It’s from Judas Priest?
HELL BENT HELL BENT FOR LEATHAAA
It’s about motorcycling I believe

This is what one pundit says:

“Hell bent for leather seems to be a very recent usage in which two phrases: hell-bent and hell for leather have been run together. The bent in hell-bent means “determined” or “resolute”, as in “bent on revenge”, so hell-bent means “intent on going to hell”.

Hell for leather, on the other hand, means “fast”. It occurs twice (1889, 1893) in Kipling’s stories of the British Army in India. In both cases it refers to horse-riding and leather probably refers to the saddle. It may have originated as Army slang or it could possibly have been one of Kipling’s inventions.

For the meaning, we can only suggest that you ask the next person who uses it in conversation with you. It is understood to mean “as fast as possible”, having retained the meaning of hell for leather with the extraneous bent.”

I was fishing this one out of my memory, knowing that it was two separate phrases of fairly old origin recently (and erroneously) combined, but Darwin got there first with the right answer.

I do differ slightly with the first explanation, though. I don’t think it means “intent on going to hell” so much as it invokes hell as a kind of oath in expressing the determination to do something. The sense of this is like “sure as hell I will” or “crazy as hell,” which use hell as a way of expressing something not only extreme but dangerously so. Similarly, we hear expressions like ”[I’ll be] damned if I don’t,” which is not about being damned but about saying “I will” in emphatic terms. Its use is “hell-bent on,” as in “He was hell-bent on making vice president by the age of 35.”

@teh_kvlt_liberal : thanks for the suggestion, but i’m pretty sure it goes back to well before any members of that band were born.

@Darwin : thanks for the link.

@Jeruba : thanks for contributing.

@teh_kvlt_liberal : any connection with motorcytclists’ “leathers”?

@Darwin : now that i’ve explored the link, i’m hell-bent on thanking you even more fervently for it!

@Jeruba : on second reqaing, it all makes even more sense—thanks again.

leather jackets?
I dunno I was talking about the song

Sorry—i didn’t mean to confuse you.