IndyCar manufacturers Chevrolet and Honda are taking a deep look into their oval aero kit packages following two spectacular crashes this week at Indianapolis Motor Speedway.

They haven't found a common denominator yet, though safety concerns continue to loom over the Indianapolis 500. The lingering image of three big crashes, two that sent drivers airborne, has many wondering if this already risky business is being compounded by the debut of the new packages on the series' fastest track.

Friday's practice finally went off without a hitch, something those working on and driving the cars expected.

"I think that people have no clue what they're talking about. They speculate," said Tony Kanaan, the 2013 Indy winner who drives for Chip Ganassi Racing. "The two accidents were completely distinct. One was driver error and actually flipped the car. The other one a tire went down that went underneath the car and made the car roll over. It didn't flip. So we're not having cars flying in the air."

The replays paint a different picture, which is why series officials and the two engine manufacturers are looking into what happened.

IndyCar already has tweaked one rule — making the centerline wicker optional instead of mandatory. The part is designed to help keep cars keep all four wheels on the track.

Series spokesman Mike Kitchel said the adjustment was made because Chevy did most of its testing without the part, and team owner Ed Carpenter said Thursday his team was advised by Chevy to remove the wicker.

A few hours later, one of Carpenter's drivers, Josef Newgarden crashed in almost the exact same spot three-time Indy winner Helio Castroneves did Wednesday. Both hit the wall in the first turn and started rolling backward before the air flipped over both Chevrolet-powered cars.

Neither was seriously hurt.

"There's no wind tunnel test that you can run going backward. You just can't do it," Honda Performance Development president Art St. Cyr said. "This is the proving ground, they're new kits. The feedback that we get is that the car's planted and stable. We haven't had any stability concerns raised."

And while the accidents looked similar, the cause was not.

Newgarden's crash was believed to be the result of a cut tire, while Kanaan blamed his fellow Brazilian, Castroneves, for making a rare mistake.

Jim Campbell, Chevy's U.S. vice president of performance vehicles and motorsports, issued a statement Friday saying the removal of the wicker made a difference for Newgarden, who called it one of the hardest hits he's ever endured.

"Following Helio's incident, we met with IndyCar and agreed that the best course of action was to remove the centerline wicker," Campbell said. "In Josef's case, prior to his car making contact with the wall, the removal of the wicker demonstrated its desired result because the car, while traveling at a high rate of speed, nearly completed a full spin with no aero lift. It was only after the car hit the wall and lost body work that its tires lost contact with the racing surface."

While crashes like this have been decreasing in the IndyCar Series, they are still not unprecedented.

Two-time Indy champion Dan Wheldon was killed when his car sailed 325 feet through the air and hit a catch-fence post during a 2011 race in Las Vegas. Former IndyCar driver Mike Conway sustained serious back and leg injuries when his car flew into the catch-fence late in the 2010 Indy 500. Three-time 500 champion Dario Franchitti sustained career-ending concussion symptoms when his car flipped into the catch-fence in a frightening scene at Houston in 2013.

But Castroneves, of Team Penske, and Newgarden, an American, hardly missed any track time. Castroneves returned to the cockpit in his backup car about five hours after his crash and finished eighth on Friday's speed chart at 229.852, slightly behind his teammate, Simon Pagenaud, who had the best lap of the day at 230.698.

Team Penske president Tim Cindric also said the team worked with three or four different body configurations Friday and had no problems.

Newgarden drove 52 laps Friday, posting a top speed of 227.855 and was 28th and never gave it a second thought.

"I feel pretty confident in the car, the series, Chevrolet," Newgarden said. "Everything that we're doing, I don't feel any different than I did coming into the event."

The fears could have been predictable.

Two years ago, IndyCar officials announced they wanted to safely chase the track's speed records, a goal they'd like to achieve next year when the 500 holds its 100th race. Arie Luyendyk posted the fastest qualifying lap in Indy history, 237.498, and the fastest four-lap average of 236.986 in 1996.

Speeds are now increasing again, and some believes Sunday's pole-winner will top 233 mph — a number that is rekindling the decades-old question about how fast is too fast?

"As you go up in speed, the risk goes up," said Bobby Rahal, the 1986 Indy winner and one of the series' team owners. "Certainly things like the SAFER wall have made racing on ovals much, much safer than it was in my era. But as we've seen, it still carries a certain degree of risk out there and the faster you go, the higher that degree becomes."

That's why the manufacturers are back at work.

Drivers can usually avoid big trouble in a practice crash because the cars are spread out. But when 33 cars are going flat out at the May 24 race, a car going airborne could become a disaster.

"We've done multiple simulations in various configurations to make sure there's not some unattended issue that we haven't seen yet," St. Cyr said. "Everything that we've run says that we're as good as we can be based on computer simulations."