ST1100 Cracked Tail Frame

Paul and all,

That bracket (which I would not call a Frame) was important to me when I first started looking at ST1100s in 1999. I had owned a Kopysaki ZG1000 Concours which had only a tiny luggage rack that was, in my opinion, so poorly designed that one would damage the rear cowl no matter how one loaded it with any significant weight. (Going from memory)

My Honda dealer had a new, standard ST1100 in stock. Not only did he let me take it for a test ride; I talked him into letting me disassemble the tail of it right on the showroom floor! With the rear cowl off, I could see that it would be possible to put weight on those top four bolt holes without cracking the plastic cowl. The ST had cleared a hurdle that was important to me.

Honda was not unwise when they offered only a small, optional top box for the ST1100s. That location is a convenient place for the rider(s) to store luggage. At the same time, it is a piss poor place for weight if one wants a bike that performs well enough to avoid accidents. I sometimes load an ST as if it were a two wheeled pickup truck; but then I adjust my riding style accordingly to keep the risk of an accident down. (I think I damage the rear shock though.)

By the way I have never damaged one of the subject brackets, and I am currently riding my eighth ST1100/A.
Henry the Eighth, as I call that ST, has a Givi top box which includes a mounting that is decent, as far as I can tell.
 
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Hmm, to me it looks like it was a fatigue crack working its way through for a while. Notice the rust on the aft half of the exposed crack? Still a terrible place to put a big hole, right in the middle where it's the most stressed section of the bracket. If it were me and I wanted to do some welding, I'd clean & weld up the crack, then add two plates to cover both holes.
 
jdmccright said:
Hmm, to me it looks like it was a fatigue crack working its way through for a while.
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I'm no metallurgist but yeah I think metal fatigue is the culprit if not aiding and abetting an overload incident. It may also be that even keeping to Honda's recommended limitations the piece(s) still would have cracked if they didn't plan accordingly.

No doubt the holes were for style only. Had the brackets been thicker I'm sure the holes wouldn't have been an issue. So yeah a bad place if Honda wanted to save some material costs. But I still think cutting out something equal to or > .0125" with holes and shaped to match and fit the brackets' shape and style would preserve their look and integrity.

The ST1100 is a beautiful bike and it would be a shame to mar that even a tiny bit with some patchwork.
 
ST Gui said:
No doubt the holes were for style only.
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The bracket is 100% hidden and out of view with the plastic cowling in place so I'm pretty sure esthetics had nothing to do with it. I think the hole is a poorly placed weigh saving effort.

Or maybe the hole is a type of fuse, if blown, or cracked, this is an indicator to the owner that they are carrying too much weight in a place where it might negatively impact handling to a dangerous extent.
 
For what its worth ...

The FJR has the same problem with the OEM top box bracket breaking. Its such a common concern that one of the forum members over there has found it worthwhile to make and sell a "stiffy kit" (his name for it), modeled after the Givi 357 bracket.
 
Paul, can you post up some pictures of the repaired parts when they're done? I always like to see quality fab and repair work.
 
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