The other night at the track, shooting for the 12s, i launched my car at about 5k. There was TONS of wheel hop, followed by a loud bang, and i thought i had blown up my diff. I lightly coasted to the end of the track, and the car didn't make any noise, except when the wheel was even SLIGHTLY turned. Going straight it was silent, even under power, but any turn and it was making a noise that was like 2 piece of metal were hitting each other. I pull the PPF off, and there is a 2" crack about 5" from the differential, through both pieces of metal. Could this be what broke, or may it be the rear end/axles. Thanks

 

Cracked PPF can definitely cause a loud racket when engaging with your gearbox and diff.. the gearbox would shake a lot too! Just a question if I may, how long did it take you to take it off? Did you have a lift or on ground?

 

sounds like you may have also smashed the planetary gearsi n the diff, hence the grinding when you turn.

 

Well your PPF is cracked and yes that will make a loud noise.

You should also remove the rear cover of your diff and have a look inside too.