the level of the stock trunk floor, with at least 2 solid steel straps around it, each 1/8 in thick and 2 in wide. (Rule 7.4.2)

• Rules 7.4.3, 7.4.5 The steel container, the mounts and the rest of the fuel cell rules are under Fuel, fuel cell and fuel lines. (Rules 7.4.3, 7.4.5)
• Rule 7.4.4 Rear firewall. A firewall goes between the driver and the fuel cell and runs from quarter panel to quarter panel. (Rule 7.4.4)

The dash, the seat back, the rear cage hoop, the speaker deck (the tin shelf behind the seat) and the 12 in firewall setback are all measured back from the rear of the engine. (Rules 4.5, 4.7.3, 2.7, 4.4, 1.11)

Firewall and floor

A fabricated firewall and floor are 18-gauge (0.049 in) steel welded solidly to the frame. Shape the floor like a factory floor pan. If you're building from a donor car, you can keep the factory firewall and floor, or cut them out and replace them this way. (Rule 1.11)

• Rule 1.11 Front firewall. At least 24 in tall. A built firewall can be flat. (Rule 1.11)
• Rule 1.11 Setback. Set it back no farther than the first factory frame seam or 12 in behind the back of the motor. The seam is where the C-channel (a frame rail with a C-shaped cross section) is welded to the front stub (the front section of the frame). (Rule 1.11)

• Rule 4.4 If you build interior tin (sheet metal that forms the cockpit), you still need a full front firewall, but you can leave out the floor pan under the tin. If you're building from a donor car, that means you can cut out the factory floor pan under the tin. (Rule 4.4)
• Rule 7.4.4 The rear firewall, between the driver and the fuel cell, is under Trunk and tail. (Rule 7.4.4)

Dash and interior sheet metal

• Rule 4.5, Diagram H Dashboard. No more than 36 in back from the back of the engine block. Keep the dash flat and level, except for a raised dash cowl right in front of the driver (part of the dash, not the body cowl at the base of the windshield). (Rule 4.5, Diagram H)
• Rule 4.4 Interior tin. Optional. Sheet metal can run from the passenger door to no farther left than the left side of the driveshaft tunnel, and from the dash or firewall back to the rear of the seat. (Rule 4.4)
• Rule 4.4 Tin height. No higher than the top of the door and no lower than the top of the top door bar, level front to back and side to side. (Rule 4.4)
• Rule 4.4 If the tin only runs from the top of the door to the right-side door bar, it can slope down to that bar. (Rule 4.4)
• Rule 4.4, Diagram I Speaker deck. The rear speaker deck can run straight across, quarter panel to quarter panel, back from the driver's seat or from the rear of the interior tin. It stops at the C-pillar (the rear roof pillar) or at 99 in behind the back of the engine, whichever comes first, and can't sit higher than the deck lid or the opera window. (Rule 4.4, Diagram I)
• Rule 4.4 From the back of the C-pillar or the 99 in mark, whichever comes first, everything behind slopes downhill to the back of the car. (Rule 4.4)
• Rule 4.4 The penalty for a speaker deck that runs past the 99 in mark is under Cockpit and seat. (Rule 4.4)

Seat position

• Rule 4.7.3 Seat back. No more than 72 in behind the rear of the engine block. Seat mounting is under Cockpit and seat. (Rule 4.7.3)

Cage-to-body fit

These cage dimensions set the room the body has to fit around. The rest of the cage rules are in the Roll cage section. (Rules 2.4, 2.5, 2.7)

• Rule 2.4 Hoop width. The front and rear hoops are welded to the frame and at least 47 in wide, outside to outside. (Rule 2.4)
• Rule 2.5 Down bar spacing. At least 40 in between the front and rear down bars (the cage tubes from the halo to the frame), measured at the top of the door panel. (Rule 2.5)
• Rule 2.7 Rear hoop. No more than 76 in from the back of the engine to the front edge of the rear hoop. (Rule 2.7)
• Rule 2.7 Halo. The top halo (the top hoop of the cage over the driver) is at least 40 in left to right and 29 in front to back, outside to outside. (Rule 2.7)

Build on a stock frame with no changes, or on the Speedway replacement frame. GM unibody cars are allowed too (see Unibody cars), and the rules for converting a street car are under Donor cars. (Rules 3.5, 3.1)

Which frame

• Rule 3.5 Frame. Use a stock OEM frame, unaltered, or the unaltered Speedway OEM replacement frame (#91678880), Speedway Motors' new-built copy of the GM metric frame. (Rule 3.5)
• Rules 1.1, 3.1 Frame types. The car can sit on a full frame (a separate frame that runs around the car under the body) or be a unibody (body and frame are one welded structure). (Rules 1.1, 3.1)
• Rule 3.10 Titanium. No titanium parts anywhere on the car. (Rule 3.10)

Allowed frame changes

• Rules 3.5, 3.11, 3.4 Apart from the X-bracing and rear frame replacement below, and shortening a Ford full frame under a Ford unibody (see Unibody cars), no changes to the frame or crossmembers, not even for engine placement or suspension clearance, and no widening. (Rules 3.5, 3.11, 3.4)
• Rules 3.9, 3.8 You can X-brace the frame. Suspension parts can't mount to the bracing. (Rules 3.9, 3.8)
• Rule 3.6 Rear frame. Behind the rear tires, you can replace the rear of the frame in the stock location with 2 in by 3 in steel tubing with a 0.095 wall. Start no farther forward than 1 in behind the factory seam. (Rule 3.6)
• Rule 3.6 Leave the factory seam visible, and put back the same length of material you cut out. (Rule 3.6)

Donor cars

A donor car is a street car whose body and frame you convert into the race car.

