Now I have something "new" to me... and a new project

Willsmotorcycle said:
This is getting very exciting, you’re getting close Robert. I may want to ride out to IA for the maiden voyage.
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I could use a rider to follow behind to watch if the trailer rides steady or sways while at speed. I might have to install a bar end mirror on one side just to keep an eye on it while riding.
 
Yeah, I remember that happening once or twice with my other trailers on my other bikes. I could feel it even though it was very minor. I even felt it one time when pulling a bike on a U-Haul mc trailer with my car. Again, a very minor event that settled down quickly.
 
rjs987 said:
Yeah, I remember that happening once or twice with my other trailers on my other bikes. I could feel it even though it was very minor. I even felt it one time when pulling a bike on a U-Haul mc trailer with my car. Again, a very minor event that settled down quickly.
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The uni-go I had on the ST1300 would wobble if I had delkevic 2-pc exhaust but not w/oem 1-pc exhausts... just took that little bit of structural weakness to cause the wobble... and you'd feel it after about 50mph... so, as stated above, you will know if you have an issue and need to firm something up..
 
rjs987 said:
@Mellow , Was that due to structure or airflow? (I remember reading about your adventures with your Uni-Go).
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Structure.. the delkevics are attached to the bike via the strap and that's the rear part of the exhaust, then another pipe attached to the exhaust and pipe coming from exhaust header... whereas the oem exhasst i s a single piece that is very solid.
 
That would be consistent with what Uni-Go says will cause the trailer to wobble. They told me that the biggest reason for wobble is if there is a hitch that is not solid and allows a bit of wiggle. This is my biggest concern in my case as well... if the hitch I make will be solid enough for this trailer. I know the stainless steel tubing that I have is very solid, but the entire assembly of the hitch tubing and bike frame and connecting bolts (with or without spacers) needs to be solid. I am thinking more about the idea of putting 2 90 deg bends in the flat bar bracket for the front attachment points to put that bar tight to the solid side of the bike frame C channel rather than having the bolt go through the spacers. I know the 1.25" length of the spacers *could* be enough to amplify or leverage any wiggle or twisting of the frames at that point whereas mounting the hitch frame to the solid part on the other side of the bike frame would minimize that. (I didn't say eliminate it but minimize it).
 
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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.
 
I've been thinking a bit more about the idea of putting two 90 deg bends in the flat bar, like an S curve, to put it on the outside of the upper bike frame. That would then allow the flat bar to be directly mounted to the solid side of the C channel of the bike frame and eliminate the need for the spacers with that bolt. There is plenty of length at the end of the bar to reach the hole already made in the bike frame. But I wonder if there is a good reason to not do this.
 
This is what I was talking about in my last post...
The bend would offset the flat bar about 1.5" on one side and 1.75" on the other side. Just concerned about the twisting force that just using the spacer can put on the C channel.
AK 550 hitch frame detail 01.jpg
 
Al st1100 said:
KISS... your not pulling a horse
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Very true. But I was considering a way to do away with having the spacer. Although, on another forum a member suggested forming a leg with a flat bar welded on the initial flat bar so there would be one on both sides of the bike frame. But as you said... I'm not pulling a horse... or horse trailer. I have not noted any twist when I had the tubing bolted in tight during a test fit and I grabbed the ends to try and wiggle them around in all directions. The entire bike and hitch tubing moved as one unit. Just like if I had grabbed the rear wheel and wiggled that around. Actually, it was very little movement if any at all since it did more scooting on the center stand pads on the garage floor than any actual frame movement (just an indication of how hard I was pulling it around).
 
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If there was twisting force coming down tubing, it would cause exactly same twist on C-channel with both those attachments anyway. As it is, there is no longitudinal twisting of C-channel frame tubing in either configuration of attachments with or without spacer.

Once you have rear crossbar attached, both tubes will be held at constant separation at mounting points and function as one unit. Will create lateral pivot axis for both tubes to be loaded and move in unison like with swingarm. This will prevent any twisting of individual tubes.

There will be mostly vertical forces on tubing from trailer resulting in torque around axis of clamping bolts. With dual bolts per side, this results in just vertical bending forces on C-channel like someone standing on rear-most section of frame.

With lateral yawing motion of trailer going around corners, this applies tiny lateral bending forces on C-channel. But is very minor compared to vertical loading. No twisting in either case.
 
