USRA Factory Stock body rules

Run a stock-type rear bumper. Up front, a fabricated bumper is allowed, and where it goes depends on whether the car has an aftermarket nose. (Rules 1.14, 1.14.1)

Nose

• Rule 1.2 Rule 1.2 allows a stock-appearing aftermarket plastic nose piece. You can drill it for air, but you can't extend it with any kind of material. (Rule 1.2)
• Rules 1.2, 1.8, 15.15 Plastic nose and tail pieces are a rulebook conflict: see Panel materials under Body and panels. (Rules 1.2, 1.8, 15.15)
• Rule 1.4 No valances (panels under the nose or bumper). (Rule 1.4)

Bumpers

• Rule 1.14.1 Rear: if the car has a tail piece, the tail piece has to cover the rear bumper. (Rule 1.14.1)
• Rule 1.14.1 Front, with an aftermarket nose: a fabricated bumper can reach past the frame rails for support and reinforcement, but it has to sit behind the nose piece. (Rule 1.14.1)
• Rule 1.14.1 Front, without an aftermarket nose: put the fabricated bumper in the stock location and cap it to the fenders. No sharp edges. (Rule 1.14.1)

Bars ahead of the radiator

• Rule 2.9 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 2.9)
• Rule 3.4 Radiator bars also have to sit lower than the hood (see Hood). (Rule 3.4)
• Rule 1.14.1 Tow chains: weld chain of at least 5/16 in diameter to the front and the rear of the car, set up so a tow truck can hook to it. (Rule 1.14.1)

Run a stock-appearing hood made of aluminum or steel. (Rule 1.13)

Hood

• Rule 1.13 Hood rake: no more than 5 in, measured from the back of the hood to the front of the nose. (Rule 1.13)
• Rule 1.9 Hood opening: at least 42 in, centered between the frame rails. (Rule 1.9)
• Rule 1.9 No holes drilled in the hood for air. You can trim the hood, but not excessively. (Rule 1.9)
• Rule 1.4 No hood scoops or air scoops. (Rule 1.4)
• Rule 3.4 Every bar ahead of the roll cage has to sit lower than the hood. (Rule 3.4)

Engine placement

• Rules 13.1, 13.1.8 Standard engine (Option 1): mount it at the stock height and setback, within plus or minus 1 in. (Rules 13.1, 13.1.8)
• Rule 13.1.9 Standard engine in a GM metric frame (GM's 1978-88 mid-size rear-drive perimeter frame, used under the G-body cars such as the Monte Carlo, Cutlass Supreme, Regal and Grand Prix): the center of the fuel pump sits at least 1.75 in ahead of the unaltered crossmember. (Rule 13.1.9)

• Rules 13.4, 13.4.1 Radiator: 1 only, and it has to fit in the original location with no changes to the body. (Rules 13.4, 13.4.1)

The doors and sides keep their factory shape, and the driver's side gets a steel door plate on the cage's door bars. (Rules 1.10, 2.7)

Doors and quarter panels

• Rule 1.10 Doors and fenders stay stock appearing at OEM (original factory) dimensions, the same on both sides. (Rule 1.10)
• Rule 1.10 No straight slab sides. (Rule 1.10)
• Rule 1.9 You can trim the fenders, but not excessively. The rulebook doesn't set an amount. (Rule 1.9)

Skirts and ground clearance

• Rule 1.4 No skirts (strips added along the bottom edge of a panel). (Rule 1.4)
• Rule 1.5 Body to ground: at least 5.5 in. (Rule 1.5)

Rub rails and nerf bars

• Rule 1.7 No nerf bars (tube bars outside the body). (Rule 1.7)
• Rule 1.7 You can run a rub rail (a strip along the body side that takes contact) on each side, steel or Lexan (clear polycarbonate sheet), up to 1 in wide by 2 in tall, bolted flush to the body. (Rule 1.7)

Door bars and door plate

• Rule 2.7 Door bars: 3 horizontal bars on each side. (Rule 2.7)
• Rule 2.7 Uprights from the frame to the top door bar: at least 4 on the driver's side and 3 on the passenger side. (Rule 2.7)
• Rule 2.7 Door plate: steel, at least 18-gauge (0.049 in), welded solidly to the outside of the driver-side door bars. (Rule 2.7)
• Rule 2.8 The plate covers from the top door bar down to the rocker panel (the sill under the doors), and from the rear down post forward to 6 in ahead of the seat. Leave it visible for inspection. (Rule 2.8)

