Home-built motorcycle trailer

My friend John has pulled a motorcycle trailer on the last couple trips we've been on. It's been very handy. When we went to Asheville his trailer was packed full. Now that I have a larger bike I'm going to build a trailer so we can split the loads.

Home-built motorcycle trailers are fairly popular. Two great sources of info are the Gadget trailer page and the Delphi Motorcycle Trailer Towing forum. I decided to build my trailer using the ever popular Harbor Freight trailer and Sears/Karrite cargo carrier.

I got the cargo carrier at Pep Boys for $109. This is the same carrier John uses. This is a side-opening carrier.

Here is the trailer kit from Harbor Freight. $139 with free shipping. The kit is normally $179 but is often on sale.

I bought a 9' piece of 2"x2" tubing I will be using for an extended trailer tongue.

Here is the trailer unpacked.

The frame is longer than it needs to be so I cut 10" off of it.

The frame is wider than it needs to be so I cut 2" off each end of the cross braces. The lower hole will still match the side frame (one less new hole to drill).

After cutting the final dimension is 38" x 36".

The carrier fits much better on the smaller frame. I would have liked to make the frame even smaller, but the tires stick up too far.

I assembled and squared the frame then mounted the longer tongue tubing. After ensuring it was centered I welded it. For extra strength I will also be bolting the tongue on. The normal 2 1/2" tongue uses two bolts per crossmember. The 2" tubing I'm using is slightly too small to use the provided bolt holes so I drilled a center hole in the crossmembers.

I also marked the holes for the lights and drilled them as well as the holes for the ball coupler.

I fabricated a cooler mount out of a piece of old bed frame. The cooler fits nice and snug.

The axle had to be shortened by 4" to match the frame. About 10 seconds into cutting the axle with the chop saw the saw died in a blue flash (armature burned) so I had to finish with a sawzall. I butted the two pieces together and welded them. John used a 1" water pipe to strengthen the cut axle, and I did the same. It fits into the axle tubing perfectly. The pipe is welded to the axle and now it's ready for a coat of paint.

With the fabrication complete it was time to prime and paint. I ran a piece of water pipe through my center tube, mounting one end on my workbench and the other on a sawhorse. This allows me to rotate the whole assembly. I started to use a scuffing wheel to rough up the paint but found 220 grit sandpaper was quicker and easier.

Here is the primed and painted frame. This is blue Rustoleum I got at Walmart. It is one of the prettiest blues I've seen and it has metalflake in it.

If you're going to do much can spray painting one of these Can Guns is the way to go.

A tip gleaned from the Gadget page is to remove the second leaf for a smoother ride. I removed the center bolt (1/2" wrench), cut the strap, and the leaf was separated. The center bolt is re-inserted.

Removing the smaller leaf leaves an unpainted portion on the longer leaf spring. Here they're getting ready for a coat of black paint along with the primed axle.

After letting the paint dry overnight I installed the front and rear running lights. I ran the main wires through the main tube to the back of the trailer where all the wiring will meet. I'm using LED lights on this trailer in place of the supplied lights. The rear brake/stop lights are leftover from my tour pak project and were purchased at KMT Trailer Parts.

Next I installed the leaf springs.

Another tip from the Gadget page is to run the rear leaf spring bolt through a hose for quieter operation. A 2" piece of 5/8" hose works nicely.

The axle bolts on next. The shortened axle fit perfectly in the leaf spring locator pins.

Since the tubing I used for the tongue was 1/2" narrower than the normal tongue I had to use washers to shim the coupler.

Yet another Gadget tip is to use a bicycle kickstand when parking the trailer. I got this one at Walmart for a few dollars.

I spent an evening finishing the wiring. All the connections are soldered and I used ziploom as much as possible. All the wiring runs to a central junction point at the rear.

With the fenders mounted the carrier fits nicely between the fenders.

I trimmed a treated 4x4 to use to support the rear of the carrier.

The only thing left on the trailer itself was mounting the wheels. The wheel bearings need packed with good grease first. The outer bearings are loose behind the caps, but the inner bearings need some effort to get out. I could see they needed repacking so I used an 1 1/4" deepwell socket I had to drive out the bearings and seals without damaging either.

It's hard to tell from this picture but the bearings have almost no grease inside them. The grease they do have looks more like Vaseline...probably just there to keep them from rusting.

I repacked all the bearings using a bearing packing tool I had left over from the old days when cars still had bearings that could be repacked, not the non-serviceable $400 bearing assemblies they have now. A happy, packed bearing.

With the wheels on the trailer part is finished. Time to mount the carrier.

I installed eyebolts in each corner to bolt the carrier to the frame and to provide tie points for the cargo net. There was a gap at the rear of the carrier so I made some spacers out of some scrap aluminum tubing I had. I also screwed the carrier into the wood brace I had installed earlier.

I installed the carrier top and added a couple stop/turn lights to the top.

A couple pictures of the lighting.

The tongue is a little longer than I had planned. I'll see how it tows. I can always shorten it if it is a problem.

My ratio was 94/44 = 2.14 which is a little longer than the rule of thumb.

Update - The trailer tows just fine with the long tongue. I was afraid it might drift to the inside on turns, but it doesn't. It tracks very nicely.


Cargo carrier116.19
Trailer tongue tubing52.76
LED lights136.92
Spare tire37.98

I splurged on the LED lights. If you used the basic kit lights and tongue the trailer can be built for right around $300.

The trailer performed flawlessly on our 2007 Asheville trip.

Update 1/2008 - I remodeled the trailer to more match my new Goldwing.

Other good sources of trailer building info:

Wayne Herbert's page

EZ Glide's trailer build - 12" wheeled trailer

DaveDragon's trailer page

E-mail me