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Nosewheel bearing question

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czechsix(at)juno.com
Guest

Posted: Mon Mar 20, 2006 9:16 pm Post subject: Nosewheel bearing question

Guys (those of you with a nosedragger),



I still don't have my wheel fairings on.  This weekend during preflight I

noticed some black goo, tar-like stuff oozing out around the rubber

bearing seals on my nosewheel.  It did not appear until I had about a

dozen landings on the airplane.  Since the grease that was in it

originally was the normal amber color I was a bit surprised to see this

color, and also a bit surprised to see it leaking out as it had been

perfectly clean up until this point.  Anybody else seen such a thing?  



I also checked the rolling friction of the tire and it is still REALLY

stiff to turn by hand.  I know that when a wheel is properly installed

there should be enough load on the bearing to provide friction....i.e. it

should not continue to spin around freely after you give it a whirl by

hand.  But from the first time I installed the nosewheel--properly

torqued per the plans with a calibrated wrench--it seemed excessively

stiff to me.  I remember the plans said that it would be this way until

it was broken in a bit.  I don't know how long that should take but I

checked the nosewheel on my hangar mate's new -7A (with fewer hours than

I have) and his wheel turned much easier.  I tried loosening the nut on

the axle bolt and that made it turn more freely but then I noticed that

the spacers were spinning too.  I torqued it back up and now it's

ridiculously stiff again.  My hangar mate's -7A has the wheel pant

installed so I can't see whether the spacers are spinning on his.  I

called Vans and Gus said that it's quite common for people to call and

complain that the spacers have been spinning instead of the bearing and

galling up the fork assembly.  He suggested that I could put some screws

in through the fork into the spacer to keep them from spinning.  This

would allow me to reduce the pressure/friction on the bearings, but he

cautioned against reducing the torque on the axle bolt too much since

Matco calls out 7-10 ft lbs for this assembly.



Personally I think the whole design is a bit iffy from the perspective

that there's a very small margin between having enough pressure to keep

the spacers from turning without so much pressure the that rotational

friction on the bearings/seals is excessive.  It makes me wonder how many

people are flying around out there with the wheel pants on, completely

unaware that the spacers are spinning away while the bearings are doing

nothing.  On the other hand, if the rotational friction is excessive it

*may* have contributed to some of the bent nose gear incidents that have

occurred in recent years.  It's pretty scary watching the nosegear at

high speed, even during a good landing....the more rotational friction,

the further the gear is going to bend back/under when it first makes

contact at high speed.  I think I'll disassemble the whole thing, check

the bearings for overheating, repack them, put screws in through the

fork/spacer assembly, and tighten it up until it feels "about right".



Any comments/experience from others with this assembly would be

appreciated.  FWIW, I understand that the -6A's had a different design

(which some local RVators consider to be superior to the current

design...).



Thanks,



--Mark Navratil

Cedar Rapids, Iowa

RV-8A N2D flying 15.8 hours

Charles Heathco

Joined: 10 Jan 2006
Posts: 201

Posted: Mon Mar 20, 2006 9:41 pm Post subject: Nosewheel bearing question

Mark, I would asume the dark stuff is grease. as for the tightness/spacers 

spinning, I noticed  the spacers spinning problem (I didn build the 6a)When 

I took off the wheel at cond insp. I ended up adding a washer on one side of 

spacer which allowed me to tighten the axel bolt properly without binding 

the wheel. Charlie heathco

---

Hopperdhh(at)aol.com
Guest

Posted: Tue Mar 21, 2006 4:45 am Post subject: Nosewheel bearing question

I had this same problem (spacers turning by the torque of the seals) when I  

first flew my -7A.  At first I was going to put in roll pins like a Cessna  

150, but decided on a different solution which has worked very well.

 

I made a steel sleeve about 3/4 inch OD to put between the bearing spacers  

on the axle bolt inside of the wheel.  Once this sleeve was fine tuned to  the 

correct length, I could tighten the axle bolt to full torque without  actually 

having the bearings support the bolt tension.  To support the  sleeve while 

taking the nose wheel on and off, I have a length of 3/8 inch rod  that gets 

pushed through when installing the axle bolt.  This rod is a  little shorter 

than the distance between the forks.

 

Dan Hopper

RV-7A Flying 148 hours

SSoule(at)pfclaw.com
Guest

Posted: Tue Mar 21, 2006 5:04 am Post subject: Nosewheel bearing question

Dan,



This sounds interesting. What did you use for the stock from which you made

the sleeve? 