Run the complete factory steel roof for that model, in its factory spot and at its factory rake and angle. G-body cars (GM's 1978-88 rear-drive mid-size cars) can use an OEM fiberglass replacement roof instead. (Rule 1.12)

Roof

• Rule 1.6 Sunroofs and T-tops have to be reinforced and enclosed. (Rule 1.6)

Pillars and windshield

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

Windows and visors

• Rule 1.8 No glass (see Cutting and gutting). (Rule 1.8)
• Rule 1.10 Window openings stay stock appearing at OEM dimensions, the same on both sides. (Rule 1.10)
• Rule 1.6 Front visor: up to 7 in. No visors on the side or rear windows. (Rule 1.6)
• Rule 1.12 Openings should be covered so the driver is closed off, subject to track approval. (Rule 1.12)

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)
• Rule 4.5 If you carry a passenger, the passenger needs a window net and a fire suit too. (Rule 4.5)
• Rule 15.13 Recommended: approved racing arm restraints. (Rule 15.13)

The fuel cell rides inside the trunk, and the rear of the car is sealed off so the cell isn't exposed. (Rules 1.3, 7.4, 7.4.1)

Trunk lid

• Rule 1.13 Use a stock-appearing trunk lid made of aluminum or steel. (Rule 1.13)
• Rule 7.4.2 The lid has to be removable, so an official can look down at the fuel cell from above. (Rule 7.4.2)
• Rule 1.9 Trunk opening: at least 42 in, centered between the frame rails. (Rule 1.9)
• Rule 1.10 Rear deck (the top panel behind the driver): its front edge sits no more than 8 in ahead of the center of the rear end, and it falls at least 2 in, without a break, from front to rear. (Rule 1.10)
• Rule 1.4 No spoilers, not even factory ones. (Rule 1.4)

Tail piece

• Rules 1.2, 1.14.1 A tail piece with no holes is allowed, and it has to cover the rear bumper (see Bumpers). (Rules 1.2, 1.14.1)
• Rules 1.2, 1.8, 15.15 Plastic tail pieces are part of a rulebook conflict: see Panel materials under Body and panels. (Rules 1.2, 1.8, 15.15)

Fuel cell and rear firewall

• Rule 1.11 The OEM rear firewall stays in its stock location. (Rule 1.11)
• Rule 7.4.1 Fasten the fuel cell solidly inside the trunk, with no part of the cell ahead of any part of the rear end. (Rule 7.4.1)
• Rule 7.4.1 The cell sits in a steel container, held by at least 2 solid steel straps around it, each 0.125 in thick and 2 in wide. (Rule 7.4.1)
• Rule 7.4.1 The cell needs a check valve. The vent, cap vent included, needs check valves, a flapper spring or a ball-type filler valve. (Rule 7.4.1)
• Rule 7.4.1 Fuel lines that pass through the cockpit run inside metal pipe or metal conduit, and no fuel filter goes in the cockpit. (Rule 7.4.1)
• Rule 2.10 Fuel cell protection bar: required, mounted frame rail to frame rail inside the trunk and no higher than the fuel cell. Tube up to 1.75 in diameter, 0.095 in wall. (Rule 2.10)

Seal the cockpit off completely from the engine, the ground and the trunk. (Rules 1.11, 4.6.3)

Firewall and floor

You can cut out the factory front firewall and build your own from 18-gauge (0.049 in) steel, or keep the factory one where the factory put it. The factory rear firewall stays in its stock location either way (see Trunk and tail). (Rule 1.11)

• Rule 1.11 Whichever front firewall you run, it has to be full and complete and match the frame you use, and the OEM mount has to stay visible. (Rule 1.11)

• Rule 1.11 Front firewall: vertical, and no farther back than the rear of the "oval frame hole". (Rule 1.11)
• Rule 1.11 Front firewall height: at or between 24 and 26 in by the rule's digits. The rule's words say twenty to twenty-six, which puts the minimum at 20 in. (Rule 1.11)

• Rules 4.6, 4.6.1 Floor: you can cut the OEM floor pan in a straight line from one side to the other and replace it with fabricated steel, at least 18-gauge (0.049 in), welded solidly to the frame. (Rules 4.6, 4.6.1)
• Rule 4.6.2 The floor stays flat and OEM appearing from frame rail to frame rail, level with the rails. (Rule 4.6.2)
• Rule 4.6.2 The one exception is a driveshaft tunnel up to 8 in tall, about the size of an OEM tunnel. (Rule 4.6.2)

