Repairing or rebuilding a utility trailer.

If you have an old utility trailer that needs repair, I hope you can avoid the pitfalls I experienced, and learn from my mistakes. Fixing up an old trailer can be fun and expensive. Here I will help you to know what expenses to expect, and what ones you may be able to avoid. What worked and what didn’t.
When I first bought the utility trailer it had a fresh coat of green “industrial” paint. It was not completely dry yet, and it had some snow on it. I found out later that the cold prevents paint from curing. Driving around, I noticed that it was the only green trailer in town. All the other trailers were black. And every time it rained, the light green uncured paint would run all over everything. I solved that by painting black latex paint over the green which, as I had hoped, also acted as a curing agent for the green paint.
This year it was six years since I bought that old trailer, and it was getting rotten. The plywood sides were separating their plies and some of the bolts holding the sides on were sliding right out through rotted out wood. I had been putting off the inevitable replacement of the sides for two years, but at this point it had to be done. Both tires and the spare had several large cracks. They seemed to hold air for now, but they also needed to be replaced. Also the taillights had always been dim, so I wanted to replace those as well.
Thinking about how to build the new trailer walls, it was the perfect excuse to buy an arc-welder, and I think I’ve wanted one for twenty years. I had read all the boxes and got all the accessories and a cheap arc-welder in the shopping cart, but when I added it up, It was more than half as much money as buying a brand new trailer, so what would be the point of that?
I managed to take the trailer on one trip to the dump this spring, getting rid of a winter’s worth of junk that had collected in it. I had tied a tarp over it and ropes around from under the corners, as much to hold the sides on as to hold the load in. On the way back I stopped at a metal shop to pick up some angle iron rails or bars to make a frame for the new sides that I was planning to build for the trailer. When I pulled into the parking lot, the right rear plywood and taillight were hanging by the taillight wire. I ended up getting six aluminium angle bars ten feet long by one inch by one inch (1/8” thick).
Back at home I only pushed lightly on the other back corner, and it folded right down and broke off. Then with the sides, they came right off the bottom and swung forward and out like wings still attached to the front, and then they broke off. The front took a slight amount of persuasion to break off, but the floorboards were easy.
I pried the wheel wells off the floor boards to use later. They were attached through the bottom of the floorboards with about two hundred staples.
The spare tire mounting bracket was on the front wall. It came off easy, but the two bolts holding the wheel onto it were rusted solid. And so were the nuts holding the other two wheels on the hubs.
On the right edge of the floor, a couple of feet from the front, there was a metal threshold which had been hidden by the two by four at the base of the wall. And under the metal threshold was a strip of vinyl flooring. So I believe that that plywood had been the original sub floor of the tent-trailer that it once was.
There is a tongue jack like a crank-down foot just behind the hitch. I don’t know why I was surprised at the amount of rust on the frame when the floorboards came off. Rust encrusted the entire trailer frame in big flakes and under those flakes was more rust. That didn't put me off, after all the aluminium was already here.
Then I noticed something about the trailer that would have been useful many times in the past. For six years they had been folded up inside the frame. In the back corners there are feet that swing out and extend down. Several times the trailer had started tipping back when I stepped onto the back while it wasn’t hitched up. I had to quickly hop off so it wouldn’t tip farther. Now with all three feet down it never tips. And by extending the tongue jack more with the back feet down, the wheels come right off the ground for changing tires.
I found my old round wire brush to use with a drill and went once over the whole frame to get most of the flaky rust off.
I applied some undercoat for cars to the top and outer side of the frame with a putty knife. That stuff stays a bit sticky for weeks, even when most of it seems dry, and I have the black stripes on the back of my pants to prove it.
Having measured the trailer frame, I decided on 19½" for the height of the walls. I knew that my band saw with a metal cutting blade would zip through the aluminium. Having worked for years in a wood-shop, I should have known better but ... not thinking far enough ahead, I had the measurements planned and the aluminium marked; but when I took it to cut at the band saw, the saw only has nine inches from the blade to the neck. The longest piece that can be cut straight is 9 inches. To get around that - By cutting the aluminium at an angle, I could cut any length through without it hitting the saw's neck. But then I had to cut straight ends on one or both pieces. So it is two or three times as many cuts, and additional wasted metal. It would have been better to use any other type of saw, rather than a band saw, to be able to cut any length of aluminium at a 90° angle with only one cut.
The post at each corner would fit on the corner of the frame.
Three posts equally spaced on each side of the trailer, would have one edge against the trailer frame, and the other edge jutting 1 inch away from the trailer. The side posts would be rounded at the bottom, and would have the top corner cut in 1/8" to line up with the outer edge of the top rail.
The top rail along the side wall from front to back would rest one edge on top of those three side posts and the two corner posts. The other edge would hang one inch down on the inside of the new wall. The end of the top edge of the rail would be 7/8” longer at each end (with that 7/8” of the hanging edge notched back) to fit over the corner posts. The other side was done the same. The ends of the front rail would rest on the front of the side rails at the corners.
That would make the top rail across the front 1/8” higher than the side rails, so the three in between posts for the front needed to be 1/8” longer. The back was to have a large gap in its wall for loading. It would have two walls at the corners about a foot wide. The struts that hold the bumper are not the same distance from the sides, and they are used to mount the rear posts. So the two back walls are slightly different widths. It is not noticeable, but it makes a difference when you are cutting the parts.
To assemble the aluminium parts I used bolts and nuts, but I also threaded the holes in the aluminium and in the trailer frame. Drilling all those small holes broke a few drill bits. A couple of unexpected trips to the hardware store for 9/64” drill bits were necessary before I could continue.
The ratchet set would not fit in some of the inner corners of the trailer frame to tighten the nuts. I bought a combination wrench set at Wal-mart, and a new set of taillights at Canadian Tire. The wrench set had 4mm, 5mm, 6mm, 7mm, 8mm, 10mm, 12mm, etc. But the nuts turned out to be 9mm. I found a combination wrench set at Princess Auto with SAE and metric with the 9mm size. It was on special with twice as many wrenches for less money.
Threading all those holes was time consuming, but the resulting frame for the walls is solid. When I push on the new wall frame, the whole trailer moves. I think that part of it was worth the effort, but only because I didn’t buy a welder.
I painted the rest of the frame and the aluminium with black rust paint.

