USRA Hobby Stock body rules

Front and rear bumpers are mandatory. (Rule 1.12)

Nose

• Rule 1.3 Aftermarket nose pieces are allowed. (Rule 1.3)
• Rule 1.3 The front nose piece stays 8 in above the ground. (Rule 1.3)

Bumpers

Mount each bumper frame end to frame end, in the stock location. No sharp edges. (Rule 1.12)

• Rule 1.12 Hollow bumpers only: no filled, solid or reinforced bumpers. (Rule 1.12)
• Rule 1.12 The center of each bumper sits between 16 and 20 in off the ground, and no part of either bumper hangs lower than 12 in. (Rule 1.12)
• Rule 1.12 Cap each bumper to the fender across the full width of the bumper. (Rule 1.12)
• Rule 1.12 Tube bumpers are allowed: tubing no bigger than 2 in by 0.095 in, bent to fit, with rounded ends. (Rule 1.12)
• Rules 1.8, 1.12, 15.15 A tube bumper has to be covered by a molded plastic nose piece or tail piece. Rule 1.8 says all plastic comes out, and rule 15.15 allows it only in the areas listed under Panel materials. (Rules 1.8, 1.12, 15.15)

Bars ahead of the radiator

• Rule 2.10 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 2.10)
• Rule 2.9 Tow hooks. A tow hook is required at the front and at the rear. (Rule 2.9)

The hood is mandatory and keeps the factory look. Seal the back of it off from the cockpit. (Rules 1.6, 1.11)

Hood

• Rule 1.6 Use the OEM (original factory) hood, or an aftermarket hood in steel or aluminum that keeps the factory body lines and sits in the OEM location. (Rule 1.6)
• Rules 1.3, 1.6 Rule 1.6 allows an aluminum hood, but rule 1.3 says replaced body parts must be steel; the rulebook conflict is under Body and panels. (Rules 1.3, 1.6)
• Rules 1.6, 1.11 Fasten the hood securely with pins, not bolts. (Rules 1.6, 1.11)
• Rules 1.3, 1.6 No concave hoods and no air scoops. (Rules 1.3, 1.6)

Engine placement

• Rule 3.5 The motor sits in its stock location. (Rule 3.5)
• Rule 3.5 On G-body cars (GM's 1978-88 rear-drive mid-size cars, such as the Monte Carlo, Cutlass Supreme, Regal and Grand Prix), keep at least 1.75 in from the center of the fuel pump to the front of the crossmember, and leave that crossmember unaltered. (Rule 3.5)
• Rule 3.9 You can't alter the frame or crossmembers to make room for the engine. (Rule 3.9)

The doors and quarter panels (the body sides behind the doors) are the body's factory steel panels or steel replacements. They sit in the factory location and keep the stock shape. No skirts (strips added along the bottom edge of a panel). (Rule 1.3)

Doors and quarter panels

• Rule 1.9 Secure every door shut, by welding, chaining, bolting or something similar. (Rule 1.9)
• Rule 1.3 The door bottoms stay in the OEM location: no more than 5 in outside the frame, and no lower than the bottom of the frame. (Rule 1.3)

Rub rails

• Rule 1.4 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 1.4)

Door bars and door plate

The door bars are the horizontal cage tubes beside the driver, inside the door skins.

• Rule 2.7 3 horizontal door bars on each side. (Rule 2.7)
• Rule 2.7 At least 4 uprights from the frame to the top door bar on the driver side, and at least 3 on the passenger side. (Rule 2.7)
• Rule 2.1 Door bars use the main cage tubing; see Cage-to-body fit. (Rule 2.1)
• Rule 2.7 Driver-side door plate: steel, at least 18-gauge (0.049 in), welded securely to the outside of the 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 (the cage tube from the halo down to the frame behind the driver) to 6 in ahead of the seat. Keep it visible for inspection. (Rule 2.8)

The car has to have its factory steel top. G-body cars are the exception: they can run an aftermarket fiberglass OEM replacement roof. (Rules 1.1, 1.3)

Roof

• Rule 1.2 Sunroofs and T-tops have to be reinforced and enclosed. (Rule 1.2)

