Why did ducati put a double sided swing arm on the 749 899 and 959 but not on 748 or v2? And what’s best performance/stability wise?
SSSAs have been around for a long time. As far as I remember, Ducati developed the SSSA initially for endurance racing and crossed over into SBK and SS so had to be homologated, hence the 916SP/SPS and 748SP/SPS/R. I guess the SSSA is synonymous with Ducati (and Honda) and it just keeps reappearing. As to the merits of SSSA vs twin spar, I've not got a clue. Andy
Agreed. Honda came up with SSSA for endurance racing but a twin went on the 999 so they could win WSBK. Substance over style the race team asked for. SSSA are loads heavier to make up the strength of a twin . As @Sev so eloquently states.
Sev and everyone else have pretty much covered all bases on the pros and cons of sssa, the main reason they exist now is just for aesthetics, they look cooler than penguin piss and show off the rear wheel a treat. In my previous life, before I retired and was still working ( day prison ) I was Tooling manager for a few big firms, at the last one I used to place work with a sand casting factory in Imola , Italy This supplier used to cast the sssa for Ducati and MV Augusta, so I was lucky enough to be walked through the process on one of my visits by their technical manager, he knew I was a mad keen Ducati fan,..used to refer to me as “Ducati man” to his staff and even organised a one to one tour around the Ducati factory for me with the contact he used to deal with there,.bloody marvellous! I’ve seen first hand how much more aluminium goes into making up a sssa, at a rough guess I would say it Is about 1.5 - 1.7 times the material as a dssa, a few pictures here, an MV sssa here.. The internal cavity is made up of a sand/resin mix that is then laid into a steel die, closed up and the aluminium cast around it. Once the cast swingarm is removed from the die, it is then heated up enough to burn the resin off the sand internal core and then the swingarm is put in a vibro bowl to basically shake the sand out of it. Internal cores- once the sand is mixed with the resin it has a biscuit like texture and holds its shape well the red parts are where the cores have been repaired or need a smoother finish, top rhs shows a metal bush loaded that will be cast into the inside of the sssa. The finished items after powder coating and machining.. No doubt about it, they do look pretty but they are also a chunk heavier than a conventional dssa as the wall sections are a lot thicker to withstand the torsional forces. Just a final thought, in the technical development hotbed of MotoGP racing,..how many of the MotoGP teams are using a sssa??…None!..and that includes Ducati, says it all really ?
These guys really knew their stuff Sev, that’s the reason why the job ended up in Italy,..have a look at the cores for these internal air channels in the manifold I placed with them.. I was constantly amazed at the highly complex castings they could produce from something as simple as basically “ sticky sand” ..something we all take for granted on a stroll along a beach ( not the same sand of course) this was a highly refined fine grain foundry pattern sand. They also did work for Lamborghini, their conference room was full of Lamborghini cylinder heads, inlet manifolds, Ducati swingarm etc, I used to love dealing with them and Imola itself was a beautiful place to visit.
Doubt any of us on here could tell the difference between a ssa and a normal one. Except on looks. Fitted one to my rgv for that very reason rides no differently, but while the arm is heavier, the wheel is a lot lighter. Wonder what the unsprung weight difference is?
Agreed ducv2, probably only top level racers could detect a difference, but as you say,..unsprung weight is another matter When I put the BST carbon wheels on my 899, the rear one alone saved 4.4kgs of unsprung weight,..the bike was absolutely night and day different
That's why I put carbon hoops on my sssa 899. I think the swingarm is lighter than the 899 double sided job. It's the heavy hub and axle that shoves the weight up. But I'm splitting hairs. Single sided jobbies rule
The other disadvantage with SSSA is that chain adjustment is not linear rather through an eccentric and as such affects the ride height and /or the rear suspension squat on acceleration
I come down firmly on the side of the fence that's allocated to those who enjoy a conventional double sided swing arm. I understand that SSSAs work, although at a weight penalty. I understand that in a racing situation they make life easier. I understand that the bikes people see racing on telly and in person sell bikes to road punters, and they want their bikes to look like the race bikes. I understand that the SSSA set the 916 apart from other bikes and Ducati marketed the 'trick' look. I even understand, that like everything else, fashion has a role to play in selling bikes. But, I just don't like them, I don't like the look, and would rather have a lighter SA than a fashionable one. I don't think I'm a good enough rider to tell the difference on the road, but my engineers brain just doesn't like them. If I was a pit crew strategist I'd probably be happier to weigh-up(see what I did there) the pros and Cons. It's why I like the 749/999 and Multi Enduro. One of the projects in my head is a 1098 or 1198 with a 999 swingarm, but it will probably never happen.
