hang on for dear life

Translations
держаться изо всех сил
He had to hang on for dear life as the roller coaster sped down the track.
Ему пришлось держаться изо всех сил, когда американские горки мчались по рельсам.
Definitions
To hold on very tightly or persistently, often in a difficult or dangerous situation, usually out of fear or desperation.