Pillars and windshield

• Rule 1.4 Windshield bars. At least 3 windshield bars in front of the driver. (Rule 1.4)

Windows and visors

• Rule 1.8 No glass (see Cutting and gutting). (Rule 1.8)
• Rule 1.5 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 1.5)

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 15.13 Recommended: approved racing arm restraints. (Rule 15.13)

The trunk lid is mandatory, and the fuel cell rides in the trunk with a firewall between it and the driver. (Rules 1.11, 7.4.2, 7.4.4)

Trunk lid

• Rule 1.6 Use the OEM trunk lid or an aftermarket one in aluminum or steel. You can gut it, meaning strip the inner structure and keep the outer skin. (Rule 1.6)
• Rules 1.3, 1.6 Rule 1.6 allows an aluminum trunk lid, but rule 1.3 says replaced body parts must be steel; the rulebook conflict is under Body and panels. (Rules 1.3, 1.6)
• Rules 1.6, 1.11 Fasten the lid securely with pins, not bolts. (Rules 1.6, 1.11)
• Rules 1.3, 1.6 No concave trunk lids, and no spoilers or wings. (Rules 1.3, 1.6)

Tail piece

• Rules 1.3, 1.12 Aftermarket tail pieces are allowed. A tube rear bumper has to be covered by a molded plastic tail piece; the plastic conflict is under Nose and bumpers. (Rules 1.3, 1.12)

Fuel cell and rear firewall

• Rules 7.4.1, 7.4.3 Use a commercially made fuel cell in a steel container. No boat tanks or stock automotive tanks. (Rules 7.4.1, 7.4.3)
• Rule 7.4.1 Up to 22 gallons. (Rule 7.4.1)
• Rules 7.4.2, 1.14 Fasten the cell securely inside the trunk, higher than the level of the body's factory trunk floor. It sits over the trunk floor section described under Trunk floor. (Rules 7.4.2, 1.14)
• Rule 7.4.2 Hold it with at least 2 solid steel straps around the cell, each 0.125 in thick and 2 in wide. (Rule 7.4.2)
• Rule 7.4.5 All mounts are steel and attach to the frame or the roll cage. No adjustable mounts. (Rule 7.4.5)
• Rules 1.14, 4.4 The rear firewall follows the factory pattern and location of the body you're running. Like the front one, you can repair the factory one or build it from 0.049 in steel to the factory dimensions; see Firewall and floor. (Rules 1.14, 4.4)
• Rule 2.11 A fuel cell protection bar is mandatory: frame rail to frame rail, inside the trunk area and no higher than the fuel cell, in tubing up to 1.75 in diameter, 0.095 in wall. (Rule 2.11)

Trunk floor

• Rule 1.14 No trunk floor over the rear end, back to the spot where the body's factory trunk floor steps down. If you're building from a donor car, cut that section out. (Rule 1.14)
• Rule 1.14 You do need trunk floor under the fuel cell. You can build that section from 0.049 in steel, kept above the frame rails. (Rule 1.14)

Five interior measurements run back from the rear of the engine: the front firewall, the dash, the seat back, the rear hoop and the speaker deck. (Rules 1.8, 1.14, 2.5, 4.4, 4.6.3)

Firewall and floor

Each firewall follows the factory pattern of the body you're running, sits in its factory location and reaches all the way out to the body. You can repair the factory firewall or build a new one from 0.049 in steel, keeping the factory dimensions. (Rule 1.14)

• Rule 1.14 Front firewall: at least 24 in tall, and it can be flat ("flat or straight" in the rulebook). (Rule 1.14)
• Rule 1.14 The front firewall is the one exception to the factory location. You can move it back, as long as it ends up no more than 7 in behind the back of the motor. (Rule 1.14)
• Rule 15.15 The piece that closes the gap from a firewall's edge out to the body skin can be plastic. Rule 15.15 names it as one of the two areas where that rule allows plastic; see Panel materials. (Rule 15.15)
• Rule 9.10 The brake master cylinder mounts on the firewall in its stock location. (Rule 9.10)
• Rule 1.14 Floor: build it new or repair the factory floor in steel, keeping the factory dimensions. The rule's words say forty-nine hundredths (0.49 in) thick; its digits say 0.049 in. (Rule 1.14)

