Trak Auto Corp. reported a substantial improvement in profits for the second quarter.

Trak earned $1.1 million (18 cents per share) on sales of $54.8 million for the quarter ending July 31, compared with losses of $114,000 (2 cents) on sales of $46 million for the same period last year.

For the six months, Trak had profits of $2.2 million (36 cents) on sales of $101.4 million, compared with $324,000 (5 cents) on sales of $86.3 million for the same period last year.

Trak now operates 224 discount auto parts stores, compared with 203 stores a year ago.

Crown Books Corp. reported a 3 percent increase in second-quarter earnings.

Net income for the quarter ending July 31 was $610,000 (12 cents per share) on sales of $37.4 million, compared with profits of $591,000 (8 cents) on sales of $34.4 million during the same period last year.

For the six months, Crown had profits of $1.8 million (34 cents) on sales of $70.5 million, compared with net income of $1.9 million (25 cents) on sales of $65.5 million.

Crown currently operates 202 bookstores in the Washington area, California, Houston, Chicago and Seattle, compared to 195 stores a year ago.

Classic Corp., a Maryland manufacturer of waterbeds and waterbed components, announced financial results for the fiscal year ending June 30. The company lost $613,000 (35 cents per share) on sales of $30.4 million this year, compared to losses of $927,000 (49 cents) on sales of $35.5 million last year.

In the fourth quarter, Classic lost $693,000 (41 cents) on sales of $6.9 million, compared to losses of $324,000 (17 cents) on sales of $7.3 million for the same period last year.

Isaac Fogel, chairman and chief executive officer of Classic, also announced a restructuring of the company's top management. Stuart Kaplan, who had been the company's executive vice president, has resigned. Marvin A. Davis, who is associated with the California Management consulting firm of Grisanti, Galef, Goldress, has been elected interim president for an anticipated six-month period. The firm also has new vice presidents of sales and marketing, and operations.

Federal Home Loan Mortgage Corp. announced profits of $77 million ($76.18 per common share) for the second quarter, up 30 percent over second-quarter 1986 earnings of $59 million ($59.18).

For the first six months, corporation's earnings totaled $139 million ($128.49), up from first half net income of $112 million ($102.62) last year.

Leland C. Brendsel, Freddie Mac's president, attributed the corporation's record quarterly earnings to an increase in the volume of mortgage purchases and mortage security settlement