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

[rjs987]

Warm weather is here for a week or more so I pulled one of the cars out of the garage and started with taking apart the AK. I needed to remove the entire rear body of the AK to expose the rear frame so I could drill for the mounting bolts.

First, I test fitted the hitch frame sides and marked them for bending/distorting the flat bar end brackets to lay flush against the bike frame. This took many test fits. Once that was done I marked the bike frames with a pencil where the top of the hitch frames crossed them. This is so that I know where they should be put when the body is off the bike leaving no other reference.

The entire rear body comes off in one piece including both side body panels, the tail light module, the wheel well, and the rear fender/mud flap. I started the removal by first removing the tail cover behind the seat on top of the tail light module. 2 plastic rivets, slide it back a half inch, then lift slightly to clear the hooks and finesse it out from under the rear of the seat. Then I removed the Givi luggage rack and handles in one piece. There are only those 4 bolts, 2 plastic rivets, and 2 screws at the front points of the side body panels on each side that hold the rear body on the bike as well as 3 bolts holding the rear fender to the rear of the bike frame cross plate. I had to remove the clutch/CVT cover panels under the foot boards and then pull the foot boards and clutch/CVT cover panels back a half inch as one unit to pull the clutch/CVT cover panels away from the side body panels since there is one small screw on each side behind those covers. I also had to remove the gas tank cover to get at the 2 plastic rivets under that. Once that was done the entire rear body pulled off to the rear in one unit. Oh, I also had to unplug the LED light bar and license plate light and tail light plugs. The first two pictures are of each side after removing the fasteners and the rear body is just sitting loose. In one of those pics I am holding the little screw where it goes on that side. The next two pictures are of the rear body off the bike.
https://photos.app.goo.gl/bk6RrSUX27nvzAjq5

Then I clamped the hitch frame tubing onto the bike frame aligning it with the pencil marks I made earlier. I started drilling the bike frame and let the drill bit go through to mark the stainless steel where that should be drilled. I took the hitch frame tubing off the bike to drill that on the marks. That's when I discovered a snag. All the drill bits I have are HSS but not cobalt bits so not really good for drilling stainless steel. I was able to drill through the bike frame aluminum easily but the stainless steel tubing is another matter. I have some cobalt bits coming from Amazon. The local hardware store and Lowe's have them but the cost is a little more. They'll be here tomorrow.

While waiting for the drill bits to arrive I went to work on the electrical connections for the trailer harness. I now have all the connections done except actually plugging in the trailer harness/cable. After I have the bike body back on the bike and also mount the hitch then I'll feed the trailer cable into the body of the bike and plug it in at the connections I have reserved for it. This last picture shows what LOOKS like a mess but believe me it really is a perfect order of wiring and connections. You can also see here the exposed rear end of the bike.
https://photos.app.goo.gl/iRifeD6oYLDP9Lmk9

[rjs987]

Waiting this morning on a set of cobalt drill bits to drill the stainless tubing so worked on a few other things today. I started shaping and cutting the hanger bar and figured out where I'll connect it to the tail end of the bike frame. I decided I would use the drilled and threaded M8 holes that are already in the frame. I also decided I would start the upper bend for the square tubing closer to where the tubing exits the wheel well. That will allow me to run a bar across between the tubing just after that bend and I'll connect the hanger bar to the top of that cross bar. I removed the rear fender from the body unit and cut the slot where the hanger bar will drop through under the tail light.

Then the drill bits arrived this afternoon so I could go back to drilling holes. Even though it is said that cobalt drill bits are best for drilling in stainless steel it still takes a long time to get through with a 5/16" bit. It was only slightly easier starting with drilling a pilot hole and follow that with the bigger bit. The 1/4" stainless bar takes a REALLY LONG time to drill through. The 2 sides of 1/8" on the square tubing are easy by comparison... but still not fast going. I think by the time I'm done with the hitch frame I'll have to look into sharpening the bit or replacing it.

