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fastpilotrv8
Joined: 28 Dec 2006
Posts: 21
Location: Chicago Area
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 Posted: Mon Nov 05, 2012 3:07 pm Post subject: Landing Gear Shimmy on RV8a |
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I on my 2002 RV8a has had the landing gear shimmy has gotten much worse in the last 6 flights . I am running 45 lbs air , no flats spots . The mains are really shaking a lot. anyone with Ideas please watch the video on You Tube and please give me your Ideas
http://www.youtube.com/watch?v=_HrcTKt3zBc
my email is fastpilotrv8(at)aol.com
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Painless
Joined: 10 Jan 2006
Posts: 40
Location: Peshtigo, Wisconsin
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| Posted: Mon Nov 05, 2012 3:54 pm Post subject: Landing Gear Shimmy on RV8a |
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How often are you needing to replace the tires? What type/ manufacturer of tires are you using now?
I had a similar, but not as severe shimmy in one main gear leg on my 6A. Replacing the worn original kit tires with a set of Monster retreads from Desser Tires solved the problem completely. I was amazed at the difference.
Jeff Orear
RV6A. N783P
Peshtigo, WI
Sent from my iPad
On Nov 5, 2012, at 5:07 PM, "fastpilotrv8" <fastpilotrv8(at)aol.com> wrote:
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Jeff Orear
RV6A N782P
Peshtigo, WI |
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bob194bn(at)verizon.net
Guest
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| Posted: Mon Nov 05, 2012 3:57 pm Post subject: Landing Gear Shimmy on RV8a |
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What is the tire wear like on mains ?
Just a thought looks like might have toe out .tire pulls and then snaps back .
Was it at all possible that mains might not of been indexed for positive track when plane was built/left right.
Bob Watson
N194BN 9-A
From: fastpilotrv8 <fastpilotrv8(at)aol.com>
To: rv-list(at)matronics.com
Sent: Monday, November 5, 2012 3:07 PM
Subject: Landing Gear Shimmy on RV8a
--> RV-List message posted by: "fastpilotrv8" <fastpilotrv8(at)aol.com (fastpilotrv8(at)aol.com)>
I on my 2002 RV8a has had the landing gear shimmy has gotten much worse in the last 6 flights . I am running 45 lbs air , no flats spots . The mains are really shaking a lot. anyone with Ideas please watch the video on You Tube and please give me your Ideas
http://www.youtube.com/watch?v=_HrcTKt3zBc
my email is fastpilotrv8(at)aol.com (fastpilotrv8(at)aol.com)
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=386965#386965
= (And Get Some eroElectric httpre http://www.bp://www.homebuilthelp.com/" target="_blank">http://www.homebuilthelp.com/p; -Matt Dralle, List bsp; -->
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robin(at)PaintTheWeb.com
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| Posted: Mon Nov 05, 2012 4:01 pm Post subject: Landing Gear Shimmy on RV8a |
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Ok, I hate to take you way off the reservation here but Vans miss-shipped some RV-8A kits with RV-9A gear legs. Ask me how I know? I purchased a partially built kit from about your era (Builder # 80721) and it shipped with the 9A legs. We knew something was not right when we tried to align the wheels. This was most obvious when pushing backwards. The only reason I of know this is the same thing happened to at least 2 other 8A builders that contacted me through the list. We cleaned up the legs and returned them to Vans for a free replacement ~8+ years later. (Thank you Vans!). At least one flew several hours before discovering the issue. Mine would not push backwards more than a few feet w/o skipping so I have no idea one can push in/out the plane in this configuration. Now this is pretty unlikely to be your issue and I am sure that others will chime in on the shimmy problem. Just wanted to let you know of the gear leg issue just in case.
Robin
--
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craigtxtx(at)yahoo.com
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| Posted: Mon Nov 05, 2012 5:04 pm Post subject: Landing Gear Shimmy on RV8a |
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I had a significant decrease in vibration after balancing the wheels.
