You may be surprised, that we are picking up the subject of the 'Kadett' once again, the reason is, to take a closer look at it's technology. Even more so in fact, when what we mean is it's suspension. Now, what can be so special about the rigid axle in the first Kadett of modern times?

Ok, at first sight it seems to be simply a rigid axle with leaf springs, which apparently, also guide the axle. This however, is the first wrong assessment, because the leaf springs are not, as is usually the case, rigidly connected with the axle, but allow it a certain amount of twist.

Without a doubt, in this case the final-drive is part of the unsprung masses, indeed, the drive shaft cannot be seen because it's cased in by a tube. This tube, together with the rigid axle, forms a unit and is connected to the car body by a so-called central universal joint.

It's exactly here, that the drive shaft has it's only joint, and where it goes on to disappear further towards the front inside a second tube. This central joint is thus named, because next to those on the front left and right, it also forms the third support of the drive train block.

Thus, on the arch around the central joint, the rear axle can be compressed and, at the same time, twist slightly. The braking- and driving forces are taken over from the tube to the central joint. The leaf-springs are freed from the braking- and driving forces and can be compressed without hardening by possibly taking on an S-shape.



Here you can see a sketch of the rear axle principle. In this case, the central joint is only incompletely shown and replaced with a leaf spring. This should depict the demands made on it in the event of one-sided strain. In their prospect, Opel especially points out the stabilizer effect on the rear axle, this time without the torsion bar, with which we are more familiar.

The front axle also has leaf springs, although it serves a double-wishbone. No, here the leaf spring does not also have to take care of the wheel guidance. It is made up of three layers, each with a certain distance from the other. Since its job is not to absorb, this is taken care of by the front- and rear telescopic shock absorbers.

Neither does the front axle have a stabilizer, this is not really as necessary as in the rear. If the transverse leaf spring in the middle were to be rigidly mounted to the superstructure, each side would make demands on one half of it. The correct term would then be 'cantilever leaf-spring'.

However, because it is mounted slightly flexibly, it should have the effect of a transverse stabilizer. If you ask me, exactly the opposite is the case. This theory fits in well with the understeering tendency of the front-engine car, together with the already mentioned stabilizing effect of the rear axle. 01/15