''WILLYS JEEP'' LEAF SPRING SUSPENSION

''Willys Jeep'' Leaf Spring Suspension

''Willys Jeep'' leaf spring suspension

Introduction

It is said that the leaf-spring suspension is the oldest suspension used for automobiles. The leaf-spring system has been in use since the World War 2. Many even prefer to utilize the leaf-spring rear suspension design in their fabricated Late Model Stock and Modified race cars.

Like all other racing components, there is a science and methodology to the use of leaf springs in stock cars, for both dirt and asphalt. The construction of the car may depend on the type of leaf spring to be used and where it will be driven (Bargh, 2000, 253).

Basic Design

There are four basic designs of leaf springs that are used in stock car racing:

1. The monoleaf spring is a low-rate, thinner spring that serves to locate the rear end laterally, like a Panhard bar, but offers little spring rate to hold the car up nor much stiffness to bending to help control axle wrap-up. The design of the car must include additional springs to support the car and a system for controlling accelerating and decelerating forces that will try to rotate the rear end.

2. Multileaf springs are just as described, made up of multiple leafs of diminishing length. These tend to be increasing rate springs and are useful for supporting the car as well as controlling axle wrap-up.

3. Parabolic leaf springs can be a single-leaf or multileaf design whereas the leaves are thicker near the axle and have a tapered thickness design out to the eyes. These, too, support the weight of the car without the need for extra springs and do a fair job of controlling axle rotation under acceleration and braking. They can provide a much smoother ride due to the fact that the leaves do not develop the friction associated with standard multileaf designs.

4. Composites are fairly new in racing and have been further refined recently. These leaves come in various rates and, with the lower rates, will need additional springs to support the weight of the car.

(Bargh, 2000)

Advantages to Using Leaf Springs

The monoleaf spring has just one leaf and can be either a single low-rate spring or a parabolic leaf design, where the spring is thicker and higher rated.

From the information we have gathered from several excellent sources, leaf-spring suspensions are very forgiving on tacky and rough dirt surfaces. The leaf cars seem to be a lot more consistent under those conditions. The leaf performs several functions that other suspension systems might need additional hardware to serve. The leaf does the following:

1. Supports the chassis weight

2. Controls chassis roll more efficiently--high rear moment centre and wide spring base.

3. Controls rear end wrap-up

Also, a leaf spring can be used in conjunction with a coil or coilover spring to enhance the spring rate adjustability function for chassis setup balance. Teams will often put a high-rate leaf spring on the left rear and a low-rate monoleaf spring on the right rear along with a coilover spring and ...