Approval of the UAW’s agreement with General Motors gained momentum as workers at Detroit-Hamtramck Assembly and three facilities in Pontiac gave it solid majorities in voting that concluded today. .

The vote remains close, but the trend is toward ratification. About 700 members, 54% of UAW Local 22 members at Detroit-Hamtramck voted yes while 581 voted no. Similar to the pattern at most plants, production workers backed it by even larger majorities, but most skilled trades people voted no.

Workers at Pontiac Metal Center approved the four-year contract by 64% to 36% margin with 577 people voting. Production workers passed it with 74%, while skilled trades workers approved it with 51%, according to Mike Warchuck, Local 653 president. That local also includes a parts distribution center, workers at a power train operation in Pontiac and about 300 workers at GM’s Milford Proving Grounds.

The agreement was ratified by 91% of 217 people at a West Chester, Ohio, parts center north of Cincinnati.

Results were also expected later this evening from workers at the Spring Hill, Tenn., assembly plant and a small facility in Flint.

On Thursday about 3,900 workers at GM’s Fort Wayne, Ind., truck plant can vote, as well as those at a stamping plant in Parma, Ohio.

At mid-day Wednesday locals representing about 20,000 of the union’s 52,700 GM workers had voted.

Early Wednesday the local at GM’s metal casting plant in Defiance, Ohio, reported that members voted 65% to 35% in favor of the agreement, although a 56% majority of skilled trades workers voted no. Late Tuesday production workers at Saginaw metal casting approved the agreement by 64.5% to 34.5%. Skilled trades voted yes by 55% to 45%.

The pattern at Defiance has occurred at many plants where the production workers — the people on the line — are approving the pact, while skilled trades — the electricians, pipefitters and others who fix machines or keep the automation running — are rejecting it.

There are between three and four production workers for every skilled trades job so that would tend to indicate the contract will be ratified. But of Wednesday afternoon only about half the union’s locals had voted.

There are also concerns among thousands of temporary or flex workers, who would receive a $2,000 signing bonus and less generous health care than their permanent coworkers, if the contract is ratified. Some of them aren’t convinced they will have a path to permanent status. Temporary workers can vote on the agreement.

“I’m not surprised the trades are voting no more often,” said Kristin Dziczek, director of the labor and industry group at the Center for Automotive Research in Ann Arbor. “They’re ticked off they were not included in the special attrition program that offers $60,000 for a bridge to retirement.

The contract also would enable GM to continue erasing the strict job classifications that define which skilled tradesmen can perform specific tasks.

People outside the auto industry, or those in nonunion workplaces may wonder why this vote is close at all.

If ratified, about 57,200 GM hourly workers would receive an $8,000 signing bonus and a raise. Entry-level production workers currently paid between $15.78 and $19.28 per hour would see their wages increase to between $17 and $22.50 per hour and would eventually earn about $29 per hour.

Workers hired before 2007 would receive 3% raises in the first and third years of the contract and 4% lump-sum bonuses in the second and fourth years of the agreement.

“It’s always pretty close,” Dziczek said. “The ideal ratification margin from management’s standpoint is 51% because it means you didn’t give up too much, and the union’s not satisfied. But that’s nerve-wracking.”

Contact Greg Gardner: 313-222-8762 or Follow him on Twitter @GregGardner12