I was trying to put my rear suspension together and ran into a problem. The springs are lowering springs and seem to are to short to allow the top hat to preload. You can see in the pictures that the spring doesn't touch the rubber top hat and when the strut is flip over there is about 1-1.5" of room before the collar is seated. The only idea that I have come up with so far is to make a spacer that fits below the bottom collar to raise it up enough that I can preload the spring.

 

The weight of the car will compress the shock and pre-load the spring. Worst case, you'll get a clunk from the spring after hitting a big bump. If you want to fine tune your preload, you should get adjustable spring perches like a ground control setup.

 

what he said, just make sure when lowering the corner that the spring seats properly and not off to a wonky angle