You want some preload on those shocks with no load on them. Your swing arm should extend down (axle end of course) quite a ways. Is your swing arm hitting something when you move them down? Or is the problem when you have one shock on, and you can't get the other shock on? Or is your brake anchor/stay still connected? Chain still connected? Is the swing arm hitting the frame before you have it low enough to facilitate shock installation? Is the swing arm axle frozen within the confines of the swingarm bushings? No matter what else is going on, 1/4 inch is nothing in the world of shocks.