Maintenance officials for the Metro subway system have changed inspection procedures and slightly eased the wear limits for a six-inch aluminum part that had caused 40 subway cars to be taken out of service.

The changes mean that many of the subway cars may be returned to the tracks on Monday, a step that could ease overcrowding on the rail system that has been swamped by a record number of commuters because of the gasoline shortage.

Erich Vogel, chief of Metro car maintenance, said the changes would not cause any safety problems.

"We'd rather be more conservative than we have to be," Vogel said, "but we don't want to keep any cars out of service that shouldn't be out."

The part involved, called a caliper link, attaches part of the brake mechanism to each car's wheel assembly. Using the old inspection procedures, Metro mechanics thought that many of the links had become excessively worn and loose. But Vogel said when they were taken apart in the shop, many appeared to be in relatively good condition.

The new procedures and wear limits were worked out Friday, Vogel said, at a meeting between Metro officials and an engineer for the part's manufacturer, Abex Corp., of New Jersey.

Even though the part is still under warranty, Metro has had difficulty getting spares, causing the cars to be sidelined.

Yesterday, Matthew Darcy, a mechanic at Metro's New Carrollton yards, contacted the Washington Post and said his supervisors had put ten cars into service even after he had reported their caliper links were damaged.

Vogel said in late afternoon that Darcy's reports could not be verified, but he said he had ordered six of the cars Darcy mentioned to be taken out of service. The other four had been reinspected and found satisfactory yesterday morning, he said.

Because of "confusion" about the new inspection procedures, Vogel said the caliper links would be inspected again today on all of the approximately 250 subway cars Metro has available for passenger runs. He said an extra crew of mechanics has been called in to work while subway service has its usual Sunday off.

"I think we are having some communications problems," Vogel said. "We are going to give [the mechanics] more detail so they know exactly how these inspections should be made.

"Listen, wear limits [on a part] aren't the same as safety limits. There's a big margin here for safety," Vogel added. "Just to remove the air of uncertainty we're going to have all of [the caliper links] checked so that no one can hit the gun and say we are running an unsafe railroad."