Tarmac Rally Stratos Build begins

[Strat Fan]

So this was the sort of failure we were attempting to avoid with the additional strap


Now 'm not saying this is absolutely correct, but here was our thinking on the situation


- the failed section is after the gearbox mount, so it won't be subject to any loads generated between the diff output to the chassis


- the only Force that part of the gearbox casting is subject to is created from the gear shaft bearings


- As the gears are loaded up the shafts will try and spread apart, this is reacted by the bearing housings in the casting


So our thoughts were, a failure occurred in the casting between the 2 bearings, as mentioned it is very very thin in there, once a crack formed the 2 gears spread apart further and caused the carnage seen in that photo


What would be super helpful would be a photo of the failed casting parts, if the 2 bearing housing are still attached together in the end plate that would falsify our theory

I haven't got any other pics of the failure so can't comment on what the other piece looked like.
You can try DM'ing the owner, Sando on here but he sold his car a couple of years back and hasn't checked into the forum since Nov 2020.
You may be right on the failure being caused by the shafts trying to separate, I was thinking it was related to the thrust on the shafts induced by the helical cut of the gears/crown wheel.