Nose wheel shimmey

[Jeff Phelps]

We have been plagued with a nasty shimmey in the nose gear of our 415-C. We have tried many fixes in the last ten years. We have replaced scissor linkage bushings, replaced inner cylinder bushings, tried different tire pressures, and just this week we replaced the ball and socket steering connector with the STC'd version that uses the bolt and bearing. It still shimmeys. We are running out of ideas. We have the double arm fork. One thing that we have noticed is that on most Ercoupes with the double nose fork, the wheel axle is directly in-line with the hydraulic cylinder if you were to draw an imaginary line through them. However, on our 'coupe the axle is set behind this imaginary line at least 1"-1 1/2". The fork looks different than most I have seen. It bolts to the inner shaft instead of being pressed on like most.Could this offset cause the shimmey?   It only shimmeys under deceleration after landing. Never during full power on takeoff. It seems to be only at a certain ground speed. Feels like a harmonic inbalance. Two things bug us about this problem. 1. What other unseen damage will this shimmey cause on the engine, engine mounts, airframe, etc... 2. I do not like the fear it puts into passenger when I land. Has any body else been cursed with this problem?   Jeff & Jim Phelps N2749H  Sidney, NE