Thanks to you all adding your observations for us all to share.
Additional tech. for those new to the Traditional Morgan front suspension...….
1. If one has "zero droop" on a suspension, rather than allowing droop as well as bump from static ride height, the roll stiffness is doubled. But zero droop causes the occasional knock as the suspension tries to droop after a compression. Thus some compliance in droop softens that, hence a rebound spring.
2. By controlling droop the front instantaneous roll centre moves from below ground to ground level. That lifting of the roll centre, reduces the 'roll moment' and thus increases roll stiffness.
3. If you have a gap between the slider/hub and the rebound spring you loose that initial high roll stiffness. If you have the rebound spring compressed you not only get harsh initial ride but the roll centre moves as you enter a corner so the balance of the car changes, not nice. Read
http://www.britishv8.org/Articles/Morgan-Plus-8-Road-Test.htm "...……..and by the front-end suddenly going softish.." That is the slider/hub coming off the rebound spring! You need a main spring that can be preloaded to balance the corner weight and set the rebound spring contact.
4. MMC do know the effect of the rebound spring and do try to get the main springs the right length but there are so many weight variants they prefer the compressed rebound spring option, rather than a gap - playing on the safe side. But of course Morgan supply the RS as an option on new builds anyway.
5. Morgan have relied for decades on that high initial spring rate to get the car to turn in quickly by loading the outside front. However also for decades all other cars (saloon & sports) have softened the front suspension springs to get better ride comfort but then have increased the low velocity bump force provided by the damper to get turn in. Many Morgan dampers on production cars have very little bump damping so still rely on the high initial spring rate with compressed rebound spring, but then having to accept consequential the poor ride. However when one goes for a softer initial spring rate one must add low velocity bump force in the damper. So not any old damper off the shelf but a damper valved to give that specific required low velocity force to get the car to turn in but then the valves must open to give good ride - at the same time! This is what damper tuning is so much about. Fit a damper designed for a different spring rate and car weight and it will not be optimum degrading both ride and handling.
6. Many other makes of cars are now using dampers with internal rebound springs to give increased roll stiffness and better ride BUT with much smaller anti roll bars. The current Merc E Class is the best example. The first dozen or so M3W (& the demo cars) is another example with the SUPLEX coil overs, that is before production went to SPAX without any internal rebound springs and hence more roll. The early 5 door 'Mini's (also the BMW X3 etc) are among the worst; come off a full width speed bump and the suspension feels quite soft, drive along a country lane with undulations on the near side and your head is continuously nodded side to side, uncomfortable - ARB 'too' big! BMW are too going to internal damper rebound springs - Morgan were first!
A lot of ride and handling is indeed subjective, but there is a book full of 'rules of thumb' that gets one quite close to the required ride and handling characteristics before the detailed spring and damper tuning to suit the character of the car and the customers.
If you are still awake, thanks for your attention. Regards Peter.
Declared interest Director SSL.
Current SSL suspension projects include; Porsche 356C & 911S, Jensen CV8, FIA ACCobras, FIA MGB, off road rapid response 4x4 truck etc. as well as Morgans of course for road and track.
