AMC 20 4.56 Ring and Pinion Gears

The 4.56 ratio is a highly popular aggressive upgrade for the AMC 20 rear axle in 1976-1986 Jeep CJ5, CJ7, CJ8, and similar models, delivering exceptional low-end torque, outstanding crawl capability, and quick acceleration compared to milder ratios like 3.73 or 4.10—making it ideal for 33-35" tires on moderate to heavy off-road builds or up to 35-37" tires on dedicated trail rigs, though it pushes highway RPMs higher (typically 2800-3200+ RPM at 65-70 mph depending on transmission, overdrive, tire diameter, and final drive setup). It requires the 3.07-up carrier (per AMC 20 carrier breaks) and is commonly chosen for serious regearing after significant tire upsizing to regain lost power, excel in rocks, steep inclines, mud, or low-speed crawling, improve towing grunt, or optimize performance with manual transmissions—though it may feel revvy on long highway drives without overdrive. Browse a wide variety of AMC 20 ring and pinion gears in 4.56 ratio from trusted brands including Revolution Gear (M20-456), Motive Gear (AM20-456), Yukon Gear, USA Standard Gear (ZG M20-456), Alloy USA, Crown Automotive, and others to pair with installation kits, precision bearings, heavy-duty shafts, and traction devices for a complete, durable regear that unleashes maximum off-road capability while maintaining reliability.