Next Gen analysis: Digging into the car changes for Bristol dirt race

2022april12 Next Gen Dirt Bristol

Editor’s note: Bozi Tatarevic is a professional racing mechanic and pit-crew member. He will provide technical analysis for throughout the 2022 season.

The NASCAR Next Gen car is set to race on dirt for the first time later this week at Bristol Motor Speedway, and like the previous generation car, it required some changes in order to make the shift from pavement to dirt. Most of these changes are pretty straightforward with the ultimate goal of not collecting dirt on body panels and suspension components.

Bozi Tatarevic
Bozi Tatarevic

Rules Bulletin No. 8 was released a couple of weeks ago, and it jumped into many details of what the specs would look like for dirt racing with the Next Gen car. The first updates are seen in the safety section and show us our first view of some of the unique components for the Bristol dirt race. One such example is the panel that sits below the engine, so the rules have been updated to add specific wording and diagram on how that engine panel must be tethered to the chassis, including the specific anchors that must be used.


An array of approved parts has also been added to the “Dirt Event Debris Shields” section under rule 14.6, which lists approved panels that must come from Fibreworks, along with shims and mounts that teams may supply on their own. In addition to the parts list, updates have been added for specific changes related to the underwing and diffuser, including parts that will be omitted for dirt events, such as the diffuser flap cable, diffuser flap assembly and diffuser scoop extension panel.


As many of the composite parts used for the rest of the schedule are being replaced with metal pieces for dirt events, there is now also an added clause stating that “deburring and breaking sharp edges will be permitted within reason on all metal parts” as tied to internal heat shielding and bracing. In addition to those changes, additional shielding will be permitted from the front firewall forward to prevent mud and dirt from collecting in the engine bay.

Screens will also be permitted for rocker box vents and rear wheel tub vent. The exhaust exit shrouds must be mounted on the inside of the rocker boxes versus their typical mounting on the outside, which is likely to prevent dirt catching on them. The final update will be welcomed by fans of color-matched side skirts and rocker boxes as it states “paint or vinyl will be permitted on the outside vertical surface of the rocker boxes” for dirt events.

On the suspension side, another rule has also been added in that section that will allow spring bags to be installed on the damper assembly for dirt events. Installing spring bags is likely being allowed because it would prevent dirt from getting behind the springs and inside the dampers as it would fully cover them.

RELATED: Full Bristol Motor Speedway schedule

Dirt event details have been added to the vehicle inspection measurement pages as well, and as with other races, the wheelbase specification is 110 inches. However, for dirt, the allowable tolerances have been adjusted by a few tenths of an inch specifically for that surface, but the upper and lower limits remain within less than an inch of each other.

The other update is in the ground clearance section that states skid blocks, commonly called rub blocks, must be removed for all dirt events. A cover plate that is 0.125 inches thick must be added in lieu of the skid blocks to protect the recovery strap location and conical receiver reference surface.

Most of these components were tested and validated at Lancaster Speedway last year and finalized in the months since then. Once the final package was assembled, the test car was sent to Bristol with Stewart Friesen behind the wheel again and tested in conditions similar to what we will see in the race in order to confirm the parts and pieces.

In addition to the components that were previously approved, replacing the windshield with a mesh screen was also tested but not chosen at this time due to the requirement for more research from the safety side and the likelihood of having to build some type of deflection cover for the driver’s hands.

The Next Gen car looked very much at home on the dirt at Bristol as Friesen tested, and initial videos appear to show the Cup car has picked up some speed over what we saw last year. That wouldn’t be surprising considering the range of adjustments available with the new car, especially when it comes to the independent rear suspension. Seeing a full field of Next Gen cars on the dirt this weekend should provide for a great show as drivers try to slide their way to a victory.