Shannon Campbell is one of the most dominant figures in Ultra4 Racing, with three King of the Hammers titles to his name (2008, 2011, and 2017). His 2011 win, however, was particularly groundbreaking—it marked the first time an independent front suspension (IFS) vehicle conquered the world’s toughest off-road race.
This victory not only cemented Campbell’s legacy but also sparked a shift in Ultra4 technology, proving that IFS could compete with and even outperform traditional solid-axle setups. Revisiting my original report from February 2011, I uncovered the key innovations behind Campbell’s revolutionary 5AZ—a prototype that forever changed the future of off-road racing.
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Shannon Campbell stands as one of the most legendary and successful drivers in Ultra4 Racing. With three King of the Hammers titles (2008, 2011, and 2017), he has firmly etched his name in off-road racing history. His 2011 victory was especially groundbreaking, marking the first time an independent front suspension (IFS) vehicle triumphed in the world’s toughest one-day off-road race. Revisiting my original article from February 2011, I’ve uncovered the technical innovations that made this pioneering rig a true game-changer.
While researching for a new article on the King of the Hammers, I stumbled upon a deep dive into the long-standing debate between solid axles and independent suspension. At the end of the discussion, a list of past winners from 2007 to 2025 caught my attention, specifying whether each champion’s vehicle featured solid axles or IFS.
King of the Hammers Winners and Suspension Setup
- 2007: JR Reynolds (Solid)
- 2008: Shannon Campbell (Solid)
- 2009: Jason Scherer (Solid)
- 2010: Loren Healy (Solid)
- 2011: Shannon Campbell (IFS) – First-ever IFS victory
- 2012: Erik Miller & Robert Ruggiero (Solid)
- 2013: Randy Slawson (Solid)
- 2014: Loren Healy (Solid)
- 2015: Randy Slawson (Solid)
- 2016: Erik Miller (Solid)
- 2017: Shannon Campbell (IFS)
- 2018: Jason Scherer (IFS)
- 2019: Jason Scherer (IFS)
- 2020: Josh Blyler (Solid)
- 2021: Randy Slawson (Solid)
- 2022: Raul Gomez (IFS)
- 2023: Raul Gomez (IFS)
- 2024: JP Gomez (IFS)
- 2025: Kyle Chaney (UTV IFS)
The First IFS Victory in King of the Hammers History
Shannon Campbell is one of the few drivers to have won the King of the Hammers three times. However, his 2011 victory was particularly significant—it marked the first time an IFS-equipped vehicle had won the grueling event, proving that independent suspension could not only compete but also dominate against traditional solid-axle setups.
Reading through this information felt like stepping back in time. I was there in Johnson Valley on that Friday in February 2011. I witnessed this pivotal moment in off-road history firsthand and had written a technical report on Campbell’s revolutionary vehicle. I immediately dug into my archives, uncovering my original photos and article from that unforgettable race.
Campbell 5AZ: The Game-Changing Prototype
“Sometimes, defying conventional wisdom and embracing unconventional technical choices can be the key to success. In this case, that bold decision earned the protagonist of our story the title of ‘King’ and led him to victory in the 2011 Ultra4 Series.”
“I’m talking about Shannon Campbell, the founder of Campbell Enterprises—a U.S.-based company specializing in off-road race vehicle fabrication—and, of course, about his groundbreaking prototype that secured him a place in the record books.”
Two fundamental aspects set this Ultra4 rig apart from the competition: its independent front suspension system and its single-seat tubular chassis. The latter design choice meant Campbell had to race without a co-driver—something that could be a disadvantage in tricky situations. However, as Campbell pointed out, this setup significantly reduced weight and improved the vehicle’s balance.
After closely analyzing his vehicle during the King of the Hammers, I completely agreed with his assessment. Even in the most demanding rock trails of Johnson Valley, the combination of raw horsepower, superior vehicle agility, and Campbell’s exceptional driving skills made a co-driver unnecessary.
The second major design choice—the IFS suspension—gave Campbell’s 5AZ a clear edge in handling. The system allowed for greater precision, particularly on the high-speed sections that make up about 80% of the King of the Hammers course. His 2011 victory wasn’t just a personal achievement; it was proof that IFS technology could succeed at the highest level.
Shannon Campbell’s triumph changed the landscape of Ultra4 racing, paving the way for future champions to embrace independent suspension. What was once seen as an unconventional gamble became a game-changing innovation—one that continues to shape the evolution of off-road competition today.
The Secrets Behind Shannon Campbell’s 2011 5AZ
Shannon Campbell’s 2011 5AZ is a powerhouse, boasting 550 aggressive horsepower from a Corvette LS3 6.2L Small Block V-8, expertly modified by Turnkey Engine in California. Unlike traditional setups, the engine is mounted at the rear of the chassis, which brings unique characteristics to the transmission system.
A dual Dynomax steel exhaust handles the outflow, while cooling is managed by a large Ron Davis Racing aluminum radiator equipped with two vertically mounted electric fans positioned behind the engine.
Due to the rear-engine configuration, both the Hughes Performance Turbo 350 automatic transmission and the Advance Adapters Atlas 3.0 transfer case have been installed in an inverted position, occupying the space typically reserved for the co-driver inside a central tunnel. To withstand the immense torque and stress, the 1350-series driveshafts are custom-built by Arizona Driveshaft.
Axles & Differentials
One of the most distinctive aspects of this vehicle is its axle setup. The front suspension features independent arms connected to a Currie 9″ Center Section, sending power to the wheels through reinforced axle shafts. The rear axle is a custom-built 9″ Currie Enterprises unit, with the differential offset to the right for perfect alignment with the drivetrain. Differential locking is managed by an ARB air locker, ensuring optimal traction when needed.
Suspension & Steering
At the front, the IFS system consists of a large, reinforced lower A-arm paired with an upper tubular control arm, securing the hub assembly with high-performance uniballs. Suspension duties are handled by Fox Bypass shocks combined with Coilovers, offering impressive wheel travel thanks to the arm length and optimized geometry.
The rear suspension, designed for durability and articulation, follows a more traditional setup with a 3-link system, including two robust lower arms and a single upper tubular link. A Panhard bar is positioned behind the axle, directly mounted to the frame for lateral stability, while a Currie Antirock sway bar enhances control. The rear also features long-travel Fox Bypass and Coilover shocks to maximize axle movement.
Steering is powered by a Howe Performance rack-and-pinion system, operating through a track bar that moves laterally to control the hub-mounted steering arms. This setup ensures precise handling without altering wheel alignment during suspension articulation.
Chassis, Exterior & Interior
The entire chassis was custom-engineered and fabricated by Campbell Enterprises, reinforcing the vehicle’s aggressive, speed-focused design.
Mounted above the steering system, a Warn 9000 winch provides recovery capability. The vehicle rolls on 40×13.50R17 Goodyear Wrangler tires wrapped around 8.5×17 Walker Evans Racing Beadlock alloy wheels. For night racing, a roof-mounted frame holds three high-output KC lights with protective covers.
Inside, a MasterCraft Safety racing seat with multi-point harnesses keeps the driver secure. The minimalist dashboard is positioned to the right of the driver, housing all essential controls. A quick-release Sparco racing wheel ensures optimal maneuverability in high-speed conditions.
Technical Specifications
- Wheelbase: 3,040 mm
- Track width: 2,130 mm
- Weight: 1,573 kg
- Fuel capacity: 95 liters (Fuel Safe fuel cell)
This vehicle was a game-changer in Ultra4 Racing, setting the stage for the future of IFS rigs at King of the Hammers.