Steve Soule 

Vermont 



--

alexpeterson(at)earthlink
Guest

Posted: Tue Mar 21, 2006 5:25 am Post subject: Nosewheel bearing question

 	  Quote: 	
		   

 

 

 Guys (those of you with a nosedragger),

 


	


SNIP



 	  Quote: 	
		   Personally I think the whole design is a bit iffy from the 

 perspective that there's a very small margin between having 

 enough pressure to keep the spacers from turning without so 

 much pressure the that rotational friction on the 

 bearings/seals is excessive.  It makes me wonder how many 

 people are flying around out there with the wheel pants on, 

 completely unaware that the spacers are spinning away while 

 the bearings are doing nothing.  On the other hand, if the 

 rotational friction is excessive it

 *may* have contributed to some of the bent nose gear 

 incidents that have occurred in recent years.  It's pretty 

 scary watching the nosegear at high speed, even during a good 

 landing....the more rotational friction, the further the gear 

 is going to bend back/under when it first makes contact at 

 high speed.  I think I'll disassemble the whole thing, check 

 the bearings for overheating, repack them, put screws in 

 through the fork/spacer assembly, and tighten it up until it 

 feels "about right".

 

 Any comments/experience from others with this assembly would 

 be appreciated.  FWIW, I understand that the -6A's had a 

 different design (which some local RVators consider to be 

 superior to the current design...).

 

 Thanks,

 

 --Mark Navratil

 Cedar Rapids, Iowa

 RV-8A N2D flying 15.8 hours


	


Mark, am I correct in understanding that on the newer (non 6A) nosewheel

designs that the tapered roller bearings take the load from the axle bolt?

If so, this is a terrible design.  The 6A has a stout, hollow aluminum tube

taking the load between the two larger hollow cylinders which directly touch

the fork.  This is as Dan has described that he did on his 7A.  On my 6A, I

could tighten the axle bolt until it breaks, and the wheel bearings will not

be affected.



Please tell me that the new design doesn't simply have the bolt mash the

bearings with nothing in between, although I heard this also from a local

builder.  This simply isn't acceptable. Put a thrust tube in between, and

use some shim stock to tweak it in.  Van makes the best product available,

but sometimes I feel they put more emphasis on hiring people with airplane

building experience and not engineering.



It is easy to imagine bad things happening when things in that assembly

deflect under load...



Alex Peterson

RV6-A N66AP 729 hours

Maple Grove, MN

Hopperdhh(at)aol.com
Guest

Posted: Tue Mar 21, 2006 5:42 am Post subject: Nosewheel bearing question

Steve,

 

The spacer is made of mild steel rod.  Aluminum would be OK, I  think.  

Actually, I had help.  The idea should be credited to a local  craftsman named Carl 

McCain.  He first used the idea on an RV-9A.   From another post I see that 

the 6A used something similar, and that it is good  engineering practice.  Glad 

to see I wasn't flamed right away!

 

Dan

RV-7A

N766DH

 

 

In a message dated 3/21/2006 8:05:02 A.M. Eastern Standard Time,  

SSoule(at)pfclaw.com writes:






Dan,



This sounds interesting. What did  you use for the stock from which you made

the sleeve? 



Steve Soule  

Vermont 



--

Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Tue Mar 21, 2006 8:31 am Post subject: Nosewheel bearing question

Mark, Charlie, Alex & Dan-



I've got the same problem as Mark on my -6A.  Having to leave the nut on the 

axle bolt looser than spec just so the wheel turns has "worked" for almost 300 

hours, but still makes me nervous- grateful for this discussion!  When Mark 

sent the original post, I dragged out dwg. 62 from my preview plans and it 

shows the older style Cleveland wheel- there is a long aluminum "axle" (U-609) 

that is trapped between the fork halves and allows the bolt to be properly 

tightened, and thus no side-load on the bearings.  My nosewheel sounds just like 

Mark's, with the separate spool on each side.  Does anyone have the actual 

drawing (not preview) that shows the current (Matco) configuration and does it show 

a spacer between the two spools?



The way Dan fixed it almost sounds like a no-brainer and would explain a lot, 

but I'm really wondering how many of us "sissies" are out there with a bogus 

nosewheel arrangement because the design was changed and the prints were 

either not updated or wrong? (spacer omitted?)



By the way, I just had to replace my nose tire due to wear (300 hours- does 

this sound a bit soon?), which obviously is accelerated by the tire rotational 

resistance.  I've also been told I have occasional shimmy in my front gear 

which is likely related as well.  Carefully balancing the new wheel did seem to 

help that problem considerably, though...



Mark Phillips

_________________
From The PossumWorks...

Hopperdhh(at)aol.com
Guest

Posted: Tue Mar 21, 2006 8:50 am Post subject: Nosewheel bearing question

Mark,



The shimmy problem is usually due to too free of swivel of the castoring 

nose wheel.  My gear leg had a problem that would lead to abnormal  wear causing

this joint to become loose.  The collar at the top was not  square to the

bearing.  I forget the exact arrangement right now, but I  filed a long time

getting it to meet over the whole area.  Part of the bend  of the gear leg actually

went below the collar -- not a perfect situation!   I have never had a shimmy

problem when the castor nut was tightened to  spec.  High tire pressure would

also aggravate shimmy.  I run about 32  psi.  This seems high but I have the

200 hp angle valve engine.