I would need to take the trailer to the lumber yard to get the plywood for the walls and floor of the trailer. And to do that, it would first need the licence plate back on and the new taillights. So I just put pieces of scrap plywood on for the small back walls, leaving a one inch gap under them for the floor to fit later. And then I mounted the taillights. The ground connections screw into the frame. The other wires run along the rails of the frame, held in place by a few clips, and by feeding the wire through holes in the frame. The paint seems to help keep the wires from jostling, jumping out of place, rubbing against the rust and wearing out. However painting after the taillights were wired in place, it was a pain to try not to get paint all over the tail lights.
I wrapped rubber tape around a section of the front wires and frame to reduce strain on the wires.
The licence plate bracket that came in the taillight set would hold the plate too far to the side. So I cut a couple rectangles of scrap wood to layer behind the licence plate to position it properly centered on the left back wall, and far enough out to be under the licence illumination part of the tail light. When I hooked up the new lights, they didn’t seem much brighter than the old ones. In sunlight the taillights were not really noticeable.
Since the old floor was approximately one inch thick; I figured 2 sheets of one inch thick plywood for the floor, and two sheets ½” thick for the walls (all pressure treated) would do it. There is about four feet and five inches between the wheels, and there are no wheel wells on there yet, so the plywood sheets will need to be tied on real good, to avoid shifting over and rubbing on the tires.
When I got to the lumber store I was in for a shock. They only had ¾” They didn’t carry one inch. But that wasn’t the shock. I had no idea how expensive plywood had gotten! $54.00 Canadian for one sheet of ¾” pressure treated construction grade plywood. I’m sorry, but there is just no way. There were new trailers for $650.00 Cdn. and I have already spent $70 on aluminium, $60 on paint, $20 on screws, and I figure I would probably need to spend $170 on tires, and now plywood will run another $180 to $200 that adds up to almost the price of a brand new trailer. I decided to just get two sheets of rough untreated ½” for the floor for $20 each.
The trailer frame has a narrow bar from front to back that is not positioned symmetrically. It is four feet over from the left side, and the original sub floor joint was along that bar. I set the new wood as close to the correct place as it could get, and had to use a square to mark guidelines for cutting the shape of the two floor pieces. The things that were in the way were the back walls, the other wall posts and the wheels. Otherwise I could have put the four by eight sheets of plywood where they should go, and simply marked on the bottom of the plywood around the edge of the trailer frame.
I am making the new floor to extend back onto the rear bumper, to make loading easier. I cut rectangles out of the back corners where the walls are. I cut notches for the taillight wires to go through the back corners of the new floor. And I cut rectangles for the wheel-wells to fit.
It is tricky to get the new floor pieces in place because the wall frame and back wall plywood are already mounted. I have to angle the floor resting it on top of the front wall, place a board under the floor to span the gap to the bumper. Then go around the front and lower the floor while jostling it into the one inch gap under the back wall. Then slide it a couple of inches to the side edge. Then it was ready to trace along the back edge of the bumper to trim that off. Finally trim the edge of each piece to align with the floor seam support bar.
After the plywood for the floor fit properly, I took it off and primed it, and later painted it black. And with vice grip pliers I pulled out the two hundred staples from the old wheel wells. By this time I am starting to think it would have been better to buy a new trailer.
