Alloy USA 4.56 Ring & Pinion Set for 76-86 Jeep CJ with AMC Model 20 Rear Axle

Bigger tires can transform the capability and appearance of a classic Jeep CJ, but they can also reduce the fun of the drivetrain. Increasing tire diameter effectively raises the vehicle's overall gearing, which can leave the engine working harder to accelerate, climb grades, or crawl through technical terrain. The Alloy USA 4.56 Ring & Pinion Set gives Jeep owners a way to bring that mechanical advantage back with a deeper 4.56:1 axle ratio.

Designed for the AMC Model 20 rear axle used in applicable 1976–1986 Jeep CJ models, this ring and pinion set replaces the existing differential gears as part of a properly configured axle regear. The 4.56 ratio turns the driveshaft 4.56 times for every rotation of the axle shafts, providing greater torque multiplication than numerically lower axle ratios. For a CJ running larger-than-stock tires, that can mean stronger low-speed response, easier starts, and improved control when the trail starts pointing uphill.

The benefits aren't limited to crawling over rocks. Matching axle gearing to tire diameter can help return the drivetrain to its intended operating range. That means less reliance on excessive throttle to get moving and improved access to the engine's useful powerband. For owners building a CJ around larger tires, the right gearing can make just as much difference in how the Jeep drives as many more visible modifications.

Alloy USA engineers its ring and pinion gears for the demanding loads generated inside an off-road differential. Precision-machined gear teeth promote proper engagement between the ring gear and pinion, while high-quality gear steel provides the durability required for repeated acceleration, trail work, and everyday driving. Proper professional setup remains critical, since backlash, pinion depth, bearing preload, and gear contact pattern all directly affect performance, noise, and service life.

The Alloy USA 4.56 Ring & Pinion Set is an excellent foundation for a complete AMC 20 axle rebuild or a CJ drivetrain upgrade built around larger tires. When changing axle ratios on a four-wheel-drive Jeep, the front and rear axle ratios must match. Installation also requires the right bearings, shims, seals, and related setup components, so a master installation kit is a smart addition when completing the regear.

Fitment Note: Designed for applicable 1976–1986 Jeep CJ models equipped with an AMC Model 20 rear axle. Verify the vehicle's axle model and differential configuration before ordering. On four-wheel-drive vehicles, the front axle must use a matching 4.56 gear ratio before operating the vehicle in four-wheel drive.

Installation Notes

Installation Difficulty:

Level 4Experts Only

Installation Time: 4-6 hours

Parts Included

Ring Gear
Pinion Gear

Warranty

Minimum 5 Year Limited Warranty.