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Joined: Dec 2009
Posts: 37,405 Likes: 977
Tricky Dicky Member of the Inner Circle
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Tricky Dicky Member of the Inner Circle
Joined: Dec 2009
Posts: 37,405 Likes: 977 |
When I see pics of the cracks it looks like the steel is very brittle - almost like cast iron when it breaks. It would be interesting what a metallurgist would make of its content and suitability in a chassis that has so much torsion and loading. I can see someone producing a replacement chassis for these cars in the future where the steel has more flexibility. I very nearly bought a 3 wheeler but the issues around the chassis put me off. If they were definately cured I coukd be tempted again in the future. They have the potential to be amazing. I did metallurgy at university, albeit a long time ago. I think you are absolutely correct and there is something wrong with the steel the chassis is made from. On past experience with Morgan, I am guessing they will buy the tube from a broker or steel stockholder, to whom they will give a specification but want a cheap deal. The broker or stockholder, to maximise his profit, buys the steel piping from the cheapest source he can, which is likely to be India or China. There are problems with a lot of their steel. It has a high scrap/recycled content. Nothing wrong with that if it is properly processed but to do this requires long period of puddling with high temperatures to make the melt totally homogenous, all using expensive energy, so the temptation is to short circuit this process. This results in steel with so called inclusions in it. These act as a stress concentration points and starting points for failure. They also encourage corrosion by acting as a voltaic cells. The second problem is poor control of sulphur and phosphorous content. It is expensive to reduce the content of these elements from the steel melt. A higher content of them leads to the steel behaving inconsistently and being more brittle than its spec. Sounding familiar so far? In my view there is only one suitable material for making a tubular chassis and that is chrome-molybdenum steel tubing from a known steel maker in the UK, France or Germany. The best known version of this is Reynolds 531. This is tough, strong and very resistant to fatigue failure. I bet the M3W chassis is not made from it but it should be. Wilson Thanks for that interesting lesson in metallurgy fascinating.
2009 4/4 Sport Henrietta
1999 Indigo Blue +8
2009 4/4 Sport Green prev
1993 Con Green +8 prev
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Joined: Aug 2013
Posts: 1,562
Talk Morgan Enthusiast
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Talk Morgan Enthusiast
Joined: Aug 2013
Posts: 1,562 |
Should we club altogether and get a proper metallurgy test done on the chassis steel ?
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Joined: Sep 2016
Posts: 1,033 Likes: 33
Has a lot to Say!
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Has a lot to Say!
Joined: Sep 2016
Posts: 1,033 Likes: 33 |
I think the problem is just as likely to be the chassis design as it is the material. Perhaps both.
The later chassis have been modified to address a design weakness not a material one.
I'm surprised that an owner has been told to weld the crack and monitor it, I can tell him exactly what will happen. It'll crack again.
Actually on reflection I'm not surprised.
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Joined: Dec 2009
Posts: 37,405 Likes: 977
Tricky Dicky Member of the Inner Circle
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Tricky Dicky Member of the Inner Circle
Joined: Dec 2009
Posts: 37,405 Likes: 977 |
I think the problem is just as likely to be the chassis design as it is the material. Perhaps both.
The later chassis have been modified to address a design weakness not a material one.
I'm surprised that an owner has been told to weld the crack and monitor it, I can tell him exactly what will happen. It'll crack again.
Actually on reflection I'm not surprised. [i][/i] This owner lives Stateside I think doesn't he - disgraceful and IMHO downright irresponsible and dangerous advice as they have no quality control on the welding taking place. I fear the worst will happen one day with these frame failures and they will have to face their responsibilities then and it could well take the company down, surely it's better to grasp the nettle and be in control of the situation right now. Hiding your head in the sand will suffocate you one day for sure.
2009 4/4 Sport Henrietta
1999 Indigo Blue +8
2009 4/4 Sport Green prev
1993 Con Green +8 prev
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Joined: Oct 2015
Posts: 1,490
Has a lot to Say!
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Has a lot to Say!
