There are 40 splines on the inner each one is "worth" 9°. The outer end has 44 splines so each one makes an 8.182° change.
Here is the link to some threads on ShopTalk about it:
Spring Plate Thread #1
Spring Plate Thread #2
And another from Air Cooled Volkswagen:
Spring Plate Atricle
Hope this helps!
Cheers