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RV-6A Nose Wheel Shimmy
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djtoddb

Joined: 26 Mar 2010
Posts: 14
Location: Mesa, AZ

Posted: Wed Aug 12, 2015 5:29 pm Post subject: RV-6A Nose Wheel Shimmy

Has anyone have experience in dealing with the Nose Wheel Shimmy on a RV-6A? What are the causes and remedies?

_________________
Titan Tornado II with Jab 3300

tlaw(at)northwestel.net
Guest

Posted: Wed Aug 12, 2015 9:49 pm Post subject: RV-6A Nose Wheel Shimmy

Could be a tire balance issue or excessive speed that starts the shimmy.  



When new (2005) my RV-6A did it and I torqued the big nut up a little

tighter and the past 200 hours have been trouble free.



Tom Law

RV6A   C-GNJI

Canada



From: owner-rv6-list-server(at)matronics.com

[mailto:owner-rv6-list-server(at)matronics.com] On Behalf Of djtoddb

Sent: August-12-15 6:29 PM

To: rv6-list(at)matronics.com

Subject: RV-6A Nose Wheel Shimmy






Has anyone have experience in dealing with the Nose Wheel Shimmy on a RV-6A?

What are the causes and remedies?



--------

Titan Tornado II with Jab 3300





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=445867#445867

recapen(at)earthlink.net
Guest

Posted: Thu Aug 13, 2015 3:03 am Post subject: RV-6A Nose Wheel Shimmy

In addition to torqueing the big nut as others have suggested, I also balanced my nosewheel pant.





--

falconav04(at)yahoo.com
Guest

Posted: Thu Aug 13, 2015 3:51 am Post subject: RV-6A Nose Wheel Shimmy

I balanced the nose pant and haven't had an issue with shimmy.

  



     On Thursday, August 13, 2015 6:10 AM, Ralph E. Capen <recapen(at)earthlink.net> wrote:

  

  



 --> RV6-List message posted by: "Ralph E. Capen" <recapen(at)earthlink.net (recapen(at)earthlink.net)>



In addition to torqueing the big nut as others have suggested, I also balanced my nosewheel pant.





--

djtoddb

Joined: 26 Mar 2010
Posts: 14
Location: Mesa, AZ

Posted: Thu Aug 13, 2015 5:45 am Post subject: RV-6A Nose Wheel Shimmy

How do you balance the nose wheel pant???



 

Todd Bristol

  Interactive Entertainment DJs and Events,

   

  



     On Thursday, August 13, 2015 4:03 AM, Ralph E. Capen <recapen(at)earthlink.net> wrote:

  

  



 --> RV6-List message posted by: "Ralph E. Capen" <recapen(at)earthlink.net (recapen(at)earthlink.net)>



In addition to torqueing the big nut as others have suggested, I also balanced my nosewheel pant.





--

_________________
Titan Tornado II with Jab 3300

djtoddb

Joined: 26 Mar 2010
Posts: 14
Location: Mesa, AZ

Posted: Thu Aug 13, 2015 5:49 am Post subject: Re: RV-6A Nose Wheel Shimmy

How do you balance the the nose wheel Pant??? Fore and aft of the nose wheel "axel"  or from some other reference point??

_________________
Titan Tornado II with Jab 3300

recapen(at)earthlink.net
Guest

Posted: Thu Aug 13, 2015 6:02 am Post subject: RV-6A Nose Wheel Shimmy

To multiple requestors,



Here's what I did to balance the nosewheel pant...:



Using the nosewheel axel holes in the wheel pant as the balance point, I determined approximately how much weight was required to balance.

Essentially, lead shot in a ziplock bag taped to the front of the nosewheel pant 'cone'.  I actually used a little less than what was in the bag as there was epoxy to bind it inside the 'cone'.  Roughed up the inside of the 'cone' with sandpaper, mixed a small batch of epoxy, poured the lead shot in to the epoxy and stirred it up well.  The epoxy/shot mixture was then poured in to the 'cone' and covered with two layers of BID glass cloth.  When that cured, I re-tested the balance (which came out almost perfect so I left it) and reinstalled.



Ralph Capen





--

BSchroeder(at)rideuta.com
Guest

Posted: Thu Aug 13, 2015 6:20 am Post subject: RV-6A Nose Wheel Shimmy

Ok, but how do you balance a wheel pant and what is the purpose?



--

langpe(at)comcast.net
Guest

Posted: Thu Aug 13, 2015 6:49 am Post subject: RV-6A Nose Wheel Shimmy

The first thing to look at is the tire pressure. It should not exceed 30 psi or it is likely to shimmy. Start at 28 psi. It requires the additional friction of the lower pressure. Next, check to be sure it is lubricated correctly at the fitting. Next check to be sure the breakout tension is set to spec.