Craig Gallenbach
RV8A N184CG 260 hrs
Sent from my iPad
On Nov 5, 2012, at 6:07 PM, "fastpilotrv8" <fastpilotrv8(at)aol.com> wrote:
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chasb(at)satx.rr.com
Guest
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| Posted: Tue Nov 06, 2012 12:55 am Post subject: Landing Gear Shimmy on RV8a |
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I had similar shimmy problems on my 6A. I tried balancing the tires with little or no help. Van's answer was to reduce the tire pressure. As I remember, Van's recommendation was about 20 psi. My shimmy stopped at 25 psi and I have used that ever since. I have found that lower to higher ambient temperature will change the tire pressure enough that the shimmy will sometimes return. Likewise, my 25 psi flatland tire pressure didn't work in Denver, and lowering the tire pressure to less than 20 psi solved that.
Another possible cause is the axle nut(s) being too tight. Make sure all the tires will spin freely with the airplane jacked up. I had that problem with the nose gear which caused the nose gear to bounce vertically on landing. Basically, the axle was too tight due to the design, and the tire wouldn't freely rotate more than 1/2 turn. I went to a Grove wheel and axle and that solved that problem.
Charlie Brame
RV-6A N11CB
San Antonio
-----------------------------------------------------------
[quote]Time: 03:08:03 PM PST US
Subject: Landing Gear Shimmy on RV8a
From: "fastpilotrv8" <fastpilotrv8(at)aol.com (fastpilotrv8(at)aol.com)>
I on my 2002 RV8a has had the landing gear shimmy has gotten much worse in the
last 6 flights . I am running 45 lbs air , no flats spots . The mains are really
shaking a lot. anyone with Ideas please watch the video on You Tube and
please give me your Ideas
http://www.youtube.com/watch?v=_HrcTKt3zBc
my email is fastpilotrv8(at)aol.com (fastpilotrv8(at)aol.com)
[b]
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Hopperdhh(at)aol.com
Guest
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| Posted: Tue Nov 06, 2012 3:49 am Post subject: Landing Gear Shimmy on RV8a |
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Hi ??,
The nose wheel looks to have low tire pressure but does not shake. Could it be the mains have too much pressure? I run about 38 to start with in my RV7A (200 HP) mains. By the time I add air they're usually down to about 32. I've been told they shake a lot though.
What changed in the last 6 flights? Do the wheels turn free, or are the bearings too loose? Maybe clean up the bearings and look for signs of corrosion, etc. Could it be that it has always done this and you just became aware of it? Look at the brakes,too. Could they be getting into the act somehow?
Back to the nose wheel. I have the AntiSplat gear leg brace, and now run 50 PSI in the nose tire. Only have a few hours since putting it on. So far, so good!
Just some ideas.
Dan Hopper
N766DH
In a message dated 11/5/2012 6:08:35 P.M. Eastern Standard Time, fastpilotrv8(at)aol.com writes:
[quote][b]
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mr.sun
Joined: 30 Jan 2007
Posts: 85
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| Posted: Tue Nov 06, 2012 6:56 am Post subject: Landing Gear Shimmy on RV8a |
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My thought when I saw your video was that something is loose. Did you jack it up and really wiggle everything good? I run 35-37 psI and have a small amount of shimmy sometimes when increasing taxi speed. If I touch the brakes, it goes away and all is well.
I found that lower pressure helps my landings, eliminates shimmy but rubs on the wheel pants on touchdown. Rubbing on the sidewalls of my expensive Michelin tires bothered me.
How do you attach your camera to the wing? I see the suction cups for the GoPro camera but just don't trust that. Do you back out a few screws from the wing and screw down a mounting plate?
