NASCAR announced a new practice adjustment for the O’Reilly Auto Parts Series at Darlington Raceway, permitting teams to change rear springs while the cars are on the track during practice sessions.
For years, teams have been restricted to minor tweaks such as tire pressure, trackbar and shock modifications, with the removal of any component—particularly at the rear of the car—largely prohibited.
The COVID‑19 pandemic further limited practice time, shortening sessions and curtailing the ability to swap parts or make effective use of a second set of tires.
Although practice sessions were later extended to a full 50 minutes, the rulebook still barred spring changes, leaving teams to rely heavily on pre‑session simulation work.
The NASCAR Cup Series adopted comparable adjustments, but stopped short of expanding beyond tire set swaps, keeping the O’Reilly Series as the testing ground for more liberal practice rules.
Rear spring alterations have been permitted in special cases, such as when resin is applied at Dover, demonstrating that NASCAR has occasionally allowed this type of modification when the situation demands it.
The Darlington change is welcomed by crews because it offers additional setup flexibility, giving both well‑funded and smaller teams the chance to fine‑tune their cars without depending as much on simulator preparation.
A right‑rear spring swap at Darlington can dramatically alter handling characteristics, helping drivers adapt to the track’s unique surface and improve overall performance.
Series officials view this step as a potential precursor to broader practice rule revisions that could eventually filter down to the Cup and Truck divisions, signaling a shift toward more dynamic and equitable competition.