I did finish the mounting of the right side hitch tubing to the bike frame. The 1" spacers I bought were 3/16" short but I could make up the difference with a few extra metal washers. I couldn't find 1.25" or 1.125" spacers with a thick wall so this will work. Next up is to do the same on the left side. I do already have the first hole in the bike frame for the left side and started drilling the 1/4" bar but decided to call it a night. This old body can't take this kind of work for very long.
Here is what all that looks like. Let me know if the picture problem is still an issue and I'll post the link to the pictures as before.
One picture is taken from slightly behind and below the rear frame looking up at the mount points. And of course the other is straight on to the side.

https://photos.app.goo.gl/mev9FuZoGjXujGTV6

[rjs987]

Today I finished drilling holes in the bike frame and square tubing. For each side I had drilled the front mounting holes and then bolted the tubing to the frame to lineup for where to drill for the rear mounting holes. Then I dressed up the rats nest of wires making sure I could get to the connection points for the trailer electrical harness wires and also to make sure the hitch frame tubing didn't rub on the wires. I also re-routed one or two factory cables to give them a bit of slack to get around the hitch frame tubing.

After this I removed the hitch frame tubing and installed the rear body of the bike without the rear fender. As I was reinstalling the hitch frame tubing with the body on I found that the way the tail light module wraps around the sides and the wheel well braces where they connect to the body side panels prevented installing the rear mounting bolts. So I backed off the body about 2 inches and was then able to first install the rear mounting bolts. I also installed the front mounting bolts on each side but left all of them a bit loose. Since the hitch frame tubing angles inward going to the rear I cannot back off the rear body very far. One of the pictures below distorts the angle of the tubing but the very end is a lot narrower than at the front mounting point. After the bolts were in and tight I put the rear body all the way on (a screw on each side at the front and a plastic rivet is really all that holds the body unit on, but the 2 tail light bolts and rear fender bolts and grab handles help to hold it tight.

Several times while trying to put the washers and spacers on the bolts I dropped one or three. Only once did the washer not fall out where I could easily get to it... like the floor or the back outside of the final drive cover. One time the washer fell INSIDE the final drive cover and I found it laying on the tooth side of the final drive belt right up close to the rear final drive sprocket. That would have been disaster for the belt if I didn't find it. But I wasn't going to give up looking until I did for just that reason. I finally got a little smarter and put a rag over the exposed engine and final drive parts.

Tomorrow I'll measure for where to make the V cuts for the bend points on the hitch tubing. I'll also figure out about the hanger bar. I did grab the ends of the tubing mounted on the bike and it is VERY stiff with the bike frame. When I tried to wiggle side to side really hard the entire rear of the bike wiggled with the hitch frame tubing and there was no wobble between the two.

https://photos.app.goo.gl/7LbtUrb584vCFxRA8

[rjs987]

I am now leaning toward bolting the end plate on the hitch frame tubes. I've considered that there are many major frame assemblies for bikes and cars that are bolted together. Many other major parts, like engines and suspension parts, are bolted on vehicles rather than welded. The most common reason is to enable parts and assemblies to be removed and replaced without replacing the entire vehicle. Bolts used in these situations do hold just fine in spite of a welded joint, if done right, is a bit stronger.

Now to figure out how exactly to make the best strong bolted union. Maybe use the cut off ends of the square tubing welded onto the plate and then run the bolts sideways through the hitch tubing and the tubing welded onto the plate.

Today I bolted on the hitch tubing again and re-measured the angle deviation from horizontal that they now are. The deviation angle did change, but only by one degree. The drop from horizontal is now 3 deg and it won't be changing from that since this is with the final mounting to the bike. I also measured to verify the angles of each bend needed and came up with the upper bend at 36 deg from the straight tubing and the lower bend at 51 deg to make that last leg vertical. I decided to make that last bend 1 deg less to account for extra sag in the rear from if I pack a little heavier than anticipated (though I am anticipating a little extra since I will be pulling a trailer) and also to account for any slop in forming and welding. Being off by one degree will not be significant since the receiver angle will likely change +/- 1-2 deg just for normal suspension variation while riding.

