"We are taking all measures to ensure that we deliver on our commitments to our customers," Bombardier spokesman Marc Laforge said in an interview.
He declined to specify how the company will avoid production delays, but said all measures will be legal.
The plant northeast of Quebec City is building the sidewalls and roofs for an order from Toronto for 420 subway cars, interior finishings for 706 Chicago transit cars.
Other contracts for 100 multi-level New Jersey transit cars and 54 multi-level cars for Maryland transit, along with nearly 500 Montreal Metro cars, aren't yet in production.
A spokeswoman for the Montreal transit authority said it is being updated daily by Bombardier on the state of negotiations.
"Bombardier assures us that for now there is no impact on the contract to build Montreal Metro cars nor on the delivery schedule," said Odile Paradis.
The union says 332 members of the Confederation of National Trade Unions began the plant's first strike in more than 30 years over concerns about sub-contracting, pensions and wages.
"We gave negotiations a chance," Mario Levesque, president of the Confederation of National Trade Unions manufacturing federation, said in an interview.
"We negotiated intensively hoping that there would be an end to the deadlock but after a long session last night the workers decided to intensify pressure by launching an unlimited strike."
The union said a company proposal Wednesday stepped backward on key issues of sub-contracting and pensions. It said Bombardier also hasn't responded to the union's monetary proposals, including salaries.
Levesque said workers accepted concessions in 2003 and 2007 to preserve their jobs and he thinks a protracted strike will have an impact on deliveries.
"If it last two or three months there will certainly be problems with deliveries," he added.
The union has long complained that Bombardier isn't honouring its commitment to create hundreds of jobs at the plant, saying it is "outsourcing" work to facilities in Ontario, the United States and Mexico.
Levesque has said the company has failed to live up to an agreement signed in February 2010 that the union says guaranteed that Montreal Metro work would be done in La Pocatiere. He said some of the work is going to Bombardier's plant in Mexico while other components are being shipped to outside companies in Quebec and Milwaukee, Wis.
Nearly 96 per cent of union members gave the union a strike mandate last Saturday. The last contract expired Sept. 30, 2011.
Bombardier also faces a strike of Learjet employees in Wichita, Kan., that's in its fourth week.
Bombardier's shares closed at $3.76, down four cents in Thursday trading on the Toronto Stock Exchange.