A parabolic spring is basicly a leaf or a set of leaves which are tapered in a parabolical way rather than a liniear. So from the middle, where it is thick, to the ends , where it is thinner, the tapering steps down in a parabolical manner i.e. Y = Xsquare + n where Y and X are related to the thickness and the lenght of the leaf. (every 1 mm the leaf tapers by a parabolical calculated value). The shape, camber, of the spring is not parabolical but semi-eliptical. Parabolic tapered springs may not be confused with linear tapered springs (every length step is tapered with the same value). Although linear tapered springs can look the same they will not be as good as the parabolicaly tapered springs. The reason why the parabolic spring is more comfortable is simple. The multy leaf springs have interleaf friction which makes them "bouncy" since it needs a cerain amount of force to contra act the interleaf friction. Even if you grease the leaves you will still have a multy leaf spring and it will never come close to a parabolic spring since they still have interleaf friction which is on the parabolic spring nearly nil. The tapering of the parabolic spring handles the force distribution from the body to the axle. If you make a multy leaf spring with only two leaves (non tapered) it will break because it can not distribute the force correctly. The rate of a parabolic spring is linear in contrast to the degresive rate of a multy leaf spring. This means that the inward movement is similar to the outward movement. The convetional multy leaf spring will need more force on the inward then on the outward movement so this will result in a highly uncomfortable ride.

The differences and advantages

First of all, the parabolic tapering of the spring. This tapering is in a parabolic way to asure maximum force deflexion and tranfer from the ends to the middle section. This gives the best results in both comfort and longlivety.

Second, the number of leaves. The front springs have only two leaves instead of nine or eleven. The rear springs have three (load level B) or four (load level C & D) instead of ten or eleven leaves. 

Third, the spring leaves do not rub against each other over their entire length. Instead, the lower leaves are shaped at the ends and 3 mm spacers are fitted between the leaves in the centre, thus leaving a space along the length of the spring with friction only at the ends. 

*) Linear tapered springs will not give this result instead they could be less comfortable and possibly easier sprone to break.

The differences and advantages

A much improved combination of spring characteristics with the reduced thickness at the ends of the springs provide improved comfort, wheres the strong central part ensures a very goad load capacity. 

Because the leaves are not rubbing together and the outer ends are serperated by PU blocks, the problem of a build up of friction and rust is prevented. 

Un-sprung weight is reduced because, for example, the front springs weigh only about half as much as the standard type.

On and Off road

The improved spring characteristics result in a more comfortable ride on-road and off-road as well. The irregularities of the road surface are better absorbed by the springs and there is good control of the vehicle on corners. The typical LandRover feel of the vehicle remains but the unpleasant bumps are gone. Off-road, the axle articulation is very good, with some vehicles already being used for trialling. Conclusion There is indeed a world of difference. The much improved spring characteristic is a development which the Land Rover owner has waited a long time for. This improvement is achieved with no alteration to chassis or axles being necessary (as in coil spring conversions). We recommend these parabolic springs to those owners who want to use their LandRover as an everyday vehicle, on or off road, and want to keep their vehicle leaf sprung. Whether you are doing a full restoration or just dealing with the regular maintenance of your Land Rover, these springs will enable you to enjoy your vehicle more. We use them on our own Land Rovers - can we say more?