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Serious Front Axle Maintenance Issue on the RV-10
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rvbuilder(at)sausen.net
Guest

Posted: Fri Aug 11, 2006 5:37 am Post subject: Serious Front Axle Maintenance Issue on the RV-10

I don't think they are saying leave them loose.  What they are saying is

you don't want to crank down taper bearings as you will destroy them at

a much greater rate than normal and cause even more of the slop you are

seeing.  What I think they are missing is that this is a design problem

because the small surface area of the SS bushing is in direct contact

with the aluminum fork.  No matter what you do to make sure the axle

stays SNUG, this WILL eventually ware into the fork without something

else to increase the surface area against the fork.  This could be a cap

or simply a steel washer.



In my opinion you have the right idea Tim, machine down the axle

whatever the thickness of the washers are and put them in with it.



Michael Sausen

RV-10 #352 Buildus Interuptus due to moving

--

Tim(at)MyRV10.com
Guest

Posted: Fri Aug 11, 2006 6:12 am Post subject: Serious Front Axle Maintenance Issue on the RV-10

I just had this exchange off-list that might be nice for

the list.  Michael wasn't thinking of how the bearings

are torqued down, and now he realizes that it's by the

spacer length.   So I'll post my off-list talk here just

for the list's benefit.  (I'm really sorry this is getting

so long, but I think we're all eventually going to learn

and benefit from this discussion).

--------

Ok, I'll leave you with this thought then....



The forks by design will lay right on the axle, a fixed distance.  The

spacers also lay directly against the fork.

With this design, as you tighten it, the outer faces of both the axle

and the spacers will be flush, and flat against the fork.  Therefore

there isn't really any bearing force adjustment possible, because it is

controlled ONLY by the length of the spacers...and it will be perfect

only if the spacers are the perfect length....and it will stay perfect

only if there is no wear.   If one were to only snug the

axle bolt slightly, the center axle itself in theory could be less tight

and not flush with the forks,while the spacers ARE.  That would make a

whole additional problem in that the axle itself could be the part that

easily turns.



There's one thing that sure would make this a much slicker design....to

have the axle made so the center axle can't turn, and then to have a way

to keep the bearings from rotating on the axle...so they only rotate in

the hub.  If that could be done (i.e.

a press-fit, or splined attachment, or something like that) then the

spacers would never spin, and all of this would be a complete non-issue.



This is where Van's really should step in and clarify the torque,

because IMHO, if you're going to just snug that bolt down, you're just

LOOKING for problems.

The design itself is not great....but certain assembly things could

really make it bad.



Think about it a minute, and if you see what I'm saying, maybe I should

move this post to the list.  If you think I'm nuts though, then we

should investigate this further.



Tim Olson - RV-10 N104CD - Flying

RV Builder (Michael Sausen) wrote:

 	  Quote: 	
		   

 

 I don't think they are saying leave them loose.  What they are saying is

 you don't want to crank down taper bearings as you will destroy them at

 a much greater rate than normal and cause even more of the slop you are

 seeing.  What I think they are missing is that this is a design problem

 because the small surface area of the SS bushing is in direct contact

 with the aluminum fork.  No matter what you do to make sure the axle

 stays SNUG, this WILL eventually ware into the fork without something

 else to increase the surface area against the fork.  This could be a cap

 or simply a steel washer.

 

 In my opinion you have the right idea Tim, machine down the axle

 whatever the thickness of the washers are and put them in with it.

 

 Michael Sausen

 RV-10 #352 Buildus Interuptus due to moving

speckter(at)comcast.net
Guest

Posted: Fri Aug 11, 2006 6:27 am Post subject: Serious Front Axle Maintenance Issue on the RV-10

Glastar has this same issue.  The difference is that they use a Cleveland wheel that has seals like the main axels.  They use an aluminum spacer between the fork and the bearing (slipped over the axel) and then a small roll pin in the fork that seats into a small slot on the spacer to stop rotation.

 With the radius on the bearing that we have the only solution is to have a spacer that has the same radius and a large surface area.

 Another thing to try is to have a spacer inside the wheel on the axel so that when you clamp up the whole assembly the inner race of both bearings are clamped between the spacers and thus you can clamp the bearing race tight without preloading the bearing excessively.

