The steps mentioned below are what I took to put together a 40×48″ trailer kit. There are many companies that provide them. Please note that these are the steps that I took but you should consult and following the instructions that came with your trailer.
I also considered this trailer since it has a little more room for standing on the trailer, while putting the bikes on top. I wouldn’t install the side rails or gate on this option. The advantage of this one is you also do not need to extend the tongue or add wood decking.
1) Spread out all parts
2) Place the two longest side rails in parallel. The side with the square cutouts should be facing up. This is the top of the trailer.
3) Place the three shorter length cross members perpendicular to longer rails. The cross members should have the “U” shape pointing down.
4) Bolt together the components with the provide fasteners
5) Install the tongue using the four fasteners provided
6) Install the four leaf spring hangers making sure the two in the rear of the trailer have the small partially bent piece installed on them. I forgot to install it initially. These covers the hex head so the leaf spring does not rub up against it. The front ones do not need them since the leaf spring has an eyelet on the front.
7) Set the leaf springs in position with the eyelet of the spring towards the front of the trailer.
8) Install the fasteners and then insert the cotter pins.
9) Using the provided u-bolts, mount the axle to the springs.
10) Place the tire assembly on the axle and tighten the nut snuggle but still having the ability to rotate the tire. Insert the cotter pin through the nut.
11) After flipping over the trailer, mount the fenders.
12) Install the ball receiver and chain.
13) Mount the 90 degree bracket for the rear lights.
14) On the drivers side of the trailer, mount the light with the clear bottom and the license plate holder. The clear bottom of the light allow the license plate to be seen at night.
15) Install the front running lights. We will wire them later.