Dash and interior sheet metal

• Rule 1.11 Rear of the dash: no more than 35 in from the center of the distributor, or no more than 28 in from the center of the stock hood's back edge. (Rule 1.11)
• Rule 1.11 The interior sheet metal (interior tin) can't slope (no rake), and no spoilers inside the car. (Rule 1.11)
• Rule 1.10 No enclosed interior and no decking (sheet metal laid over the cockpit to close it in). That's not the rear deck behind the driver, which the car keeps: see Trunk lid. (Rule 1.10)

Seat position

• Rules 4.8, 4.8.1 Use a factory-made racing seat that officials accept. No homemade aluminum, plastic or fiberglass seats. (Rules 4.8, 4.8.1)
• Rule 4.8.1 Recommended: a full-containment racing seat (the rule says strongly recommended). (Rule 4.8.1)
• Rule 4.8.2 Mount the seat with fasteners and washers of at least 3/8 in. (Rule 4.8.2)
• Rule 4.8.3 The part of the seat at the driver's shoulders, where the shoulder harness passes through, sits at least 25 in ahead of the centerline of the rear-end housing. (Rule 4.8.3)

Cage-to-body fit

• Rules 2.4, 2.5 Run a full-perimeter, four-post cage of continuous hoops, with all 4 posts welded solidly and directly to the frame. (Rules 2.4, 2.5)
• Rule 2.1 Main cage and door bar tubing: at least 1.5 in diameter, 0.095 in wall. (Rule 2.1)
• Rules 2.1, 2.9 No square tubing or galvanized pipe in the main cage, no aluminum or other soft metal and no offset cage. (Rules 2.1, 2.9)
• Rule 2.1 Front hoops are allowed. No adjustable bars or slip joints on the cage. (Rule 2.1)
• Rule 2.5 Halo (the top hoop of the cage over the driver): at least 40 in left to right and 29 in front to back, outside to outside, with at least 1 cross bar. (Rule 2.5)
• Rule 2.5 Down bars (the cage tubes from the halo to the frame): at least 40 in between the front and rear bars, measured at the top of the door panel. (Rule 2.5)
• Rule 2.4 The rear hoop gets an X-brace, and the front down bars are tied together. (Rule 2.4)
• Rule 2.4 Rear kickers (diagonal braces from the rear hoop toward the back of the frame) are required. (Rule 2.4)
• Rule 2.4 X-brace and rear kickers: at least 1.25 in diameter, 0.083 in wall. (Rule 2.4)
• Rule 2.5 Rear hoop: its front edge sits no more than 76 in behind the back of the engine. (Rule 2.5)
• Rule 2.6 With the helmet on and the driver belted into the seat, the top of the driver's head can't stick up above the cage. (Rule 2.6)
• Rules 2.2, 15.13 Pad every roll bar within the driver's reach with a material officials accept, and every bar around the driver with approved roll bar padding. (Rules 2.2, 15.13)
• Rule 2.2 Recommended: fire-retardant padding. (Rule 2.2)
• Rules 2.1, 2.3 Weld the cage connections properly. Officials have to accept the installation and the workmanship. (Rules 2.1, 2.3)

Hang a stock American-made passenger car body on a stock full frame (a separate frame that runs around the car under the body) with no alterations except the changes listed under Allowed frame changes. You can start from a bare frame or convert a donor car (a street car whose body and frame you turn into the race car); the donor-car rules are under Donor cars. Chrysler and Ford unibodies (body and frame one welded structure) are allowed too. (Rules 1.1, 3.1)

Which frame

• Rules 3.1, 3.7 Speedway frame. The Speedway replacement frame (#91678881) is Speedway Motors' new-built copy of the GM metric frame, and you run it unaltered. Rule 3.1 says it's allowed. Rule 3.7 says it will be allowed in 2027. (Rules 3.1, 3.7)

• Rule 1.11 The front firewall has to match the frame you use, so read Firewall and floor under Interior, firewall and floor before you pair a body with a frame. (Rule 1.11)

Allowed frame changes

• Rules 3.1, 3.3, 3.5 No frame alterations: don't widen, narrow, shorten, lengthen, cut or bend it, or alter it in any way to change the suspension brackets. That includes cutting it for tie rod or oil pan clearance and narrowing the right rear for tire clearance. (Rules 3.1, 3.3, 3.5)
• Rules 2.11, 3.2 The exceptions: behind the upper shock mounts you can replace the rear of the frame with round, square or rectangular tubing, and you can X-brace the frame. (Rules 2.11, 3.2)
• Rules 2.9, 2.11 X-bracing and any bar you add to the frame or cage: round tube up to 1.75 in diameter, 0.12 in wall, or square tube up to 1.25 in, 0.12 in wall. Square tube still can't go in the main cage (rule 2.9). (Rules 2.9, 2.11)
• Rule 2.1 No adjustable bars or slip joints on the frame. (Rule 2.1)

