WHEN YOU DRIVE UP TO THE tall black iron gates of Sugar Ray Leonard's $750,000 Potomac mansion, you wind your window down and follow the security system directions. Punch the proper three buttons and identify yourself and the gates swing open. You pull into the circular driveway and stop behind the Mercedes 500SEL with the license plate "BOXER."

"It came with air bags -- they must know me over there," said the squire of every- thing in sight. "If I had had air bags in my Jeep . . . "

Leonard, 28, looked fit enough to climb into a ring -- lean, smiling, unmarked, no apparent effects from the Jan. 2 crash of a pickup truck into the side of his Jeep as he was driving in Beltsville. "God, I was lucky. I saw the Jeep on the news. It was like smashed."

Despite the early hour, Leonard was elegantly attired for a noon engagement at the Department of Transportation, where he would be honored for wearing his seat belt at the time of the accident. He had on a starched white shirt, black tie with a gold-colored pin (a likeness of Sherlock Holmes), wide pin-stripe suit trousers, white hose and white shoes with shiny black tips. He wore a terry cloth robe, white trimmed in black, be- cause he was busy in the kitchen making coffee.

He served the coffee at a large round table at one end of the huge kitchen. Immediately following the accident, he said, he blacked out a few times, then spent two nights in the hospital, had a huge bump on his forehead where it smashed the windshield and ached from a bruised chest muscle from slamming forward into the steering wheel. "I'd have been history. I'd have gone straight out, if I didn't have on my seat belt," he said.

So there is irony -- happily so -- in Leonard's words, "There is life after boxing."

Juanita Leonard, his wife, certainly would agree. She is overjoyed that he's out of boxing: "It's been a great lift off my mind. I just don't think he's staying busy enough."

"Can you believe that?" exclaimed Leonard.

His eyes gleamed, he feigned innocence. He can charm as Muhammad Ali once could.

In the ex-champ's view, he's got plenty to do. He's a full-time father to Little Ray, who's 11 now and in the sixth grade, and 8-month-old Jarrel, he said. He does boxing commentary for CBS and HBO. He's a part- time trainer for Canadian welterweight Shawn O'Sullivan, who is managed by Leonard's adviser, Silver Spring lawyer Michael Trainer. Magazine writers were coming to interview him. He endorses Carnation sugar- free hot cocoa mix, Church's Fried Chicken, Franklin sports equipment and the Devon chain of department stores, all of which keep him traveling, making personal appearances. He does a Carnation commercial with Little Ray, as he once did for 7-Up. People still talk about the 7Up ad. "That's how I got famous, to be honest with you," Leonard said. " . . . I poured my life into the ring, and people know me from the ad."

Leonard had plans to fly to Reno for CBS the next day to help cover Boom Boom Mancini's return bout with lightweight champion Livingstone Bramble. Despite the obvious differences between Leonard and Mancini -- one man is black, one is white; Mancini is a brawler, Leonard was an artiste -- Leonard identifies with Mancini.

"I wanted to fight (Roberto) Duran the second time for personal reasons," Leonard said. "There are personal reasons why Mancini wants to fight Bramble. At the time Mancini was champion, Bramble made derogatory remarks that ticked Mancini off. He called him a murderer" -- a reference to the death of South Korea's Duk Koo Kim from blows by Mancini. "That's low; that's really low."

Leonard also was contemplating his role in Reno -- commentator not com- petitor. Not being in the ring has taken some adjustment. "I can sit at ringside. I don't break out in a sweat anymore." He sipped his coffee. "I have no feelings of going back, because I got it out of my system."

That happened last May 11 in Worcester, Mass., when he fought for the last time, in his one-bout comeback against an ordinary opponent named Kevin Howard. Leonard won, but was shocked when Howard knocked him down in the fourth round. But retirement, especially at only 28, would have to take some adjustment when you consider the fistic heights to which Leonard aspired only last year. He craved one more watershed moment: After he had beaten Howard, he wanted to meet Marvelous Marvin Hagler, the middleweight champion, in what promised to be the greatest boxing payday ever.

