THE RECENT RACIAL upheavals in South Africa came as no surprise to readers of James McClure's fine suspense novels over the last few years. Within the framework of the police procedural, McClure has drawn a disturbing picture of South African aparthied society while following the murder investigations of a white Afrikaner lieutenant and his detective sergeant, a Zulu "boy".

McClure makes his point, not with rhetoric, but with the little details of daily living in separate but unequal societies. Take McClure's latest mystery, The Sunday Hangman (Harper & Row, $8.95). Zondi, the Zulu sergeant, cannot enter a bar for whites and must use the reflection from a gun magazine to signal his boss, Lt. Trompie Kramer. While making his social observations, McClure does not neglect mystery, suspense, action, and chase. He is master of the arresting opener and the unraveling of clues.

In The Sunday Hangman , a long-time criminal is found hanged from a tree, but Trompie and Zondi have doubts about suicide, and it proves to be the first in a series of executions. The Sunday Hangman is among McClure's best, which is a high recommendation indeed when you consider his such superior suspense novels as The Steam Pig, The Gooseberry Fool , and The Caterpillar Cop .

LYON WENTWORTH, children's book author and amateur balloonist, again is reluctantly drawn into a murder investigation, and so begins another delightful, offbeat adventure, Death Through the Looking Glass (Bobbs-Merrill, $7.95).

This is the third of a series by Richard Forrest featuring Lyon and Bea, his politician-wife who speaks in capital letters when her hearing aid is not working. Along with quirky, very human characters, Forrest adds a special twist in his mystery puzzles. Lyon, sailing a hot-air balloon over Long Island Sound, watches a friend's plane plunge into the water. Knowledege of toys and literature helps Lyon trap the killer.

THERE IS NO DOUBT about Jacob Asch's roots. He can be traced back to Raymond Chandler and Dashiell Hammett by way of Ross Macdonald as a private eye of the hard-boiled school. In Dead Ringer (Mason/Charter, $7.95), Asch is in his milieu investigating the murder of a South American heavyweight contender against a background of Los Angeles ringsides and Reno gambling casinos and brothels.

Arthur Lyon writes such sentences as, "It was a place where dreams came to die" and sprinkles the dialogue with scatological words. Still, for its kind, Dead Ringer is a quite solid performance. In one delicious scene a whore comes out waving a $20 bill and supplies a seven-letter word for "ease" that has stymied her colleagues who are working a crossword puzzle while waiting for customers. Too bad that Asch has such a penchant for philosophizing.

JOAN FLEMING WRITES civilized, witty novels that can't be conveniently filed in a niche. So it is with Every Inch a Lady (Putnam, $7.95). Nathaniel Sapperton starts out to investigate the murder of York Craig, his old school friend, and that of Craig's father soon after. His only lead is a photgraph of a sexy woman supplied by York's young widow. A clue from an unexpected source saves Sapperton from becoming the third victim. On the Margin

ON FIRST INTRODUCTION in Edwin of the Iron Shoes (McKay - Washburn, $7.95), Sharon McCone seems to be someone you would like to meet again. She is a private investigator, employed by a legal cooperative in San Francisco, who gets involved in the murder of an antique shop owner. Marcia Muller writes briskly and pleasantly about art smuggling, big real estate deals, and the junk-antique business.

THERE SEEMS TO BE no end to "ehtnic" cops. Now it's a Nisei police detective who is a Zen Buddhist, karate expert, and lover of roses. Masao Masuto also learns about stamps in The Case of the One-Penny Orange (Holt, Rinehart, and Winston, $6.95). It's a reasonably entertaining, if unspectacular debut for E.V. Cunningham.

FAR MORE IMPRESSIVE is the first American appearance of two British detectives in Ruling Passion (Harper & Row, $8.95). Reginald Hill has written a first-rate police novel with a clever plot and distinctive characters. There is, for instance, fat, crude Superintendent Dalziel, who proves to be neither stupid nor unfeeling.

Hill starts with two separate plot threads and brilliantly brings them together. There is a mass murder, and Sergeant Pascoe finds himself in an uncomfortable emotional role. He had been on a weekend holiday in the country - taking a break from his investigation of a London house-rifling ring - when he discovered his three friends slaughtered.

IN CONFESS, FLETCH, Boston Police Inspector Francis Xavier Flynn stole the lead away from amiable letch, Gregory McDonald's hero of the earlier prize-winning Fletch. So McDonald, one of the bright young mystery writers, decided to give the smart, tough, sarcastic cop his own novel, Flynn (Avon, $1.95). Unfortunately, Flynn can't stand the exposure. What were likeable quirks have become precious in this story about the sabotage of a Boeing 707 with the murder of 118 passengers. Still, McDonald is a crackling good writer to be watched when Fletch returns this summer.

THE MYSTERIOUS PRESS is a new publishing house specializing in limited editions of crime, detective, suspense, mystery and espionage fiction. One of their first handsome issues is Lew Archer, Private Investigator ($10), the first hardcover collection of short stores featuring the famous private eye. Author Ross Macdonald adds an introductory essay on what make a good private investigator in real life: He is "a little like a potential criminal or possible writer."