Dash and interior sheet metal

• Rules 1.8, 4.2 No interior tin or other covers, apart from the dash tin below. (Rules 1.8, 4.2)
• Rules 1.8, 4.2 The dash, dash tin included, reaches no more than 32 in back from the rear of the engine block. (Rules 1.8, 4.2)
• Rule 1.8 The dash is flat and level, except for the cowl (the panel between the hood and the windshield) in front of the driver. (Rule 1.8)
• Rule 4.4 The rear speaker deck (the shelf behind the seat, under the back window) stays OEM, in its factory location. If it reaches more than 99 in back from the back of the engine, you carry at least 25 lb of lead on the right front cage hoop, ahead of the shock and spring location, until it's repaired. (Rule 4.4)

Seat position

• Rule 4.6.3 Mount the racing seat with fasteners and washers of at least 3/8 in. (Rule 4.6.3)
• Rule 4.6.3 The seat back sits no more than 70 in behind the rear of the engine block. (Rule 4.6.3)

Cage-to-body fit

The cage is a full-perimeter, four-post cage (4 main uprights down to the frame) of continuous hoops, welded securely to the OEM frame. Officials have to accept the installation and the workmanship. (Rules 2.3, 2.4, 2.5)

• Rule 2.1 Main cage and door bar tubing: at least 1.666 in diameter, 0.095 in wall, with every roll bar joint properly welded. (Rule 2.1)
• Rules 2.1, 2.10 No offset cages, no aluminum or other soft metals and no square tubing or galvanized pipe in the main cage. (Rules 2.1, 2.10)
• Rule 2.1 Front hoops are allowed. (Rule 2.1)
• Rule 2.5 Top halo (the top hoop 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)
• Rules 2.4, 2.5 At least 40 in between the front and rear down bars (the tubes from the halo down to the frame), measured at the top of the door panel. Tie the front down bars together. (Rules 2.4, 2.5)
• Rule 2.5 No more than 76 in from the back of the engine to the front edge of the rear hoop. (Rule 2.5)
• Rule 2.4 An X-brace (two diagonal tubes crossing in an X) in the rear hoop, plus rear kickers (diagonal braces from the rear hoop toward the back of the frame), both in tubing at least 1.25 in diameter, 0.083 in wall. (Rule 2.4)
• 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)

Build on a bare frame: an unaltered OEM frame, or the Speedway replacement frame, Speedway Motors' new-built copy of GM's metric frame (the 1978-88 mid-size rear-drive perimeter frame). You can also convert a street car, unibody cars (body and frame one welded structure) included; those rules are under Donor cars and Unibody cars. (Rules 3.2, 3.9, 3.10)

Which frame

• Rules 3.3, 3.6, 3.9 Frames and crossmembers stay OEM and unaltered, apart from the changes under Allowed frame changes, and you can't change them for engine placement or suspension clearance. (Rules 3.3, 3.6, 3.9)
• Rule 3.10 The Speedway OEM replacement frame, part #91678881, is allowed, unaltered. (Rule 3.10)
• Rule 3.1 Frame, engine and body all come from the same maker: GM with GM, Ford with Ford and so on. (Rule 3.1)
• Rules 3.1, 3.10 The Speedway frame is a copy of GM's metric frame, so for the same-maker rule it goes with a GM body and engine. (Rules 3.1, 3.10)

Allowed frame changes

• Rule 3.3 You can X-brace the frame. (Rule 3.3)
• Rules 2.10, 2.12 X-bracing and any bars added to the frame or cage: no bigger than 1.75 in diameter, 0.12 in wall round tube, or 1.25 in, 0.12 in wall square tube. Square tube still can't go in the main cage. (Rules 2.10, 2.12)
• Rule 3.6 Starting no farther forward than 1 in behind the factory seam (a factory weld where frame sections join), you can replace the frame behind the rear tires with 2 in by 3 in steel tube, up to 0.12 in wall, in the stock location. (Rule 3.6)
• Rule 3.6 The factory seam stays visible, and the new tube replaces the same length of frame 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 1.1 If you're building from a donor car, it has to be one of the allowed cars under Body and panels. (Rule 1.1)
• Rules 3.1, 3.9, 3.10 The frame under it follows the same rules as any other frame (see Which frame), including the same-maker rule. The rulebook doesn't require the donor's own frame. (Rules 3.1, 3.9, 3.10)

