REFLECTOR:Nose Wheel Shimmy Brake Problem

[Chris Martin]

Don,

I did have the very same problem and I chased it all over the place. I
found that the shimmy in the nose gear was the result of a shimmy in the
mains. The mains had a small shimmy that was harmonic with the nose gear
strut at about 20 MPH.

Try tightening the through bolts at the main pivot points for the nose gear
and the mains. This was my biggest problem and solved almost all of my
shimmy. Put the plane up on jacks and cycle the gear up. Place a box or
some sort of 6 inch high block on the ground where the wheels come down.
Then dump the emergency hydraulic release and let the gear down. The gear
will stop on the blocks allowing you to lift them and feel the side to side
play. I think you will find that they are loose. Lubricate the pivot points
and tighten them up as much as you can without binding the gear. That
should fix most of the shimmy.
 
Let me know if it helps.

Chris Martin


> [Original Message]
> From: <Don19dw@aol.com>
> To: <reflector@awpi.com>
> Date: 6/12/2003 12:57:05 PM
> Subject: REFLECTOR:Nose Wheel Shimmy Brake Problem
>
> Have not been able to solve the following problem: when braking to a stop
or 
> to turn off runway, get nose wheel shimmy, at low speed, 20 to 30 mph.
The 
> harder the braking the worse the shimmy, and it ceases shortly after
brakes are 
> released. Have installed latest Matco brake discs and pads. Discs look
smooth 
> and OK and are properly aligned. Checked nose wheel OK for balance and
not out 
> of round. Also have extra tight shimmy damp torque of maybe 30 to 40# of
force 
> to move tire sideways. Talked to both Matco and Velocity and tried their 
> suggestions.  Only condition I find unusual is nose gear strut is about 7
degrees 
> forward at bottom end and factory says 2 degrees is normal. 
> Any ideas?????  Did Chris Martin have this problem???
> Don White     N19DW    XL/RG 
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