Hi Everyone,
My tail is shuttering during rollout after landing and I have pulled my yoke fully back towards me. I suspect that I need to tighten my tailwheel, but I wondered if you agreed. Any suggestions about how tight is tight enough?
Thanks!
Mike
[b]Tailwheel shake[/b]
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
tailwheel shaking
Hi Everyone,
I just found a thread that discussed adjusting the main king pin nut and chains for the Scott 3200 tailwheel. I'm going to look at my tailwheel tonight and see whether the same advice holds:
1) Tighten the nut in 1/6 turns until the binding is becoming tight;
back off the nut 1/6 a turn.
2) Examine my chains' tension on the ground and with the tail lifted.
Anything else I should know?
Thanks,
Mike
I just found a thread that discussed adjusting the main king pin nut and chains for the Scott 3200 tailwheel. I'm going to look at my tailwheel tonight and see whether the same advice holds:
1) Tighten the nut in 1/6 turns until the binding is becoming tight;
back off the nut 1/6 a turn.
2) Examine my chains' tension on the ground and with the tail lifted.
Anything else I should know?
Thanks,
Mike
Hi Mike,
My tailwheel shimmy went away when I replaced my tailwheel tire & tube. I replaced the tailwheel because all three tires needed to be replaced, the shimmy going away was not expected. The theory was that the tire/tube was out of balance. The shimmy occurred on something like 1 out of 20 landings, and easing the yoke forward always made it go away. One more thing to consider, it might be your tire/tube.
My tailwheel shimmy went away when I replaced my tailwheel tire & tube. I replaced the tailwheel because all three tires needed to be replaced, the shimmy going away was not expected. The theory was that the tire/tube was out of balance. The shimmy occurred on something like 1 out of 20 landings, and easing the yoke forward always made it go away. One more thing to consider, it might be your tire/tube.
Joe
51 C170A
Grand Prairie, TX
51 C170A
Grand Prairie, TX
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
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DensityDog
- Posts: 64
- Joined: Fri Jun 14, 2002 3:38 am
Pretty good advice in all.
You might be careful about just shooting gobs of grease into your tailwheel assy. The shimmy damper (those phenolic plates sandwiched between the fork & spring attachment) require a certain amount of friction to help prevent shimmy.
Make sure you get this fixed soon, the shimmy can wreck the inner workings of your tailwheel pretty quick.
Tom at XP Mods has a good explanation about adjustments on the Skywagon site in the Knowledge Base section.
You might be careful about just shooting gobs of grease into your tailwheel assy. The shimmy damper (those phenolic plates sandwiched between the fork & spring attachment) require a certain amount of friction to help prevent shimmy.
Make sure you get this fixed soon, the shimmy can wreck the inner workings of your tailwheel pretty quick.
Tom at XP Mods has a good explanation about adjustments on the Skywagon site in the Knowledge Base section.
I received an email that a person's tailwheel shimmy was solved by replacing their tailwheel tire & tube shortly after this post. Interestingly, this past Saturday for the first time since new tailwheel/tube last December at annual, I had a tailwheel shimmy again. That has been over 150 hours. The wind was a gusty 15+ knot crosswind and I was doing touch and go's to practice the gusty conditions at different airports in the area. Wondering if during crosswind conditions the tailwheel is turned by the wind and that contributes to the shimmy, as before, easing the yoke forward stops the shimmy. It has not done it since the crosswind Saturday. Thinking maybe if the wheel is turned a little and not lined up on touchdown that it starts a shimmy and when you ease it up and sit it back down it is lined up straight and does not shimmy???N1478D wrote:Hi Mike,
My tailwheel shimmy went away when I replaced my tailwheel tire & tube. I replaced the tailwheel because all three tires needed to be replaced, the shimmy going away was not expected. The theory was that the tire/tube was out of balance. The shimmy occurred on something like 1 out of 20 landings, and easing the yoke forward always made it go away. One more thing to consider, it might be your tire/tube.
As a side note: The August 2002 issue of Light Plane Maintenance has a tire article that explaines the mark on the tire is the light point of the tire, and the mark on the tube (default if no mark is the tire stem) is the heavy point of the tube. Thus, a natural balance by matching up the light point of the tire with the heavy point of the tube.
Joe
51 C170A
Grand Prairie, TX
51 C170A
Grand Prairie, TX
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Jeff Matthews
- Posts: 16
- Joined: Wed Dec 11, 2002 12:44 am
If easing the yoke forward stops your tailwheel shimmy, have a look at the kingpin angle. It should be about vertical. If it's got any notiecable rake to it, either something's worn somewhere between the fork and the fuselage, or the master leaf hasn't got enough arch.
I've heard the caveats about greasing the swivel. My own experience is to give it a shot about every 10 landings or so. I started with a brand new Scott on a 180, gave it a shot a couple of times a week, and after a thousand hours it still didn't shimmy. Since the 180's set up different from 170's, Cubs and Champs. there's not much you can do about angles.
I've heard the caveats about greasing the swivel. My own experience is to give it a shot about every 10 landings or so. I started with a brand new Scott on a 180, gave it a shot a couple of times a week, and after a thousand hours it still didn't shimmy. Since the 180's set up different from 170's, Cubs and Champs. there's not much you can do about angles.
Oil Filter failure fixed tailwheel shimmy
Hi -
I was having the same problem with the tailwheel. It would shimmy until I eased the back-pressure.
