Jeremy Wilkinson (69), Hunter Haas (67), Brett Wetterich (67), Franklin Langham (67) and Kyle Thompson (68) are knotted in third place at 7-under-par 135.
Simpson, who was one behind club profession Bob Boyd after the first round, flew out of the gate on Friday with three birdies in his first four holes. He three-putted for bogey from 25 feet at the fifth, then dropped another shot thanks to a buried lie at nine.
But Simpson came back on the second nine at the TPC at Wakefield Plantation. He collected back-to-back birdies from the 13th, then rolled home a 20-foot birdie putt at the last to take sole possession of the lead.
'I played extremely solid once again,' said Simpson. 'I'm hitting the driver long and very accurately and I'm hitting a lot of shots. I missed some good opportunities, but it's great to be playing well again.'
Simpson, 48, finished in the top-10 on the PGA Tour money list in 1989 and 1990. A battle with lyme disease and tremors in his left hand forced him to leave the sport in 1997, but his health is back and so is his golf game.
'It's so great competing again,' said Simpson. 'It's just incredible. My health wouldn't allow me to compete for six or seven years, but I'm going to keep fighting. It's been a while since I've been here, but I haven't forgotten how to win.'
Jones was flawless on Friday with three birdies on each nine. The Australian feels like he's back home with the course conditions at the TPC at Wakefield Plantation.
'You've got hard-running fairways and the greens are quite firm,' said Jones. 'In Australia, you learn not to miss it in the wrong place and when I did miss, I missed in the right spots.'
Todd Demsey (69), Jess Daley (68), Michael Long (70), Paul Gow (70), Chris Zambri (69), Chris Sessler (68), Chris Anderson (70), Wook-Soon Kang (72) and P.H. Horgan III (71) are tied for eighth at minus-5.
Boyd struggled on Friday with a 4-over 75. He is part of a group tied for 25th at 3-under-par 139.
The 36-hole cut fell at 1-under-par 141 and 76 players made it to the weekend.