"Do you have pictures you can share? I suppose any M3W owner would like to see them and check their own chassis in the same spots your own has cracked and where that made it also bend." Yes good suggestion
This is a photo of a pre 2014 M3W being built. You can see how its balanced on the trestles with the engine and transmission already fitted. The tubing does look substantial, but the gusset on the 2014 chassis looks far stronger.
Whatever the fault was with Hughs car, (hopefully a rogue weld) its not good and obviously the 2014 chassis was beefed up for a reason. There must be substantial loads going through those top rails.
Good luck with getting it quickly and properly resolved Hugh.
Hugh It's a real bugger when these things happen. When mine was found it took about ten minutes before it was confirmed that it was going back to the factory to be sorted. Sounds like your chassis has gone in a different place from mine but that whole area appears to be highly stressed and it might be a bit of a toss up where a crack will start to propagate from - mine was from one of the top wishbone rear mount bracket welds. Some of the info that has been posted is not quite right, sorry Dan but the two chassis pictures are just that; two separate chassis, not one before and after welding in of the cross bracing. I am aware of three variations of bracing at the front ends of the chassis; 2012 bolt in cross brace only 2013 stiffener plates welded in plus bolt in cross brace 2014 welded in cross bracing only I'm not going to state any specific dates but I can say that in November 2012 my car went into build, in November 2013 it got rebuilt with a new chassis (which incidentally also required a new pedal box I believe to make it fit.) In January 2014 the 2014 chassis cars were definitely being built. There are other changes in the various chassis only a very few of which I am remotely aware of.
It looks like the major engine mounts are the lower two. All two and three speed twins have the engine on two pairs of engine plates and are held to the chassis with four big bolts.
These photos taken during the rebuild of my car should clarify I think.
Car without engine:
And with:
So I'm thinking my engine to chassis connection is somewhat better than a five speeders. Perhaps?
After seeing Callums' pics I'm somewhat relieved I've got a 2013 chassis with the stiffening plates.
I'm assuming the cross brace needs to be removable for some reason on the 2012/13 chassis, so what has changed to allow the welded cross bacing arrangement on 2014 cars?
The new bracing allows the engine to come out without needing to remove the bolt in brace and I believe is actually a stiffer and stronger arrangement. I think it may have been a "why didn't we do it that way from day one" type of moment rather than any really good reason for having the bolt in brace.
