Installing a hitch on my AK 550 to tow a small cargo trailer

[rjs987]

I just made a deal with a buddy rider to buy his Uni-Go trailer. He rides a Gold Wing and pulled it with that a few times. But now he travels with his GW in a toy hauler where I meet up with him and many others from the ST-Owners group. Since there is such a large market for the AK 550 in the USA (...NOT) I'll be fabricating and installing the hitch myself. I've done similar fabrication but not on this scale for my bikes. I had a hitch on my GW years ago, and I installed a purchased hitch for my ST1100. The electrical connections/harness will be easy for me as I've done that on several bikes.

So far I've decided to use steel DOM tubing, 1" x .12" and mount it to the rear frame of the AK running out and down through the plastic on each side of the wheel well. Not the painted plastic but the black plastic under that which is really part of the wheel well panel. The hitch will terminate at the rear with a bracket that bolts to each tube and forms the bracket for the Uni-Go coupler. That coupler is different than any other "normal" trailer coupler in that it does NOT use a ball. Instead it has a rectangular bracket with what amounts to a universal joint. Since this is mono-wheeled trailer that tracks exactly where the bike tires track this is the only type of coupler that will hold the trailer to the same orientation with the bike yet allows for flexing left/right and up/down... just doesn't allow the trailer to lean differently than the bike.

I'll be documenting the project when I finally get around to work on it.

Now, I'm just waiting for my friend to bring the trailer. He lives on the other side of the state but says he looks for excuses to travel to my area to visit his daughter who attends the state university near me. I'd expect that to happen within the next 2 weeks since he'll likely be coming this way to pick up his daughter for the holiday break.

[Iahawk]

interesting..looking forward to following this build.

[Ruffus]

..echo hawk👍

[randyo]

I've seen the type of hitch yer fabricating, on a V-Strom that was pulling a Uni-Go

following

[rjs987]

Well, I WAS thinking of going for a ride today... the first day of the year. But instead I got caught up in redesigning the electrical diagram for my added farkles to include the connector for the trailer. Lost track of time and before I realized it was getting dark. Oh well, there's always tomorrow. The weather is just a few degree above normal for this time of year but no snow on the pavement and otherwise perfect riding conditions.

Anyway, here is the link to the new and improved electrical diagram. Trailer harness/plug in the upper right. I also show the wire colors to tap into just before the rear light assembly plug to trigger the relays that turn on power to the trailer lights as needed. The main 10A fuse under Relay A may be changed once I get the trailer and see what it should be. This would be in addition to the factory electrical diagram that I also have.

AK 550 electrical farkle diagram

[Super Dirt Dud]

Happy New years and thanks for posting the project I am looking forward to how the trailer works for you my AK is a great highway scooter the trailer would make is even better .

[rjs987]

FINALLY heard back from Unigotrailers.com about a question I asked relating to constructing the hitch frame. I asked if 1/16 walled tubing was enough or if I should go for 1/8 walled tubing. They said to stay with the 1/8 inch walled tubing. They didn't say anything about round or square and I really don't know that it will matter in this application. That eliminates a few choices of parts I was looking up.

They also stated/recommended that I make sure to have 2 attachment points on each side. I will have that, but because the 2 attachment points will be very close together compared to how much of the frame will stick out the back. So I do intend to add a 1/8 x 2 inch hangar bar from up in the tail section down to the end of the hitch frame. I just haven't figured out the exact details of that part yet.

[CROSSBOLT]

Nice job on the wiring! Love that diagram!

A hitch for a trailer is a challenge on a mc/scoot. Huge challenge for a one wheel trailer. Looking forward to pictures of your solution.

I have modeled a hitch arrangement for a two wheel trailer that hooks to the bottom of the shock mounts. I will see if I remember how to post pictures here...

[rjs987]

Thanks, Not my first rodeo on that front.

I have decided to go with stainless steel stock as much as possible. Costs more but saves me a lot of work to make common steel more weather resistant and I really don't want rust causing me any trouble. Too bad aluminum isn't stronger. I've also decided to use square tubing for the main hitch frame. That will attach better to the square C channel of the bike rear frame.

I'm not a fan of attaching a trailer as un-sprung weight to the bike. It affects the handling and can actually add to the wear on the final drive parts/belts more than just pulling a trailer the more common way. With the trailer as sprung weight it is more like, though I know not exactly like, adding a passenger... at least for this trailer since the total weight of the trailer and load in it will be less than 140 lbs. A trailer as un-sprung weight would be like adding mass and drag directly to the rear wheel.

[randyo]

that was going to be my next question, weight of the trailer, not a bike, but my 1050lb UXV450i is rated to pull 1500 lbs, and I've done it before, maybe even a little more, kinda scary going down a hill on a gravel road 45mph when your trailer starts pushing you, I've even wondered what it would take to have trailer braking

[rjs987]

that was going to be my next question, weight of the trailer, not a bike, but my 1050lb UXV450i is rated to pull 1500 lbs, and I've done it before, maybe even a little more, kinda scary going down a hill on a gravel road 45mph when your trailer starts pushing you, I've even wondered what it would take to have trailer braking

I've never had trailer brakes on any of my mc campers. The Time Out camper I pulled with my GW was likely around 350 lbs loaded and I never had any issues with it. Trailer brakes can be tricky on a trailer pulled by a motorcycle. They have to be adjusted perfectly and can never be adjusted to fully stop the trailer by themselves or the motorcycle will end up being pulled around when attempting a controlled stop. They are only for assisted braking.

