How to Race King of the Hammers 2024: Ultra4 Cars Explained  

Do you want to be part of the gnarliest single-day off-road race ever created? It's not the Dakar Rally or the Baja 1000—those are longer than 24 hours. And the Mint 400? Short course racing? Rock bouncing? Not quite "gnarly" enough. Instead, King of the Hammers holds the crown as the most difficult one-day off-road race on the planet—and here's why.

King of the Hammers is unique because it combines high-speed, wide-open desert racing with technical rockcrawling. It's called Ultra4 racing and it tests every off-road skill of both racer and race machine. During the race, cars can travel over 100 mph across dry lakebeds and open desert tracks then bash their way through narrow canyons choked with dumpster-sized boulders. Each vehicle in the King of the Hammers race is built specifically to withstand each of these challenges, and then some. Before we dive into what makes an Ultra4 car the ultimate off-road machine, let's look closer at what King of the Hammers is.

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What Is King of the Hammers?

King of the Hammers began as a challenge among a handful of friends, with its first official race in 2008. The event has grown significantly since then to include multiple racing classes strung out over nearly three weeks where anything from Volkswagen Bugs and dirt bikes to side-by-sides and trophy trucks can race. King of the Hammers is held in Johnson Valley, California and each year, Means Dry Lakebed is transformed into a sprawling desert metropolis of dust and metal where racers and off-road enthusiasts come to enjoy the festivities. More than 50,000 fans have been known to bring their RVs and camp out Burning Man-style on the lakebed for the duration of the event. But what if you want to be more than a spectator at King of the Hammers?

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What Is an Ultra4 Race Car?

Ultra4 cars are the ultimate off-road machines because they are built to excel in a variety of extreme conditions—anything from hard-core rockcrawling to screaming across the desert at outrageous speeds. Ultra4 races held outside the California desert throw mud, muddy rocks, water crossings, and trees into that mix. What parts does it take to build a machine this capable? Josh Sowell, a racer from SoCalEx Motorsports, gave us the breakdown on how his 4800 Ultra4 car is equipped to race during King of the Hammers, and beyond.

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What Is the 4800 Class?

King of the Hammers, like other races in the Ultra4 series, is divided by race classes, each with a set of rules governing how the car is built. For example, the 4400 class is limited only by itsminimumtire size (at least 37 inches in diameter) and adherence to the safety guidelines. Cars in the 4400 class can be powered by any engine of unlimited power and use any combination of chassis and suspension configurations with any number or type of shock absorbers or even engine positions. Other classes, like the 4800 class come with tighter restrictions. Cars in the 4800 class must have a solid axle in the front, a front-mounted engine, a single shock absorber per corner, and tires can only be as large as 37 inches. Engine output is unlimited in the 4800 class.

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Race-Ready Chassis

While some classes require the original body and frame, 4800 Ultra4 cars can have tube-frame construction. Josh's chassis was built by Randy Slawson of Bomber Fabrication. Slawson is a multiple-time winner of the King of the Hammers race and the maker of race-ready tube chassis kits and other componentry.

Unlimited Engine Options

With no restrictions on engine displacement in the 4800 class, Josh's car gets its power from a modified LS3 V-8 fitted with LS7 heads, and more. Power flows rearward through a 4L80 automatic transmission and into an Advanced Adapters Atlas 2 transfer case. The modified engine is said to put about 650 horsepower to the dirt.

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Hammer-Ready Axles

Ultra4 cars thrash what is essentially a Jeep Wrangler suspension through unforgiving rocks and across the desert whoops at dizzying speeds. Yes, this car and many others like it rely on a pair of beam axles suspended by one shock absorber per corner to dispatch irregularities in the racecourse. Unlike the stock hardware underneath Wranglers, Josh's axle housings are armored for battle, gusseted for even more strength, and stuffed with 40-spline axle shafts and 5.43:1 differential gears. Cars opting for independent suspension are inherently more compliant in higher-speed bump scenarios, but they suffer drawbacks. IFS cars lose ground clearance as the suspension compresses and their design requires far more moving parts than a beam axle setup. Diligent racers often spend close to $5,000 in routine maintenance on axle and suspension parts alone due to the complexity of the systems. By comparison, what beam axles lack in their high-speed bump-taming abilities, they regain in stone age strength, reliability, and serviceability. Which is best for King of the Hammers? By the numbers, more cars with beam axles have taken home the crown.

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Hard-Core Off-Road Suspension

Rules constrain 4800 cars to a single shock absorber per corner—and those dampers must be tuned to handle triple-digit speeds as well as the head-toss of dancing across refrigerator-sized hunks of rock. Fine-tuning the sway bar, shock mounting points, and type and number suspension linkages can affect a car's performance. Josh's car uses a dual-triangulated four-link suspension in the front and rear.

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Ultimate Grip Tires

With tire diameter limited to 37 inches in the 4800 class, Josh runs 37-inch Milestar Patagonia mud-terrains and beadlock wheels from Vision Wheels. Aiming those big meats is made easier in the rocks with a full-hydraulic steering ram kit.

Extreme Upgrades

Ultra4 cars get stuck—and they have the gear to get un-stuck. Up front, there's a Warn winch capable of pulling 9,000 pounds. Underneath the car, the skidplates are made from UHMW poly material (think: cutting board plastic) to reduce weight and maximize the car's ability to skid across rocks rather than hanging up on them. Spare parts carried onboard often include extra belts, hoses, axle shafts, U-joints, wiring, fans, fluids, tires, and other items needed to coax a damaged car across the finish line.

Want to Race King of the Hammers?

It can be easy! While some choose to hand-build these cars, you can rustle one up in the classifieds for $100,000-$200,000. Outlets like Bomber Fabrication can deliver a race-ready machine with all the accoutrements within the $200,000-$350,000 range. With the car secured, racing King of the Hammers is as simple as acquiring a race license and a pit crew. A rookie program has even evolved to build a welcoming community for those new to the off-road and Ultra4 racing scene.

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King of the Hammers 2024 (KOH2024)

King of the Hammers 2024 takes place in Johnson Valley, California between January 18 and February 3. Racing includes everything from King of the Motos and the Kids' Race to Baja VW Bugs and the penultimate Race of Kings on the closing day of the event. Don't give a hoot about racing? Fine! Bring your off-road vehicle of choice and camp out in the epic Johnson Valley OHV area alongside thousands of dirt enthusiasts.