He suspected from the moment he stepped into the ring to face Howard that the fight with Hagler would be an appointment he could not keep; he knew it when he hit the canvas. What troubled him had nothing to do with the detached retina he had suffered in

1982, or minor surgery for a retinal weakness in his right eye in February 1984, he said. It was this: He had lost his competitive edge.

"It was an accumulation," he said. "I was only 28, but the experiences, the trauma, the pressures I had been through . . . To admit to myself I didn't have it, that was tough for anybody to do.

"When I got into the ring, it just was not there. I didn't feel that drive, the adrenaline flowing. There was this wrong psychological obstruction. When I was knocked down, it happened so fast. It was like my Jeep accident. Then it dawns on you, this is it, man. I thought, 'Let me win this sucker, I'll give it up.' I promised myself. I was in pain, too. Every round was a struggle. I had to push myself.

" . . . When I got back to the dressing room, I saw Juanita and Little Ray, the subdued expressions on their faces. I knew then."

In the dressing room he turned to Juanita and said, "This is it, I'm giving it up."

She, who so many times had asked him to retire, said, "You can't retire. People will think Kevin Howard made you retire."

Sugar Ray Leonard looked at her tenderly and said: "Sweetheart, he did." ALTHOUGH HE LOOKS as if he could take on Hagler tomorrow, Leonard isn't working out much. "I procrastinate. I've got a basket out there on the driveway. I've got golf shoes, golf clubs. Tennis, I'd like to get involved in tennis. But I always come up with a cold. I've been doing sit-ups."

"How many did you do?" Juanita asked.

"About five."

She just looked at him.

"So I did 'em. Okay, it's the first time I did 'em in two years.

"I'm slowly but surely getting to it," he added. "When you retire, you lose initiative, motivation."

Leonard likes his leisure -- he's got all the room a man could want. The Leonards moved from Mitchellville, in Prince George's County, to Potomac a year and a half ago. "He's just got to have space," Juanita said.

Ray opened a sliding door -- a swimming pool was on the other side -- and cool air wafted in.

Some days he's home a lot. No wife likes a husband underfoot, as if it were possible in that house. Half-jokingly, Juanita said, "I tell you, it's a little harder having him home more." But it's nothing compared with having to watch him in the ring.

"Personally, I don't like it," she said. "Personally, I don't think it should be called a sport."

"Holy Christmas, Juanita. It's an art."

"It's not a sport. I'm not a fan."

"She says what's on her mind."

"I was behind him 100 percent. I feel bad for him, he wanted to continue. For him, I feel bad."

"I had created my scenario," Leonard said. "It was going to be Hagler, and I was going to knock him out. I accept it, I didn't have it any longer . . . The moral to the story is, if one dream doesn't come true, go back to sleep and have some more dreams." His second retirement, he said, isn't nearly as hard as was his first, from November 1982 to December 1983. He retired the first time, he said, because people kept telling him to because of the detached retina. He did, and he was restless.

"I didn't want to quit because of medical reasons," he said. "I'm a proud man . . . The second time I quit was in my best interests but not because of medical reasons. It just wasn't there. You can't worry about that."

Boxing days are past, Juanita reminded him. She'd like to go into business with her husband, open a roller-skating rink with him. She wants to continue her education at Montgomery College in September; she attended Prince George's Community College for a year.

"I'm going to go regardless -- if it takes me 10 more years," she said.

When he visits schools, Leonard said, he urges students to take advantage of every academic opportunity. "I let those things go by. I could have been somebody way back then."

"Education is so important," she said. "I'd take it any day over fame and fortune."

The Leonards offered a tour of the house. She hasn't finished decorating -- "There are so many rooms" -- but she's done much of it, working from the top down. Her first-floor pride is the oriental-style decor of the dining room. The house has five bedrooms. The master bedroom has a high- standing bed with steps to climb up into it. Each boy has a room, and there are two guest rooms. Juanita's younger sister, Pamela Wilkinson, lives in, helping care for the children. At the end of a hall on a balcony overlooking the living room, seven lavish championship fight belts are displayed in trophy cases. "I just have to get used to this height," said Leonard, holding on to the railing and looking over.

