A request for a restraining order preventing the move of the Detroit Express to Washington was denied by a Detroit federal court judge yesterday, clearing the way for the North American Soccer League team to move here for the 1981 season.

Judge Horace Gilmore denied the request of Horace Van Arnem to prevent the move of the club. Van Arnem, a limited partner (4 percent) in the Express, had filed suit against the club a year ago after being demoted from general to limited partner. That suit still is pending. On that basis, he asked for a temporary restraining order until his litigation against the club has been resolved.

But Gilmore denied the request, meaning the Express will begin moving its operation to RFK Stadium today. The new Diplomats open their season in Fort Lauderdale March 28. The home opener at RFK Stadium is scheduled April 11 against the Montreal Manic.

General Manager Duncan Hill is expected to meet today with Gordon Bradley, coach of the old Diplomats, to discuss his role with the new club. Bradley is expected to be involved in player personnel and community relations. Although many Washington area soccer people have pushed Hill to name Bradley coach, he apparently is determined to stick with Ken Furphy, who coached the team throughout its three-year existence in Detroit.

Furphy replaced Bradley as coach of the Cosmos at the start of the 1976 season when Bradley moved into the front office. Bradley then replaced Furphy midway through the season when the team stumbled. The loss that cost Furphy his job was a 5-2 defeat to the Diplomats at Woodson High School.

Once the new Diplomats set up offices here, they will begin preparing for training camp, set to begin March 11.The plan is for the club to tour England and Saudi Arabia from the 11th until a few days before the opener. Since the Express played indoor until the last week in February, the team will not need much time to get in shape.

Hill also has mentioned the possibility of playing an exhibition game at RFK to get the city acquainted with its new team, but time may be too short to do that.

Because there is so little time to market the new team, the new front office will be trying to contact as many of the old Diplomat season-ticket holders as possible. The front office staff remaining from the old regime likely will play key roles during the transition.

Ticket prices have not been set. Hill has said he does not believe in giveaways, but does believe in family plans and reduced-price plans for youths. g

Hill's job the next two weeks will be to strengthen the team, pick up a defender, a midfielder and a striker. Hill knew Alan Green, the Diplomats' all-time leading scorer, when both men were at Coventry City in the English first division. Since Green and Paul Cannell, who will definitely be one of this team's strikers, played together here two years ago, Hill might try to swing a deal with the Jacksonville Tea Men to bring back Green.

"It's going to be a hectic four weeks," Hill said. "There's a lot to do."

And now, there is no doubt. There will be professional soccer here in 1981. It will take a while to answer all the questions about the team, its front office and its ownership; Hill says he will begin working on those answers today.