Greg
do not archive
On Tue, Nov 6, 2012 at 12:54 AM, Charles Brame <chasb(at)satx.rr.com (chasb(at)satx.rr.com)> wrote:
[quote]I had similar shimmy problems on my 6A. I tried balancing the tires with little or no help. Van's answer was to reduce the tire pressure. As I remember, Van's recommendation was about 20 psi. My shimmy stopped at 25 psi and I have used that ever since. I have found that lower to higher ambient temperature will change the tire pressure enough that the shimmy will sometimes return. Likewise, my 25 psi flatland tire pressure didn't work in Denver, and lowering the tire pressure to less than 20 psi solved that.
Another possible cause is the axle nut(s) being too tight. Make sure all the tires will spin freely with the airplane jacked up. I had that problem with the nose gear which caused the nose gear to bounce vertically on landing. Basically, the axle was too tight due to the design, and the tire wouldn't freely rotate more than 1/2 turn. I went to a Grove wheel and axle and that solved that problem.
Charlie Brame
RV-6A N11CB
San Antonio
-----------------------------------------------------------
| Quote: | Time: 03:08:03 PM PST US
Subject: Landing Gear Shimmy on RV8a
From: "fastpilotrv8" <fastpilotrv8(at)aol.com (fastpilotrv8(at)aol.com)>
I on my 2002 RV8a has had the landing gear shimmy has gotten much worse in the
last 6 flights . I am running 45 lbs air , no flats spots . The mains are really
shaking a lot. anyone with Ideas please watch the video on You Tube and
please give me your Ideas
http://www.youtube.com/watch?v=_HrcTKt3zBc
my email is fastpilotrv8(at)aol.com (fastpilotrv8(at)aol.com)
_blank">www.aeroelectric.com
.com" target="_blank">www.buildersbooks.com
="_blank">www.homebuilthelp.com
_blank">http://www.matronics.com/contribution
t="_blank">http://www.matronics.com/Navigator?RV-List
tp://forums.matronics.com
|
[b]
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Greg RV-7 |
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chaskuss(at)yahoo.com
Guest
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| Posted: Tue Nov 06, 2012 6:58 am Post subject: Landing Gear Shimmy on RV8a |
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Robin,
Is there a way to visually determine if you have the 9A legs? How do they differ from the 8A units?
Charlie
--- On Mon, 11/5/12, Robin Marks <robin(at)painttheweb.com> wrote:
[quote]
From: Robin Marks <robin(at)painttheweb.com>
Subject: RE: Landing Gear Shimmy on RV8a
To: "rv-list(at)matronics.com" <rv-list(at)matronics.com>
Date: Monday, November 5, 2012, 7:00 PM
--> RV-List message posted by: Robin Marks <[url=/mc/compose?to=robin(at)painttheweb.com]robin(at)painttheweb.com[/url]>
Ok, I hate to take you way off the reservation here but Vans miss-shipped some RV-8A kits with RV-9A gear legs. Ask me how I know? I purchased a partially built kit from about your era (Builder # 80721) and it shipped with the 9A legs. We knew something was not right when we tried to align the wheels. This was most obvious when pushing backwards. The only reason I of know this is the same thing happened to at least 2 other 8A builders that contacted me through the list. We cleaned up the legs and returned them to Vans for a free replacement ~8+ years later. (Thank you Vans!). At least one flew several hours before discovering the issue. Mine would not push backwards more than a few feet w/o skipping so I have no idea one can push in/out the plane in this configuration. Now this is pretty unlikely to be your issue and I am sure that others will chime in on the shimmy problem. Just wanted to let you know of the gear leg issue just in case.
Robin
--
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
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robin(at)PaintTheWeb.com
Guest
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| Posted: Tue Nov 06, 2012 7:16 am Post subject: Landing Gear Shimmy on RV8a |
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I don’t know if you can tell visually but they will be a touch "toe in" and when rolling the plane in reverse they will splay a bit and then skip. It seemed to roll forward more normally then it would when pushed in reverse. The alignment was not immediately obvious (just a few degrees) but the reverse push test made the misalignment obvious.