I also drilled the mounting hole in the hanger bar for mounting up under the tail of the bike. I am planning to weld the nut onto the bar at the hole to enable mounting since I am finding it will be impossible to mount that bar after the rear body is installed AND impossible to mount the rear body after that bar is mounted. So this way the nut will be on the bar. I can get to the bolt side but not behind the bar with any tools. This will be a M8 bolt/nut.

I also marked and made the V cuts for bending one hitch tube. For the 36 deg bend I made 2 cuts at 18 deg and for the 50 deg bend I made 2 cuts at 25 deg.
I haven't cut off the end to the intended length yet however. I'll do that after the bend points are welded.

https://photos.app.goo.gl/eyrHpZz6Bsg4Tv237

[rjs987]

Took some time this afternoon to mark and cut the V cuts on the other square tube. The last few days were busy with the grandkids. Thursday and Friday were cooler anyway and it rained all night Thursday night and all day Friday. I'm getting so I don't like working in the garage when the temps are below 50F and especially not if temps are close to 45F or lower. Temps today were right at 47-48F but I figured I should get the cuts done today in case there was something else I think of that might need to be done. I called and arranged to go in to the weld shop on Tuesday but will set the time on Monday when the guy has his schedule figured out.
https://photos.app.goo.gl/NsWfxBWLEK24V31P8

[rjs987]

I took the tubing with the V cuts to the welder on March 12 to have it bent and welded. He took a bit of time to clean up all the welds including the welds on the flat bar that were done earlier. He used his grinder to polish the tubing to clean it and give it a little bit of shine so the coating I put on will stick better. He also welded on the nut to the top end of the hanger bar since I won't be able to fit any wrench on the back side of that when I install it. This picture is the result of the tubing. I don't yet have the ends cut to length. The ends to the right will be cut off about 4-4.5 inches from the last bend so I'll have plenty of extra stainless steel square tubing left over. I also show the pattern for the angles I cut from some scrap aluminum sheet I had laying around so we'd have a guide while welding. A paper or cardboard pattern would burn if used while welding.

https://photos.app.goo.gl/7WmfkSoFQTFabtkQ7

Those of you who do much welding know that any weld joint will shrink as it cools. We checked and checked and checked the alignment to the angle on the template I made to ensure it was right BEFORE the welding was done and also JUST after the initial tack weld was made. Later in the evening when I was home I was rechecking the 2 tubes and noted that the angles on one were off from the other one. So I checked on the template again (finally) and found that both tubes angles were off by a few degrees. All angles were too sharp and needed to be opened up a few degrees. I calculated and determined that the lower angles on both tubes were within a half degree of each other but the upper angle bends were off by 3-4 degrees or more. So the next day I went back and the welder cut both tubes at the bend and we opened up the angles over compensating for shrinkage and drawing in the angle. This time we clamped each tube directly on the template with one leg offset by a few degrees. We did not clamp on tube to the other tube to line them up since that didn't work the first time. This time both tubes were exactly inline with each other and the last leg was 1 deg more than I originally wanted. Close enough.

After some thought I found that since the plate is angled back 1 deg that is easily corrected by the thickness of a single washer at the bottom bolts for the plate. So I'll likely put a washer between the hitch tube ends and the plate for the bottom bolts to bring the plate to true vertical OR put the washer between the plate and the receiver on the bottom pair of bolts for the same result.

Today I bolted both tubes on the bike, as tight as my fingers could get the nuts. I had cut off the end legs as long as they needed to be (4.25 inches from the top of the lower bend) and both tubes lined up perfectly. With the tubes on the bike the ends of the tubes were inline and level with the bike straight up. I clamped the end plate on the last leg to see if I needed to cut off any from the length and the plate was 1/8" wider than the outside of the tubes so I decided to leave it alone. 11-3/4" for the outside width from one tube to the other and the plate is 12" wide. I lined up the bottom of the plate flush with the bottom of the tubes and put a level on the plate. It is perfectly level. I estimated the height from the floor to be close to 1" lower than the previous owner of the trailer had the receiver on his Gold Wing. I marked and drilled the holes in the plate. 4 holes, 2 on each side, 1" from top and bottom and 7/8" in from the outer edge. Then I marked where to drill the holes for bolts in the lower leg of each tube.

