Both Mustangs copped damage when Vaughan made contact with and spun Dalton during a concertina incident at the exit of the final corner.
Dalton explained that he’d let Aaron Cameron through at the final corner before following the Kelly Racing Mustang into the pits.
“We were just coming into the pits and the pit entry is very awkward here, it’s right on the racing line, when you’re trying to commit to the throttle you’re out that wide,” Dalton told Speedcafe.
“I was cooling down, I’d seen Aaron coming through, I’d backed off and let him through, Aaron and I came to the pits and Brad was obviously starting a lap.
“Unfortunately he just nailed the rear of me and put me in the fence. It was a pretty decent hit, I was facing the wrong way.
“It’s unfortunate, it’s not really anyone’s fault I don’t think, it’s just the nature of this circuit.”
Vaughan added: “Everyone has checked up into the last corner there.
“I’ve come out of the corner starting my lap, and they’ve all checked up. It was probably no one’s fault, just one of those Sandown things that happens.”
The two cars completed the session sporting notable panel damage; Vaughan ninth-fastest and Dalton 12th.
Vaughan is on double duties at Sandown, also making his Supercars Championship debut as co-driver to Matt Chahda in the Boost Mobile-backed Camaro wildcard.
Eggleston Motorsport’s Kai Allen set the pace in Practice 1 for the Super2 Series ahead of Zach Bates, Jobe Stewart, Jack Perkins and Cameron.