Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Chassis reinforcement

Yes they did, but not necessarily wisely. Here are some thoughts to consider. (I enjoy the intellectual exercise such things encourage!) The following is merely for discussion purposes.

1. Gussets are great, but one must understand them and their effect before designing, making and using one.

Some preliminary background. A few decades ago, the MMC discovered to their dismay that the combination of the strength at the bulkhead cross member combined with a flexing chassis, cracked the frame at the bulkhead, a place that cannot even be patched. And patching a Morgan chassis anywhere is anything but a forever job on what should otherwise be a forever car. Gussets are a MUST. (However, many homemade chassis (chassis are wear parts on a used Morgan) and even one prominent supplier in the US, omit them making the result the vehicles using them far more vulnerable for the want of a costless addition requiring an extra 1/2 hour in labor. The lack of them are often the reason a new chassis was required in the first place! Habit is a stronger determinant of action than common sense.

Gussets move destructive forces where the gusset directs. That is the reason why the suggestion of a welded reinforcement strap straddling the car would merely ensure the worst place for a chassis crack, at the bulkhead cross member, for the same reason cracks appear at either end of a patch. A welded strap is, (unhappily) a bit better used following the frame, not the cross member.

However, in the immediate post-gusset Morgans, the MMC soon discovered they had merely created a new plague of cracked chassis at a different place. I think of such things the Deadly Domino Effect. Read on.

2. Additionally, for some bizarre reason (cost?), Morgan went through model eras where they passed exhaust pipes through the CHASSIS, a huge no-no. The frame around the large hole (s) is constantly being hyper heated and cooled, expanding and contracting the remaining metal around these holes. Yet the gusset ended at the hole!!!! That made chassis cracking even more likely. (see pics below). AND in many cases, owners (like me) received chassis with such frame holes when their exhausts went through the valances! I can think of no perfectly safe remedy for these cars.

3. Next the tried remedies. But instead of merely extending the gusset past the holes, they added a metal strapping. So now we have a flexing chassis that cannot flex equally in that area.

However, the old crack point was moved away from the bulkhead. That was a good thing I guess. It allows for cracked chassis be emergency patched. We don't hear about these cracks as much as the earlier ones, (though from this perch they are more frequent). IMHO, a patch on a Morgan chassis is like a unpleasant brother-in-law that has come to live with you forever or until you or he move to that great garage in the sky.

This is all to point out the obvious. Morgan aftermarket engineering types have confirmed that the gussets should theoretically extend to the front end of the frame. The one displayed above is too short, exhaust hole or not. However, Morgan trad frames are open ended in front. I think we are fine if they extend 24+ inches with a trad that has not been "exhaust holed" or 8-10 inches past the hole if they are.

I hope I wasn't too confusing here. Morgan trads are deliciously simple if we think out of box that assumes owners can never understand automobiles.

gmg

P.S. In 2002, the MMC and I added rear frame gussets when we recreated my original car. Also important are gussets at the rear but for suspension and safety reasons rather than structure. Another day..

Interesting post ... and I agree regarding stresses being moved rather than eliminated ... the gusset in the pic of my 4 seater resto was just a direct like-for-like replacement for the original MMC one which had suffered from tin-worm (wirh the addition of weld run along the top edges of the gusset as well as the underside to prevent water wicking between it and the chassis .. the cause of the original corrosion) ... as the chassis was nearly 50 years old and had, to my knowledge, been used off-road for Sporting Car Trials by the last 2 owners for decades and showed no cracking I reckoned it would likeky see me out !🙂

K

Yes. I realized that Image.I had no intention to criticize, merely to share some thoughts with one who is astute enough, in this and other areas, to be concerned and ask questions.
Answers are certainly much easier than it is to notice and see something that isn't there (yet) and ask a question. My compliments.

gmg