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R1100RT gas tank tupperware fastener surgery

rich t

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This week, I was forced to do surgery on some cross threaded gas tank threads. You know, three screws on each side of the gas cap that get harder and harder to get the Tupperware screws into. First off I had to remove at least one side panel and the screws from the other. I also had to remove the fuel filler cap, which was just a case of removing the eight or so screws around the fuel filler cap. Once off, you can pop the middle panel off the fuel tank.


So what the heck is under the plastic? Turns out, acorn nuts. The nuts are recessed into the gas tank molding, so you have to at least remove some plastic with a drill or dremel to get the nut out.


To remove the first nut, I had to cut the top of the bolt off. Seems a ham fisted mechanic (with my name) forgot how dumb it is to use power tools to install the fairing bolts...in his defense, he thought the driver was low enough torque not to strip or cross thread...not so with brass inserts. So after cutting the top of the screw and removing the Tupperware, I was able to pop the first nut out of the tank. The second one was carefully drilled out (brass drills pretty easy). I took the drilling a little at a time and the tip of the acorn ended up popping out, so I never felt like I was going to drill through into the gas tank.


So, in case you don't know, the threads are M5 8.0.


I didn't know these were acorn nuts, and if I did, I probably would have still ordered open ended fasteners. It's tough to say how deep you want the screws to go in, besides, junk always gets caught in the bottom of the acorns, so it may be nice to have some free space in the bottom of the screw holes.

so I had pre ordered replacement nuts from http://www.mcmaster.com


Zinc-Plated Steel High Hex Nut

Low-Strength, M5x0.8 Thread Size, 8mm Wide, 5mm High



With the frightening part out of the way, how do we get the new inserts/nuts in place?


The nut that I popped out was pretty snug, so I used JB Weld because it mixes a little thinner. I lightly lined the insert hole, then pushed a nut, with a screw attached to it. I left the screw attached so I wouldn't smudge a bunch of epoxy around.


The hole I drilled out, ended up a little sloppy, so I used epoxy stick on that one. Same method.


I didn't end up seating the nuts as deep, so we will have to see how well they hold, but I'm not too worried, as these three screws don't have to do a whole lot.


Hope these notes can help some of you who may have been nervous about what to do about stripped or cross threaded inserts. Really not too big a deal to fix.


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Interesting. If these are the same fasteners I'm thinking they are, I'll have to file this away for future reference. I kept cross treading the shiny stainless screws that came on the bike. I switched back to the OEM black pointy screws and they went in like a dream-not the slightest cross treading issue. Of course I've only put them in once, maybe next time it will be a different story. Thanks for sharing the part numbers and the technique.

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Interesting.....I kept cross treading the shiny stainless screws that came on the bike. ...


Just out of interest if that is the case, have you checked these screws are actually M5 x 0.8 threads and not an 'Imperial equivalent'?

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I did not. I bought they at the local hardware in the stainless Metric section. Now that you ask I think I'll go back and compare the tread and size to the specs posted above. Thanks for the idea Andy. P.S. The original screws were in the bike when I bought it. I got local replacements when I lost a screw or two in the garage.

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I think it is important that the six gas tank fairing screws be tapered on the end, and that they be driven by a driver that starts the alignment accurately.


I made such a driver from an old screwdriver, cutting the tip off, drilling a 1/8 inch hole in the end, and ramming a cut-off piece of 3 mm hex key stock into the hole.


Obviously a commercial 3 mm driver screwdriver would be at least equal or maybe better, but this was something I could kludge when needed. It always travels with me.

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