So, what are parabolic springs?
The original leaf spring suspension fitted to Series Land Rovers is affectionately referred to a “cart springs”. These springs are made up of up to 11 elliptical “leafs” bolted together in the middle (where the axle sits) and fixed to the chassis at either end. As the vehicle travels over uneven ground, the leaves “bend” and transmit the force from the axle to the chassis. During this movement, the leaves move against each other, but before they can begin to move, they must overcome the “inter leaf friction”, and with 11 leaves, touching along their entire length, this is quite a lot of friction. Over time, with the build up of dirt and corrosion, the interleaf friction become higher and the suspension less effective.
Parabolic leaf springs on the other hand, have just 2 leaves (more if required but not higher than 4) that only touch at the ends; therefore less interleaf friction. The materials used are are a lot stronger so few leaves are required to handle the force transmitted from the axle.
They also allow for a smoother ride and improved axle articulation.
In this instance, the downside to fitting these springs is that it raises the ride height of the vehicle by about 1.5 inches which means, dear reader, I wont be able to get the finished vehicle out of the garage without replacing the up and over garage door.
At the same time I fitted some new stainless steel brake pipe shields from Bits4Landys as the originals were made of mild steel and by this time paper thin and not much good for anything.