riversbikes Posted April 6, 2020 Report Share Posted April 6, 2020 Hey all -- so I've got a monster 796 swingarm test-fitted to some old 900ss cases. It slots right in, with the usual shimming of the of the swingarm. The shock mount is offset farther to the left (as you sit on the bike), but nothing impossible with some frame surgery to fabricate an upper shock mount. However, during my self-isolation, I watched a youtube video from the UK, where the builder (s2r swingarm into s4 frame) claims that without some outrigger support connecting the frame to the swingarm pivot, the SSA will/could/might/did crack the rear part of the case, where the swingarm pivots on the engine. The builder of this special talks about it at about the 10minute mark of this video (lovely bike, BTW). Subsequent research and thinnin' has shown me that:1. The monsters that came with SSA as standard have a rearset design than helps connect the swingarm pivot to the engine case, specifically by bolting the rearsets to the case and also adding support to the swingarm pivot.2. On the other hand, if you take a look at the Ducati MH900e, they did not add any outrigger support to their frame -- the steel (heavier!) single sided swingarm simply pivoted in the case, similar to a conventional ducati arm, with seemingly no issues. A few well-heeled racers even raced these bikes, no doubt putting additional stresses through the back of the crankcase with higher speeds and grippy tires. Anyone want to weigh in with their thoughts? If you were to fit a 796/1100 swingarm to a 900ss case, would the swingarm and swingarm pivot need additional support? There are a few home-brewed ideas out there without additional case support: Quote Link to comment Share on other sites More sharing options...
Superdunc Posted April 6, 2020 Report Share Posted April 6, 2020 The loads aren't changing fundamentally. Why would the s2 arm put any more stress on the cases than the 900ss arm? I'd not be concerned with extra bracing. Quote Link to comment Share on other sites More sharing options...
2moto Posted April 6, 2020 Report Share Posted April 6, 2020 38 minutes ago, Superdunc said: The loads aren't changing fundamentally. Why would the s2 arm put any more stress on the cases than the 900ss arm? I'd not be concerned with extra bracing. Indeed. Quote Link to comment Share on other sites More sharing options...
riversbikes Posted April 6, 2020 Author Report Share Posted April 6, 2020 Thanks for the information -- I'll proceed, and I think I also have an idea for additional "outrigger" support. Quote Link to comment Share on other sites More sharing options...
TLRS Posted April 6, 2020 Report Share Posted April 6, 2020 I’d be looking at how the cracks develop. Might tell you something in which direction it is weaker. And try and get an idea how likely it is to happen. Sometimes it’s one in a thousand. At a guess the most stress comes from bumps while cornering. That would rely on flex in all associated parts. Do you like making good progress on imperfect roads? Quote Link to comment Share on other sites More sharing options...
riversbikes Posted April 6, 2020 Author Report Share Posted April 6, 2020 If you've seen my local racetrack, it's 1.6 miles of imperfect roads... Quote Link to comment Share on other sites More sharing options...
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