ULTRA4 Class Differences

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This is just a brief overview of the basic class differences that race in ULTRA4.

Please Note: If you are planning on building and racing a car, you MUST consult the rule book for ALL requirements for your desired class! This page is just a brief overview of the class differences. Also be sure to check out the article on How to pass ULTRA4 Tech and Chassis Inspection. 

4400: ULTRA4 Unlimited Class
This is the original unlimited class that started King of The Hammers. These cars compete during the main King of The Hammers race on Friday of KOH Week. 4400 Drivers have to earn a spot to compete in King of The Hammers. Currently drivers can qualify for the following year's race by: 1. Finishing top 20 at KOH or 2. Finishing as one of the top 10 non-qualified drivers at regionals and nationals.

These cars  are not limited on tire size, engine or chassis design, other than to meet the safety requirements for the class. Unlimited cars must have a transfer case and be able to be driven in 4WD. These cars can be straight axle, or independent front suspension (IFS). This is currently the largest class of vehicles at the regional races where there are anywhere from 40 to 90 4400s entered to race.

4500: Rubicon Express Modified Class
This class has been racing in ULTRA4 since 2012. It is one of the 4 classes that races on Thursday of KOH week during the Smittybilt Every Man Challenge. Currently, these cars do not have to qualify to race in the EMC race during KOH Week.  At regional races, this class, if large enough, races on their own or can be on the track with the 4600, 4700 or 4800 cars.

Class Characteristics:

  • Modified OEM Chassis or OEM Style Chassis
  • 2 -2.5 inch diameter shocks per corner
  • Mechanical Steering
  • 37” DOT approved tires

4600: Pro Comp Stock Class
This class has been racing in ULTRA4 since 2012. It is one of the 4 classes that races on Thursday of KOH week during the Smittybilt Every Man Challenge. Currently, these cars do not have to qualify to race in the EMC race during KOH Week.  At regional races, this class usually races with either the 4500 or 4800 cars.

Class Characteristics:

  • Stock OEM Frame
  • Factory Engine
  • Factory Transmission
  • 35” DOT approved tires
  • Single 2.5 inch diameter shocks per corner
  • Mechanical Steering

4700: Spec Class (Western Series Only)
This class has been racing in ULTRA4 since 2014. It is one of the 4 classes that races on Thursday of KOH week during the Smittybilt Every Man Challenge. This class consists currently of 6 identical cars that drivers can rent. For more details on 4700 spec class rentals you can visit this web site or email [email protected] These cars do not have to qualify to race in the EMC race during KOH Week.  At regional races, this class usually races with either the 4500 or 4800 cars. Currently, this class does not race in the Eastern Regional Series.

  • Chassis has the look of a classic JK but fully equipped with top aftermarket parts, including:
  • Mopar Hemi 5.7 Motor
  • Fox Racing Shox
  • Dynomax Exhaust
  • Spidertrax Axles & Housings
  • Yukon Dropouts & Lockers

4800: Legends Class - Trophy Class
This class has been racing in ULTRA4 since 2014. It is one of the 4 classes that races on Thursday of KOH week during the Smittybilt Every Man Challenge.These cars do not have to qualify to race in the EMC race during KOH Week.  At regional races, this class usually races with either the 4500, 4600  or 4700 cars.  This class is one of the fastest growing classes in ULTRA4 as older ULTRA4 cars can enter this class as long as they meet the requirements. This class is a sportsman class and races for trophies not for purse money, allowing for lower entry fees.

  • Front mounted engines only
  • Vehicle must contain 2 seats side by side
  • Single shock per corner
  • Max 37” DOT non-sticky tires
  • Only solid axles allowed (not IFS or TTB)

UTV Pro:
This class is the 2nd oldest class during KOH Week and has been racing for 7 years, since the 2009 KOH Race. Typically, the KOH UTV Race is held on the Wednesday of KOH Week. The Pro class races for a purse whereas the UTV Sportsman class race for a trophy:

  • Must be 1000 ccs or less
  • Vehicle must have a 6 point aftermarket cage
  • Belts must be 5 point harness
  • Additional tech and safety requirements apply

UTV Sportsmen: Trophy Class

The UTV Sportstman class has evolved over the last few years to include those drivers that want to experience KOH at a Sportsman Level.  Typically, the KOH UTV Race is held on the Wednesday of KOH Week. This class races exclusively for trophies allowing for lower entry fees.

  • Must be 1000 ccs or less
  • Vehicle must have a 4 point aftermarket cage used in conjunction with aftermarket rear bracing to create a 6 point cage
  • Belts may be 4 point harnesses
  • Additional tech and safety requirements apply