PDL



Sent from my iPad



 	  Quote: 	
		   On Aug 13, 2015, at 1:49 AM, Tom & Marilyn Law <tlaw(at)northwestel.net> wrote:

 

 

 

 Could be a tire balance issue or excessive speed that starts the shimmy.  

 

 When new (2005) my RV-6A did it and I torqued the big nut up a little

 tighter and the past 200 hours have been trouble free.

 

 Tom Law

 RV6A   C-GNJI

 Canada

 

 From: owner-rv6-list-server(at)matronics.com

 [mailto:owner-rv6-list-server(at)matronics.com] On Behalf Of djtoddb

 Sent: August-12-15 6:29 PM

 To: rv6-list(at)matronics.com

 Subject: RV-6A Nose Wheel Shimmy

 

 

 

 Has anyone have experience in dealing with the Nose Wheel Shimmy on a RV-6A?

 What are the causes and remedies?

 

 --------

 Titan Tornado II with Jab 3300

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=445867#445867

allen(at)checca.net
Guest

Posted: Thu Aug 13, 2015 6:50 am Post subject: RV-6A Nose Wheel Shimmy

Where in the plans does it say that is necessary?



Rv 6a 1050 hrs.



Sent from my iPad



 	  Quote: 	
		   On Aug 13, 2015, at 8:49 AM, djtoddb <djtoddb(at)yahoo.com> wrote:

 

 

 

 How do you balance the the nose wheel Pant??? Fore and aft of the nose wheel "axel"  or from some other reference point??

 

 --------

 Titan Tornado II with Jab 3300

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=445877#445877

allen(at)checca.net
Guest

Posted: Thu Aug 13, 2015 6:52 am Post subject: RV-6A Nose Wheel Shimmy

Check breakout torque and set it at factory setting.



Sent from my iPad



 	  Quote: 	
		   On Aug 12, 2015, at 8:29 PM, djtoddb <djtoddb(at)yahoo.com> wrote:

 

 

 

 Has anyone have experience in dealing with the Nose Wheel Shimmy on a RV-6A? What are the causes and remedies?

 

 --------

 Titan Tornado II with Jab 3300

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=445867#445867

allen(at)checca.net
Guest

Posted: Thu Aug 13, 2015 7:00 am Post subject: RV-6A Nose Wheel Shimmy

Try 45 psi in the nose tire. We installed the anti splat nose wheel bearing mod and had them balance the tire, I was acceptable before but even better now.



Sent from my iPad



 	  Quote: 	
		   On Aug 12, 2015, at 8:29 PM, djtoddb <djtoddb(at)yahoo.com> wrote:

 

 

 

 Has anyone have experience in dealing with the Nose Wheel Shimmy on a RV-6A? What are the causes and remedies?

 

 --------

 Titan Tornado II with Jab 3300

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=445867#445867

recapen(at)earthlink.net
Guest

Posted: Thu Aug 13, 2015 7:04 am Post subject: RV-6A Nose Wheel Shimmy

No requirement listed in the plans.  I am using a SamJames mainwheel pant as a nosewheel pant since I am also using a larger tire and fork up front.  

I operate primarily from a grass strip which is not as good as it could be.



I found that my nosewheel pant brackets were cracked - along with experiencing wheel shimmy.



Research in the archives showed others that had balanced their wheelpants fore and aft.



After balancing the nosewheel pant - both the shimmy and bracket cracking have gone...knock wood....





--

BSchroeder(at)rideuta.com
Guest

Posted: Thu Aug 13, 2015 7:28 am Post subject: RV-6A Nose Wheel Shimmy

So where is the balance point. At the axle shaft? I'm just trying to understand the logic



--

recapen(at)earthlink.net
Guest

Posted: Thu Aug 13, 2015 7:40 am Post subject: RV-6A Nose Wheel Shimmy

I did mine at the axle shaft as I was finding my brackets cracked both fore and aft of the axle.....



--

BSchroeder(at)rideuta.com
Guest

Posted: Thu Aug 13, 2015 7:51 am Post subject: RV-6A Nose Wheel Shimmy

Can I ask how many hours you had before you noticed the cracks and how many since your repair?



--

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Thu Aug 13, 2015 9:29 am Post subject: RV-6A Nose Wheel Shimmy

Ralph & Flock,



The shimmy is not caused by the wheel pant.Â  I'm sorry that I missed the origional post, the issue is vert easy to fix, here are the steps and why:

Their are two types of shimmy...

