REFLECTOR:Nose Wheel Shimmy Brake Problem

[Ronnie Brown]

I have a similar vibration - but it isn't the nose wheel.  I think (as
someone else has suggested), just a harmonic in the main gear at that speed
20-30 knots.  Brakes work great above and below that speed but at 20-25
knots I have a pretty strong chatter.  My disks are smooth and straight so I
don't think it is a warped disk.  And I don't think it is nose wheel shimmy.
Releasing the brakes stops the problem.  Reapplying brakes at this speed,
and the chatter comes back.

This is not true of our Cessna 172, once the nose wheel starts shimmying (a
very common occurrence on Cessnas - especially with the nose wheel pant
installed), it doesn't stop whether the brakes are applied or not.  Only if
the load on the nose wheel is changed (elevator) or the speed is drastically
reduced.

Are you sure it is the nose wheel?  How do you turn if you have the nose
wheel so tight?  I have mine set at 15-20 lbs and I have a hard time turning
in the grass.  My understanding is that nose wheel shimmy on Velocities are
pretty much catastrophic.

Ronnie


----- Original Message -----
From: <Don19dw@aol.com>
To: <reflector@awpi.com>
Sent: Thursday, June 12, 2003 4:56 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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