Crane Magnum Knuckles – The Strongest & Lightest Big Knuckle for Rock Crawlers, Rock Bouncers, Ultra4 & Hardcore Trail Rigs

The Crane Magnum Knuckle is the strongest, lightest, and most proven big-knuckle platform in the off-road world. Engineered to be the cornerstone of elite axle builds, these knuckles have been tested globally in Ultra4 racing, professional rock bouncing, and hardcore rock crawling—with unmatched success and durability.

Designed for maximum strength, steering performance, and serviceability, the Magnum Knuckle fits the RCV Big Bell axle stub without removing the boot, making maintenance faster and easier than any competing knuckle system. With dual tapered roller bearings, a fully greaseable design, and serviceable bearings available at local parts stores, this knuckle is built for long-term reliability on the trail and in competition.

Whether you're building a high horsepower rock bouncer, an Ultra4 endurance racer, or a bulletproof trail rig, the Crane Magnum Knuckle is the elite choice that top builders trust.

Includes:

(2) Magnum Knuckles
(2) Inner C's
(2) High Steer Arms
(2) Upper Tapered Roller Bearings
(2) Lower Tapered Roller Bearings
(2) Upper/Lower Bearing Pins
(2) Kingpin Caps
Hardware Kit

Made in USA

Specifications

Strongest & Lightest big knuckle in the off-road industry
Proven in Ultra4, professional rock bouncing, rock crawling, and global trail riding
Accepts RCV Big Bell axle shafts without removing the boot
Top & bottom tapered roller bearings allow perfect preload setting
Fully greasable bearings for extended maintenance intervals
Bearings can be purchased at any local parts store
C's available 3.5"–4.0" bored
2.5-Ton Rockwell spindle bolt pattern
Compatible with:
- 2.5-Ton Rockwell spindles & hubs
- Crane Axle Unit Bearing Adapters
- 05+ Ford Super Duty unit bearings
- RCV 40 spline inner shafts
- RCV Big Bell stub shaft
- Forged 1550 U-joint shafts
- 2.0" inner axle shafts
Works with all Crane Axle brake kits for both Rockwell and 05+ Ford hub configurations
Capable of 46° of steering (with preferred Crane + RCV setup)
Designed as a fully modular axle-building platform

Fitment

The Crane Magnum Knuckle system is designed for custom-built front axles used in:

Rock Crawlers
Rock Bouncers
Ultra4 Race Cars
Trail Rigs
Fabricated Off-Road Axles
High-Horsepower, Large-Tire Rigs (40–47")

Compatible with:

Rockwell 2.5-Ton spindle setups
05+ Ford Super Duty unit bearing conversions (when using Crane adapters)
Custom-built 14-bolt, 60, 80, and fabricated housings with 3.5–4" bores

Tech Insight

The Magnum Knuckle is the product of years of real-world racing abuse, engineering refinement, and testing across every terrain imaginable. By eliminating weaknesses found in factory and aftermarket knuckles, Crane engineered a steering platform that can handle extreme articulation, high horsepower, hydro assist, and massive tire loads without failure.

The RCV Big Bell compatibility sets this system apart—no boot removal, no stretching components, no hassle during trail repairs. Combined with dual tapered roller bearings, easily adjustable kingpin preload, and fully greaseable components, this knuckle delivers unmatched strength and service life.

Wide Open Design’s preferred race setup uses Crane Unit Bearing Adapters, 05+ Ford unit bearings, RCV 40 spline inners, and the RCV Big Bell stub. This combination produces up to 46 degrees of steering, incredible lateral strength, and the best serviceability in the industry—a true game-changer for Ultra4, rock bouncing, and extreme off-road builds.

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