Single Wheel Dual Sport Trailer - CRF250L

Discussion in 'Some Assembly Required' started by Lapchik, Jul 17, 2019.

  1. Lapchik

    Lapchik Tinkeritis posterboy

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    ***EDIT*** Quick overview if you don't want to search through the whole thread:




    Here's the main points.

    = Single wheel trailer
    = CRF250L pull vehicle
    = Modular luggage system/quick change system
    - Cooler
    - Two 5 gallon buckets for fishing
    - General luggage carrier [firewood, groceries, howitzer, etc]
    = Build with scrap laying around the garage, budget $40
    - I have a lot of junk laying around, including a wheel and hub so I can probably do it.

    Why a single wheel trailer? Because I can. I like building things. I built a sidecar, and it was ok. Needed to be redesigned for better suspension. Thought I would try a single wheel trailer while I do more research on sidecars and design a new structure.

    The existing single wheel trailers out there are pretty nice and have been tested and professionally built. Most common bikes have hitches available. BUT...they are very expensive, and nobody makes one to fit a CRF250L. I can build one dirt cheap and custom fit to my bike. So, here we go. Better put in a picture before everyone gets bored and leaves.

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    I decided to do a single sided swingarm. The hub and wheel are generic trailer stuff that is available at any farm supply or auto parts store. I sort of planned that, so that if anything happens on the road it can be fixed easily. You might notice that the wheel is worn a little unevenly. That is because it came off the sidecar, which had a little too much negative camber. If I get really energetic one of these nights, I might take the grinder to it and even it out. Bearing is in need of a repack, but that will wait until I am done with building and paint. No reason to risk getting more dirt in it with the on-off-on-off of test fitting and fabrication.

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    Test fitting the bearings and rod. Bearings are also generic farm supply stuff.

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    Trimmed off extra metal. Finished welding the spindle, rod, and welded on caps.

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    Put in gussets for the pivot rod, and mocked up some sort of swingarm/shock mount.
    #1
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  2. Lapchik

    Lapchik Tinkeritis posterboy

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    Attached a length of 2" square tube to the swingarm assembly.

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  3. Lapchik

    Lapchik Tinkeritis posterboy

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    I tried a couple different ways of mounting the shocks, but settled on this setup. The rods allow it to be height adjustable. One was modified in the past, and the one with the fresh grind marks was done for this project. I used a method called slug-and-plug to shorten the pipes. You cut a section out of the pipe, drill a hole through on both sides, then slide a solid rod inside it [slug]. Weld the pipes to the rod in the holes [plug] and then weld the seam where the tubes meet. Way stronger than just welding the single tube seam with no internal reinforcement. I will grind them down later so it looks like I didn't hack this thing together. The holes in the bracket are to reduce weight, look cool, scare old people, and reduce global warming. Note Honda shock to match the Honda tow vehicle. This shock came off something like an old 70's CB500.

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    Made a base for the cooler. Could also work for the buckets if I decide not to build a carrier for those specifically. Laid out some 1" square tube bends I had sitting in the corner trying to rust away in piece. Cut the legs down, then added electricity, argon, and a little filler.

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    I have some perforated stainless steel sheet that will get riveted on top of this frame. A few chunks of scrap angle will help support the cargo. The stainless sheet isn't thick enough to do that on its own.

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    #3
  4. Lapchik

    Lapchik Tinkeritis posterboy

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    Not a ton of progress, but a very important step so I can determine the height of the assembly with a cooler in it, or with the buckets in it. That will help guide me with building the hitch assembly up front.

    Stainless steel sheet, 1/8" inch holes. I believe it's 50% open area, and I don't remember the thickness. I ordered this about 6 years ago to make a radiator guard for something I owned at the time. It's all a blur. Installed with some 1/8" pop rivets. I don't have any rivets in the middle, only around the perimeter. If it sounds like someone threw a drum set down a flight of stairs, I might TIG weld a few little spots here and there to keep it from rattling. Should be fine as long as there's some sort of load in it.

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    Following my original design ideas, I'm trying to keep it modular. One way I'm going to do that is by bolting this assembly on to the trailer instead of welding it. That way, if I have a toolbox, or a special setup for fishing buckets, or something in that vein in the future, it's just two bolts and I'm ready to go. At this time, I'm just putting 3/8" bolts through the 2" main tube of the trailer. If those holes get all wallered out, I can always go back in later and weld a bushing in flush to the tube.

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  5. Lapchik

    Lapchik Tinkeritis posterboy

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    Started on the rail system for the cooler. I'll probably put another bar around the back so I can wall it in and carry loose items like groceries or firewood etc. The sides will mount to the base with four 1/4" bolts tapped into the 1in square tube of the base. Once again, another bolt on item to make it more modular. If I ever get a bigger cooler in the future, or want to use this base with the fishing buckets that's a possibility.

