Roll Cages

2.6.1

It is each competitor’s responsibility to present a safe vehicle for pre-event technical inspection. Competitors must maintain their safety equipment including the roll cage integrity. Ultra4 reserves the right to not allow any cage designs that, in the opinion of the Chief Technical Inspector, is not fit for competition. Competitors are ultimately responsible for their vehicle’s safety features, including the design, fabrication, quality of execution, maintenance and repair of the roll cage structure. The roll cage is considered to be the main 6-point structure that surrounds and protects the vehicle’s occupants.

2.6.2

All vehicles must be equipped with a roll cage fabricated of 1020 mild steel mechanical tubing or better (higher carbon content or alloy steel). The following minimum mild steel tubing sizes for roll cage main structure, based on dry vehicle weight rating (DVWR) in race trim, not including occupants, -are required:

• DVWR Under 3200 lb. (1452kg) - 1.5” (38mm) diameter x .120” (3.0mm) wall thickness or 1.75” (45mm) diameter x .095” (2.5mm) wall thickness.
• DVWR 3201 lb. (1452kg) - 4400 lb. (1996kg) - 1.75” (45mm) diameter x .120” (3.0mm) wall thickness.
• DVWR Over 4400 lb. (1996kg) - 2” (50mm) diameter x .120” (3.0mm) wall thickness.

2.6.3

Supporting Tubes as defined above with an unsupported span of less than 30” (762mm) are allowed to be the same diameter as the main structure in the .095” (2.5mm) wall thickness or .25” (6mm) smaller tube diameter with .120 (3.0mm) wall thickness. All unsupported span more than 30” (762mm) must be the same diameter and thickness as the main structure. No aluminum or other non-ferrous materials are permitted. (All specifications may be substituted with metric equivalent).

2.6.4

Roll cage main structure material may be CREW, DOM, WHR, or WCR mild carbon steel or 4130 chromoly alloy steel. All welds must be of high quality and craftsmanship with good penetration and with no undercutting of parent material.

2.6.5

All roll cage components (hoops, braces, gussets, etc.) must have a minimum of 3” (75mm) of clearance from any vehicle occupant’s helmet when occupant is seated in normal driving/riding position. All roll cage components that might come into contact with the vehicle occupants’ helmets must be padded.

2.6.6

Roll cages must be securely mounted to the frame, chassis, or body. Roll cage terminal ends must be attached to a frame or body member that will support maximum impact and not shear or allow movement in the cage terminal end. Cab/body-mounted roll cages must sandwich the body structure using a minimum of two .1875” (4.75mm) thick, dissimilar sized, doubler plates, one on each side of the body structure. Roll cage mounting fasteners must be at least .375” diameter S.A.E. Grade 8 (10mm gr 10.9) or equivalent or better. Sandwich plates, if used, must be oriented only in the horizontal plane. No vertical or other non-horizontal sandwich plate orientations are permitted.

2.6.7

All vehicles, including those with stock steel doors, must have at least one side bar on each side of vehicle that will protect occupants from side impact. The sidebars must be of the same tubing material and dimensions as the main frame of the roll cage. The sidebars should be as close to parallel to the ground as possible, must be located to provide maximum protection to the occupants, and must be securely welded to the front and rear hoops of the roll cage. The location of the sidebars must not cause difficulty in entering or exiting the vehicle.

2.6.8

Gussets must be installed at all major intersections, including diagonal and rear down braces, where single weld fractures can affect occupants’ safety. Gussets constructed of 3” (75mm) x 3” (75mm) x .125" (3.5mm) flat plate or split, formed and welded corner tubing, or tubing gussets made of the same material and thickness as the roll cage may be used.

2.6.9

Six (6) point mounting cages are required over the occupants.

2.6.10

A minimum .040” (1mm) flat sheet magnetic steel or .125” (3.5mm) aluminum must cover the area immediately above the occupants’ seats and be attached via welding or bolting to a steel tubing framework.

2.6.11 Engineering

• Option #1: follow safety cage rules as outlined above.
• Option #2: Provide at driver of record’s sole expense a certified engineered drawing to be reviewed by Ultra4 and FOCUS Engineering consultant for approval. Final approval will be by Chief Technical Inspector. All findings will be private between driver of record, Ultra4, and FOCUS.
• Option #3: Ultra4 will have proposed chassis design engineered and make all findings public record. Final approval will be by the Chief Technical Inspector.