Unibody cars

A full frame is a separate frame that runs around the car under the body. (Rule 3.2)

• Rule 3.3 If you're building from a unibody car, tie the rear frame to the front frame. (Rule 3.3)
• Rule 3.2 Unibodies need at least 110 in of wheelbase; see Wheelbase, ride height and weight. (Rule 3.2)

Hanging the body

• Rule 1.3 The body sits in its OEM location on the frame, the same place the factory put that body. The rulebook doesn't name the mounting points. (Rule 1.3)
• Rule 1.3 Door bottom position is under Doors and sides. (Rule 1.3)

Wheelbase, ride height and weight

• Rule 3.2 Wheelbase (center of the front hub to center of the rear hub): at least 107.5 in on full frames and at least 110 in on unibodies, with no more than 1 in difference from side to side. (Rule 3.2)
• Rule 3.8 Ride height: the frame sits between 5 and 9 in off the ground, measured behind the front tires and in front of the rear tires, with the driver in the car. (Rule 3.8)
• Rule 14.2 Car weight: at least 2,950 lb on American Racer tires. Cars on OEM passenger tires have no minimum weight. (Rule 14.2)
• Rule 14.1 The car is weighed at the end of the event, with the driver in the cockpit in full racing gear. (Rule 14.1)
• Rule 14.3 Ballast goes only in the trunk area or the motor compartment, never in the cockpit. (Rule 14.3)
• Rule 14.3 Put at least half as much ballast in the motor compartment as you add in the rear. Example: 50 lb in the rear means at least 25 lb up front. (Rule 14.3)
• Rule 14.4 Paint all ballast white, mark it with the car number and bolt it down with 1/2 in bolts, 2 for every 50 lb, with no more than 25 lb on any one bolt. (Rule 14.4)

Hobby Stock uses factory bodies: a 1960 or newer American-made OEM stock passenger car with a factory steel top. (Rule 1.1)

Allowed bodies and kits

• Rules 1.1, 3.1, 3.4 Not allowed: Camaros, Mustangs, Firebirds, station wagons, convertibles, rear-engine cars, front-wheel or four-wheel drive cars and any body from a front-wheel-drive car. (Rules 1.1, 3.1, 3.4)
• Rule 1.3 No spoilers, wings, skirts, air scoops or anything else that changes the stock appearance. (Rule 1.3)
• Rule 1.3 Aftermarket nose and tail pieces are allowed; see Nose and bumpers. (Rule 1.3)

Panel materials

• Rule 1.3 The body is OEM steel, in the OEM location. (Rule 1.3)
• Rules 1.3, 1.6 Any part of the OEM body you replace has to be steel. Rule 1.6 separately allows aftermarket aluminum hoods and aftermarket aluminum trunk lids. (Rules 1.3, 1.6)

• Rule 15.15 Plastic is allowed only from the edge of the firewall to the body skin and from the inner wheel tub to the body skin. For plastic nose and tail pieces, see Nose and bumpers. (Rule 15.15)
• Rule 1.3 G-body cars can run a fiberglass OEM replacement roof; see Roof, pillars and windows. (Rule 1.3)
• Rule 3.7 No titanium anywhere on the car. (Rule 3.7)

Cutting and gutting

• Rules 1.8, 15.15 No glass, upholstery, rear seats, lights, mirrors or chrome on the car, and no plastic except where Panel materials allows it. If you're building from a donor car, strip these parts out. (Rules 1.8, 15.15)
• Rule 1.10 The front and rear inner wheel wells are optional. (Rule 1.10)

Damage

• Rule 1.7 Repair sharp edges, torn fenders and torn body panels before the next race. (Rule 1.7)
• Rule 1.13 Officials can keep a car with excessive body damage from racing. (Rule 1.13)

Numbers and appearance

• Rule 1.15.1 Numbers. Every car carries large, readable numbers on both sides, on the roof, on the nose and on the rear panels. (Rule 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)
• Rule 1.15.2 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 1.15.2)