 All in all not a great design from Van.

 Gary

 40274

 [quote]-------------- Original message -------------- 

From: Tim Olson <Tim(at)MyRV10.com> 

[quote] --> RV10-List message posted by: Tim Olson 

 Wayne, for what it's worth, I really don't think this will work 

 that way on the RV-10. I may be wrong, but I think you really need 

 to tighten that thing well on this plane or you'll REALLY have problems. 

 I'm betting that the assembly those guys are familiar with isn't the 

 same thing as what we have. If you have any looseness, you're going 

 to really screw up your axle. I just updated that page....scroll 

 to the bottom to read tonights update. I got a little long winded again 

 (surprise surprise), but I explained the axle and rotation and other 

 things in a bit of depth. For you -10 builders, that page is really 

 worth understanding, ju  st so  you can ponder it and know what's going 

 on there....even if you come to some other conclusion. (if you do, 

 let me know...I'd love to hear it, or hear exactly what the mechanics 

 are that George thinks would be better if it were looser) 

 I'll post the text of tonights update here again, but you would be 

 much better served to just read it on the page, and see the latest 

 photos. This is just for the archive's sake. 

 Here's the link again. 

 http://www.myrv10.com/N104CD/maintenance/20060809/index.html 

 --- 

 Today I stopped by a machine shop and had them take off about .115" off 

 my axle, to accomodate 2 AN970-6 washers on the outer edge. Yes, they 

 are .063 each, so .126" would have been the standard, but I wanted the 

 axle to be even just a little more snug than before, because any flexing 

 inward will bring that valve cap closer to the fo  rk. As  a side note, 

 this from John D. today...a note someone sent him: 

 "returned the nosewheel to Matco to have it replaced with WHLNW511.25 

 which is correct for the valve stem on the tube and avoids the clearance 

 problem with the supplies WHLNW501.25." 

 In other words, Van's is sending out the wrong wheel for the application 

 on this plane...because they use this wheel for the RV-7's and such, and 

 didn't want to have to stock 2 parts. So we get to receive the one that 

 isn't made for the application, and therefore unless you swap wheels, 

 you're going to have minimal valve stem clearance.....pretty nice, huh? 

 Anyway, I had the axle cut shorter at a machine shop, and then I just 

 had to guesstimate how much to take off the 2 spacers. Knowing they had 

 worn into a taper on the inside, to fit against the bearing, I had them 

 only cut d  own by  .085" total. I did .035" on one side, and .050" on the 

 other. That way I could have a slightly longer sleeve on the left side, 

 so my valve stem had just that little extra clearance from the fork. 

 This brought forth a small problem... Tonight when I assembled it as in 

 the first photo below, it looked great. VERY much better than original. 

 Then, when I put the whole wheel together, I found that the spacers 

 had worn probably at least .120" because there was tons of slop in the 

 spacers yet, even though they now had a nice flat surface to sit 

 between, and had been cut less than the axle, and the washers were in 

 there to fill in some space. The spacers just spun. So, I decided 

 since I already ordered another axle, I'd take my bandsaw and VERY 

 carefully trim off some more axle, and just use one more washer on the 

 left side. That should keep that valve stem even FURTHER away.   If I < BR>> was right, I could get it so there would be plenty of pressure on the 

 bearings and spacers to hold them in place so they don't spin. Sure 

 enough, it worked just great. I could now torque that bolt down tight 

 and keep the spacers from spinning, and the bearing too. Just to be 

 totally sure they never spun again, I drilled a couple of holes in the 

 stainless spacers, and remounted it all. Then I made a pilot hole in 

 the aluminum axle shaft, and took it all apart and tapped it for an 8-32 

 screw on each spacer. Then I cleaned it up, regreased, and put it all 

 together. Now it is very solid, and should never wear the fork 

 again....I just am left with a crappy fork...so I'll probably just get a 

 new one. Once my new spacers and axle come in, I may tear it all apart 

 and use those pieces, but I'll still probably cut the axle and spacers 

 down and use the washers on the outer   ends.  It will prevent your forks 

 from being the sacrificial component. The bearing, for future 

 reference, is a Timken LM-6700-LA (I think that's right, but I'll 

 re-check tomorrow) 

