WAYNE, Michigan, Sept 15 (Reuters) -

Striking auto workers converged on a Ford assembly plant on the outskirts of Detroit on Friday morning to show their support for the most ambitious labor action in decades and explain the grievances that led to the three-factory walkout.

The first-ever simultaneous strikes against the "Detroit Three" automakers, including General Motors and Chrysler parent Stellantis, kicked off early on Friday after the union and companies failed to agree on new contracts. Each automaker had one plant shut down.

At Ford’s Michigan Assembly Plant in Wayne, Michigan, dozens of United Auto Workers (UAW) members were picketing the factory’s main entrance on Friday, and many rued changes to their contract and work rules over the past 15 years that especially cut new "Tier II" hires at lower wages and reduced benefits.

UAW chief Shawn Fain

has described the strike as a societal move to claw back gains take by the financial elite, a message echoed by many strikers.

Eric Mullins, 23, followed his father and grandfather to work at Ford, but the kind of lives they built are out of reach for him as a new hire on a Tier II contract, he said.

After more than three years, at Ford, he has no health care or pension at retirement.

"I can’t even afford the truck I drive,” he said of his Ford 250 pickup. “The rich people in this country want to eliminate the middle class.”

On Thursday, Chief Executive Jim Farley warned of a grim scenario if Ford acquiesced to union demands for a 40% hike in pay, an end to the tiered wage system and a return to defined-benefit pensions.

The UAW proposals would "put us out of business," he said.

But UAW President Fain has said Ford could have funded better pay and benefits for workers if it curtailed stock buybacks and dividends to shareholders. Ford reported returning $2.5 billion to investors in 2022.

Full-time Ford employee Robert Murphy, 53, said he was bothered that some workers get half the pay of others doing similar jobs. And he blamed Ford for not improving efficiency and cutting waste to find money to raise pay.

The plant produces high-profile Ranger and Bronco trucks, but it switched from the more modest Focus. During that transition, hundreds of spare transmissions and other parts were taken out behind the plant to be destroyed, a cost the company could have avoided, Murphy said. Ford did not immediately respond to a request for comment on the transmissions.

“Ninety nine point nine percent of the people here want to be part of a great workplace,” Murphy said.

The strike is ambitious in taking on

three automakers at once

, but strategic in that keeping most factories running preserves workers' strike fund.

Fain has not ruled out more drastic action, such as full company-wide strikes, if a deal cannot be reached.

The plant has been deluged since the strike began at midnight. Shortly after, one supporter of plant workers, a 38-year GM veteran who declined to give his name, said he did not think the industrial action would stop until the automakers gave into the union demands.

"We deserve what we deserve," he said.

(Reporting by Eric Cox and Kevin Krolicki; Writing by Jamie Freed and Peter Henderson; Editing by Clarence Fernandez and Nick Zieminski)