REFLECTOR: Take Off Shimmy

[tstockmn at aol.com]

Velocitites

For those of you flying fixed gear birds, I've got a question.?? I recently replaced the rubber shock mount on my front gear strut with the "new" rubber mount due to suffering three failures of the factory mount.???? So far no shimmy on landing or on the take-off roll.??? However . . . . . . I've notice that as a I climb out the first 500 feet or so, I experience a "shimmy" that starts about five to ten seconds into flight and then dissipates after 5-10 seconds.??You feel it in the fuselage, but no in the stick or rudder pedals.?? ?It only happens on takeoff and I can't reproduce it in flight while simulating takeoff or anything else.??? Nothing else has been done to the plane (600+ hrs TTAF) recently other than the gear mod.??I checked all the flying surfaces and not indication of flutter.?? Prop tight, motor mounts good.?? I even put the brakes to see if it was the main wheels turning causing the shutter.??? My rule of thumb is that the most likely cause of a problem is normally the last thing you "fixed."??? I suspect it is either due to the front wheel spinning down and being slightly off balance or some other transitory vibration coupled with the spinning wheel.???? My guess is that the previous nose gear installation was loose enough that it didn't transfer any shimmy or vibration once the wheel left the ground.??? Now with the new rubber shock mount, the nose gear is solidly pressed against the fuselage (though the bumper and capture plate) and it amplifies any transient vibration.??? 

Any suggestions or anyone have a similar problem.??? 


Bill? Stockman??? 173FGE?? N12WS

"no good repair goes unpunished"
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