My Mini Mate camper that I pulled with my ST1100 ran closer to 275 lbs loaded and also did not have trailer brakes.

This Uni-Go trailer tips the scales at 70 lbs empty and it is most likely that I'll never put even 60 lbs in it. So that 140 lbs I mentioned earlier would be likely a once in a lifetime event for me if I loaded it heavy. This little trailer is perfect for towing with almost anything. The capacity is 44 gallons, or about 167 Liters. Like having 3 of Shad's biggest 58 L top cases mounted, or maybe 4 of the more typical 42 L top cases. Bicycle trailers are lighter and are much better being pulled by a bicycle but are simply not designed for highway speeds. I do know of one or two riders who did use a bicycle trailer frame and suspension with their motorcycle but they were lucky it didn't blow up going down the road.

[rjs987]

I have begun to collect supplies for getting to work on the AK/Uni-Go hitch.
I just picked up the first 2 parts today. I bought a 6 ft length of stainless steel 1"x1" square tube with a 1/8" wall thickness from the local steel outlet. It was cheaper to buy a single 6 ft length and cut it as I need instead of buying 2 shorter lengths. I am expecting I'll only need about 2.5 ft for each main side frame but won't know exactly how long (+/- a few inches) until I start fitting it onto the bike.

I also asked about any scrap stainless steel they might have since I might be needing a few shorter bits than what they sell. The steel place only shows that they sell 3 ft lengths or longer per their web site, but I'm sure they will happily sell short stock. In their scrap pile I found a 2"x1/8" flat stainless steel bar that I may be able to use for the hanger strap if I decide I need it. I asked how much for that bit of scrap and the worker told me $7 at first and then said he'd take $5 for it. So I bought it. It was 4 ft long, was a bit dirty, and had a very slight twist from sitting in the scrap pile but it was straight. I can untwist it if I have to use that end. I only expect to need no more than half of it... if even that much. I checked their web site and a 4 ft piece of that item is listed for $29! I knew I'd find a bargain in the scrap pile.

https://photos.app.goo.gl/SQ6pGFLLyfCNeRNQ8

[rjs987]

Got a better feel for the shape of the plate at the rear of the AK rear frame where I was thinking of connecting the hanger bar. I was originally thinking I would use the 2 threaded bolt holes back there for the top of the hanger bar but there are some ribs on the underside of that plate that makes it difficult at best. Also, getting to that space to put the bolts in, or even just to fit the bar in there, is an exercise in being a contortionist if even possible at all. So scratch that idea and on to figuring out something else. The cross bar welded to the back of the AK rear frame has 2 holes that are also threaded which are sized for an M4 bolt. That's a bit small but would only really be needed to hold a bar in place to run up against the rear plate where a larger bolt going through the rear plate farther back would be used for the hanger. That larger bolt would take all the force of the hanger. This location is very easy to get to. The storage box sits on this cross bar but is raised about a half inch above it in the middle where those two threaded holes are located.

All this is IF I find I need a hanger at all. I might not depending on how firmly the 2 clamps on each side hold the hitch frame tubes. For a typical 2 wheeled trailer I would leave the hanger bar off since there is a lot less need for an absolutely immovable receiver on those trailers. But a mono-wheeled trailer needs the receiver to be very stable and completely immovable with no allowance for any vibration as if it were a solid part of the bike frame. I just need to figure this bit out before I go cutting plastic and clamping and/or welding hitch frame tube parts onto the bike. I'll install the primary hitch frame tubes and see how stable that is and then decide if I need the hanger bar.

[rjs987]

Here is a picture to show what I was talking about in my last post.
https://photos.app.goo.gl/r6xm28sng3Ew2qGz5

[rjs987]

IT'S HERE! 
Actually my friend dropped it off yesterday.
Now I can get serious bout working on that hitch... as in more than just throwing around ideas but starting to cut and bend metal, maybe a weld or two, and cut plastic. That last bit is the only thing that I am super scared or cautious about. I don't want to go searching for a replacement plastic part. I don't doubt I can find it I just don't want the hassle so I'll be cutting very carefully.

The trailer needs a bit of cleaning which will be done soon (same time as when I give the bike its annual wash). And there is a little rust on the metal on the bottom frame but treating with ACF-50 will handle that. The front corners at the very bottom have nubs that are the "feet" of the trailer to keep it upright when not connected to the bike.

Use the link below to see a few photos.
In the first photo it is close to what the end result will be hitched behind the AK. That photo also shows about where the receiver will come on the mud flap of the AK. At least where I will plan to have it. In this photo the paint also looks like there is some variation in the color but that is simply a reflection of the colors of concrete driveway and garage. The paint is in fair to good condition. Maybe someday in the future a Matte Blue paint job might happen but that's not for now.

In the second photo I dropped a typical bag of chips inside to give a sense of scale. I see lots of grocery shopping in the future in addition to bringing too much stuff when I go camping... If I'm not careful.

https://photos.app.goo.gl/Qf7Y9ngH4pKLMXEL9