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    #5
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  6. ONE2NINE

    ONE2NINE Been here awhile

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    Following. Looks like a cool build.
    #6
  7. YamaGeek

    YamaGeek Skeletor sparklemuffin.

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    I'm not worthy...:bow Some serious engineering chops, seems a little on the heavy duty side for a mere 250.

    I want to make an enlarged version of a Bob Ibex bicycle trailer for my Honda C-102 using EMT tubing. I think would end up being too lightweight.
    #7
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  8. Lapchik

    Lapchik Tinkeritis posterboy

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    EMT is galvanized, and it does not weld very nice. You would be better off buying some smaller diameter DOM steel tube, or if you have the machines to weld it, aluminum.
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  9. YamaGeek

    YamaGeek Skeletor sparklemuffin.

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    Yeah I'm aware of the problems welding galvanized dipped or electro-plated. I meant the equivalent in non-galvinized, 3/4" seamed mild steel. The local steel supplier has tubing similar to this and I have a bender. I'm not great with TIG, less so welding aluminum.
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  10. OU812

    OU812 Legend in my own Mind! Supporter

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    Hope to see this rig at CADVR!;)
    #10
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  11. smilin jack

    smilin jack Grandpa Adventurer

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    VERY NICE build you have going there. Will keep watching.

    Using a Gen 1 Moto-Mule behind my DR650 for the last several thousand miles. Works OK.
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  12. Lapchik

    Lapchik Tinkeritis posterboy

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    Chipping away at it as time allows. Tonight I finished the welds on the guard rails and reinstalled it on the trailer.

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    I also scrounged up some parts for the horizontal pivot point. I know the bolt is too short; this is just what I had on hand. When it is finished, the lower bushing will not ride on the threads. I was going to use a u-joint out of an ATV, but the angles it allowed were insufficient for what I expect to see on the road/trail. The other side will be bolted on the bike via extended axle plates. I will have a wrench clipped onto the frame of the trailer somewhere.

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  13. Lapchik

    Lapchik Tinkeritis posterboy

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    Looking at fender options. I have a steel fender off a GS550 Suzuki, a trimmed down plastic boat trailer fender, and a CR50 Honda front fender. The Honda fender actually fits the tire really well, but doesn't cover enough of the tire. The plastic one is probably the best: light, rocks will strike and not make noise, most coverage. The Suzuki one would be loud when being bombarded by gravel, and it's heavier, but it would be really hard to break and easier to mount. If all else fails, I have a pile of thin sheet scraps that I can make into something.

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  14. OU812

    OU812 Legend in my own Mind! Supporter

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    The white one looks the part and no paint needed!;)
    #14
  15. Daleah

    Daleah Long timer

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    following also. this looks cool!!
    #15
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  16. Lapchik

    Lapchik Tinkeritis posterboy

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    Trick for setting fender gap, put a block or two on the wheel. I had to put a hole in it to clear the shock mount. It was either that or trim it way down. I also bent up a couple brackets. They will be bolted to tabs that I will weld onto the swingarm.

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  17. Lapchik

    Lapchik Tinkeritis posterboy

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    The tabs [obviously] still need to be cut to final size and ground to the correct profile.

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    The rear support strut was drilled and chamfered to reduce weight.....ha. No, it was because I was bored and this makes it look better. Like I took my time and didn't just slap a strap on it and call it good.

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  18. Lapchik

    Lapchik Tinkeritis posterboy

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    Two horizontal pivot options. The first one doesn't really allow for a good weld on top or bottom. I don't think I'll use this version.

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    Second one allows for better welds, and better articulation. I won't use the tube in a tube. I just had that laying around. I'll drill a hole in the larger square tube and weld in the bushing, then cap the square tube.

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  19. Lapchik

    Lapchik Tinkeritis posterboy

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    Installed the axle blocks for the bike side attachment. Couldn't do a through-axle mount as this bike has a solid axle, and I can't attach it to the subframe because it's too weak.

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    I took the trailer outside tonight and sat it behind the bike before I took it apart for more metal work. The cooler hauler just needs a little buffing/hard corner removal and then it can get painted.
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    Drilled the hole for the horizontal pivot bushing. Next I'll trim down the material forward of the bushing, cap the tube, and weld in the bushing. I also made [not pictured] bushings for the cargo mounting holes. I don't want to pinch the main tube down when I put the cooler carrier on, and the bushing will be welded to both sides of the tube preventing damage.

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    #19
  20. Roadracer_Al

    Roadracer_Al louder, louder, louder!

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    You're a pretty proficient fabricator!

    I've been enjoying this, keep up the good work.

    I've been considering a single-wheel trailer build. I live in CA, and would hate to give up the ability to lane split!

    I'd thought about putting the hitch mount through the swingarm pivot and supporting only the tongue weight with the subframe.
    #20
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