• Rule 3.3 If you're building from a GM donor car, use a frame of the same year and make as the body, so it matches the factory floor pan and firewall. (Rule 3.3)

Unibody cars

• Rules 3.1, 3.2 GM unibodies. Allowed, with the same 107.5 in minimum wheelbase. (Rules 3.1, 3.2)
• Rule 3.4 Ford unibodies. If you're building from a 1980 or newer Ford unibody car, you can put it on a Ford full frame instead. That frame can be shortened to no less than 111.5 in. (Rule 3.4)

• Rule 3.8 Leaf springs. If you're building from a unibody car with rear leaf springs, you can under-sling the rear end (mount the axle housing below the springs). (Rule 3.8)

Hanging the body

• Rule 1.1 Centered and square. Center the body on the frame and keep it parallel to the frame, front to rear and side to side. (Rule 1.1)
• Rule 1.13 Mounts. Hang the body at the frame's stock body mount locations. (Rule 1.13)
• Rule 1.16 Front-drive bodies. If you put a newer body from a front-wheel-drive car on an older chassis, square it up on the frame. Don't offset it to the left. (Rule 1.16)

Wheelbase, ride height and weight

• Rule 3.2, Diagram C Wheelbase. Center of the front hub to center of the rear hub: at least 107.5 in on both sides, with no more than 1 in difference side to side. (Rule 3.2, Diagram C)
• Rule 3.12 Ride height. The frame sits between 5 and 10 in off the ground, measured behind the front tires and in front of the rear tires, with the driver in the car. (Rule 3.12)
• Rules 14.2, 1.1 Weight. At least 2,900 lb. With the Five Star MD3 Camaro body, at least 2,950 lb. The full weight and ballast rules are in Weight and ballast. (Rules 14.2, 1.1)

Run a 1960 or newer, U.S.-made, full-body passenger car body, on a full frame or a unibody. No panel vans and no station wagons. (Rule 1.1)

Allowed bodies and kits

• Rules 3.3, 1.1, 1.2, 1.3 Steel bodies. The body is a steel OEM body, or an aftermarket steel body made as a stock OEM replacement. Anything else has to be allowed by name: the MD3 Camaro kit below, the fabricated 1988 Monte Carlo panels under Doors and sides and the parts listed under Panel materials. (Rules 3.3, 1.1, 1.2, 1.3)
• Rule 1.1 Five Star MD3 Camaro. The Five Star Bodies MD3 Camaro body (#33131-10200) is allowed, with the 2,950 lb minimum weight under Frame and stance. Don't mix parts from this kit with OEM body parts. (Rule 1.1)
• Rule 1.1 Body lines. The body keeps its OEM body lines and shape. (Rule 1.1)

Panel materials

• Rule 1.2 Steel. Body panels are steel OEM panels or OE replacement panels (copies made to the factory pattern), steel all the way down to the frame. (Rule 1.2)
• Rules 1.3, 1.2, 1.1 Named exceptions. Not steel: an aluminum hood, the Five Star aluminum doors and lower front fenders and a fiberglass OEM replacement roof on G-body cars. Not OEM: the Five Star MD3 Camaro body and the fabricated front fenders, doors and lower quarter panels of the 1988 Monte Carlo option. (Rules 1.3, 1.2, 1.1)
• Rules 15.15, 1.7 Plastic. Rule 15.15 bans plastic anywhere except from the edge of the firewall to the body skin, and from the inner wheel tub to the body skin. The clear Lexan opera window covers that 1.7 allows by name are also allowed. (Rules 15.15, 1.7)
• Rule 1.8 Rule 1.8 allows stock-appearing plastic nose and tail pieces. (Rule 1.8)

Cutting and gutting

• Rule 1.4 Cutting. You can cut the body only to fit the roll cage or to clear the tires. (Rule 1.4)
• Rule 1.13 Gutting. Body panels keep their original size, but you can gut them. (Rule 1.13)

Damage

• Rule 1.14 Officials can keep a car with excessive body damage from racing. (Rule 1.14)

Numbers and appearance

• Rule 1.17.1 Numbers. Every car carries large, readable numbers on both sides, on the roof, on the nose and on the rear panels. (Rule 1.17.1)

• DST fix Typo Official text: nose and real panels → Fixed: nose and rear panels (Rule 1.17.1)

• Rule 1.17.1 Side numbers. These should contrast with the body color and be at least 18 in tall and 4 in thick (the width of each stroke). (Rule 1.17.1)

• Rule 1.17.1 Roof numbers. These should be at least 24 in tall and 4 in thick. (Rule 1.17.1)
• Rule 1.17.2 Advertising. Officials can assign, approve or turn down any advertising, sponsorship or similar deal tied to an event, for the public image of the sport or of USRA. (Rule 1.17.2)
• Rule 1.17.2 Neat cars. Every car must look neat, and officials approve each car to race. By racing, you agree to follow their decisions on this. (Rule 1.17.2)