The TR chassis isn't particularly stiff even with the body fitted but will be better than a Morgan one. One must remember that the body will add some stiffness.
In bare form, you can lift each corner of the Morgan chassis a couple or more inches before any other corner lifts. Torsionally stiff it is not. However......
Believe it or not, the Morgan body adds a fair bit to the overall stiffness and the introduction by Morgan of the rear suspension hoop and scuttle roll bar increased the torsional stiffness considerably. In addition, the diagonal front cross-frame brace (anti-tramp bars) modification adds a lot more. This leaves the chassis between the cross-frame and bulkhead as the likely greatest point of flex.
On an unmodified pre-1990s Morgan, much of the compliance necessary for road-holding and handling will come from the chassis and body supported by stiff springs. On later and earlier modified cars, the additional stiffness will require softer springs front and rear.
I can't remember the lengths and poundage of the front springs that Dave Rutherford developed for me but they were based on the overall and individual corner weighs of the car as well as the desired ride height (lower). On the rear springs, the middle leaf was inverted; an old but effective trick for lowering and softening the rear.
So Morgan chassis and suspension design: an early 20th century blacksmith solution to early 20th century roads. It's quirky, odd, outdated and an anachronism but somehow it manages to deliver and entertain us. Just enjoy it!