Good luck,
Robin
From: owner-rv-list-server(at)matronics.com [mailto:owner-rv-list-server(at)matronics.com] On Behalf Of Charles Kuss
Sent: Tuesday, November 06, 2012 6:59 AM
To: rv-list(at)matronics.com
Subject: RE: Landing Gear Shimmy on RV8a
Robin,
Is there a way to visually determine if you have the 9A legs? How do they differ from the 8A units?
Charlie
--- On Mon, 11/5/12, Robin Marks <robin(at)painttheweb.com (robin(at)painttheweb.com)> wrote:
From: Robin Marks <robin(at)painttheweb.com (robin(at)painttheweb.com)>
Subject: RE: Landing Gear Shimmy on RV8a
To: "rv-list(at)matronics.com (rv-list(at)matronics.com)" <rv-list(at)matronics.com (rv-list(at)matronics.com)>
Date: Monday, November 5, 2012, 7:00 PM
--> RV-List message posted by: Robin Marks <[url=/mc/compose?to=robin(at)painttheweb.com]robin(at)painttheweb.com[/url]>
Ok, I hate to take you way off the reservation here but Vans miss-shipped some RV-8A kits with RV-9A gear legs. Ask me how I know? I purchased a partially built kit from about your era (Builder # 80721) and it shipped with the 9A legs. We knew something was not right when we tried to align the wheels. This was most obvious when pushing backwards. The only reason I of know this is the same thing happened to at least 2 other 8A builders that contacted me through the list. We cleaned up the legs and returned them to Vans for a free replacement ~8+ years later. (Thank you Vans!). At least one flew several hours before discovering the issue. Mine would not push backwards more than a few feet w/o skipping so I have no idea one can push in/out the plane in this configuration. Now this is pretty unlikely to be your issue and I am sure that others will chime in on the shimmy problem. Just wanted to let you know of the gear leg issue just in case.
Robin
--
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dcw(at)mnwing.org
Guest
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| Posted: Tue Nov 06, 2012 1:31 pm Post subject: Landing Gear Shimmy on RV8a |
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I'd try two things. Bring the tire pressure down to about 30 psi. If
that doesn't work I'd change the brand of tires. I had similar issues
with my first RV-4 and this process worked.
Doug Weiler
RV-4 finished and flying
RV-7 finished and flying
On 11/5/2012 5:07 PM, fastpilotrv8 wrote:
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ianxbrown
Joined: 16 May 2009
Posts: 80
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| Posted: Wed Nov 07, 2012 5:02 am Post subject: Landing Gear Shimmy on RV8A |
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Looking at your video, that very slight hesitation at the beginning, I'd say
your bearings are too tight. Compare with the nose wheel video at
http://www.eaa538.org/images/nosegear.wmv
Ian Brown
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robin(at)PaintTheWeb.com
Guest
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| Posted: Wed Nov 07, 2012 7:53 am Post subject: Landing Gear Shimmy on RV8a |
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Greg, as far as mounting camera I use the suction mount plus safety wire to screws with a sandwich of washers to protect paint. So far suction has held well.
Robin
Sent from the new iPad
On Nov 7, 2012, at 7:49 AM, "mr.gsun(at)gmail.com (mr.gsun(at)gmail.com)" <mr.gsun(at)gmail.com (mr.gsun(at)gmail.com)> wrote:
[quote] My thought when I saw your video was that something is loose. Did you jack it up and really wiggle everything good? I run 35-37 psI and have a small amount of shimmy sometimes when increasing taxi speed. If I touch the brakes, it goes away and all is well.
I found that lower pressure helps my landings, eliminates shimmy but rubs on the wheel pants on touchdown. Rubbing on the sidewalls of my expensive Michelin tires bothered me.
How do you attach your camera to the wing? I see the suction cups for the GoPro camera but just don't trust that. Do you back out a few screws from the wing and screw down a mounting plate?
