Uni-Go Hitch Mod - BMW Luxury Touring Community
 
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post #1 of 5 Old Apr 4th, 2009, 6:46 pm Thread Starter
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Talking Uni-Go Hitch Mod

Thought folks with Unigo's might like to see a solution to a problem that I considered unacceptable. I just purchased my Unigo and must say I love it! Everything except for the fact that the entire hitch must be removed to change a rear tire. I found that to be poor design planning and since I didn't want further frustration on the side of the road when a flat tire occurred, I thought there had to be a better way. Attached below are several pictures of my hitch modification that allows the hitch to swing away by removing two easily accessible bolts. This mod required about 6 hours to fab up and a total of $16 in materials (of course I had access to a TIG welder, drill press and grinder).

Essentially the back of the hitch horse shoe was cut off and the tubing ends attached to the bike were "fish mouthed" to accept a 1.0" x 1.0" piece of round bar stock. The bar stock centers were drilled with a 3/8" hole. Two pivot bushings were created (one for each side) and welded to the tubing ends attached to the bike. Note: its best to tack everything while on the bike so you end up with a tight fit on all parts. The cut off ends of the horseshoe had a cap welded over the open hole so no dirt or fluids could enter. (I also capped the open ends of the tubes attached under the saddle bags) I fabricated the two clevis pieces that mate with the pivot bushings from four pieces 1" x 2" x 1/4" steel plates. These clevis pieces were drilled to match the pivot bushing holes and bolted in place with two grade 8, 3/8" x 2" bolts. The plates were bolted together with the pivot bushing and aligned with the horseshoe so the capped end butted up against the pivot bushings. These tack welded in place. Finally, I welded two small overlapping steel tabs (1/2" x 1.0" x 1/8") to the inside of the horseshoe next to the exhaust pipe side pivot bushing. The tabs had a 5/16" hole drilled through them and a 5/16" nut was welded to the bottom of the lower tab. A 5/16" x 1.0" allen head bolt pinched these two plates together when the hitch is closed. This small tab was probably overkill, but I wanted to insure that no amount of side loading by the trailer was going to want to make the horseshoe pivot on the two main hinges (pivot bushings). Once everything was fit checked it was fully welded and all the sharp edges ground off. I sandblasted the welded areas followed by a coat of automotive primer and several coats gloss black enamel. Unlike the Unigo trailer parts the hitch is not powder coated. Hence, creating a finish that cannot be distinguished from the factory horseshoe is easy.

There you have it! A Unigo hitch that swings away to lets the tire roll out. Some may say its not that hard to remove the hitch. Well, all I can say is that when I'm on a vacation trip and it's interrupted with a flat tire, I want as little hassle as possible when trying to get back on the road. Avoiding the time and alignment hassle of the four 6mm bolts that attach the hitch to the bike is very valuable time to me. Plus, I can now Lock-Tite those four bolts in place and never have to worry about one working loose. Another side benefit that I don't even have to disconnect the trailer or wire harness! Just pick up the trailer by the tire and swing it and the hitch out of the way.

Then again, maybe I just have to much time on my hands? FYI - I'm not going into production on this mod so don't ask! I'll be happy to answer questions if someone else wants to make this mod, but I'll be riding instead of fabricating. ;-)
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post #2 of 5 Old Apr 4th, 2009, 7:18 pm
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Re: Uni-Go Hitch Mod

That is ingenious, and well done!

As a Unigo owner I would say that taking the hitch off is not hard, but putting it back on takes longer than any other part of a rear tire change because those 4 bolts have to be lined up "just so" or it doesn't want to go back on. I have said my share of unpleasant words when reinstalling the hitch.

If you were doing the tire change at home, and if you had a lift, and if your lift has a drop tail, then the hitch can stay on when you remove/install the rear tire. But along the side of the road, it's all a moot point.

I was about ready to pick up the phone and ask how much you wanted to modify my Unigo hitch, but then I read your last paragraph.

In any event, good work.

Howard Schisler
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2005 BMW K1200LT - "Gray Ghost", traded at 120k miles
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post #3 of 5 Old Apr 5th, 2009, 7:07 am
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Re: Uni-Go Hitch Mod

Or you could always go with the hitch made especially for the K1200LT by Dauntless although it is isn't a cheap alternative. They do have a Unigo specific bracket that clips into what stays on the bike.

I like your modification, but feel that it could use some more strength and reinforcement. JM2CW

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post #4 of 5 Old Apr 5th, 2009, 9:09 am
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Re: Uni-Go Hitch Mod

Quote:
Originally Posted by hschisler
That is ingenious, and well done!

As a Unigo owner I would say that taking the hitch off is not hard, but putting it back on takes longer than any other part of a rear tire change because those 4 bolts have to be lined up "just so" or it doesn't want to go back on. I have said my share of unpleasant words when reinstalling the hitch.

If you were doing the tire change at home, and if you had a lift, and if your lift has a drop tail, then the hitch can stay on when you remove/install the rear tire. But along the side of the road, it's all a moot point.

I was about ready to pick up the phone and ask how much you wanted to modify my Unigo hitch, but then I read your last paragraph.

In any event, good work.
I'll second this.

~ron~
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post #5 of 5 Old Apr 5th, 2009, 10:19 am Thread Starter
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Re: Uni-Go Hitch Mod

Just a follow-up regarding strength concerns of the Unigo hitch mod. I ran this modification by the structural "Stress Engineers" that work for me (we supply to the Military & Aerospace Industry). Their calculations indicated that the modified design and components used had a strength factor of between 4-5 times the stock hitch design. They indicated that the basic hitch tubing would bend far easier than would any of the modification components that were added. Their key point was that the weakest link in the entire system was the four small 6mm bolts that attach the hitch to the bike. Their feelings were that any failure would occur at this point long before the hitch tubing or modified parts. All indicated that even these four small bolts were sufficient to handle the job. Initially I had considered modifying the hitch to bike attachment (changing to larger square stock with larger bolts) but was advised that it was a wasted effort since the stock components could handle the weight of the trailer assembly and load dynamics at speed. Plus, the stock system using the small bolts had a long history of successful use.

Anyone attempting to duplicate this design should do so at their own risk. I had the luxury of stress engineers to verify the design and high quality welding equipment and a certified welder to insure a high quality job. Any qualified welding shop should be able to produce similar results however.
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