A good source of leaf spring learning can be found here:
https://www.cartechbooks.com/blogs/techtips/muscle-car-handling-upgrades-rear-suspension-systemSome relevant working principles and physics are discussed, including the following observations that help to flesh out the potential advantages offered to Morganeers if we choose the BCC Ati-Tramp springs:
Then, there are the leaf-spring packs. This is a broad subject, so I cover only the main points. The front half of the spring acts more or less as a semi-flexible suspension link, due to its fixed frame mount. This locates the axle in the car longitudinally (front to rear). It also takes the majority of the load under acceleration and braking. Adding stiffness in the form of more spring leaves, thicker spring leaves, and/or longer supporting leaves that extend to the spring eye, all tend to improve straight-line traction and reduce wheel hop.And this point for anyone considering the ill-advised mod of installing the far more pronounced arch four seater springs to their two seater Morgan.
The flatter the springs are at ride height, the better they resist lateral deflection and the better they laterally locate the axle. A flat piece of steel is very difficult to bend laterally if it’s laying flat. Spring bushings, likewise, are nearly noncompliant to axial load. When you introduce an arch to the steel, you’re twisting it like a flat torsion bar. The leaf bends laterally much more easily, and the bushings (solid metallic or Delrin bushings notwith-standing) are now free to deflect radially as well. It becomes quite easy to twist the springs, and the axle can move more easily from side to side. Less spring arch also decreases roll steer. The flatter two seater springs are without doubt the better option for a two seater Morgan, and the so called Anti-Tramp version of the two seater spring where the pack is built heavier forward of the axle will improve things further because in doing so you effectively create a stiffer trailing arm that's more resistant to twist, torsional deflection is highly undesirable in a tailing arm so if you were designing a proper one you most certainly wouldn't make it out of spring steel! However, as our trailing arm is also a spring the best way to make it stiffer is to build it with more leaves, this will definitely help to reduce spring windup thus improving resistance to 'Tramp' or what the Yanks call 'Wheel Hop'.
Ultimately all we're trying achieve here is rear tyres that say in contact with the road better and for longer to improve traction, to that end damper function is actually even more important, but more on this later.Back to leaf springs, in terms of adding torsional rigidity building the pack heavier across the whole length of the spring will actually work just as well as only doing so forward of the axle, however, you will end up with a far heavier spring which is never a good thing, it's long been understood that even a small reduction in unsprung weight will yield benefits far greater than amount of weight you've removed. The second issue with just building the pack heavier across it's entire length is that invariably the ride becomes stiffer, ride quality suffers becoming far harsher than it actually needs to be and in turn the damper will have a much much harder life too. The solution is a hybrid design where the pack is only built heavier forward of the axle to give the benefits described above, but then lighter rearward of the axle to reduce weight, produce a far more compliant ride and to give the damper a fighting chance to do it's job, if you then choose a quality damper set from the likes of Bilstein suddenly they're now allowed to properly shine.
The core learning here is while it's natural to view the whole leaf spring as a single working suspension component doing one job, we would be much better off thinking about it as two separate elements, this is because the element forward of the axle has a subtle but importantantly different role to the element of rearward of the axle. Thinking of the spring as two elements helps us visualise their differing roles, keep in mind the element of the spring forward of the axle connects the axle to the chassis in a
fixed pivot point that's rigidly mounted the the chassis, while the element rear of the axle is also rigidly fixed to the axle it's other end is attached to a
swing shackle, this is a very important difference!
The advantage of the BCC Ant-Tramp design is you end up with a leaf spring that embraces the different roles of both elements of the spring by delivering the desired improved straight line stability and better traction produced by a heaver pack but only placing it where you need it forward of the axle, while at the same time avoiding adding unnecessary weight and the undesirable ride stiffness produced if that heavier pack extended the full length of the spring. At the end of day all suspension design is a series of compromises and a heavy old rigid beam axle supported by leaf springs is certainly more compromised than most, however, at least the Ant-Tramp design offered by BCC is making a stab at working with the compromises rather than adding to them, it's also a design that has given some thought to the very different working principles and roles of a leaf spring forward and aft of the axle.
It's a personal choice thing, but for all these reasons I concluded the BCC Anti-Tramp design made for the more intelligent choice, I also reasoned the damper choice was just as important if not more important (as it always is), which is why I went with Bilsteins. I could have gone with an SSL five link setup but if you look at the design closely you'll see it also comes with it's own set of compromises, in my humble opinion the SSL's five link arrangement ties the axle down a little too well to allow the suspension to articulate as it should, the solution appears to be to fit big soft bushes that allow the necessary deflection which is somewhat counter productive in my opinion.
In theory, coil springs will produce a better ride than leaf springs, but that's the only advantage I can see over leaf springs with well chosen dampers and a Panhard rod, however, for me the elephant in the room for the SSL five link setup is that it fails to remove the biggest compromise of all, the super heavy and rigid beam axle. This big old lump of cast iron unsprung mass remains so I couldn't help feeling £5k plus is a hell of a lot of money to shell out for what very likely would just amount to slightly better coil sprung ride quality, and maybe not even that if I could just find the right leaf spring and damper combination, which I did by using the Anti-Tramp springs from BCC paired with a set of Bilstein dampers from SSL themselves.
But before investing in all of that I put my money into the most important primary suspension component on any vehicle, its tyres. I was always taught that if you want to make a car handle and ride well, you should start from the road surface up; so that's
Tyres-Dampers-Springs-Bushes…..
and very much in that order