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rjs987 said:
Very true. But I was considering a way to do away with having the spacer. Although, on another forum a member suggested forming a leg with a flat bar welded on the initial flat bar so there would be one on both sides of the bike frame. But as you said... I'm not pulling a horse... or horse trailer. I have not noted any twist when I had the tubing bolted in tight during a test fit and I grabbed the ends to try and wiggle them around in all directions. The entire bike and hitch tubing moved as one unit. Just like if I had grabbed the rear wheel and wiggled that around. Actually, it was very little movement if any at all since it did more scooting on the center stand pads on the garage floor than any actual frame movement (just an indication of how hard I was pulling it around).
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Rob, I have a light duty trailer hitch on my Accord, 2000 lbs. max . Part of it is bolted thru the trunk floor, sheet metal with large metal washers.
 
I don't know about that sheet metal attachment with fender washers. But if other mounting points are on solid frame then it might be OK. My very first experience with a car hitch was in 1977 when my BIL had a hitch but it wasn't the right one for my '69 Buick Skylark. So he welded it onto the very substantial car frame. I've always had hitches mounted to at least one of my cars except either one of my current cars and all those were bolted onto the frame. Either Curtis or Hidden Hitch.

I decided to stick with the spacer. Since it is 1 inch and the space to fill is actually a little less than 1-3/16 inches I am using a few large fender washers to fill that gap just so the spacer/washer combo is tight to the flat bar (as well as the nylon washers against the stainless and aluminum). I found some washers that are a 1" OD and also have a 5/16" ID (M8). The spacers are 3/4" OD.

I took the tubing with the V cuts to the welder this morning 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. ;)

PXL_20240312_170032440.jpg
 
DannoXYZ said:
If there was twisting force coming down tubing, it would cause exactly same twist on C-channel with both those attachments anyway. As it is, there is no longitudinal twisting of C-channel frame tubing in either configuration of attachments with or without spacer.

Once you have rear crossbar attached, both tubes will be held at constant separation at mounting points and function as one unit. Will create lateral pivot axis for both tubes to be loaded and move in unison like with swingarm. This will prevent any twisting of individual tubes.

There will be mostly vertical forces on tubing from trailer resulting in torque around axis of clamping bolts. With dual bolts per side, this results in just vertical bending forces on C-channel like someone standing on rear-most section of frame.

With lateral yawing motion of trailer going around corners, this applies tiny lateral bending forces on C-channel. But is very minor compared to vertical loading. No twisting in either case.
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Basically, since the trailer weight is or will be about 150 lbs or less, it is the same or very similar to a 150 lb passenger sitting on the pillion with feet raised off the foot pegs. I know leverage due to the trailer hanging a ways out the back makes it different but also so does the detail that there should be no more than 50 lbs tongue weight on the receiver. The seat is attached near the very front by the latches and sits on rubber bumpers right next to the front latches. It is attached at the extreme rear end of the rear-most section of the frame by the seat hinge with no real support points between the front and rear. There is a weather seal around the top of the storage box under the seat but that doesn't provide much support at all since the seat doesn't squish it all the way down. And once the hitch is firmly bolted to the rear frame it should also function as one unit with the rear frame.
 
SMSW said:
At some point, as you mentioned, you will have to take the hitch off to service something else on the bike (or if you want to sell it). The level of difficulty you set for removal, i.e. how much other bodywork, framework, etc. has to be unbolted to allow this is part of the planning and design.

In post 101, top picture, you show that the hitch is inside the top frame member and outside the lower frame. If you join the two bars by welding, you won't be able to get the hitch off the bike - at least from my armchair perspective 684 miles away. I think you need to design a way to separate the two arms to allow removal. Or am I missing something?

You did not answer my q re who is doing the welding. From your pictures in post 95, the welds do not appear to me to be professionally done. I freely admit to being an amateur when it comes to welding, and I have had some welds fail. I'm not criticizing you, but a well bolted strong joint can more easily be made than a good strong weld by someone like me.
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Since I'll be bolting the end plate on the issue of removing the hitch frame from the bike separate from the body panels won't be an issue. (I guess I mentioned about that earlier).

As to the welding pro... Does it look more professionally done now (post 158 above)? The welder was waiting to finish all the welds on each tube before polishing and touching up for revealed bubbles in the welds. There were a few we found. He even cleaned up the first welds that were done (shown in post 95). He was showing me his "new" welding machine today and showed me how he sets it up. It has a dial to select a gauge of the metal being welded and then the machine automatically configures the settings for that weld. He's a 71 yo guy who continued the business his father started. He's been welding and working metal for over 40 yrs.
 
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