Broken sa bolts

[eric82930]

I've now broken my 4th swing arm bolt. The first one was on my 11 250sx and was way back when I didn't know how to ride and got stuck a lot and cranked the ski sideways to get out. I also broke the ts frame backbone 2 inches behind the sa bolt.

The last 3 have been on my vintage 300 360 and 380(they all look the same) that have the smaller 15mm bolt. Not sure why. They do vibrate but I don't jump and never get stuck.... they always break right at the step where the threads end. I just got a longer one from an old 80s model so the smooth part sticks through the frame farther and needs washers to tighten up. Fingers crossed...

 

[M5-]

My vote would be vibration induced fatigue (2 strokes). I think you are on the right track going with a longer bolt that is full thickness past the frame. The next option would be something in a higher grade, really not sure what grade the stockers are but they are probably a lower grade than one might think.

M5