Impact Of New NASCAR Sway Bar Rule Unclear Heading Into Kentucky Weekend

NASCAR’s rule changes concerning the rear sway bars of Sprint Cup Series cars are a significant story to watch heading into this weekend’s Quaker State 400 at Kentucky Speedway.

The sway bar rule has the potential to impact the performance of teams which had been making advances in that area. Those teams, which include Hendrick Motorsports, had set up the sway bar at an angle that would skew the rear ends and helped the cars turn better in the corner.

NASCAR frowns upon skewed rear ends because it makes the cars look like they’re “crab-walking” down the straightaways. In 2008, officials implemented another in-season rule change to try and restrict the angle of the rear-end housing (remember Sam Hornish Jr.‘s Charlotte car that year?).

Starting at Kentucky, the sway bar arms must be perpendicular to the ground. Therefore, the advantage some teams gained in making the cars turn might be taken away. The key word is “might,” because it’s unclear to everyone just exactly how big of an advantage it was.

“Very curious to see how that resets the competition from a speed platform,” Brad Keselowski said Thursday. “... I think it’s going to be a major game-changer on who is fast and who is competitive and who is not.”

Hendrick’s setups were not “illegal” during its recent hot streak, when it won five of six events (including the All-Star Race) prior to Sonoma. But the team had creatively found something with the sway bars that worked within the rules, and other teams began to notice and follow suit.

During the recent Michigan race won by Hendrick’s Dale Earnhardt Jr., the Richard Childress Racing cars each used the angled sway bar as part of their setups for the first time (Stewart-Haas Racing cars, which share setup information with Hendrick, were rumored to be using it as well).

“I think everybody has caught on to what they were doing with the bars...and everybody was getting ready to venture down that road and spend a lot of time (in that area),” RCR’s Kevin Harvick said last week. “There is some significant speed in that particular package.”

Keselowski estimated “half of the field” was using the angled sway bars and said those cars will “slow down quite a bit” without it.

“It was certainly worth some speed,” said Keselowski, whose Penske Racing team was not working in that area. “Those teams deserve the credit for develop those parts and making them work. NASCAR felt like they were outside the intent of the rules, obviously, by creating a rule specifically to stop it.

“They didn’t do anything illegal, they just took advantage of the rules as they stand and found some performance.”

So what kind of impact will the new rule really have for cars like Dale Earnhardt Jr.‘s No. 88? A handful of drivers polled via text message on Thursday generated opinions ranging from minimal to wait-and-see, though none predicted a dramatic slowdown for Hendrick’s cars.

In other news, the Cup teams will also lose some aerodynamic grip this week thanks to another NASCAR rule change concerning the length of the side skirts. But most people in the garage feel that rule change will have a minimal impact compared to the sway bar change.

NASCAR is changing the side skirt length in an effort to promote more side-by-side racing (the thought being that if cars depend less on aero devices, it will improve the racing).