Dan Hopper

RV-7A Flying 149 hours

In a message dated 3/21/2006 11:34:10 A.M. Eastern Standard Time, 

Fiveonepw(at)aol.com writes:



=04????=1Bmip://02bb2b68/default.html ????=1Bmip://02bb2b68/default.html =20=0E=E4=84=80

=0FQ=C3=80=13=01=14=15=17?



Mark,  Charlie, Alex & Dan-



I've got the same problem as Mark on my  -6A.  Having to leave the nut on the

axle bolt looser than spec just  so the wheel turns has "worked" for almost

300

hours, but still makes me  nervous- grateful for this discussion!  When Mark

sent the original  post, I dragged out dwg. 62 from my preview plans and it

shows the older  style Cleveland wheel- there is a long aluminum "axle"

(U-609)

that is  trapped between the fork halves and allows the bolt to be properly=20

tightened, and thus no side-load on the bearings.  My nosewheel  sounds just

like

Mark's, with the separate spool on each side.  Does  anyone have the actual

drawing (not preview) that shows the current  (Matco) configuration and does

it show

a spacer between the two  spools?



The way Dan fixed it almost sounds like a no-brainer and would  explain a

lot,

but I'm really wondering how many of us "sissies" are out  there with a bogus

nosewheel arrangement because the design was changed  and the prints were

either not updated or wrong? (spacer  omitted?)



By the way, I just had to replace my nose tire due to wear  (300 hours- does

this sound a bit soon?), which obviously is accelerated  by the tire

rotational

resistance.  I've also been told I have  occasional shimmy in my front gear

which is likely related as well.   Carefully balancing the new wheel did seem

to

help that problem  considerably, though...



Mark  Phillips

ronlee(at)pcisys.net
Guest

Posted: Tue Mar 21, 2006 9:33 am Post subject: Nosewheel bearing question

 	  Quote: 	
		  By the way, I just had to replace my nose tire due to wear (300 hours- does

this sound a bit soon?), which obviously is accelerated by the tire 

rotational

resistance.  I've also been told I have occasional shimmy in my front gear

which is likely related as well.  Carefully balancing the new wheel did 

seem to

help that problem considerably, though...


	


I thought I had a nose wheel shimmy problem and tried many things to fix it.

It was not until I had someone videotape me taxiing that it led to the real

problem being an unbalanced nosewheel/tire assembly.



Ron Lee

Mark Phillips in TN

Joined: 10 Jan 2006
Posts: 431
Location: Columbia, TN

Posted: Tue Mar 21, 2006 9:54 am Post subject: Nosewheel bearing question

In a message dated 3/21/06 10:53:19 AM Central Standard Time, 

Hopperdhh(at)aol.com writes:



 	  Quote: 	
		   The shimmy problem is usually due to too free of swivel of the castoring 

 nose wheel.  


	


 	  Quote: 	
		  >>

After watching a guy in another -6A land at a gas stop a couple of years ago 
	


with his nosewheel slamming furiously from stop to stop (he didn't even 

realize it was happening!!) I'm pretty meticulous about the tension- it's been 

checked several times with the fish scale and by "feel" anytime the nose it up and 

has only been adjusted once since new.  I WILL check squareness at top busing 

as you suggest, but balancing the new tire seems to have helped the most- 

also, I have no stiffeners on the leg, FWIW...



Thanks, Dan-



Mark

_________________
From The PossumWorks...

rv6(at)grandecom.net
Guest

Posted: Wed Mar 22, 2006 4:16 am Post subject: Nosewheel bearing question

Quoting Hopperdhh(at)aol.com:



This is exactly what we have done on all the RV's we have built and it seems to

work very well.

Ted

 	  Quote: 	
		   



 I had this same problem (spacers turning by the torque of the seals) when I

 first flew my -7A.  At first I was going to put in roll pins like a Cessna

 150, but decided on a different solution which has worked very well.



 I made a steel sleeve about 3/4 inch OD to put between the bearing spacers

 on the axle bolt inside of the wheel.  Once this sleeve was fine tuned to

 the

 correct length, I could tighten the axle bolt to full torque without

 actually

 having the bearings support the bolt tension.  To support the  sleeve while

 taking the nose wheel on and off, I have a length of 3/8 inch rod  that gets

 pushed through when installing the axle bolt.  This rod is a  little shorter

 than the distance between the forks.



 Dan Hopper

 RV-7A Flying 148 hours

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