REFLECTOR: nose wheel shimmy

Ron Brown romott at roadrunner.com
Sat May 19 06:53:51 CDT 2007


These Cessna shimmy dampers should be easy to find in any Cessna repair shop 
or salvage yard.  We repaired ours as Sid suggested - new O rings and 
refilled with engine oil.  Worked a little better.  Then we replaced it with 
the Lord damper ($700) which was supposed to solve our Cessna's shimmy 
problems - NOT!

So far, my new nose strut and the thicker Bellville washers are working well 
on my 173 Elite RG.  No shimmy and steering is acceptable, even in the grass 
(I had to taxi about 100 feet from the hangar to the runway).

Ronnie


----- Original Message ----- 
From: "Sid Knox" <sbjknox at earthlink.net>
To: "Velocity Aircraft Owners and Builders list" <reflector at tvbf.org>
Sent: Friday, May 18, 2007 10:26 PM
Subject: Re: REFLECTOR: nose wheel shimmy


> ----- Original Message ----- 
> From: "Scott Derrick" <scott at tnstaafl.net>
>
>> Thats on a retract isn't it.
>
> Yes.
>
>> Whats the turning radius with the damper connected?
>
> Don't know the aircraft turning radius but the measured swing of the wheel
> is about 45 deg  left, 30 deg right.  Obviously, I don't have the geometry
> correct but it does what I need.  Between my hanger and the taxiway is a 
> 90
> deg turn followed immediately by a 120 deg turn in the opposite direction.
> Before (using the Belview washers), it was a major pain-in-the-butt
> negoiating these turns... often going off into the grass.   Now, with the
> free-turning nosewheel, it is simple.   And, no shimmy, no worrying about
> adjustments.
>
>> When turning in tight quarters do you bottom out or top out on the damper
>> often?
>> No worries the damper would break from over extending?
>
> For the above mentioned turns, I feel no indication that I have hit the
> ends.
>
>> How big is that damper?  It looks big in the picture,  got a part number?
>
> It is a damper off of some older model Cessna that a friend had in the 
> scrap
> pile because someone had "ruined" it (by certified standards) trying to 
> get
> it apart and damaged the piston and bore.  I cleaned it up, got some 
> o-rings
> from AutoZone and it feels good as new.   I am using Shell 100 for a 
> working
> fluid.  I tried hudraulic oil (John Deere) but because of the scoring in 
> the
> bore, it did not damp as much as I wanted...it had essentially two
> orfices... the proper one and the score.  So, the heavier oil compensates
> for the higher internal bypass.  There is *no* leakage to the outside.
>
> This is probably not a good mod if one must buy a good damper as they are
> *very* expensive! (typical Certified B.S. pricing).
>
> Sid
>
>
> Sid
>
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