Joined: Oct 2015
Posts: 1,490 |
Who is going to assess whether the chassis caused the car to veer off into the tree, or the crack was caused upon hitting the tree?
The Original Ken
11,000 miles.
2014 BMW R9T
2005 Saabaru
2005 Saabaru
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Joined: Mar 2016
Posts: 213
L - Learner Plates On
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L - Learner Plates On
Joined: Mar 2016
Posts: 213 |
When I see pics of the cracks it looks like the steel is very brittle - almost like cast iron when it breaks. It would be interesting what a metallurgist would make of its content and suitability in a chassis that has so much torsion and loading. I can see someone producing a replacement chassis for these cars in the future where the steel has more flexibility. I very nearly bought a 3 wheeler but the issues around the chassis put me off. If they were definately cured I coukd be tempted again in the future. They have the potential to be amazing. I did metallurgy at university, albeit a long time ago. I think you are absolutely correct and there is something wrong with the steel the chassis is made from. On past experience with Morgan, I am guessing they will buy the tube from a broker or steel stockholder, to whom they will give a specification but want a cheap deal. The broker or stockholder, to maximise his profit, buys the steel piping from the cheapest source he can, which is likely to be India or China. There are problems with a lot of their steel. It has a high scrap/recycled content. Nothing wrong with that if it is properly processed but to do this requires long period of puddling with high temperatures to make the melt totally homogenous, all using expensive energy, so the temptation is to short circuit this process. This results in steel with so called inclusions in it. These act as a stress concentration points and starting points for failure. They also encourage corrosion by acting as a voltaic cells. The second problem is poor control of sulphur and phosphorous content. It is expensive to reduce the content of these elements from the steel melt. A higher content of them leads to the steel behaving inconsistently and being more brittle than its spec. Sounding familiar so far? In my view there is only one suitable material for making a tubular chassis and that is chrome-molybdenum steel tubing from a known steel maker in the UK, France or Germany. The best known version of this is Reynolds 531. This is tough, strong and very resistant to fatigue failure. I bet the M3W chassis is not made from it but it should be. Wilson Thanks for that interesting lesson in metallurgy fascinating. Good synopsis. One must consider China's steel making facilities are state of the art, being relatively new. But how they manage their quality control is, as mentioned above, unknown. Sulfur and phosphorous content tend to make steel brittle at temperature extremes,ie below zero F, can't quite remember which is which, I think the sulfur makes if cold short. I also think a huge factor here is joint design, the metallurgical changes in the heat affected zone from welding ie grain growth which makes the fracture look like cast iron, and fatigue stresses, which can be hard to estimate. Using a chrome-moly alloy usually requires post weld heat treatment, difficult and expensive for a small manufacturer. Plain old mild steel is pretty ductile and can take a lot, IF the joint is properly designed to keep the stresses well under the fatigue limits. I still think a broke frame can be welded IF properly reinforced to lower the stresses, including minimizing residual stresses from the welding.
Inge
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Joined: Aug 2012
Posts: 2,360 Likes: 2
Talk Morgan Expert
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Talk Morgan Expert
Joined: Aug 2012
Posts: 2,360 Likes: 2 |
The Only good News is that you can have A new chassis
There is No failure for the moment on it And it is made with NVH support.
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Joined: Feb 2012
Posts: 5,654 Likes: 4
Charter Member
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Charter Member
Joined: Feb 2012
Posts: 5,654 Likes: 4 |
It's the responsibility of the manufacturer to specify and purchase it's materials. If this is the case, MMC is responsible and accountable.
Martin (Deano)
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Joined: Jun 2015
Posts: 580 Likes: 2
Talk Morgan Regular
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OP
Talk Morgan Regular
Joined: Jun 2015
Posts: 580 Likes: 2 |
Do Morgan make the chassis of the M3W or is it outsourced? Anyone seen them being made at Malvern?
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Joined: Feb 2012
Posts: 5,654 Likes: 4
Charter Member
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Charter Member
Joined: Feb 2012
Posts: 5,654 Likes: 4 |
They are outsourced, but they will be made to a MMC specification.
Martin (Deano)
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