He competed in the World Wrestling Federation against many top wrestlers in 1983-84. He fought against many top level opponents, including then WWF Champion Bob Backlund, Hulk Hogan and Sgt. Slaughter, Jimmy Snuka and others.
In 1986, he returned to the World Wrestling Federation and became Super Machine with André the Giant as Giant Machine and Blackjack Mulligan as Big Machine. The three Machines were introduced as rivals of Bobby Heenan and his massive tag team, Big John Studd and King Kong Bundy. He later dropped the Machine gimmick and left the WWF.
In January 1987, Ax returned to the WWF and formed the tag team Demolition with Smash. Though they began as heels, their unique brawling style and charisma made them so popular that they became faces in November 1988. They won the WWF Tag Team Championship three times as a team of two, but lost the belts at SummerSlam 1990 after they turned heel by forming a threesome with Crush. The trio concept was precipitated by a mutual decision to phase out the Ax character and for Ax to take a backstage role in the company.
Ax's new position eventually fell through and his final WWF appearance was at Survivor Series 1990. This event also marked the last time that he and Smash worked together for sixteen years.