Light Aircraft Association

Anyone here have know what could cause a nosewheel to start to shimmy and therefore what remedial action could be taken.

Several things can cause this including:
Incorrect pivot (castor) angle ?
Is this
a new build problem (spec wrong? or
was it ok but is now an ongoing problem - heavy landing permanently altered the angle/damaged the fork?) or
intermittent ie when a certain weight is on it the castor angle changes sufficiently to cause shimmy.

Insufficient friction? - my free swivelling nose wheel has 3-5lbs force at the tyre damping friction.

Wheel out of balance?

Loose wheel bearing?

Loose pivots?

Tail wheel steering cable/spring tensions?
Regards
Steve

"Tail wheel steering cable / spring tensions?"
Cause nose wheel shimmy????

Can't think of too many aircraft with a steerable nose wheel and a steerable tailwheel, come to think of it I can't think of too many with non steerable nose and tailwheel iether.
Certainly no shadows...is this an approved mod?

Oops - you're right - while compiling my response I started thinking generally rather than the specifics of the question. At least someone with tail wheel shimmy might benefit since the other causes listed affect both!
Regards
Steve

Having owned two Shadows and a Streak in the past (!!) I seem to remember that nose-wheel shimmy was simply a matter of tightening up the wire strop that retained the movable nosewheel tube inside the bonded mounting tube. This was a highly technical procedure.... you simply leave the aircraft sitting on it's tail-skid and twist the nosewheel one full turn! Too tight and it becomes obvious that it is (too tight), but if it's 'loose' then it will shimmy!

one very simple thing you could try is the tyre pressure if you have not already ?