Suspension

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Front Suspension

The E34 has a McPherson strut arrangement at the front, the tops of which are bolted to the wheel wells and visible from the engine compartment.  (A McPherson strut is simply a large spring-loaded shock absorber that is used as part of the suspension and steering structure.  It's an efficient suspension design and has been used for decades mostly on European and smaller American cars.)

The bottom of the strut is restrained by two control arms which complete the geometry for both wheel guidance and steering pivot. Each of those arms has a conventional ball joint at the wheel end, one of them appearing to be slightly above the other - prompting the factory designation of "upper" and "lower."  In fact both are "lower" in suspension function.  I will refer to the front arm as the Control Arm and the rear as the Thrust Arm, although you may see the latter referred to in some catalogs as the Upper Control Arm (or Rod.)

In my E34 the (front) Control Arm is made of forged aluminum and has what appears to be a large spherical bearing at the body end. The Thrust Arm on the other hand is equipped with the infamous and appropriately named "Thrust Arm Bushing" which upon close inspection always looks to be falling apart.  This bushing has substantial compliance (it's very soft) and in effect allows the wheel to move fore and aft (about 3/8") as you drive over bumps.

The forged steel wheel stub axle is further equipped with a steering arm towards the rear, which is attached to the steering tie rod with conventional ball joints.  You will note on observation that the control arm is angled more across the car, while the thrust arm is angled more in-line with the car.  Those angles are designed, in my best engineering opinion, to minimize camber and toe-in change over the normal compliance range of the thrust arm bushing, at the expense of caster.

Due to the steering caster angle (like a motorcycle front fork) and the dead weight of the car, the thrust arm is actually loaded in tension when the car is parked, giving the false impression the bushing is separated.  As not to disappoint you, the bushings are known to commonly fail anyway well below 100,000 miles and will cause or aggravate a nasty front-end shimmy at between 50 and 60 mph.

  The infamous thrust arm bushing

As I haven't had to replace the bushings yet, there's not much more I can tell you about it.  The job appears fairly simple, but clearly requires that the body be raised with the front wheels hanging down to unload the suspension.  The control arms can be removed and taken to a repair shop to press in the new bushings.  It seems to be common knowledge that 7-series bushings are a better buy, refer to your OEM parts house.

Rear Suspension

The rear suspension is a "semi-trailing arm," common on most older BMW's and Mercedes but not seen on many other cars.  It's a rugged design and is generally known as a "luxury" rather than a "performance" suspension.

On the E34 there is a modifying link at the outer pivot points, the purpose of which presently eludes me.  It appears to change (or correct) the toe-in over suspension travel, most likely to reduce the semi-swing arm's reputation for inducing oversteer.   In addition, the moderate camber change over suspension travel and the resulting uneven tire wear is the reason why BMW advise not to rotate the tires front to back.