The attic is converted into a theater, complete with a screen almost large enough for a movie house. "My pride and joy -- second to my wife," Leonard said. IT WAS TIME TO LEAVE for the Department of Transportation. Parked outside was the chauffeured limousine Trainer's office had ordered. Trainer's secretary also serves as Leonard's secretary, keeping track of his appointments and correspondence. Leonard periodically works out of Trainer's office and also has an office at home.

Leonard's regular driver, Nate Hardmon, was waiting. Leonard put on his double-breasted suit coat,and carried his mink. Juanita brought a portable telephone. They settled into the cushioned seats.

Riding along, the Leonards talked with each other about their life. She wishes he would do more work around the house.

"I do take the trash out."

"Everything he does is like the sit- ups."

"Everything I do, I do in moderation."

He fitted the baby's new car seat into the car.

"Two hours," she said, "and after two hours he had the seat in backward."

She's more mechanically inclined. "I used to work at a gas station," she said. "I worked there for a year."

"That's where my income was coming from," he said.

"I learned to change spark plugs," she said.

"I know nothing of cars." Except how to buy them. Besides the Mercedes in their driveway, there's another Mercedes, hers, in the garage, and a Rolls-Royce. Recently, he's had a white Porsche and a red Porsche and a Maserati and another Rolls and a different Mercedes. In the last six years, he's had six Mercedes.

"I wish I had more land," he said.

"Ten acres," she said.

"Ten acres," he repeated.

"I always dreamed of a driveway lined with trees," he said.

"Set back in the woods," she said.

"Drive through the trees," he said.

He looked out the car window at the Potomac, and began talking about a story he'd read in the paper, the accidental death of a child. It upset him.

"It's just nature, the world, how things happen," said Juanita, leaning toward him.

When the limousine stopped for lights, young people on the sidewalks peered into the windows. At the Department of Transportation, the chauffeur pulled into the basement. Leonard was met a host of department officials. Upstairs, a woman said, "I have to tell you that those ads with your little boy are the cutest things I've ever seen." In front of a phalanx of photographers, Secretary of Transportation Elizabeth Dole, dressed in a red blouse and black skirt, introduced the president of the American Seat Belt Council, Charles Pulley, who gave Leonard a plaque. "I guess I would not be here . . . ," Leonard said, beginning a short speech. "People take so much for granted . . . We really need to buckle up, and I'm one who stands behind that."

Back in the car, under the building, Leonard said, "Short and sweet. That's how I love 'em."

He looked at the plaque. "You know, I almost had to kill myself to make a point," he said seriously.

"That's a lifetime commitment," said Juanita, meaning that Ray must wear his seatbelt.

"I know," he said. LATER, AT LUNCH at Tartufo restaurant, they leaned back in their chairs after ordering.

"Fifteen years," Juanita Leonard said she has known her husband, "and it's beginning to catch up with me. I thought I was going to look young forever."

"We're together forever."

"Pact?"

"Pact."

They held hands a moment.

There are always rumors about them, said Juanita. "There were many bets downtown that we couldn't stay married a year," she said. They've been married since January 1980.

And before they were married: "Once that kid hits it big, he's going to drop her like a hot potato."

"We're still here," he said.

What really hurt, she said, was the "paternity suit" headline in August 1976: "P.G. Files Paternity Suit Against Champ." The story broke just after he had won the Olympic gold medal. She has never forgotten it. A single mother, she said she had been accepting public assistance for a year and a half for herself and Little Ray, then 2. She was still in high school. Leonard, in training for the Olympics, did not deny paternity but had no money. "New procedures" had been required, she recalled, and she had to "fill out these papers." The story "blew it out of proportion."

