Chicago Democrats, fearing that the city's bitter mayoral election campaign soured their chances of snaring the 1984 Democratic National Convention, were on their best behavior this weekend during a visit by the national party's site-selection committee.

Lame-duck Mayor Jane M. Byrne and Mayor-elect Harold Washington, arch foes during the primary and general election campaigns, acted like old friends at a reception for the site-selection officials at the Hyatt Regency Hotel.

Police Superintendent Richard J. Brzeczek, who once said that downtown Chicago streets would no longer be safe if Washington were elected and has since resigned effective inauguration day, April 29, shook hands with Washington at the reception and whispered words of encouragement in his ear.

Thomas V. King, a business executive who tried briefly to mount a general election write-in campaign for Byrne that would have split the Democratic Party further, insisted that reports of intense racial and political strains in Chicago have been grossly exaggerated.

"This city is not in turmoil," said King, general manager of Merchandise Mart and chairman of a business group bidding for the national convention.

Washington, a two-term congressman who Tuesday became the first black to be elected mayor of Chicago, strongly endorsed the city's $6 million convention bid and assured site-selection officials that local politics would not impede the holding of a successful convention here.

"Since the election, we've made substantial strides toward eliminating friction and differences within the party," he said Friday.

Some of the selection officials said today that they were impressed by the sudden surge of post-election party unity and by Chicago's convention and hotel facilities.

However, many members reportedly are leaning heavily toward San Francisco, in part because national party chairman Charles T. Manatt is a Californian. Also bidding aggressively are the District of Columbia, Detroit and New York City.

The final vote on the site is to be taken in Washington Thursday.

"Obviously, there will be some negative political fallout from the Chicago election," said Peter G. Kelly of Connecticut, a vice chairman of the 27-member selection committee. "But I have a feeling it's going to come together politically a lot better than people thought."

Theodis (Ted) Gay, chairman of the D.C. Democratic State Convention and a committee member, questioned whether there is enough time to allay all of the political concerns about Chicago.

The committee delayed visiting Chicago until after Tuesday's election to give local politicians and business leaders time to regroup.

DiAnna Schimek of Nebraska, the committee's other vice chairman, said she did not know what to expect when she arrived here Friday.

"I thought the reception attended by Byrne and Washington was a good indication that the city leaders are going to try to work together," she said.

Over the weekend, national party officials acknowledged that San Francisco had greatly improved its chances of being host to the convention by agreeing to augment its 1,900-member police force with about 2,000 suburban and state police during the week of the convention.

Party officials, wary of a repeat of the violence that marred the 1968 national convention in Chicago, felt that San Francisco's own police force was too small to protect presidential candidates and handle possible demonstrations.