How To Build A Utility Trailer

I needed a trailer to haul around a snowmobile so I decided that I might get better use out of a general utility trailer instead of a snowmobile trailer. I checked the local trailer retailers and found that the going rate for a 5′ x 10′ utility trailer was around $1,300 Cdn. The trailers weren’t very strong and were made mostly from light angle iron. Always looking for a good project, I decided to build one instead.

The objective was to build a better trailer for about the same cost. I also wanted to build in a tilting feature to make loading easier. Using rectangular tube instead of angle for the main frame would make a stronger trailer, but would add steel cost which would hopefully be offset by free labor.

I bought some inexpensive plans from ebay to get some guidance. They didn’t offer much value at all. They included a drawing of a frame but stated that there were too many axle types to include those in the plans. I was hoping that they would answer questions I had about axles and tongue weight but they really only showed how to build a frame.

I ended up drawing my own plans in AutoCAD that you are free to download for reference if you like. They are not totally complete, but I used them to get a weight estimate, a steel materials list and details on some pivot pieces.

AutoCAD File

Steel Shopping List

Trailer Budget Plan

The axle kit shown below was purchased locally from Intruder Trailers. Unfortunately they went out of business a few years ago, but Princess Auto would be a good place to look for axle kits. Key decisions for choosing an axle kit are weight capacity(3,500 lbs here), type of suspension (leaf spring, torsion bar, etc.), width of frame, and height of the hitch. This kit was pretty much the stock 5-foot wide trailer kit, although custom widths can be ordered.

Axle Parts

The steel was ordered from a local supplier. I found that it is well worth it to comparison shop when purchasing steel. The most expensive retailer was over 2x the cost of the least expensive.

Steel Order

The first step was to cut up the main frame pieces and weld it up. Make sure that the axle will fit to the plans before cutting and welding. I used an abrasive cut off saw and a stick welder for most of the cutting and all of the welding.

It is important to make sure things are square and flat at this stage of the game. 3-4-5 triangles will ensure that things are square, and for flatness, I tied two strings diagonally from corner to corner (like an X). I made sure that the strings were just touching each other at the intersection of the X to check for flatness.

Basic Frame

Positioning the axle depends on a few factors. Since I was building a tilting trailer, the axle typically goes pretty close to the center of gravity to allow for easy tilting. Most trailers that don’t tilt seem to have the wheels positioned slightly more towards the rear. The main thing is that you end up with some tongue weight when everything is done. I figure that you probably want about 5% of the gross weight of the trailer as tongue weight. My axle is only about 6″ behind the center of the frame. I was thinking that if I needed to add more tongue weight, I could add a toolbox to the front of the trailer, but it turned out not to be necessary. I ended up with about 30lbs at the tongue when it is unloaded and it tows very nicely.

The other critical item at this point is to make sure that the axle ends up square and centered on the centerline of the frame (centered with the hitch). The distance from the hitch to each wheel has to be the same to ensure straight tracking. As long as the tongue is square and centered to the frame, then the axle can be square and centered on the frame.

Positioning the Axle

In the photo below, the frame is upside down. I’m mounting the tongue to a crossbar that is just ahead of the axle. The tongue is a square tube which has a 1″ solid round bar through it at the end. Gussets reinforce the round bar. The round bar is sandwiched between two 1/2′ mounting tabs with 1″ holes. This arrangement provides the pivot action for trailer. Since this crossbar is taking all the pulling and braking force, I used a 2″ x 3″ rectangular tube instead of lighter material which was used on the other crossbars.

Hinge for Tongue

The latch shown below is widely available at trailer part suppliers. It prevents the trailer from tilting when it’s not supposed to. Just weld it in place, and weld something on for it to latch to.

Latch

The fenders were a bit difficult to weld with a stick welder without blowing holes. I used smaller rods and low heat. I found when welding the sheet metal to heavier metal that if I struck the arc on the heavy metal first, then worked the molten pool onto the sheet for a short period of time, I could get a strong weld without blowing a big hole. Later on, the fenders are reinforced by some angle iron that also serves as mounting points for the lights and license.

Fenders

The side rails are just angle iron. I attached the top of the fenders to the sides to strengthen everything up. At the back of the trailer, the vertical side pieces were made from two angle iron pieces welded together to make a C-channel. This allows me to drop a board across the back of the trailer if I need a ‘tail gate’ for any loads.

Side Rails

The whole trailer got the wire cup treatment to remove any surface rust or weld spatter, and then was primed and painted.

Primer

Remember to make provision for a good ground connection through the pivot to prevent dimming tail lights.

Ground Jumper

Here the trailer has its wood decking installed and final paint. There are many more pictures showing the step by step progression in the photo album linked below.

Finished Trailer


More Pictures

Comments

comments powered by Disqus