It was time to tackle the wheels. Before attaching the floor permanently there is easy access to the wheels. I put some oil on each bolt beside the nut, and used a combination wrench to get two bolts off the spare tire. The nuts are welded to the mounting bracket which simplified the task, but it took a lot of effort and time. And the short handle and odd end shape of the combination wrench made it hurt applying sufficient torque without enough leverage.
When I first tried to get the nuts off of the left wheel, I was pleasantly surprised to find that they could be turned with less than half the force of the spare tire bolts. But then there did not seem to be much progress. Looking at the back of the hub, I saw the whole bolt was turning as well as the nut, and I was getting nowhere. So I got out the ratchet set, but the shallow sockets would not reach the nut, and the deep sockets were not wide enough.
Being determined to get the wheels off that day, I went to Princess Auto looking for a set of long sockets that included an 11/16” socket. They had a set on special with a 3/8” drive, but I had a sixteen inch long breaker bar, like a handle for sockets with a flippy ½” drive. This deep socket set has a ½” drive.
And to be on the safe side I got a new twenty four inch breaker bar with a ½” drive. Here it is with the old sixteen inch breaker bar.
The bolts head in the back of the hub are 5/8”, and the nuts on the front of the wheel are 11/16”. With one breaker bar on the back and one on the front, they started to loosen. I could not turn it a full 180 degrees at a time and swivel the breaker bar around because of the length of either handle was blocked by the ground and the trailer frame. But at least it was working. Turning those rusty nuts at maximum torque made the loudest squawks and creaks. As the nuts and bolts came off, they were too hot to hold from the friction.
After a long time doing that I got a great idea that was not so great. I got a two inch diameter pipe from the basement and stuck that on a ratchet handle propped against the ground on the bolts at the at the back of the hub. That made it so the breaker bar on the nuts on the front of the wheel could be used as if it were a ratchet. Just push the breaker bar back and forth, and the ratchet at the back keeps things turning in the right direction. It was working so much faster that I didn’t notice the bolt coming out the back was pressing the ratchet against the axle spring bracket, twisting and loosening the ratchet in its handle, nearly breaking it. I think the shortness of the ratchet handle is designed to match the maximum torque of its mechanism, so I would not recommend using the pipe on the handle idea.
It would have been better to do the wheels before the aluminium of the walls was in the way. In this picture I set one floor board in place over a new wheel.
After the new wheels, were on and the floor was screwed down, I tried stapling the old wheel wells back in place. The longest staples available (9/16”) would not hold them. So I used wood screws, which held them. I installed the wheel wells from the top rather than pushing them through from below, because I thought that would make it easy to remove them to change the tires later. I would not recommend putting the wheel wells in on the top, because they are more secure when they are pushed through the floor from the bottom. It is possible to change the tires with the wheel wells in place.
I splurged another $40.00 on plywood for the walls, and tailgate. I cut the plywood for the walls short, so there would be a 1¼" gap between the top rails and the plywood. The tie down ropes are easy to attach to all the rails that way.
I threaded the holes in the aluminium for the wall mounting bolts as well.
The tailgate is just a piece of loose plywood. It fits just in front of the two small rear walls, with a hasp at each end of the tailgate to hold it in place. I tried dropping a bolt in each hasp to keep them closed, but the nut was loose and dropped off and the bolt hopped out at a small bump in the road. So now I use security snaps (those rock climbing type chain link clips) on the hasps, they are quicker than bolts and they stay on.