While I have the tubes bolted on the bike I started working on the cross bar for the hanger. I am bending the cross bar to account for clearing the suspension travel of the tire. The rear fender has an angle that the tire will never reach and that is where the cross bar will arch into. That will put the cross bar about 3" down from the top bend in the tubes. I am heating the bend points on the cross bar with my Propane torch. It does get the steel red and easy to bend with a big pipe wrench I have but it does take a little time to heat it up. I'm not finished shaping the cross bar yet but will go back out later tonight to work on it some more... maybe.

Here is what the end plate looks like on the hitch frame. It is wide but that's OK with me. The perspective of the picture makes it look wider than it really is compared to the bike.

https://photos.app.goo.gl/sEMsyBHrmMmfhAac7

After those photos I did drill the holes in the end plate to mount to the square tubes and marked the square tubes for drilling those.

Then we went on a short vacation (one week) to visit my son and his family in Lafayette.
I was back home a few days ago from visiting in Lafayette so back at this project. Doing daycare for our granddaughter today and tomorrow so not much time to work on the bike. But I did get a little done late afternoon. Connected the trailer harness wires and drilled the holes for the end plate in one of the square tubes. Hope to drill the other square tube tomorrow.

I did a lot of rethinking about the hanger bar. I am not able to bend the bolt plate that would sit on top of the bike end frame just under the seat hinge enough to clear the seat hinge as I was wanting to so I need to think of something else. I might be able to mount the top end of the hanger bar a little farther forward without going into the tail. Or maybe I won't need it at all. I am close enough to see how strong the hitch will be without it so will decide after a test pull of the trailer. That test pull will happen after I drill the other square tube, drill the hitch end plate for the Uni-Go receiver, and mount all the hitch frame parts to the bike. Then I can go for a ride with the trailer to see how it pulls.

Here is a picture of the wire mess behind the rear right side body of the bike. I will be tying the wire bundle to make it a lot neater before I close it all up. In the lower left of the photo can be seen the square 5 pin connector I added to make it easier to disconnect the trailer wire harness. I may yet rethink that as well since I am using mainly Posi-Tap connectors which are easy to disconnect wires from. I just happened to have that square connector in my electrical parts box.

https://photos.app.goo.gl/bR5Adidke8cY8qZm6

[rjs987]

Yesterday afternoon I drilled the holes in the hitch end plate for the Uni-Go receiver and also drilled the holes in the square tubing where that plate will attach. I then bolted the receiver to the end plate for a test fit using regular stainless M8 nuts on the factory bolts. The Uni-Go factory sent me a new bolt kit but didn't yet contact me about paying for it! That's on them. They have 2 bolt kit sizes, a long and short. They sent me the long bolts. Although I think the short bolts would have worked fine. I may cut the bolts shorter. The factory bolt kit comes with 4 flat head bolts, washers, and nylon insert lock nuts. I am waiting to use the nylon insert nuts until the final install. All parts in the bolt kit are stainless the same as the receiver and also the end plate.
Here are a few pics of the receiver bolted on.
https://photos.app.goo.gl/4cem9g2yDFPnrb2Z6

[rjs987]

Decided to not use the square trailer harness plug. Those square plugs are hard to connect and disconnect and the only reason I'd need it is to do as I did with my ST1100 trailer harness. On my ST I pulled out the trailer harness cable when I wasn't pulling the trailer. On the ST that was easy to so since the cable just slipped out through the bottom from under the seat. This time, on my AK I'd have to remove the left side hitch frame tube if I used that square plug. I'd also have to pull the storage box out to get to the plug inside. So I just connected the end of the trailer harness cable to the wires/Posi-Tap connections. I made a notch in the hole for the left square tube to allow the trailer harness cable to pass out of the body along the top of the tube. When I'm not pulling the trailer I have a cover/cap for the flat 5 pin connector and will just tie it to the receiver.