 A note about tightening the axle nut... Tonight on the RV-10 list, 

 someone said that George Orndorff (A Van's tech center place), says that 

 the bolt should only be snugged, and then rechecked often in the first 

 few hours. I don't personally believe this is true on the RV-10, but 

 perhaps it is on the other models. Here's why. I studied this long 

 and hard, and now I fully understand why this is such a huge freaking 

 issue. It didn't make sense at first, having worked on dozens and 

 dozens of automotive bearings in the past. You see, on automotive apps, 

 the bearings are pressed in on the backside, and a nut and washer holds 

 the bearing tight. But it pushes against a different area of t  he > bearing. And the grease seal is usually a seal that is pressed into the 

 hub, with a seal around the shaft on the ID of the seal. This is NOT 

 how these bearings are on this application. On THIS application, you 

 are expecting that the sleeves, the axle, the bolt, AND the inner race 

 area of the bearing do not ever rotate. The problem is, if these 

 bearings were a tight knurled, or press fit onto that axle shaft, it 

 might be easy to keep them from rotating by just not letting the shaft 

 spin. But, what happens here is that the grease seal is a large seal 

 that the wheel spins around....so the seal is on the OD of the bearing 

 in this case. That's why my stinking seals were so torn when the wheel 

 wobbled. The kicker to the problem is, if you don't have the spacers 

 very tight against the bearing, there's not enough force to keep the 

 bearing from turning on the shaft. If the   beari ng spins on the axle 

 shaft, then it's becoming USELESS as a bearing. At that point, you're 

 using the aluminum axle as the bushing, and the wheel is rolling by 

 spinning the hard steel bearing race against your soft aluminum axle 

 shaft.....instead of turning the roller bearings inside of the wheel's 

 outer race. The seal itself has a lot of drag against the wheel as it 

 spins, and this drag will make it so that the wheel tries REALLY hard to 

 make the bearing spin. As it turns out, if you don't have tight 

 spacers, it's really easy to get that bearing spinning. And once the 

 bearing is spinning, the spacers stuffed right up against it will spin 

 too. And once they start spinning, they'll spin against the fork. If 

 you have the stainless ones like me, they'll ABSOLUTELY then start 

 carving into your forks. If you have the new and improved thick 

 aluminum ones (that I can't   comme nt firmly on because I haven't seen 

 them), then they would have more surface area against both the bearing 

 and the fork....so on one hand the bearing will try to turn it harder, 

 but the fork will prevent it harder as well. To me, this is STILL 

 going to be a less than ideal situation until you PREVENT the spacers 

 from turning, and you PROTECT the forks from being worn if they do turn. 

 The lock screws I put in should keep the spacers still. The washers 

 will protect the forks. The one further improvement that would be 

 simple would be to drill a tiny hole in the fork on one side, that 

 drills into the aluminum axle, and then tap for a small hex head 

 internal setscrew lock, so that you could pin the axle from rotating at 

 all too. Beyond that, the only real improvement I could think of is if 

 you could find a way to either press-fit, or hold that inner bearing 

 from tur  ning o n the axle. Perhaps knurling it, epoxy, a small keyway 

 and shear key, or something like that would be the ticket. If you've 

 done all of the other steps, and have tight spacers, you probably 

 wouldn't have any huge issues from that point. 

 The worst thing about it is that no matter what you do, you really don't 

 have independent control over how tight the bearings are 

 seated...separate from how tight the axle bolts are and how long the 

 spacers are. Just to let you know how this all ends up the way I have 

 it tonight, the wheel will not continue rolling if you spin it by hand. 

 I don't think it's too tight from a bearing perspective, but the 

 grease seals against the wheel hub provide a lot of drag, so they don't 

 let the wheel spin real freely. 

 A couple other tips, while I'm at it. By the time you get to 25 hours 

 on your plane, re-check that large nut   that  holds the fork on. Mine 

 needed to be tightened almost one full flat to the next castle stop, to 

 retorque it after it took it's set. I think the spec is about 24lbs. 

 pull of breakout force to rotate the nose at an angle. 

