Roush Fenway Racing teammates Greg Biffle and Trevor Bayne will start in the back of the field in their Daytona 500 qualifying race Thursday.

Both of their teams changed rear gears following issues Wednesday, an adjustment that caused them to lose their qualifying spots for the Cam-Am Duels.

Biffle and Bayne are in the first of the two races. They will join 2007 Daytona 500 winner Kevin Harvick in the back of the 22-car field.

Harvick and Stewart-Haas Racing teammate Brian Vickers were forced to the back of the field after NASCAR officials determined the track bars on their cars were not in compliance with specifications following pole qualifying Sunday.

Vickers and Martin Truex Jr., who failed to make a qualifying lap Sunday, will start in the back of the second race.