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Maintenance Tips

McCauley Tailwheel Shimmy
Author Last Post
Tire is good and Pressure is 60 to 70 lbs.  The problem is either in the stinger or the tailwheel.  I suspect it is wear/lack of preload in the tailwheel. Next step is to check torque/preload etc and try.  I had it rebuilt about 600 hrs back and the problem seems to have  shown up over time.  Thanks for the heads up on parts suppliers.  That would have been my next question.   I'll keep you posted on progress. I always wheel land and  its been a while since I have flown with  an adult in the back seat.

Fly Safe!!!

Don
 
I've solved mine by bringing tire pressures up to where they're supposed to be. I generally use 60 psi

On Tue, Aug 1, 2017 at 2:02 PM, David Lloyd (skywagon@charter.net) <mailer@mail2.clubexpress.com> wrote:
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Reply to forum at MaintenanceTips@skywagons.club (be sure to copy the message subject exactly so your reply is attached to the correct thread)     Reply directly to David Lloyd at skywagon@charter.net
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Tail Wheel Shimmy. . . .   The sure cure is to have a tailwheel "lock" set-up, but, most 180's do not have that option.   I can think of 3 main causes of shimmy. . .   1.) The hub thru bolt is not torqued to the correct bearing pre-load. This pre-load loosing up with time and ground steering seems fine, but, shimmy is guaranteed on landing, 3-point. 2.) The internal hub friction springs are worn, missing, too few, etc. 3.) The caster angle on the hub has changed into the unstable region. This can be a couple of things.  The "stinger" is bent or flexes too much from load or is just undersize.  The snubber on the front of the stinger staff is damaged, old, loose, etc.  The hub is loose on the aft stinger end. That is usually secured with epoxy and then bolted.   Tailwheel Tom is the guy to call. He also has larger diameter, stiffer tail wheel shafts (stinger) that keeps the caster angle in the correct angle configuration. . . D        ----- Original Message ----- From: Alan Roberts (Captna320@aol.com)  To: Maintenance Tips  Sent: Tuesday, August 01, 2017 9:28 AM Subject: re: McCauley Tailwheel Shimmy <<$177727523065$>>
 I had a shimmy problem on my 180J, so I took my Scott Tailwheel apart and found a few worn parts. It was going to cost about $700 to replace all the worn parts, so I ordered a new Alaska bush wheel for $1700 instead. All was good until I did a three point landing and the shimmy came back. I called the good folks in Alaska and they said it sounded like negative chamber or a bent or weak tail spring. I've done a half dozen wheel landings since then with no problem. I may have to change tail spring and bushings in the future.
Alan Roberts N556WC

Sent from my iPhone

                        Virus-free. www.avast.com



 
Tail Wheel Shimmy. . . .
 
The sure cure is to have a tailwheel "lock" set-up, but, most 180's do not have that option.
 
I can think of 3 main causes of shimmy. . .
 
1.) The hub thru bolt is not torqued to the correct bearing pre-load.  This pre-load loosing up with time and ground steering seems fine, but, shimmy is guaranteed on landing, 3-point.
2.) The internal hub friction springs are worn, missing, too few, etc.
3.)  The caster angle on the hub has changed into the unstable region.  This can be a couple of things.
        The "stinger" is bent or flexes too much from load or is just undersize.
        The snubber on the front of the stinger staff is damaged, old, loose, etc.
        The hub is loose on the aft stinger end.  That is usually secured with epoxy and then bolted.
 
Tailwheel Tom is the guy to call.  He also has larger diameter, stiffer tail wheel shafts (stinger) that keeps the caster angle in the correct angle configuration. . .
D
 

 
----- Original Message -----
Sent: Tuesday, August 01, 2017 9:28 AM
Subject: re: McCauley Tailwheel Shimmy <<$177727523065$>>

I had a shimmy problem on my 180J, so I took my Scott Tailwheel apart and found a few worn parts. It was going to cost about $700 to replace all the worn parts, so I ordered a new Alaska bush wheel for $1700 instead. All was good until I did a three point landing and the shimmy came back. I called the good folks in Alaska and they said it sounded like negative chamber or a bent or weak tail spring. I've done a half dozen wheel landings since then with no problem. I may have to change tail spring and bushings in the future.
Alan Roberts N556WC

Sent from my iPhone

Virus-free. www.avast.com
 
Give Tom Anderson at www.TheLandingGearWorks.com a call.  Tom knows tailwheels inside and out.  He can talk you through the challenges of the dreaded “tailwheel shimmy”.

Jim Hill
N2393C
54’ 180


On Aug 1, 2017, at 9:01 AM, Don McKeown (skywagon350@yahoo.com) <mailer@mail2.clubexpress.com> wrote:

Hello All.


When I let the tail down after landing close to or at gross weight  the tailwheel shimmys pretty bad. Loaded light with two people in the front seat I don't notice it but add a third adult to the rear seat and the shimmy appears.  I am about to take the tailwheel apart and fix whatever ailes it and would like to have the benefit of other's experience  on this project.

Thanks,

Don 

 
Here's how I address shimmy in the order of least expensive to most expensive:

1.  Start with a new tire and tube. I have had this completely fix the problem on more than one occasion. Even if the tire looks good, it could be out of round and out of balance. Also make sure all the bolts are tight on the tailwheel head and not loose on the spring.

2.  If that doesn't work, try a tailwheel rebuild kit from Airframes Alaska.

3.  If that doesn't work, you may be looking at a new tail spring.

4. The nuclear option is to replace both the tailwheel spring and tailwheel will with new ones from Airframes. This would also include the rubber parts around the saddle. 

Good luck. 
Paul Brown

Sent from my iPhone

On Aug 1, 2017, at 09:01, Don McKeown (skywagon350@yahoo.com) <mailer@mail2.clubexpress.com> wrote:

Hello All.


When I let the tail down after landing close to or at gross weight  the tailwheel shimmys pretty bad. Loaded light with two people in the front seat I don't notice it but add a third adult to the rear seat and the shimmy appears.  I am about to take the tailwheel apart and fix whatever ailes it and would like to have the benefit of other's experience  on this project.

Thanks,

Don 
 
I had a shimmy problem on my 180J, so I took my Scott Tailwheel apart and found a few worn parts. It was going to cost about $700 to replace all the worn parts, so I ordered a new Alaska bush wheel for $1700 instead. All was good until I did a three point landing and the shimmy came back. I called the good folks in Alaska and they said it sounded like negative chamber or a bent or weak tail spring. I've done a half dozen wheel landings since then with no problem. I may have to change tail spring and bushings in the future.
Alan Roberts N556WC

Sent from my iPhone
 
Hello All.


When I let the tail down after landing close to or at gross weight  the tailwheel shimmys pretty bad. Loaded light with two people in the front seat I don't notice it but add a third adult to the rear seat and the shimmy appears.  I am about to take the tailwheel apart and fix whatever ailes it and would like to have the benefit of other's experience  on this project.

Thanks,

Don 
 
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