 The second tip that I can't yet verify is fairing balance. To prevent 

 shimmy, I've heard that a good idea is to balance your fairing. Since I 

 had a little lead shot around, and I wanted this all to be perfect now, 

 tonight I weighed out a little lead and taped it to the nose of the 

 nosewheel fairing. I got it so that I could hold it where it mounts, in 

 the centers of those 4 screw areas, and get it to be about neutrally 

 balanced. Then I just took a little shot away, poured the rest into 

 the nose of the fairing, and mixed a couple of squirts of epoxy. I 

 poured the epoxy into the nose over the shot, put down one layer of 

 cloth, and then a   little  more epoxy. By tomorrow that stuff won't be 

 going anywhere, and I already re-checked the balance and it's now much 

 less tail heavy, so maybe that will improve things too. 

 --- 

 Tim Olson - RV-10 N104CD - 107 hours Flying 

 Wayne Edgerton wrote: 

 > I'm currently building in Justin, TX in George Orndorff's hangar, he's 

 > the one that makes the RV building videos and is also a Van's tech 

 > center, and I was talking to him about this problem, wondering if I 

 > needed to take some type of action on mine. His response to me on this 

 > issue was that this was a quite common occurrence on the RV's. He said 

 > the reason he believes it happens is that when the builder tightens down 

 > the bolt holding on the bushing and tire that they tighten it down too 

 > much. He said I should just tighten it down j  ust un   Downl  BR>&gt

Randy(at)abros.com
Guest

Posted: Fri Aug 11, 2006 8:35 am Post subject: Serious Front Axle Maintenance Issue on the RV-10

If the axle spins you have serious problems. You have to have the yoke

tight enough to hold the axle tight. The extra length of the spacers is

only enough so the bearings have a slight preload. The axle must be

locked by the yoke. As Tim has confirmed the axle was not spinning just

the outer spacer. Randy



--

jjessen

Joined: 22 Apr 2006
Posts: 285
Location: OR

Posted: Fri Aug 11, 2006 9:15 am Post subject: Serious Front Axle Maintenance Issue on the RV-10

There are thousands of production planes with front forks, obviously.  What

do these look like relative to the problem?   This cannot be a unique issue

that hasn't been solved years, decades ago.  



John J

   Tailcone



do not archive



--

wayne.e(at)grandecom.net
Guest

Posted: Sat Aug 12, 2006 3:14 am Post subject: Serious Front Axle Maintenance Issue on the RV-10

Hi Tim,

  

 I talked to Gus at Van's yesterday about this issue0 and since I also have the steel sleeves he will be sending me out the aluminum0 ones. But I did ask him about the tightness issue and he told me I should0 tighten the bolt to about 160 to 190 " lbs and the wheel and if I try and turn0 it by hand it will be a little hard to turn and shouldn't spin0 freely.

  

 Again for what ever that worth

  

 Wayne Edgerton 

  

 #40336

KiloPapa

Joined: 24 May 2006
Posts: 142
Location: Pearblossom, CA

Posted: Tue Aug 15, 2006 9:47 am Post subject: Serious Front Axle Maintenance Issue on the RV-10

_________________
Kevin
40494

do not archive

KiloPapa

Joined: 24 May 2006
Posts: 142
Location: Pearblossom, CA

Posted: Tue Aug 15, 2006 10:11 am Post subject: Serious Front Axle Maintenance Issue on the RV-10

I have attached a pic from the parts manual of the nose wheel and axle of a 

C-182 for reference.



Kevin

40494

tail/empennage



do not archive

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C-182_wheel_&_axle.jpg

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_________________
Kevin
40494

do not archive

Vern(at)teclabsinc.com
Guest

Posted: Tue Aug 22, 2006 2:03 pm Post subject: Serious Front Axle Maintenance Issue on the RV-10

Hi All,



I've lost the email, but someone asked about ship dates of finishing

kits and if they had the aluminum or stainless spacers (part number

U-1032.) I checked and my kit was packed on 2-6-06 and included the

stainless steel spacers.



