As chairman, Crafar, together with current MotoGP stewards Andrés Somolinos and Tamara Matko, will be in charge of penalties during the races.
They review all incidents and decide whether or not to apply a penalty and what that penalty should be, according to the FIM Grand Prix World Championship regulations.
“I’m really looking forward to taking on this new challenge. I did not take the decision lightly to make this change and accept this appointment, as it means leaving a role I’ve enjoyed a lot, but after seven years in MotoGP commentary I am ready for something new,” Crafar said.
“I will approach this new position utilising my experience on and off the bike as rider, technician, coach and journalist, but more importantly with my love for our sport and respect for its competitors.”
Spencer, also a retired champion motorcycle racer, became the inaugural chairman of the panel in 2019.
He said: “It has been a pleasure ... to have worked to put in place the incredible people and procedures we have now.
“When I was asked to be the chairman, I accepted as I wanted to contribute to the sport and I’m proud of my tenure. I’m looking forward to some exciting projects in the future, and I know the team will be in great hands with Simon.”
The MotoGP, short for Grand Prix motorcycle racing, is the highest class of motorcycle road racing events in the world. It is sanctioned by the Fédération Internationale de Motocyclisme (FIM).