I happened to call by my "local" dealer this morning on a completely unrelated mission. While there they said that they needed to check my pedal box and chassis which took all of five minutes; I never had the early M3W pedals and my chassis is not cracked at the foot of the vertical tube by the lower wishbone mount.
When I took delivery of my car at the end of 2012 I was slightly surprised that it didn't have the M3W pedals but it was pretty clear that there was a reason for the change so I was not bothered about it. Subsequently, whatever the reason for the change at the time (cost/delivery issues/failures or any other) it became fairly clear that there was a higher failure rate than is acceptable for a pedal box (not that the failure rate would have to be very high to reach this threshold) and MMC has now effectively acknowledged this. "Not before time" may well be a fair comment but this is progress, hopefully is a good sign for the future and I certainly do not see it as a reason to condemn Morgan whether as part of a vendetta or otherwise. The chassis checks appear to be different from and unrelated to the cracking of the upper chassis rails at the upper wishbone rear mounting brackets that led to the bolt-on brace a couple of years ago for pre-2014 chassis or indeed, new chassis for those of us that have experienced the cracking of the 2012 and 2013 chassis. I would be very surprised if anyone outside of the factory knows how many chassis have failed on this vertical tube and given the nature of the internet, it may well be a very, very low number that have gone: I am aware of one such failure, possibly two, but internet forum self selection of the sample always leads to distorted results. Put simply this does not mean that there have not been more failures but let's just say there are 100 M3Ws on this forum and there have been 2 failures, to then assume that the overall failure rate is 2% is rubbish. Again, I'm going to take what appears to be the contrarian view to many: this "recall for inspection" is progress on MMC's part, and I hope it continues. It may well be down to the new owner's influence and policies, and it also may well be some of the MMC engineers now being allowed to act where before this kind of action was discouraged. I'm not a factory insider, don't have access to any inside information but am quite willing to read between the lines along with everyone else but not necessarily coming to the same conclusions.
NDT of the chassis to pre-empt a failure is unlikely to be viable; magnetic particle testing is going to need clearance round the tube for clear visual access and removal of all coatings; think body and engine removal followed by grit blasting then you can test it. Dye penetrant much the same but you would want to chemically remove the coating rather than grit blasting. X-ray? Again a bare chassis required and I would be surprised if even a seriously good radiographer could identify any cracking that wasn't already visible or MPI detectable. Eddy current inspection would also need clear access to work round the welds and tubes with the probes and I suspect would not give definitive results given the thin walls, the geometry and the shape of the fillet weld caps. Ultrasonic testing would be a waste of time due to the thin walls and the fillet welding. This pretty much leaves visual as the only viable in-service inspection method. I do not expect that any fatigue cracking of these tubes would be otherwise detectable in a bare chassis environment for very long before being clearly visible if you look for it; think rapid propagation due to the high vibration, high cyclic loading of thin walled tubing going from initial incipient crack to "oh bugger" in not many hours. My suspicion is that the root cause of the failures of these chassis tubes is more in initial QA/QC than in-service conditions; what batch testing is done on the chassis; what batch testing of the raw tubes is carried out; what trade testing is carried out on the welders; what control over the welding process is carried out; how much do you really want to pay for a chassis? Cracked chassis are neither a new thing nor unique to MMC; it's not even unique to separate chassis: monocoques crack and tear too!
if all this seems a bit too much on the "glass half full" side then reflect on this, my glass is actually empty right now, has been empty all day, and I'm off to do something about it!
Slainte.