Donor cars

• Rules 1.1, 3.1 If you're building from a donor car, its own frame is legal as long as it stays stock and unaltered. (Rules 1.1, 3.1)

Unibody cars

• Rule 1.1 If you're building from a unibody car, it has to be a Chrysler or a Ford (no Mustangs or station wagons). (Rule 1.1)

Hanging the body

• Rule 1.5 Hang the body on the frame's stock body mounts. You can shift it up to 1 in either way from the original body mount rubber bushing position. (Rule 1.5)

Wheelbase and weight

• Rule 3.6 Wheelbase (center of the front hub to center of the rear hub): at least 107.5 in, with no more than 1 in difference from side to side. (Rule 3.6)
• Rule 14.1 Car weight: at least 2,950 lb, measured after the race with the driver in the cockpit in full racing gear. (Rule 14.1)
• Rule 14.2 Ballast goes only in the trunk area or the motor compartment, mounted only to the frame or roll cage. (Rule 14.2)
• Rule 14.2 No ballast in the cockpit or on any rotating or suspension part. The rule also bars it "outside of body or hood area", which reads either as outside the body or hood, or as outside the body and anywhere in the hood area. (Rule 14.2)

• Rule 14.3 Fasten all ballast securely and paint it white with the car number. (Rule 14.3)
• Rule 14.3 Ballast bolts: no more than 25 lb on a single 1/2 in bolt. The rule also calls for 2.5 in bolts per 50 lb of ballast. (Rule 14.3)

Any stock American-made passenger car body is allowed, except Camaros, Mustangs and station wagons. (Rule 1.1)

Allowed bodies and kits

• Rule 1.1 Chrysler and Ford unibodies are allowed (see Frame and stance). (Rule 1.1)
• Rules 1.4, 1.9 The car has to keep its stock OEM appearance: no wings and nothing else that changes the stock look. Spoilers (see Trunk lid), skirts (see Skirts and ground clearance), valances (see Nose) and scoops (see Hood) are banned too. (Rules 1.4, 1.9)

Panel materials

• Rule 1.13 Hood and trunk lids: stock-appearing aluminum or steel. (Rule 1.13)
• Rule 1.12 Roof: OEM steel, or the OEM fiberglass replacement roof on GM G-bodies. (Rule 1.12)
• Rule 1.2 Plastic, rule 1.2: a stock-appearing aftermarket plastic nose piece is allowed, and so are tail pieces with no holes. (Rule 1.2)
• Rules 1.8, 15.15 Plastic, Rules 1.8 and 15.15: read together, no plastic anywhere on the car except in the gaps from the edge of the firewall to the body skin and from the inner wheel tub to the body skin. That leaves no room for a plastic nose or tail. (Rules 1.8, 15.15)

Cutting and gutting

• Rule 1.9 No cutting, channeling (dropping the body down over the frame), shortening or other changes to the body. (Rule 1.9)
• Rules 1.5, 1.9, 1.11, 4.6.1 The cuts the rulebook does allow: gutting (strip the inner structure and trim, keep the outer skin), trimming the fenders and hood as long as it isn't excessive, cutting out the front firewall to build your own and cutting the floor pan straight across to replace it (see Firewall and floor). (Rules 1.5, 1.9, 1.11, 4.6.1)
• Rule 1.8 No glass, upholstery, lights, mirrors or trim on the car. For plastic, see Panel materials. (Rule 1.8)

Numbers and appearance

• Rules 1.15, 1.15.1 Numbers. Every car carries large, readable numbers on both sides, on the roof, on the nose and on the rear panels. (Rules 1.15, 1.15.1)
• Rule 1.15.1 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 1.15.1)
• Rule 1.15.1 Roof numbers. These should be at least 24 in tall and 4 in thick. (Rule 1.15.1)
• Rule 1.15.2 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 1.15.2)
• Rules 1.12, 1.15.2 Neat cars. Every car must look neat and the body presentable, and officials approve each car to race. By racing, you agree to follow their decisions on this. (Rules 1.12, 1.15.2)
• Rules 13.2, 13.2.4 With a factory-sealed crate engine, put a "Crate" decal in plain view near the A pillar (the windshield post). (Rules 13.2, 13.2.4)