[robo]

I think big vern is right, the nose of that diff needs to be well and truly controlled. When you think that a few thousand rpm and a dropped clutch that pinion is trying to climb that crownwheel, that beam across the back is only there to hang the diff unit in place the rest of the forces go to the front mount. i had a quick look round the mx5 fourms and there are dozens of failures with a thousand reasons why, I dont know if I would want something as hit and miss as that an inch from my spine. You could also fabricate a steel brace to run the whole length of the thing and bolt it through the ali bit. It could crack then but at least it would all stay in there.

Bob

Edit: An extract from another forum


Join Date: Jun 2005
Location: Arizona
Posts: 2,007

They do break there very easily.

I also think the alloy or casting method somehow makes them excessively brittle too.

I had an diff assembly accidentally roll off a floor jack close to the floor and produced the exact same break off with a really minor impact. The exposed cross section's inside looked like classic metal fatigue.