Autopsy findings:

Suprisingly the dog teeth had zero damage. Only remanants of third gear teeth came out of the case. The driver earlier described a 'ticking' in third gear which I believe was the first tooth (possibly partial) failure on third gear. When he 'hammered it' in third he took another tooth or two out and third gear was done.

Dentist90: Move to the front of the tranny rebuilder class (again). During the rebuild I neglected to clean out the diff. Fortunately I had the owner run the tranny for half an hour using an electric drill, the remaining debris came out in the ensuing flush (prior to driving the car).

Final conclusions: Too much torque, missed shift, or simple gear failure? I suspect third gear failed from too much torque. This 915 had a 3.8 on it for a while, now it has a 3.6, so long term it might fail again, espescially given the owners propensity to 'hammer it' on the track. :)

Never knew about the 3.8, but I have witnessed the owners propensity first hand....:D

Just out of curiousity but did this happen on an upshift or a downshift? The handful of instances when I have seen teeth rip off without the help of loose dog teeth it's almost always been a hard downshift with engine braking that's ripped them off.

Of course, even if it happened on the upshift, since it was ticking previous to the catastrophic faiilure who is really to know when the damage that cause the failure really occurred.

Bill Howard said he had a 3.8 in Ruby for a while, prior to going Varioram.

It began making a ticking noise while driving it on the street. The next track day killllllled it, since it's a mostly 3rd gear track.