WATKINS GLEN, N.Y. – A confluence of events — contact with another car, excessive heat of a broken caliper and a gradual stop – caused the bizarre explosion in Derrike Cope’s car Saturday.
NASCAR vice president of officiating technical inspection Elton Sawyer said Cope picked up a right-front vibration that apparently came from hitting a competitor on the previous lap and shearing off the caliper from the spindle. Cope began to slow down his No. 70 Chevrolet, seeking an exit from the track as he realized his brakes were failing.
As he nearly came to a stop in the inner loop of Watkins Glen International, the excessive heat generated by the loose caliper melted the bead on the right-front tire and caused the fabric in the sidewall to deteriorate.
When Cope began to stop, the radiant heat (and a lack of airflow to dissipate it) built pressure within the tire, causing its sidewall to blow out. The resultant concussion was violent enough to crumple Cope’s hood.
Sawyer said it was likely the first time NASCAR had witnessed such an incident. Melted beads from excessive brake aren’t uncommon at tracks such as Martinsville Speedway, but the key variable is that they normally happen at speed, causing rapid deflation of the tire.
Because Cope was slowing down to exit the 2.45-mile track, the tire hadn’t gone flat before the sidewall exploded.
“As soon as the vehicle comes to a stop, you have all the radiant heat sitting there, basically the soft point of the sidewall is where it explodes,” Sawyer said. “We’ve seen tires blow at speed and go down so we don’t see it in a static situation like (Cope’s incident). All the same symptoms led up to this other than he stopped.”
A massive plume of what seemed to be black smoke erupted from Cope’s car after the explosion, but Sawyer said it was brake dust, and that nothing ignited within the car.
“There was never any actual fire,” he said.
NASCAR returned the car to Cope’s team after its postrace evaluation, and Sawyer said the incident would be reviewed at the R&D Center in Concord, North Carolina, for potential changes.
“When you’re at a high speed place where high braking, a Martinsville, we see (melted) beads all the time,” he said. “The situation here is when the vehicle came to a stop, there’s probably no air moving, so that’s probably the biggest issue. … It’s not something we’ll sweep under the rug. We’ll take a look at it, but it nothing I could equate to Martinsville if we have that situation.”
Derrike Cope Racing also released a report on the incident Sunday morning, saying the damage to the nose, hood and fenders was mostly cosmetic.