In order from top to bottom :

Flat hex head bolt mates to the top of the upper control arm which is flat. Perfect mating surface.

The bottom of the upper control arm is flat which mates to the top of the flat taper (spacer).

The bottom of the spacer (non-tapered) is flat and mates to top of the balljoint which is flat.

The bottom of the balljoint is a flexible/swivel joint connecting to the lower arm.

With these facts in mind, the heads of the bolts are seated on a flat surface which is the top of the upper arm.


Upper arm -> taper -> flat bottom -> balljoint -> swivel joint.

If the balljoint was a solid shaft connecting the upper and lower arms, then a tapered spacer would not physically work.

Because the balljoint flexes, it allows for the taper which is there to correct the 'extra height' that throws off the camber.

The taper can be viewed as the bottom angle of the upper control arm.

Side profile pic below.

If this was not tapered, you would see the balljoint pushed outwards to the left side of the picture, away from the Monty.