Greg
do not archive
On Tue, Nov 6, 2012 at 12:54 AM, Charles Brame <chasb(at)satx.rr.com (chasb(at)satx.rr.com)> wrote:
| Quote: | I had similar shimmy problems on my 6A. I tried balancing the tires with little or no help. Van's answer was to reduce the tire pressure. As I remember, Van's recommendation was about 20 psi. My shimmy stopped at 25 psi and I have used that ever since. I have found that lower to higher ambient temperature will change the tire pressure enough that the shimmy will sometimes return. Likewise, my 25 psi flatland tire pressure didn't work in Denver, and lowering the tire pressure to less than 20 psi solved that.
Another possible cause is the axle nut(s) being too tight. Make sure all the tires will spin freely with the airplane jacked up. I had that problem with the nose gear which caused the nose gear to bounce vertically on landing. Basically, the axle was too tight due to the design, and the tire wouldn't freely rotate more than 1/2 turn. I went to a Grove wheel and axle and that solved that problem.
Charlie Brame
RV-6A N11CB
San Antonio
-----------------------------------------------------------
ectric.com
">www.buildersbooks.com
builthelp.com
.matronics.com/contribution
//www.matronics.com/Navigator?RV-List
ics.com
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[b]
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ianxbrown
Joined: 16 May 2009
Posts: 80
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| Posted: Wed Jun 05, 2013 6:19 am Post subject: Re: Landing Gear Shimmy on RV8a |
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I'm interested whether you fixed your shimmy or not. I'd suggested tight wheel bearings. All other suggestions are really excluded by your case history. Got worse without changing gear legs, tire pressures or without having flat spots, etc.
The conical bearings have a capability of tightening up, or not turning freely. Did this start after a re-lube of the bearings? The wheels really have to turn freely. One other thought on the mains, brake pads binding?
I'm a believer in AntiSplat Aero's wheel bearing mod, and perhaps their balancing.
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sarg314(at)gmail.com
Guest
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| Posted: Wed Jun 05, 2013 6:57 am Post subject: Landing Gear Shimmy on RV8a |
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On my 6A, reducing the nose wheel tire pressure helped a lot.
--
Tom Sargent
[quote][b]
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Hopperdhh(at)aol.com
Guest
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| Posted: Wed Jun 05, 2013 7:42 am Post subject: Landing Gear Shimmy on RV8a |
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Something definitely needs to be done to improve the nose wheel axle arrangement on the RVs.
I made a spacer so that I could tighten the axle bolt without causing the bearings to feel the added pressure. It takes a few tries to get it just right, but when you do the wheel should turn as free as with ball bearings. The spacer makes the system much more stable.
I made my spacer out of steel about 3/4 inch diameter. With the wheel off the plane you can measure between the outsides of the aluminum adapter hubs and then subtract their combined thickness for a first try at the spacer length. Start a few thousandths of an inch too long and the wheel bearings will be too loose. Face off a couple of thousandths and try again until its just right -- just a little or no play.
There is nothing wrong with the AntiSplat ball bearing mod if you want to spend the money. I'm poor!
Dan Hopper
RV-7A 766DH Flying since 2004 -- only nosed it over once! That (and seeing the result of a couple of other accidents) made me a believer in the anti-splat gear leg brace. Great invention! Be sure to watch the videos on their web site.
In a message dated 6/5/2013 10:21:04 A.M. Eastern Daylight Time, ixb(at)videotron.ca writes:
| Quote: | --> RV-List message posted by: "ianxbrown" <ixb(at)videotron.ca>
I'm interested whether you fixed your shimmy or not. I'd suggested tight wheel bearings. All other suggestions are really excluded by your case history. Got worse without changing gear legs, tire pressures or without having flat spots, etc.
The conical bearings have a capability of tightening up, or not turning freely. Did this start after a re-lube of the bearings? The wheels really have to turn freely. One other thought on the mains, brake pads binding?
I'm a believer in AntiSplat Aero's wheel bearing mod, and perhaps their balancing.
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=402069#402069
|
[quote][b]
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