Rules changes for Kentucky and Michigan races

Changes to the rear spoiler, front splitter and rear deck fin will be put into play for two upcoming NASCAR Sprint Cup Series races as the sanctioning body continues to reduce aerodynamic downforce and sideforce in an effort to promote closer competition on the race track. The changes, announced Thursday morning, will be in effect only for upcoming races at Michigan in June and Kentucky in July and are in addition to previous adjustments made by the officials in recent weeks. Initial moves implemented before the start of the season combined with a Goodyear tire matched more closely to the lower downforce package have resulted in closer competition through the season's first 12 races.

Why more changes? "I think we look at it as a never-ending journey; if we can improve we're going to do that," Steve O'Donnell, executive vice president of competition and chief racing development officer said. "We wanted to go the direction of low downforce, see how that worked, not kind of go all the way in and hope that we are directionally right. And we are seeing that play out. We've seen some great racing at the beginning of the year. But we also knew that we had some more levers that we could pull if the direction kind of proved out, so we've tried some of those things. We've tested it and what we've also wanted to do is lower some of the corner speeds to allow for even more passing. That was one of the areas where we've seen minimal change, but there are some levers we can pull to really drive that down."

The changes for those races consist of a reduction in spoiler height from 3.5 inches to 2.5 inches, a splitter reduction of two inches and a re-sizing of the rear deck fin to complement the spoiler change. Beginning with this year's race at Kansas Speedway, NASCAR required teams to weld truck arm mounts; for the recently completed Sprint All-Star Race at Charlotte Motor Speedway, downforce-generating electric fans were removed and the rear toe alignment was reset to zero to reduce sideforce. The changes to truck arm mounts and fans are to remain in place for the remainder of the 2016 season. The rear toe adjustment was initially only in play for the All-Star event but now will be incorporated into the June Michigan and July Kentucky races. Downforce is the pressure created across the surface of a vehicle at speed. Likewise, sideforce is generated by the flow of air along the sides of the vehicle.

O'Donnell said limiting the latest changes to two upcoming races is beneficial in two ways: Teams have spent plenty of time in development of setups with the initial base package and that information will still be relevant; and focusing on two tracks will give teams and officials much-needed information as they look ahead to 2017. "We have worked collectively on some directions we want to go in, but to do that right we think the final step is to let that play out on one or two tracks," he said. "And these are the two — Kentucky and Michigan — that we've played out and let the teams concentrate really on what they've done to prepare for the year. We think that's manageable and that'll give us enough data to look at for 2017."(NASCAR)