I connected the trailer cable and tied up the wire mess. In this picture I have the harness cable zip tied on the rear cross bar. The 2 threaded bolt holes just outside where the zip ties are seen is where the rear bolts go for the storage box. There are nubs on the storage box that hold it off the cross bar giving plenty of space for the ties.
https://photos.app.goo.gl/mSWjNVBdXRYmaFSSA

[rjs987]

Put it all together today. Temps in the garage were just barely 50F but I put on an extra sweatshirt and went to work. I torqued the bolts on the receiver to a tight 3 finger mechanics tightness... actually 4 fingers tight with my hand close to the ratchet head. Then I installed the square tubes on each side. There was a bit more adjusting to do with the flat bar on the ends of the square tubes to be tight and flush with the spacers AND the bike frame. The bolts to the bike frame were also torqued same as the receiver bolts. Since these nuts and bolts are a metric 10.9 grade hardness I could tighten them even just a little more without worry of them being over torqued.

Then came time to mount the end plate on the ends of the square tubes. The holes at the ends of the tubes were not perfectly aligned so I inserted my round file in my drill and filed them a bit to enable the bolts to be pushed in without too much pulling in on the tubing ends. There is still barely a little stress on the tubing ends pulling them inward just slightly. Since the end angles of the tubing was about 1 to 1.5 deg off I added a washer to the bottom bolts between the end plate and the square tube ends. When all the bolts were tightened I put a vertical level on the end plate and found it was less than 1 deg forward at the top. This is where I wanted it to be since that will level out with a little extra sag on the rear of the bike when loaded in the storage box and in the trailer. I will leave the extra length of the bolts alone for now since the long receiver bolts are behind the mud flap. The end plate bolts are well outside the rear tire so no worries there.

In the picture where the trailer is hitched to the bike I put a board under the rear wheel same as is under the front wheel of the bike to level it. That shows close to how the trailer will sit behind the bike. I'm sure a little more sag in the rear suspension will have the front of the trailer down just a little but it looks like I might not have to adjust the trailer tongue down any. I have the receiver 2 inches lower than the original owner had it. Will see when I have a test load in it. Also in that picture the single safety chain (all that is needed for this type of trailer) is just hanging. I am waiting for a special threaded quick link that will be used to hook the safety chain to the receiver. While the trailer was hooked up and the electrical harness plugged in I tested all the lights and everything works as expected.

With all the bolts tight I grabbed the end plate of the hitch and wiggled it up and down, left and right, forward and back as hard as I dared. This hitch as it is so far, without the hanger bar, is the strongest stiffest sturdiest hitch I've had on any bike... maybe my old Gold Wing hitch was about the same but that one was bolted directly to the frame under the saddle bags. Other hitches, like on the ST1100, had more wiggle than the hitch I just installed on the AK. I could wiggle the entire bike but the hitch itself did not wiggle at all separately from the entire bike. The bike and hitch frames are one unit. I really don't think any way of adding a hanger bar will make any difference in the sturdiness of this hitch.

The next thing I plan to do is to put some load in the trailer and in the storage box on the bike and go for a few test rides so check how it tracks behind the bike. Once that is done, if all goes well, I will be removing the hitch parts again and cover all the parts with a rubberized coating. Then I'll install the hitch frame permanently.

https://photos.app.goo.gl/qFYFNSExMpwee3278

[rjs987]

My wife took our granddaughter for an outing so I took some time to load up and hook up the trailer and put a load on the bike to see how it sits. I put a big bag of mulch inside the trailer along with my tent and a few other camping things and also put a 20+ lb bag of rubber mulch on the pillion to simulate a full storage box under the seat. The result being a VERY full load. The front bottom of the trailer needs to be level... or better just higher than level than the rear bottom of the trailer in front of the wheel. I also wanted to see if the end plate was still vertical with a load on the bike and in the trailer.

