Today we're going to show you how to install a typical leaf spring onto a trailer. What we have here is a typical 4 leaf spring on a 3500 pound axle. The first step involved is loosening this bolt here and this bolt here on the bottom and this top one we do not have to worry about for now. The next thing we have to do is loosen these U-bolts here. The nuts are on the bottom, so we loosen these out so we can get our axle away from the spring. What we're going to do first is take off this bolt and then we'll come around and do this one. We're going to let this spring down and our axle is going to hang down a little bit. What we did was keep the axle tight on the other side so it will come down some but it will take off most of the weight so that way we can do one at a time.
If the bolt is jammed in there a few whacks on the hardened bolt will be okay but we'll put the nut back on to protect the threads a little bit more. With the spring away you might as well take a moment to inspect the shackle links here, this is a part that is supposed to wear down over time. What you'll see is that this hole will become oval shaped as the weight sits on the trailer. This ones in pretty decent shape so we won't have to change it out, but if you see any hole egg shaped, its probably time to change it out. Now we'll re-install our spring bolts with a reversed procedure. What you want to do now is leave the outside spring bolts and mount our U-bolts into place. You want to leave this loose so you can have a little wiggle room. Since we have our bolts in place we can start tightening them down, we'll start with the U-bolts and we'll tighten them down equally. Basically we'll do a criss cross pattern then back and forth. The main object here is to tighten these down equally, one or two threads difference is not going to make that big of a deal, but it's what you want to aim for. Torque wise, you want to make sure the plate is bending up slightly, once you've done that then you're tight enough. Now we go back to our spring bolts and tighten those down. Now we'll repeat for the other side. There you have it, your spring install is complete.