Soaring above Johnson Valley, California. (Image/Proving Grounds’ Facebook Page)

We introduced you to Proving Grounds Racing a few weeks ago, as the race team was preparing for the grueling King of the Hammers annual off-road race.

Since the literal dust has finally settled, we wanted to see how the Proving Grounds Racing team fared in this year’s event with its new 4400-class Ultra4 racer.

4400-Class Ultra4 Racer #4415

Despite being an all-new build and the team logging very little seat time, 4415 qualified well and was ready for race day. (Image/Proving Grounds’ Facebook Page)

All eyes were on 4415, the one-off custom off-roader made specifically to campaign in the 4400 Unlimited class for Ultra4 events like the King of the Hammers. It was a freshly-built off-road buggy and the team hoped it was ready to tackle the demanding 90-mile race.

Qualifying runs were held on a distinct 1.14-mile course that served as a sample of what the main course throws at you. The Proving Grounds team qualified 49th out of a field of over 100 vehicles—quite an impressive feat given how little driving time the team had in the all-new 4415.

On race day, the 700-horsepower 4415 roared past the green flag. The first lap of the course was over 75 miles long, by far the longest single run of the truck’s early career. It tackled the course well, navigating complex rock obstacles and blasting across the dry lakebed, with an easily-fixed loose power steering fluid filter as the sole setback.

Then disaster stuck.

While tackling one of the more intense uphill climbs, a front axle shaft grenaded. Nonetheless, 4415 limped on for a short while, before the Proving Grounds team made the decision to retire and spare the off-road rig from any further damage.

Here’s a look at 4415’s knuckle after the axle had some separation anxiety. Bummer. (Image/Proving Grounds’ Facebook Page)

2021 King of the Hammers Post-Race Thoughts

Despite retiring early, the Proving Grounds Racing folks have a lot of good takeways. While they were optimistic going into the King of the Hammers, 4415 was still relatively untested and it was debuting in what is arguably the toughest off-road race in the world.

In reality, 4415 performed flawlessly on both the rock crawling and flat-out sections—a catastrophic failure like a sheared axle was something that could’ve happened to any rig.

So, as all good race teams do, Proving Grounds has set its sights on the next stop on the Ultra4 schedule. They’re heading to the Lasernut “Area BFE Beatdown” in Moab, Utah this April. And we’re sure we’ll see them again in the 2022 edition of the King of the Hammers.

You can see the entire Ultra4 racing schedule here. This year is packed with events, so you can cheer-on Proving Grounds and the other off-road racers all year ’round.

Click here for the results from the 2021 King of the Hammers event.

Ultra4 racer 4415 poses with its teammate, a 4500-series truck number 4570 that’s based on a Jeep Wrangler Unlimited TJ/LJ. (Image/Proving Grounds’ Facebook Page)
Author: Paul Sakalas

Paul is the editor of OnAllCylinders. When he's not writing, you'll probably find him fixing oil leaks in a Jeep CJ-5 or watching a 1972 Corvette overheat. An avid motorcyclist, he spends the rest of his time synchronizing carburetors and cleaning chain lube off his left pant leg.