Vern (#40324)

bcondrey

Joined: 03 Apr 2006
Posts: 580

Posted: Tue Aug 22, 2006 6:49 pm Post subject: Re: Serious Front Axle Maintenance Issue on the RV-10

I just received my new wheel from Matco today and already had the spacers so it was swap time.  After reassembly and torque to standard value (160-190 in lbs) I was dismayed to see the spacers turning with the wheel.  Only way this can happen is that the axle is slighly longer than the wheel/bearing/spacer assembly.  I'm going to call Van's tomorrow to see what they recommend before shaving a bit off the axle or doing another mod like set screws through the fork, etc.  Seems like with some preload they wouldn't be able to turn at all...

Tim(at)MyRV10.com
Guest

Posted: Tue Aug 22, 2006 8:46 pm Post subject: Serious Front Axle Maintenance Issue on the RV-10

That's getting pretty far along in an absolute and complete

contradiction to the "very few kits shipped with" that someone

was told on the phone.  I mean, if you ship kits for a couple

of years, that's just not "very few" anymore.



Tim Olson - RV-10 N104CD - Flying

do not archive

Vern W. Smith wrote:

 	  Quote: 	
		   

 

 Hi All,

 

 I've lost the email, but someone asked about ship dates of finishing

 kits and if they had the aluminum or stainless spacers (part number

 U-1032.) I checked and my kit was packed on 2-6-06 and included the

 stainless steel spacers.

 

 Vern (#40324)

Tim(at)MyRV10.com
Guest

Posted: Tue Aug 22, 2006 8:50 pm Post subject: Serious Front Axle Maintenance Issue on the RV-10

Yeah, and if there's not enough preload to keep the spacers from

spinning, there's probably not enough preload on the bearings to

keep everything as tight as it should be to prevent slop....and

it'll only get worse over time as things wear in.  The axle shaving

thing is scary, but if you're willing to put in the AN970 washers

on the outside, then at least adding washers can make up for some

removed material.



Tim Olson - RV-10 N104CD - Flying

do not archive

bcondrey wrote:

 	  Quote: 	
		   

 <bob.condrey(at)baesystems.com>

 

 I just received my new wheel from Matco today and already had the

 spacers so it was swap time.  After reassembly and torque to standard

 value (160-190 in lbs) I was dismayed to see the spacers turning with

 the wheel.  Only way this can happen is that the axle is slighly

 longer than the wheel/bearing/spacer assembly.  I'm going to call

 Van's tomorrow to see what they recommend before shaving a bit off

 the axle or doing another mod like set screws through the fork, etc.

 Seems like with some preload they wouldn't be able to turn at all...

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=56548#56548

bcondrey

Joined: 03 Apr 2006
Posts: 580

Posted: Wed Aug 23, 2006 6:43 am Post subject: Re: Serious Front Axle Maintenance Issue on the RV-10

I just talked w/Tom at Van's and his suggestion is to check spacing with a feeler gauge and adjust the axle accordingly.  He also said that behavior would be possibly be very different with the wheel off the ground than with full weight on it.



I guess I'll be measuring and adjusting the front axle length tonight...



On related note - what's the best way to jack up the plane for nose wheel work?  I've been using my engine hoist but assume there's another option for "in the field" work.



Bob

wayne.e(at)grandecom.net
Guest

Posted: Thu Aug 24, 2006 3:18 am Post subject: Serious Front Axle Maintenance Issue on the RV-10

Hi Bob - I saw this lift type thing the other day  that might do the trick.

  

 http://www.rvtraining.com/html/handy_jack.html

  

  

 Wayne Edgerton   #40336

   [quote][b]

Ray.R.Doerr(at)sprint.com
Guest

Posted: Mon Aug 28, 2006 6:56 am Post subject: Serious Front Axle Maintenance Issue on the RV-10

I have a ratchet strap around 6 - 50 lbs bags of gravel (300 lbs total) that I connect to the tail tie down.



Thank You

Ray Doerr

CDNI Principal Engineer

Sprint PCS

16020 West 113th Street

Lenexa, KS 66219

Mailstop KSLNXK0101

(913) 859-1414 (Office)

(913) 226-0106 (Pcs)

(913) 859-1234 (Fax)

Ray.R.Doerr(at)sprint.com 

--

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