The Verizon IndyCar Series’ new aero kit rules were always expected to generate a significant increase in downforce, and it didn’t take very long for the custom bodywork from Chevy and Honda to cross a major – and somewhat concerning – threshold once testing began in October.

After years of delays, aero kit regulations were finally confirmed in May of 2013, and one of the earliest questions asked by teams, drivers, aero kit manufacturers, and even this writer, involved the Dallara DW12’s design limits and tolerances.

Was the DW12, which was penned in 2011 using Dallara’s spec wings and bodywork, capable of withstanding the increased forces put through the suspension (and other load-bearing items) from the new high-downforce aero kits?

The question was about safety; no one wanted to have the DW12’s stock suspension buckle under the supreme downforce generated by the new-for-2015 aero kits. And at the other end of the argument, many team owners have bristled at the thought of spending money on aero kits, which made asking them to purchase new, stronger chassis components to better cope with the added downforce a non-starter.

Of the available options to the series’ technical staff, calling for changes to the aero kit regulations – after Chevy and Honda produced and started testing their respective kits – was made late last year. With both manufacturers headed in different directions on filling the various open aero development areas atop the DW12, IndyCar modified the rules with the one sizeable, common item used by both brands, and has taken downforce away from the spec Dallara floor.

The series made a pre-emptive move prior to initial aero kit testing when it introduced holes on both sides of the floor next to the sidepod radiator inlets which, according to IndyCar president of competition, reduces about 300 pounds of downforce. That change was done in anticipation of increased downforce numbers, but once the series saw the figures that were returned from early aero kit testing, it became clear a second round of reductions would be required.

Chevy and Honda were instructed to remove the diffuser strakes from the new Dallara floor, and to pull both diffuser sidewalls, which then required a significant re-working of their aero kits to function with less underbody downforce and increased drag. At present, strakes and sidewalls will not be allowed on road and street courses, or short ovals.

It's hard to complain about any changes being made in the name of safety, although both aero kit manufacturers did tell RACER rule changes coming late in the game, and at their expense in terms of time and money, was less than optimal.

“Yes, there’s been a modification by IndyCar with the aero kits to specifically take away some of the performance the kits will make,” Honda Performance Development vice president Steve Eriksen confirmed. “It was done very last minute, I must say, to make sure the aero kit gains did not go so far that other parts of the car had to be replaced.”

“Anytime you’ve got carry-over components on a vehicle you’re trying to improve, you’ve got to understand the loads and what those load limits might be,” added Chevy IndyCar program manager Chris Berube. “That goes all the way to the tires, frankly. There were changes made later than were desired, but we have no choice but to react to them. I’ll just say it would have been nice to know that earlier to avoid some re-work.”

Like Berube and Chevy, Eriksen says Honda has taken the changes in stride.

“When they made the change, we’d already begun production on certain aero kit components, and I understand why they made it; that’s their responsibility as the governing body to make sure everything is safe, so we of course supported it in the end,” Eriksen noted.

Coupled with the 300 pounds of downforce carved from the new floor, the lack of strakes and sidewalls should bring the total reduction to something in the 700-pound range. Each aero kit manufacturer has spent time working to adjust their designs to account for the change, and as one would expect, Chevy and Honda have done their best to claw back as much of the new 400-pound loss as possible in their final submissions to the series.

The next question to be answered is whether the homologated aero kits and subsequent aero development through 2015 and 2016 will push the downforce figures back into the danger zone.

“Whatever level of performance we come out of the box with in 2015…we’ll have to see,” Eriksen said. “There are other freedoms we’re allowed to make – open development areas, if you like – which could bring the [downforce] figures up again, so we’ll have to see if IndyCar implements more countermeasures as a result.”

All of the aero kit rule changes and late-stage bodywork alternations have taken place in private, and as a result, Berube says the look of the aero kits prior to the rule change will remain private.

 “It’s definitely impacted what we’re allowed to do, but the fans’ reference is the DW12, so they won’t really know what could have been,” he explained. “They’ll see what we’ve come up with in light of the changes. I’m told the [Chevy and Honda] kits will look quite different, and for those who are interested in technical details, they’ll see a lot of new parts and technical solutions. The changes did alter the shape of the car, but no one on the outside will be able to tell.” ​

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