In this picture you can see the angle at the bottom of the tailgate to help when lowering it into place. I cut the tailgate ¼" narrower than the opening, and it fit fine until the primer was on it. Now it has to be jostled down, so I'll have to cut some more off the end. And then it needs black paint on the walls. The tailgate sits about 1/2 inch in front of the rear walls, because of the bolts that hold the tail lights in place. So the tail gate and hasps had to be positioned after the tail lights were installed.

With the new lights dim like the old ones were, I thought the rusty frame was causing too much electrical resistance on the ground connection. So I added a wire for ground from the coupling to each light, with the frame still grounded. That did the trick; the lights are properly bright now. So there was probably no need to get the new lights. The old ones must have only had the same grounding problem. Adding the ground wire at the end was worse because it meant getting under the trailer to feed the wire through, and the paint is not holding it, only the holes and clips.
How much simpler would it have been to get the wood ahead of time, so things could be done in proper order:
1) Measure the trailer, plan and get all materials especially all the large materials that would require a trailer to move.
2) Remove the old wood, and remove loose rust from the frame.
3) Remove the old wheels with the frame standing on its three feet.
4) Feed wires for tail lights including ground wire but don't install the lights themselves yet.
5) Mark and cut the plywood for the floor including holes for the wheel wells, primer the floor plywood but don't install the floor yet.
6) Paint or undercoat the frame, and paint wood for floor.
7) Install the new wheels.
8) Put the wheel wells through bottom of plywood floor (still not on the trailer) and screw the wheel wells into the plywood.
9) Install floor.
10) Cut and install aluminium for walls, and cut-primer-paint and install wood on walls.
11) Touch up paint whole trailer.
12) Install tail lights.
13) Cut-primer-paint and install tailgate with whatever connectors.
14) And put the licence plate on last.
I couldn't do it that way because the trailer was falling apart when I was picking up the aluminium. If you decide to fix a trailer, you will have your own bunch of unforeseen problems, but that is what makes it fun, right?
Another option is to rent a trailer from Uhaul or wherever, whenever you need one. For $25.00 a day I could have rented a better trailer 25 times for less money. If you only need a trailer 4 or 5 times a year, renting one could make more sense. And that way you can get the right kind of trailer for each job.
At the end I added up the receipts for rebuilding the trailer. For US conversion I used 1.14 Cdn to 1.00 US (the exchange rate at the time), and substituted 7% sales tax instead of 15%. So each Canadian price times 0.82 to do it all at once.

You can see if there are any items from this list that you may need to add to your list when planning if it is worth fixing your trailer or not. If you need figures that are more accurate to your situation, check your local prices. This should help you think of more of the costs that you may run into.

Item Canadian   U.S.
black exterior paint 32.19    26.40
aluminium 79.93    65.64
undercoat 30.99    25.41
screwdriver bits 6.38    5.23
bolts & nuts 18.35    15.05
3/16” washers 3.44    2.82
5/16” washers 5.74    4.71
9/64” drill bits 3.31    2.71
wrenches 16.09    13.19
tail light set 66.64    54.64
plywood 91.08    74.69
primer 34.49    28.28
deep socket set 20.69    16.97
breaker bar 22.99    18.85
wheels 183.98    150.86
self taping screws (for floor) 10.21    8.37
9/16” staples 4.47    3.67
wood screws (for wheel wells) 5.19    4.26
hasps 8.03    6.58
security snaps 5.68    4.66
ground wire 6.31    5.17
black rust paint 23.90    19.60
rubber tape 8.38    6.87
Total $688.46
On the Plus side, it was a fun project, and the result is somewhat larger than a new $650.00 trailer. On the Minus side, it was a waste of time, the sides are not welded, the frame is all rusty, the floor is not thick enough, and the repairs cost more than a new trailer would have cost. So in this case the trailer was definitely not worth rebuilding. Your trailer may not need as much repair, or you may have cheaper suppliers, like or A project like this is full of expensive surprises. I hope this helps you to make a good cost analysis before you decide on your trailer rebuilding project.

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