The International Cessna^® 170 Association

I also believe the sidecar is for some covert operation. Great to see who you are with all that experience.

John

Aryana has a really nice looking '55 model. I was discussing the cableing for steering the tailwheel on the '55 model as appearing to be an improvement over the earlier models because of the apparent better mechanical vectors, However, since I once had a '55model, I am convinced that taxying a C-170 of any model is by far best controlled by the judicious use of differential braking. I've never found one that could be completely controlled by the use of the steering system alone. Of course, I haven't tried them all yet.

Dick, that "shimmy" can be dangerous, I'm glad you're addressing it.
I once, in a fit of ridership-joy, "jiggled" the handlebars of my '72 Honda CB500 while running up I-45 about 70 mph and it danged-near killed me before I could get it back under control. That gyroscope up front departed wilder and wilder with each gyration! I guarantee a fellow will only do that once! He'll either die from it....or he'll survive it and never do that silly stunt again!

I realize you'd rather do something off-color and individualistic but....I'm wondering if you've talked to the Vespa folks about it, as there might be some factory experience with it and an "approved" cure.
Have you ever wrecked it? Is the "rake" (caster) correct?
Does it have a trailing link suspension?...and is it's shockabsorber properly serviced?
Tire balanced and no broken belt? Is the steering "king" pin tightened down and bearings OK? (That latter has a dampening effect unless they get loose.)

I thought of you Blueldr when I saw a distinguished octogenarian get off his Can-Am at the gas station yesterday. The idling Rotax sounded a lot like an aircraft engine. I think it's time for Nancy to buy you a replacement for that Vespa. There are a lot of options for three-wheelers and the price range runs the gamut. Check out this one for $2000. If you want to stick with two wheels next year Lit Motors is coming out with a gyro-stabilized motorcycle. Nancy can afford it with the expat tax savings alone.

I do not believe there are any installations of sidecars on any type of two wheeled vehicle that can be safely operated without a steering damper system.