Both criteria were met today. I was holding the bike VERY CAREFULLY right at the balance to check the end plate vertical alignment and on all 3 wheels it was same as I measured earlier with the board under the front wheel and the bike on the center stand. The pictures here show that the front bottom "feet" of the trailer are just a bit higher than the flat rear bottom of the trailer. While I was sitting on the bike to check how level the trailer was with weight on everything I tried to balance the bike with my toes just barely on the ground. Perfect. I a bit of backing up to enable me room to pull forward into the garage (behind the camera) so was reminded how that works from when I did the same with my previous bike/trailer experiences.

Later tonight or maybe tomorrow I'll get out for some test riding with the trailer. Here are photos from this afternoon.
https://photos.app.goo.gl/4EDiZaEyEmAx4h4T7

[rjs987]

I did go for a little ride tonight pulling the trailer. Kept to slower roads. Started out on 25 mph roads for several blocks. Then stepped it up to 35 mph roads for several miles. Then I got it up to 45 mph for a few miles and then slowed back to 40 mph for most of the way home. I adjusted the left mirror down so I could see the trailer lid and the end of the LED brake bar just aft of the lid. That chrome LED bar told me a lot about how the trailer was tracking behind the bike. It was solid and stable behind the bike at the speeds I was going. Temps were just a little over 50F, sunny with 15 mph winds. I only rode about 14 miles.

I was told to expect this mono-wheel trailer to act like a passenger who was attempting to "help" me go around curves and turns leaning into them. So I was expecting that effect but was pleasantly surprised that the feeling was very slight. I could tell it was there but if I wasn't told about it I might have missed it. Having pulled pop-up campers before I knew what to expect with the performance of the bike. But all influences were VERY subdued compared with pulling a camper even with my current bike weighing so much less than those other bikes that were pulling those heavier camper trailers. I could tell it was back there... most of the time... as expected. Stopping on a level road was like stopping while going downhill without the trailer. Accelerating on a level road was like accelerating uphill without the trailer. Otherwise the performance was totally normal as it would be without a trailer. I did do a few hard stops and there was no dive or lifting of the rear. Any emergency stopping while turning is expected to be the same as with any trailer on a bike and should be avoided as much as possible. I count this first test as a success and proof of concept for the trailer hitch as built for this one trailer.

I am planning another test ride tomorrow (likely) or Saturday on some faster roads up to 70 mph. Maybe I'll bump it up to 75 while out there just to see what happens. My wife told me she would follow me to watch what the trailer is doing from that vantage point. I know some owners of this trailer have taken it up over a ton, but that's not me. I likely won't be riding past 75 mph with the trailer in tow. Besides, the tire speed rating is "L" which is 75 mph.

[rjs987]

My wife and I went for a little ride. Well, I went for the ride and she followed behind in the car to watch what the trailer did or didn't do. We rode about 26 miles. Some of the roads were the same speeds as the last test ride, but this time I took some faster roads as well. After getting out of the neighborhood we went on a 45 mph road for several miles. Then it was on a state highway getting up to 60-65 mph for 3 miles. Then a county road at 55 mph down to the Interstate highway where I was able to go mostly 70 mph for about 4.5 miles due to heavy traffic. I backed off a little and then boosted up to around 75 mph for a bit before others came along and cut in front of me. Then it was back roads back home at 40 mph or slower. Temps were about 58F and there were strong winds at over 10 mph with higher gusts. Some of the roads were rather bouncy and there was an 18 wheeler or two who passed or I passed along the way so there was significant wind buffeting.

