Reynolds was the fastest Holden driver and fourth quickest overall in final practice before Friday's qualifying barely 24 hours after his chances of contesting the session were all but written off.

Reynolds' quest to bounce back from a disastrous 2018 campaign appeared over after co-driver Luke Youlden hit the wall on Thursday.

His Penrite Racing team admitted they would be lucky to get the Commodore back in shape for qualifying late on Friday afternoon.

However after they worked around the clock, Youlden was back on track for Friday morning's opening one hour practice which was restricted to co-drivers.

"They worked their arses off," team official Barry Ryan said.

"After the massive effort last night ... the car's fine. It's exactly as it was before he crashed it."

Youlden overcame his mental demons to finish 12th fastest in his session.

"I did battle mentally a bit," he said.

"I just wanted to make sure it came back (to the garage).

"I can't apologise enough for yesterday."

The dramatic re-build also ensured Reynolds got valuable time behind the wheel in Friday's final practice before qualifying starts at 1600 AEDT.

It is a shot in the arm for 2017 Bathurst champion Reynolds who is out for redemption at Mount Panorama after his bid for back-to-back wins was sabotaged last year by severe cramp.

"Yesterday they were talking about not even making this session but the boys have done an unbelievable job just to make everything perfect," he said.

"They put a lot of time and effort and love and care into it."

Reynolds backed Youlden to overcome the incident and push for their second Great Race title in three years.

"He's getting himself back up to speed," he said.

"It was super important, super necessary to give him some quality laps out there because after a big shunt your confidence level can get cut in half."

Australian Associated Press