Almost Lost a Wheel

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User GDS
Veteran Member
Posts: 304
Joined: Sun Jul 01, 2012 11:59 am
Location: Big Bear Airport

Almost Lost a Wheel

Post by User GDS »

I came back from bouncing around in the desert yesterday and the right wheel was wobbly when I was taxiing back to the hangar.

On the 6" Matco, there are six bolts and nylok nuts holding the wheel together. Three are holding the wheel halves together, the other three fasten the wheel to the hub. One of the nuts on the hub bolts had come all the way off, the other two had backed off a couple of turns.

I have been using the dust covers (hubcaps) and had attached the stand-offs under the nuts to the hub bolts. There was not much thread showing from those bolts. The stand-offs may have been working the nuts loose somehow. The nuts on the left wheel were loose also, but not enough to cause wobble.

For the repair, I eliminated the dust cover standoffs to get a little more thread. The coarse thread nylok nuts are not very grippy so I used blue loktite on them. I'll call Matco on Monday for technical advice, but I think I need to replace the stock bolts with longer ones and use a different locking system. I'm not using the dust covers anymore so I can pre flight the wheels better.
GDS
So Cal
Highlander #232
Rotax 912ULS, Dynon Skyview
Jamescham
New Member
Posts: 16
Joined: Thu Jan 31, 2013 7:48 am

Re: Almost Lost a Wheel

Post by Jamescham »

Did you torque them? I have 29" with the same fasteners....torque value for 5/16 grade is 17'lbs. I worry about that also!
User GDS
Veteran Member
Posts: 304
Joined: Sun Jul 01, 2012 11:59 am
Location: Big Bear Airport

Re: Almost Lost a Wheel

Post by User GDS »

(forgot to mention, 6" Matcos with 29" Airstreaks)

They were torqued according to the Matco literature, 100 in lb. I don't know if they are AN bolts, they have coarse threads. Presumably since they are threaded through the aluminum hubs, a coarse thread is used because of the relatively low sheer strength of the aluminum.

Something I didn't know before is that you can remove the wheels without disassembling the bearings. If you take off the three nuts attached to the hub bolts, the wheel and tire come off like on an automobile. (The wheel halves are held together with the other three bolts) Unfortunately, on my wheels, those three nuts come off very easily. As a test, I re-installed them, torqued them to 100 in lb. I back them off, and it took 3/4 turn for the nylon to disengage and the nuts became finger tight. I don't know if it's just my wheels or I made a mistake installing them in the first place, but if you're concerned about it, I suggest removing one of the hub nuts just to see how secure it is. (a cautionary word from the legal staff: don't undo the three that hold the wheel halves together...)

Since the first post, I replaced the 1-1/4" long stock bolts with 1-1/2" stainless bolts and new nylock nuts. Now I've got about four threads showing. I'm not using the dust covers anymore.

I had the same wheels on my RV12 and had no problems, but that was a pavement-only machine. I really work the gear on the Highlander, gotta check everything frequently. The annual is next month and I'm replacing every nut and bolt in the landing gear, even though they only have 100 hours in service.
GDS
So Cal
Highlander #232
Rotax 912ULS, Dynon Skyview
av8rps
Veteran Member
Posts: 480
Joined: Thu May 12, 2011 5:01 pm

Re: Almost Lost a Wheel

Post by av8rps »

After learning all this about your experience I am definitely going to check mine. thanks for letting us know about this potental problem.
preacoupe
Veteran Member
Posts: 177
Joined: Sun May 11, 2008 3:35 pm
Location: Tucson, AZ

Re: Almost Lost a Wheel

Post by preacoupe »

Hey Gary,

Some time ago I was taxiing back after landing and was having some small vibration and "clicking". Found out that one of the 3 screws holding the rotor to the wheel had backed out and was hitting the caliper housing each rotation. Bent the screw. So I went to Matco website and found that those screws had been replaced by new screws AND the use of Nordlock washers. Those nordlocks come in pairs with a stepping between them. Haven't had the same problem yet. They are torqued only to 80 in/lbs. Point is, that maybe Matco has found similar "upgrades" to their other hardware.

Hope to see ya soon.

Dennis
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Tralika
Veteran Member
Posts: 385
Joined: Thu Oct 08, 2009 12:49 pm
Location: Wasilla Alaska

Re: Almost Lost a Wheel

Post by Tralika »

Sounds like a good place to use a dot of Torque Seal to make it easier to see if any of the nuts start to slip again.
John Nealon
Wasilla, Alaska
Highlander Extreme #191
mykitlog.com/jnealon
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