The reason for doing the driveshaft mod is reduced driveshaft plunge ... in the normal working zone there is MUCH less plunge with this set up.
Under power there is load between the dogbone drive pin and the out drive, this load combined with the frictional terms between the pin and out drive conspire to bind/hold the drive pin in one position, resisting the plunge needed to make the suspension move freely.
This in turn resists the suspension movement making it a little harder for the suspensopn to cope over really bumpy surfaces, the drive shaft mod helps here as the less plunge require = less rsistance.
So why didn't they just do that in the first place I hear you ask? Well the position of the outer drive joint, or more specifically the arc the center of that joint makes as the suspension moves through it's travel, also plays a part in the way the driveline works and influences the suspension as a whole. Luckily there isn't too much of a problem here with the new setup as the arc traced by the joint isn't fighting the arc swept by the suspension. With most cars it would be enough to limit the squat effects making it harder for the car to squat to a position below driveshafts level but as the FS doesn't migrate it's center of mass rearward under acceleration to create much squat it's effects are hardly noticable.
I ran the mod on a fairly bumpy track at the weekend and it definitely made the car feel a little more fluid when accelerating through the rough stuff, I can't remember my car being kicked about on some of the worst bumps that the B44s & Dingos seemed to be finding. I would however expect to be taking it off if I went to a smooth but low grip track (say indoors on slippery floor) when I was running the car below driveshafts level as a typical ride height and wanting the maximum traction out of the slippy stuff.
As an added bonus as Nick states it also allows you to run a bit more up travel without a clash between dog bone and outdrive too, another bonus.
As far as the "gull wing" mounts they are a means to an end I believe. By using those it allows them to run almost any lower shock mounting postion combination along and above/below the wishbone. This will allow them to trial almost infinite changes without having to make new wishbones each time, simply a logical engineering solution for prototyping! I would expect it to give rise to some new wishbones, not the moutns coming to the market.
With Kyosho's standard way of supplying wishbones (which they have been doing for as long as I can remember) it would make no sense for them to have none-symetrical parts like bent wishbones a-la B4 etc. Who knows that may change though.
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