In October of last year I had the gasket on an F&M Oil Filter fail and blow all the engine oil onto the belly of the plane. One landing in a field later and the purchase of a new screen (yes, there are benefits of having a screen instead of a filter (keep it simple stupid!)) and my tailwheel shimmy went away.
I'm guessing the 5 quarts of oil that passed over the tailwheel assembly did a nice job of lubricating it. Haven't had a problem since, though I do plan on shooting it with grease more often now.
Dennis Keller
4316B
I was having the same problem with the tailwheel. It would shimmy until I eased the back-pressure.
In October of last year I had the gasket on an F&M Oil Filter fail and blow all the engine oil onto the belly of the plane. One landing in a field later and the purchase of a new screen (yes, there are benefits of having a screen instead of a filter (keep it simple stupid!)) and my tailwheel shimmy went away.
I'm guessing the 5 quarts of oil that passed over the tailwheel assembly did a nice job of lubricating it. Haven't had a problem since, though I do plan on shooting it with grease more often now.
Dennis Keller
4316B
I only had shimmy for a short while. Turned out the grease I had bought from Aeroshell went to paste. Took me a while to figure it out, I was greasing the axle and kingpin and nothing coming out of the grease gun, opened it up to find paste. Had to take the wheel apart to make certain it was all clean and that one grease would not be incompatible with the other or cause some sort of reaction (I'd been warned by a "lube expert"). Now, all's good. Having said that, I spoke to a couple of old timers out here and given food for thought:
Shimmy is the action the tail wheel takes that ressembles the wheel on a shopping cart. A few things could cause that; if the tire is kept from rotating freely, it tries to brake (could be in one spot of the rotation only), starts skipping and dancing around. Or the kingpin needs lubrication or dirt somehow got in there (which means that greasing the *#%@ out of it à la Eric would push out the old dirty grease and leave you withh fresh stuff). I think that the type of grease is important and I am also told that you should stick to one grease, don't mix. If you fly in and out of wet grass or dusty, muddy, dirty environment as opposed to hard top; extreme heat or extreme cold (temperature range appropriate grease is important) if you drag your tail or gently put her down, all have to do with the longevity of the clean-up, re-pack and grease up job you have to do. I have 2 tail wheels, one winter 3200 mounted on my penetrating ski, which is my old wheel I rebuilt; the other is my 3200-A which I drag through the sand, dust, mud, dirt and hartop through the "other" season. So both wheels get taken apart, cleaned out, checked and repacked onced a year; that's about 100 to 150 for the 3200-A and 50 to 75 for the 3200.
BTW, applying full back pressure once the tail is down is what helps control ground handling, so keep it back to keep it out of the ditches, fix the shimmy. Works for me. JD
Shimmy is the action the tail wheel takes that ressembles the wheel on a shopping cart. A few things could cause that; if the tire is kept from rotating freely, it tries to brake (could be in one spot of the rotation only), starts skipping and dancing around. Or the kingpin needs lubrication or dirt somehow got in there (which means that greasing the *#%@ out of it à la Eric would push out the old dirty grease and leave you withh fresh stuff). I think that the type of grease is important and I am also told that you should stick to one grease, don't mix. If you fly in and out of wet grass or dusty, muddy, dirty environment as opposed to hard top; extreme heat or extreme cold (temperature range appropriate grease is important) if you drag your tail or gently put her down, all have to do with the longevity of the clean-up, re-pack and grease up job you have to do. I have 2 tail wheels, one winter 3200 mounted on my penetrating ski, which is my old wheel I rebuilt; the other is my 3200-A which I drag through the sand, dust, mud, dirt and hartop through the "other" season. So both wheels get taken apart, cleaned out, checked and repacked onced a year; that's about 100 to 150 for the 3200-A and 50 to 75 for the 3200.
BTW, applying full back pressure once the tail is down is what helps control ground handling, so keep it back to keep it out of the ditches, fix the shimmy. Works for me. JD
Which Scott 3200 parts?
Hi -
Well, my shimmey is back. I've greased. I've changed the tire pressure. Still there.
My mechanic says it's time to pull the things apart and clean it. While in there, he recommends replacing all the washers, caps, springs, etc.
Given this page:
http://www.aircraftspruce.com/catalog/l ... 3200tw.php
Which parts would you all recommend replacing? I'm planning on replace #3-#7 and #10 #13.
Anything else I should consider?
Thanks!
Dennis Keller
N4316B
Well, my shimmey is back. I've greased. I've changed the tire pressure. Still there.
My mechanic says it's time to pull the things apart and clean it. While in there, he recommends replacing all the washers, caps, springs, etc.
Given this page:
http://www.aircraftspruce.com/catalog/l ... 3200tw.php
Which parts would you all recommend replacing? I'm planning on replace #3-#7 and #10 #13.
Anything else I should consider?
Thanks!
Dennis Keller
N4316B
Definitely replace #9 and #18. These are what provide the "detent". They also are what commonly fail.
You should check your chain tensions if you are experiencing shimmy. The chains should ever-so-slightly tension the chain-springs at your common operating weights. Loose chains will allow shimmy.
Examine #12, bearing, as well as the tailwheel axle bearings. (Those axle bearings should have a slight pre-load on them, which is obtained by adding washers on the axle inside the fork.)
You should check your chain tensions if you are experiencing shimmy. The chains should ever-so-slightly tension the chain-springs at your common operating weights. Loose chains will allow shimmy.
Examine #12, bearing, as well as the tailwheel axle bearings. (Those axle bearings should have a slight pre-load on them, which is obtained by adding washers on the axle inside the fork.)