Harry H. Bennett, 86, a tough, confident former boxer who became one of the most powerful men in the auto industry in the 1930s as a close aide to Henry Ford, died Jan. 4 in a nursing home in California.

Valued by the founder of the Ford Motor Co. for his ability to get things done Mr. Bennett headed a tightly organized security apparatus at the company and was involved in memorable confrontations with the labor movement in the turbulent years of the depression era.

Word of his death at the Beverly Manor Nursing Home in Los Gatos reached acquaintances in Detroit only Saturday, according to the Associated Press. Reportedly he had entered the nursing home in 1975.

Described as perhaps closer to Henry Ford than anyone else at the company for 20 years or more, the bow-tied, blunt-spoken Mr. Bennett was known as the man through whom Ford put into practice his ideas on company operations.

His eventual authority in the handling of Ford's affairs was "pervasive, almost limitless," according to one biographer of Henry Ford.

"I sort of raised him," Ford was quoted as saying of Mr. Bennett, and by all accounts, he trusted and relied on him.

If Mr. Bennett was Ford's instrument, Mr. Bennett's own instrument was the Ford Service Department, through which he exercised control over labor relations, personnel and security matters.

For years after the United Auto Workers had signed contracts with other automakers, Ford resisted unionization, and the Service Department, with a reputation for repressive measures, was at the forefront of the resistance.

In 1937, one newspaper described Ford Service as the largest private quasimilitary organization in the world. Mr. Bennett characterized such charges as laughable, and called them "bunk."

Accused of having hired gangsters for Ford, he denied that he had ever put "real gangsters" on the payroll, but said the company had, out of sympathy, hired some men convicted of minor crimes.

A highlight of the union campaign to organize Ford came on May 26, 1937, with the famed Battle of the Overpass. UAW leader Walter Reuther was beaten while attempting to reach a gate of Ford's vast River Rouge plant to deliver leaflets.

Bennett insisted no Service employes or plant police were involved.

In 1941, Bennett, acting for the company, signed Ford's first contract with the UAW.

In the second volume of their history of the Ford Motor Co., Allan Nevins and Frank Ernest Hill describe Mr. Bennett as a man about whom legends swirled.

These, they said, involved his three homes, one, at Grosse Ile, with a secret stairway. They also involved his prowess as a boxer who "could still knock down hard-muscled plug-uglies, and did."

In addition, according to the history, the legends dealt with his fondness for such painful practical jokes as tripping men into the Detroit River, with his "very dangerous friends and minions" and with the "enemies who hated him and repeatedly tried to kill him."

Mr. Bennett was born in Ann Arbor, Mich., Jan. 17, 1892, and at the age of 17 joined the navy where he learned to box, and from which he took the ring name "Sailor Reese."

Later he got a job in New York with a sales and service branch of Ford Motor. Moving to Detroit, he joined a company branch making submarine chasers for World War I service.

According to accounts, a group of saboteurs attempted to enter the plant, but quickly was thrown out by workers led by Mr. Bennett. This was said to have attracted Henry Ford's attention and marked the start of Mr. Bennett's climb to power.

Known to friends as a man "afraid of absolutely nothing," Mr. Bennett, who had acquaintances in the underworld, was regarded by Henry Ford as a man who could protect the Ford family from kidnaping or other criminal schemes.

His rise was also attributed by Nevins and Hill to Henry Ford's fear in the 1930s of radicalism, and to Ford's view of Mr. Bennett as a man who possessed some of the qualities Mr. Ford's own son, Edsel, lacked.