Â a) The wheel spins freely on the axel.Â  A free spinning wheel will have a shimmy/vibration that continues after the nose wheel is lifted off the ground.Â  The FIX is to tighten the nut on the axel so when you spin the tire with moderate handÂ force you get ONLY one revolution of the tire.Â 

b) Nose fork shimmy, this is caused when the castle nut on the bottom of the nose wheel fork is too loose.Â  This shimmy will disappear as soon as the nose wheel is lifted off the ground.Â  So, how tight should it be?Â  Enough to require 20 to 25 pounds of pull AT THE AXEL to move the fork.Â  How do youÂ measure this force?Â  Use a simple Fish Scale.Â  To get this torque you should have 4 ea, cup washers under the nut... Â 2 facing down and 2 facing up, example: (( )).Â  Grease the nose fork spindleÂ and the washers.Â  Any "extream pressure" marine grease will work fine.Â 

Ralph, sorry you added extra weight to your plane, especially at the nose.Â  Their is no up & down pivoting of the nose pant as it is secured at two points: 1- The axel. Â 2- Where the nose strut passes through the pant.Â  You did seal up the hole with a rubber gasket that cuts down on drag and keeps rain and snow out? Â 

On a side note: The RV is based on a Grumman AA5x design.Â  GrummanÂ went through this same problem and they added weight to the nose of the pant also.Â  It took them a few years to learn how to fixÂ the problem.

Barry

Grumman AA5 and RV6/A pilot



On Thursday, August 13, 2015, Ralph E. Capen <recapen(at)earthlink.net (recapen(at)earthlink.net)> wrote:

[quote]--> RV6-List message posted by: "Ralph E. Capen" <[url=javascript:;]recapen(at)earthlink.net[/url]>

 

 

 To multiple requestors,

 

 Here's what I did to balance the nosewheel pant...:

 

 Using the nosewheel axel holes in the wheel pant as the balance point, I determined approximately how much weight was required to balance.

 Essentially, lead shot in a ziplock bag taped to the front of the nosewheel pant 'cone'.Â  I actually used a little less than what was in the bag as there was epoxy to bind it inside the 'cone'.Â  Roughed up the inside of the 'cone' with sandpaper, mixed a small batch of epoxy, poured the lead shot in to the epoxy and stirred it up well.Â  The epoxy/shot mixture was then poured in to the 'cone' and covered with two layers of BID glass cloth.Â  When that cured, I re-tested the balance (which came out almost perfect so I left it) and reinstalled.

 

 Ralph Capen

 

 

 

 

 --

recapen(at)earthlink.net
Guest

Posted: Thu Aug 13, 2015 10:02 am Post subject: RV-6A Nose Wheel Shimmy

Understood about cause and effect.



I think in my case the longer aft end of  SamJames mainwheel pant was the cause of my brackets breaking - not the shimmy....so the pant balance is for a different reason.

I too had tightened up the main nut on the fork...and haven't had any noticeable shimmy since - thanks for the info on the spinning wheel - I'll look at that one too.



I have a plate in the back of the pant to keep stuff from building up - and plugs for the axel holes.....



Good info - thanks again! 

--

BSchroeder(at)rideuta.com
Guest

Posted: Thu Aug 13, 2015 10:35 am Post subject: RV-6A Nose Wheel Shimmy

Thank you for the explanation. Just to be clear, it is not necessary to â€œbalanceâ€ the nose wheel pant? 

From: owner-rv6-list-server(at)matronics.com [mailto:owner-rv6-list-server(at)matronics.com] On Behalf Of FLYaDIVE

 Sent: Thursday, August 13, 2015 11:29 AM

 To: rv6-list(at)matronics.com

 Subject: Re: RV6-List: Re: RV-6A Nose Wheel Shimmy 

Ralph & Flock,  

The shimmy is not caused by the wheel pant.  I'm sorry that I missed the origional post, the issue is vert easy to fix, here are the steps and why: 

Their are two types of shimmy... 

 a) The wheel spins freely on the axel.  A free spinning wheel will have a shimmy/vibration that continues after the nose wheel is lifted off the ground.  The FIX is to tighten the nut on the axel so when you spin the tire with moderate  hand force you get ONLY one revolution of the tire.  

b) Nose fork shimmy, this is caused when the castle nut on the bottom of the nose wheel fork is too loose.  This shimmy will disappear as soon as the nose wheel is lifted off the ground.  So, how tight should it be?  Enough to require 20  to 25 pounds of pull AT THE AXEL to move the fork.  How do you measure this force?  Use a simple Fish Scale.  To get this torque you should have 4 ea, cup washers under the nut...  2 facing down and 2 facing up, example: (( )).  Grease the nose fork spindle and  the washers.  Any "extream pressure" marine grease will work fine.  

Ralph, sorry you added extra weight to your plane, especially at the nose.  Their is no up & down pivoting of the nose pant as it is secured at two points: 1- The axel.  2- Where the nose strut passes through the pant.  You did seal up  the hole with a rubber gasket that cuts down on drag and keeps rain and snow out?   

