Wiktionary
hell for leather
adv. (form of Less common form hell-for-leather English)
Usage examples of "hell for leather".
He rode off hell for leather down the valley, cross country, and we hadn't any horses, only cars.
We'll be out of the jungle by then and into open savanna, and we'll nde hell for leather for another twenty-five or thirty kloms.
Right now they're going hell for leather after Hutton - the black guy.