Both grew up poor. Leonard's first experience with money came in Los Angeles when he made a post-Olympic appearance and earned $1 for every autograph he signed. Charlie Brotman, a Washington publicist, was with him. "We went back to our hotel room," Leonard said, "and we had all these $1 bills. I had them all stuffed in my pockets, Charlie had them stuffed in his pockets. We take the money out and put it on the bed. Dollar bills all over the place. Holy Christmas, I'm rich, I thought."

Not too long after that he really was rich. How rich, Leonard's adviser Trainer declined to say recently, beyond this: "If he never did another piece of work, never received another dime of new income, his estate would continue to grow." Trainer said Leonard's portfolio includes real estate holdings, bonds, Treasury certificates. "He's set for life. I don't think he could spend it all in his lifetime."

What does Trainer see Leonard doing at age 40, or 50? "Now you're seeing a more conscientious effort by him in broadcasting. When he did it the first time (after his first retirement), he saw it as more of a sideline, a break from boxing. Now he's starting to look at it as a career. I see him doing broadcasting and associating with reputable businesses as he is now as a spokesperson and a representative, and more active in his own investments."

As lunch went on, Ray turned toward his chauffeur, Hardmon, who had joined them. "I really want to beat you on the table," he said, mean-ing his basement pool table.

"I don't know, Nate's good," said Juanita. And then to Hardmon: "I'm warning you. Whatever he plays, he finds a way to win."

"Smoke in your face, just as youre about to shoot?" laughed Hardmon.

"He talks to you." It would seem that the Leonards have everything they've ever wanted, but that isn't precisely the case. Juanita has had some ill health. She said that when she was two months pregnant with Jarrel it was discovered she had Bell's palsy, a form of facial paralysis. She had to stay in the hospital three months because of it, but now is 80 percent recovered.

Just two days earlier, she had had minor surgery. Yet she showed no ill effects. It was Ray's energy, not hers, that was flagging by midafternoon. On the GW Parkway toward home, he stretched. "I'm tired," he admitted.

She looked at him pensively, recalling a reporter covering the Howard fight who told her many women thought her husband was "a hunk."

"I think he's a hunk, too," she had responded.

"I wouldn't trade him in for an old Cadillac," she said now, looking at the trees. "A new one, maybe.

"That's what keeps us together," she added. "Being friends.

"You know that song Lucy and Ethhe asked him. " just the perfect blendship.' That says it."

He rubbed his eye. "I used to write her poems and everything."

"I met you in June '72," she said. "You were coming out of the house throwing firecrackers all over the place. You were ugly. Those loud orange pants. Polyester. Oh, he was so ugly, but he was the talk of the town."

"Oh, I was hot."

He was the rage "for the little girls. You didn't know it, but you were."

"That was unfortunate, I didn't."

"So you got me."

"We're getting deep."

"Life." AT HOME, Leonard was handed Jarrel, dressed in a shirt that said "Little Champ." He kissed his second son all over, and Jarrel responded with toothless grins. Little Ray would be home later. He had stayed after school for student government.

"All right, Nate," said Leonard. The two would shoot pool.

Juanita headed upstairs with Jarrel.

Downstairs, Leonard opened a door to where an exercise room was being completed. There was another room that contained a Zenith Space Command television set with a built-in phone. Past the wine cellar and a large bar was yet another room with the pool table in the center. There was plenty of space around the edges for a Pac-Man game, a Ms. Pac- Man and Track & Field. Another TV was up in the corner. And a big fish tank along a wall.

"Mrs. Leonard said be sure to feed the fish," said Hardmon.

As Leonard fed the fish, Hardmon picked a cue stick and chalked his hands, rubbing them together. This man looked like he knew what he was doing.

Leonard missed a couple of early shots, then took off his jacket. His chances didn't look good, but he looked as if he might stick with it for the rest of the afternoon. There wasn't any hurry.

At the front door, Juanita said there'd be no problem leaving, the gates would open as you drove toward them.

One thing you discover, you can't drive up to them too closely. The gates swing in, way in.