How would you shorten the preload spacers?
I'm talking about parts 92152 here.
Have you done it?
They're thin and have a plastic bit on the end. I could have them cut and try to reattach the plastic bit. I could cut a piece of pipe (what size?) to replace them, and drill holes for the spring compressor. I could use a shorter part from different bike if there is one.
From the diagram it looks like left and right are different lengths (the diagram shows L & L being different lengths but that doesn't seem as likely).
They are of different lengths. They can be both shortened as much by cutting them down with a hacksaw or other, to use with longer springs. The plastic bit just sits on the end of the metal tube... Why do you want to shorten yours?