The Unite union said the pay deal offered to workers at the Falkirk-based business is below expectations and a 48-hour strike will take place from 6am on September 19.
The loyal workforce brought the company "back from the brink" during a downturn several years ago, with many agreeing to work a three-day week and lobbying the Scottish Parliament for the introduction of a Green Bus Fund, Unite said.
Alexander Dennis Limited (ADL) has offered a pay deal that is 0.5% less than previous annual increases, despite the firm making a 56% rise in pre-tax profit last year, according to the union.
It is understood the offer is a 3.5% increase instead of the expected 4%.
The strike is by workers at the Alexander Dennis site in Glasgow Road, Falkirk.
Lyn Turner, an industrial officer with Unite, said: "We are dismayed that ADL management think workers who brought the company back from the brink less than four years ago should accept an increase that is below expectation while company profits and executive pay goes through the roof.
"It's testimony to the workers' commitment, modesty and long-term outlook for the well-being of jobs and skills in Falkirk that they are content to settle for the same deal that's been agreed in recent years.
"Instead, the workers feel they have been left with no choice but to strike and the sense of injustice is reflected in the significant turnout and appetite for strike action.
"It's not too late for management to do the right thing and reach a deal that is well within their budget."
The union said 75% of ADL's vehicle builders voted in favour of going on strike, following an 80% turnout.
The company employs around 2,000 people in the UK, Asia and North America.