FYI,

As previously reported, my C172 main gear shakes similar to John’s description – primarily during moderate to heavy braking  (i.e. an advantage of being able to see the gear on a high wing).  I only offer my observations as a reference point.  I generally take the pants off in the fall to protect them from snow/ice here in Michigan.  While the weight of the pants should effect the natural frequency, the C172 gear seems to shake “about the same” with the pants on or off (primarily during moderate to heavy braking).  The pants are solid/stiff to the wheels.  I do not know if the pants are balanced for/aft – I’ll attempt a crude measurement today (since they are currently now off).  I have not attempted to do a run-out measurement on the brake disk nor balance the tires as I’m not really concerned with it on the C172 (perhaps I should be), since I am used to it and it’s only a minor nuance on the C172.  The C172 gear legs are probably “springy’er” than the ES legs, but are mounted more firmly to the fuselage than many ES legs which have a little “play” in the ES gear leg weldments.  I’d guess/speculate that under the correct conditions the main gear vibration could “couple” with the nose gear natural frequency and create/initiate a more violent/catastrophic event (especially if the front ES strut damping circuit were compromised).  My C172 has a separate fluid-less Lord shimmy damper (http://www.aircraftspruce.com/catalog/lgpages/lord_shimmy.php) so that part/effect is not comparable to an ES.

Rick Titsworth

ES-Building, C172-Flying