Unified Dirt Late Model Council update (Jan. 20)
Updates issues Jan. 20 by the Unified Dirt Late Model Council that governs rules for the Lucas Oil Late Model Dirt Series, World of Outlaws Craftsman Late Model Series and several other racing organizations focusing on rear suspensions, brakes, wheels and springs:
Late Model Technical Bulletin
Rear Suspension and Suspension Components:
• Axle Housing, Rear Differential
• The axle housing must be of the “closed tube” design utilizing “full floating” magnetic steel axle shafts.
• The center section of the axle housing must be manufactured of either aluminum or magnesium.
• Axle tubes must be one (1) piece. Axle tubes must be manufactured of aluminum or magnetic mild steel. Axle tubes manufactured of exotic, heavy materials will not be permitted. The outside diameter of the axle tubes must not exceed three (3) inches. Axle tube internal inserts or external sleeves will not be permitted. The addition of any ballast weight to the axle housing will not be permitted.
• Axle Housing Mounts
• The only materials used to fabricate axle housing mounts (birdcages) that will be permitted is aluminum or magnetic mild steel. Axle housing mounts fabricated of exotic, heavy materials will not be permitted.
• When fabricating axle housing mounts detail must be paid to functionality. The completed axle housing mounts, when comparing the right and the left side, must be as similar in design as possible.
• Rear Suspension Attaching (Radius) Rods
• The only materials used to fabricate attaching (radius) rods that will be permitted are magnetic steel or aluminum
• Aluminum attaching (radius) rods may be solid or tubular material. Magnetic steel attaching (radius rods) must be tubular with a maximum wall thickness of 3/16 inch.
Brakes, Brake Components, Wheel Hub:
• Brake calipers must be manufactured of aluminum.
• The brake caliper including brake caliper pistons must be used as produced by the brake caliper manufacturer.
• Brake rotors must be manufactured of magnetic or stainless steel.
• Brake rotors must be used as produced by the brake rotor manufacturer.
• Wheel hubs must be manufactured of aluminum or magnesium.
• Wheel hubs must be used as produced by the wheel hub manufacturer.
• The combined weight of the wheel hub, wheel bearings and seal, spindle nut and washers, brake rotor and attaching hardware, the axle cap, and the wheel spacer must not exceed 27 pounds.
Wheel, Wheel Discs, Wheel Spacers:
• Only aluminum wheels will be permitted.
• Only approved wheel discs will be permitted. Approved wheel discs are wheel discs that are fastened to the wheel using a minimum of three (3),1/4 or 5/16 inch diameter magnetic steel hex head bolts.
• Only aluminum wheel spacers will be permitted. Wheel spacers must not be fastened to the wheel.
• The combined weight of the wheel, wheel hardware, wheel disc and fasteners, and tire must not exceed 40 pounds*. *The maximum combined weight in this rule is based upon current tire rules and may need to be adjusted in the event of an alternate tire.
Springs:
• Coil springs or leaf springs will be permitted.
• Coil springs must be manufactured from magnetic steel. Leaf springs must be manufactured from either magnetic steel or approved composite material.
• Spring preload adjustments for coil springs must be made using mechanical adjusting nuts on the shock body.
• Spring preload adjustments for leaf springs must be made using a mechanical adjusting device such as an adjustable shackle or threaded rod type mount.
• Other than spring dampening by the shock absorber, hydraulic, pneumatic, or electrically controlled adjusting devices, (static or dynamic) that affect spring preload or race car heights will not be permitted.
As agreed by the Unified Late Model Council –January, 20 2017 rev.10