On a side note: The RV is based on a Grumman AA5x design.  Grumman went through this same problem and they added weight to the nose of the pant also.  It took them a few years to learn how to fix the problem. 

Barry 

Grumman AA5 and RV6/A pilot

 On Thursday, August 13, 2015, Ralph E. Capen <recapen(at)earthlink.net (recapen(at)earthlink.net)> wrote: [quote] 

--> RV6-List message posted by: "Ralph E. Capen" <[url=javascript:;]recapen(at)earthlink.net[/url]>

 To multiple requestors,

 Here's what I did to balance the nosewheel pant...:

 Using the nosewheel axel holes in the wheel pant as the balance point, I determined approximately how much weight was required to balance.

 Essentially, lead shot in a ziplock bag taped to the front of the nosewheel pant 'cone'.  I actually used a little less than what was in the bag as there was epoxy to bind it inside the 'cone'.  Roughed up the inside of the 'cone' with sandpaper, mixed a small  batch of epoxy, poured the lead shot in to the epoxy and stirred it up well.  The epoxy/shot mixture was then poured in to the 'cone' and covered with two layers of BID glass cloth.  When that cured, I re-tested the balance (which came out almost perfect so  I left it) and reinstalled.

 Ralph Capen

 --

BARRY CHECK 6

Joined: 15 Mar 2011
Posts: 738

Posted: Thu Aug 13, 2015 12:03 pm Post subject: RV-6A Nose Wheel Shimmy

Correct!  Balancing of the wheel pant is not required.

Correct the tension on the axel and the fork and shimmy and vibration will

disappear.

But, just to muddy the waters...  A little...

For speed reasions, the length, trailing end of a structure should be 7

times the width.  Example:  If the widest part of a wheel pant is 6" than

the taper should be (6 x 7 = 42) ...  42" back from that point.  Well, you

can see it is not very practical to have wheel pants that long.  Of course

this 7 factor is for the perfect translation.  Which is not very practical.

Part two:  Keeping mud, dirt, water, snow AND air out of the aft end of a

wheel pant will eliminate out of ballance conditions and give more speed.

These are known as Pressure Recovery Pants. The easiest way i know to do

this is to reduce the volume of the wheel pant.  This is done by blocking

off the forward and aft areas of the pant and keeping the area around the

tire small.



Using the above information, use either fiberglass or rubber on the

backside of the nose strut to reduce the drag.



Another side note:  A round object in an air stream has TWICE the drag as a

square object of the same frontal area.



Barry



On Thursday, August 13, 2015, Schroeder, Bob (Parts Clerk) <

BSchroeder(at)rideuta.com> wrote:



[quote] Thank you for the explanation. Just to be clear, it is not necessary to

 â€œbalanceâ€ the nose wheel pant?



 *From:* owner-rv6-list-server(at)matronics.com

 <javascript:_e(%7B%7D,'cvml','owner-rv6-list-server(at)matronics.com');>

 [mailto:owner-rv6-list-server(at)matronics.com

 <javascript:_e(%7B%7D,'cvml','owner-rv6-list-server(at)matronics.com');>] *On

 Behalf Of *FLYaDIVE

 *Sent:* Thursday, August 13, 2015 11:29 AM

 *To:* rv6-list(at)matronics.com

 <javascript:_e(%7B%7D,'cvml','rv6-list(at)matronics.com');>

 *Subject:* Re: Re: RV-6A Nose Wheel Shimmy



 Ralph & Flock,



 The shimmy is not caused by the wheel pant.  I'm sorry that I missed the

 origional post, the issue is vert easy to fix, here are the steps and why:



 Their are two types of shimmy...



  a) The wheel spins freely on the axel.  A free spinning wheel will have a

 shimmy/vibration that continues after the nose wheel is lifted off the

 ground.  The FIX is to tighten the nut on the axel so when you spin the

 tire with moderate hand force you get ONLY one revolution of the tire.



 b) Nose fork shimmy, this is caused when the castle nut on the bottom of

 the nose wheel fork is too loose.  This shimmy will disappear as soon as

 the nose wheel is lifted off the ground.  So, how tight should it be?

 Enough to require 20 to 25 pounds of pull AT THE AXEL to move the fork.

 How do you measure this force?  Use a simple Fish Scale.  To get this

 torque you should have 4 ea, cup washers under the nut...  2 facing down

 and 2 facing up, example: (( )).  Grease the nose fork spindle and the

 washers.  Any "extream pressure" marine grease will work fine.



 Ralph, sorry you added extra weight to your plane, especially at the

 nose.  Their is no up & down pivoting of the nose pant as it is secured at

 two points: 1- The axel.  2- Where the nose strut passes through the pant

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