Need help diagnosing a clutch/tranny problem

[dcdoug]

A few weeks back, I gave drag racing a try in the cobra (first time ever). On my third launch it felt like something let go and the car lurched forward a bit and then didn't move (engine was still running fine). I was on Billboards, low RPM launch at about 2k RPM, specifically to limit the chance of breaking anything. I could back out from the starting line, but very slowly with a lot of slippage. 1st gear slipped so much that the car would only move on flat ground if I was given a push to start and overcome the inertia.

Thought for sure the pressure plate or disk had grenaded. Clutch has 5k miles on it. I don't do lots of burnouts, etc, and am probably easier on the car than many cobra drivers.

BUT, when we pulled it this weekend, the clutch looked fine. Nothing broken, condition looks good.

So what else would cause symptoms like a badly slipping clutch? Half shafts are find. Engine runs fine.

Here's what's in it: Tranny is a TKO 600, engine is a 427FE, standard bore/stroke, never been dynoed, but probably makes ~480hp or so at the crank.

Thoughts?