My wife confirmed what I was feeling and seeing in my mirror that the trailer tracked straight and true at any speed. It bounced a little on the bumpy road sections as expected. The wind gusts, especially from passing big rigs, didn't seem to bother it at all. At the faster speeds there was the same feeling as I remember from past experiences pulling a trailer... the winds from the side did have some effect but the bike and trailer acted as a unit even though I could feel the wind pushing me around a bit. Just like riding any bike on a fast road in high winds. All the way around at all speeds the trailer tracked behind the bike just like it should with no wobble at all. I could not detect any deviation from the path the bike was taking and my wife said she didn't see any deviation either.

She took a few pictures before and then after the faster roads. I asked if she could see the flashing brake LED bar on the bike at all and, as the pictures show, she could not. She did mention that if someone were behind me in a tall vehicle high up they might be able to. But that's not good enough. I ordered the same LED bar I have on the bike... tail light with bright flashing brake light... to put on the trailer in place of the on/off bar that is on there.

https://photos.app.goo.gl/8tKMEva2tBY78Yzr6

Next up is to uninstall the hitch frame and put insulation on the contact points between the stainless and aluminum. And I'll also add thread lock to all the nuts and bolts for a more permanent install. I am considering this project done after that.

[Ruffus]

rjs987, I followed this ambitious project with interest and would like to write down some of my thoughts as an developement engineer.

-in machine/engine/frame building we (my metallurgists and welders) avoided stainless steel of all qualities because of unpredictable behavior when welded (change of molecular structure) gets brittle, vibrations kill stainless steel, mounted static

-we rather took high quality seamless pipes (square or tubular) bent (cold or redglowing 800°C) and risked rust, which we battled with thicker walls

-even if you x-ray stainless steel after welding it is not said that's not vulnerable where welded

Now to the pic I hijacked from you and added some signs.

Red circled with green line would be the point where I would ask the welder to add a brace on both segments. (no sanding after that anymore) As seen in detail, the welder meant good and sanded and polished at parts in the corner off and weakened the material.

Two green arrows,
 there the trailer pushes/pulls constantely during driving fore and back for sure a few millimeter, material fatigue within red circle will brake eventually without braces.

Further, drilling two/two 8mm holes in your bikes alu frame MIGHT cause material fatigue there too.

[rjs987]

So Ruffus, where were you 2.5 months ago when I was buying the stainless for this project? Or 1.5 months ago when I was looking for recommendations about adding gussets? No matter, the overwhelming opinions of several in the industry who I did also talk to (metal work, working with stainless, welding, etc) is that for this application what I have done will be more than sufficient. It is a very lightweight trailer... about the weight of a passenger on the rear seat... yet I know it is sitting well behind the bike. Only about 40 lbs tongue weight and unlikely to be over 130 lbs total weight for a loaded trailer Which is well under the capacity for this trailer but I never intend to pack it to capacity for weight.

[rjs987]

NOW, as of tonight, I am calling this project complete.
This afternoon I uninstalled the hitch frame from the bike and added vinyl electrical tape to the stainless tubing and bar where they contact the aluminum bike frame. I decided to just wrap the tape all the way from the front end to where the tubing exits the bike body just to make it one continuous wrap that terminates under the rear mounting bolt nylon washers to prevent the tape from unwrapping after some time. Then I reinstalled the 2 side tubes of the hitch frame and used thread lock on the nuts torquing those tight.

Then I removed the temporary nuts I had used on the receiver to bolt that to the end plate and added the nylon lock nuts that were provided by Uni-Go for the bolt kit for the receiver. I used thread lock on those also on the threaded part of the nuts. And then I also reinstalled the end plate using thread lock on those nuts as well.

After all parts of the hitch were installed and tight I replaced the storage box and installed all 6 bolts that hold it in. Up until now I had been only using 2 of the bolts to hold the storage box in place when I wanted/needed to ride the bike. Now the only time I'll need to remove the storage box is to do an annual inspection of the frames and attachment points inside... or to install some other farkle where I need access inside the body of the bike.

Here is what the parts inside the bike are like now.
https://photos.app.goo.gl/zFn6JcXPrK1ARFQo6