Flexible Bodywork
When the Car Changed Shape at Speed
Rodney Childers had a problem with Kevin Harvick’s Ford.
NASCAR had already decided what shape the back of the car was supposed to be. Unfortunately, the shape NASCAR liked was not necessarily the shape the air liked best.
At roughly 180 mph, small changes in the way air crosses the roof, rear window and spoiler can produce useful changes in drag and downforce. Crew chiefs spend considerable time looking for exactly those advantages.
NASCAR, inconveniently, owns templates, gauges and an entire collection of people whose job is making sure nobody finds too much of one.
So the useful shape had to pass inspection first.
Then the air could finish the job.
A Perfectly Well-Behaved Race Car
Sitting still, Harvick’s Stewart-Haas Racing Ford could present itself for inspection like a respectable member of society. Roof where it belonged. Rear window where it belonged. Bodywork behaving itself while the inspectors walked around poking, measuring and generally ruining everybody’s fun.
Then came the Pennzoil 400 at Las Vegas in March 2018.
Harvick’s Ford was not merely fast. It spent most of the afternoon making the rest of the field look as though they had shown up for a different race. Harvick won both stages and the race, finishing nearly three seconds ahead of Kyle Busch while third place wound up more than thirteen seconds back.
That sort of performance gets attention.
Especially from the fellows carrying measuring equipment.
Then somebody looked at the rear window.
The Window Had Been Busy
The right side of the rear window was bowed, and the area around it no longer looked quite like the tidy shape that had gone through inspection before the race.
Stewart-Haas said a rear-window support brace had failed.
Race cars break things all the time.
They simply do not always have the courtesy to break in exactly the area where everybody in the garage has been searching for aerodynamic speed.
NASCAR later acknowledged that teams had found performance around the rear-window area and were pushing it. So here sat Harvick’s dominant Las Vegas winner with a failed support brace and a rear window that had conveniently adopted another shape after spending the afternoon under aerodynamic load.
Racing produces some remarkably helpful failures.
The Wind Did the Adjusting
The beauty of flexible bodywork is that the car can sit still and look perfectly legal while aerodynamic pressure does something more useful once the speed comes up.
No mechanic has to climb onto the deck lid at 180 mph with a wrench.
The wind does the adjusting for free.
If the rear-window area moves, the airflow leaving the roof changes before it reaches the deck lid and spoiler. That can alter pressure and rear downforce, which is exactly the sort of improvement teams spend wind-tunnel time and engineering money trying to find.
Officially, Harvick’s brace failed.
It failed in a mighty convenient direction.
NASCAR Wasn’t Buying the Coincidence
The No. 4 went to NASCAR’s Research and Development Center after the race. Officials determined that the brace supporting the rear window had failed to keep the glass rigid in all directions at all times.
That is a wonderfully specific rule unless racers have already given the rulebook writers a reason to make it specific.
The team received an L1 penalty. Harvick lost 20 championship points and seven playoff points, Rodney Childers was fined $50,000 and car chief Robert Smith received a two-race suspension.
Harvick kept the victory.
Several of the things attached to winning it disappeared.
Everybody Had Found the Same Neighborhood
The No. 4 was not an isolated curiosity that NASCAR forgot about by Tuesday.
Other teams were soon getting caught with rear-window and roof areas doing suspicious things of their own. By May, NASCAR’s competition department was openly saying teams had found performance there and that the nonsense needed to stop.
That sounds considerably less like a collection of random broken braces and considerably more like several teams had discovered the same useful idea.
Inspection had checked what the cars looked like while parked.
The garage had figured out what they could look like while moving.
Templates Work Better in the Garage
That is the weakness in inspecting a race car while it is standing still.
You can measure every curve, check every height and make sure the window sits exactly where the drawing says it should. Then somebody sends the thing down the straight at 180 mph and lets aerodynamic load start negotiating with the bodywork.
Harvick’s Ford passed through the weekend looking like one car and finished the race looking like another.
Stewart-Haas called it a failed brace.
NASCAR called it a violation.
Funny how the wind always seems to know when the templates are back in the garage.