Triple Eight is working to identify a mystery balance issue which left Shane van Gisbergen convinced something had broken on his car during practice at Hidden Valley.

The reigning Supercars champion was unable to lap within 0.3s of his team-mates Jamie Whincup and Craig Lowndes, who ended practice first and third respectively.

Van Gisbergen was able to drive around the issue to third and ninth in the two 45-minute sessions, but was adamant something on his car had failed.

“It wasn’t a very good day. The car just doesn’t feel normal, something has been broken all day, so we’ve got to find out what it is,” said van Gisbergen.

“We’re not sure what it is, otherwise we would have fixed it.

“We were still okay, it just doesn’t feel like our normal car.

“Something is quite bad. We’re still quick, but it just feels horrendous, so hopefully we can fix it.

“We had too many problems today to get a feel for the track, we’re just chasing our tail round in circles. Luckily we get another practice session tomorrow.”

Triple Eight team manager Mark Dutton says early assessments of the car following practice have failed to reveal the source of the problem.

“There is nothing obviously broken but there are some question marks as the car is behaving very differently to the test day, and there is not any clear reason for that,” Dutton told Speedcafe.com.

“We’ve got to try and analyse that tonight and come up with some solutions.

“There was no vibration or clunks but the feeling was so odd and that is why he felt there was something broken.”