RV-10 Main Wheel Pressure / Shimmy

[vic syracuse]

I thought I would ask if any of the flying RV-10's are having any of the main gear shimmy we have seen on the other RV's. I am, and it's driving me nuts (no comments about it being a short drive, please). It appears to be getting worse, so I'm thinking it might be the tires. I've rotated the tires, and put the wood dampeners on the main gear legs as well. It is very pronounced upon landing and decelerating through 32-34 knots. It is hardly noticeable on takeoff, probably because we accelerate so quickly. But upon landing, it almost wants to shake the airplane apart. It's fine faster than 34 or slower than about 28. I have verified it is the mains by having another pilot stand outside the airplane as I went by with the shake occuring. It is only noticeable on pavement. I fly off of grass 90% of the time, and have about 500 hours on the original tires, which are still showing about 1/8" of tread, deeper in the middle, and shallower on the insides and outsides (due to rotating the tires). I've had the right main brake line fail at the fuselage joint, and I'm thinking that it is most likely due to the shimmy.
Thanks in advance.

Vic

[Kyle Boatright]

Not a direct reply to your question Vic, but worn (flat spotted and/or out of balance) tires are THE driving factor when I have shimmy on my -6.

[Tony Kirk]

I had the exact same problem on my 6A - main gear shimmy between 26 & 33 mph on rollout. I never installed the wood dampers on mains or nose legs.

The solution is to static balance all the tires and apply self-adhesive weights as needed.



Use a balancer like this http://www.desser.com/accessories.html and search for these weights "BALANCE TAPE ON WEIGHTS PACKAGE 10 STICKS" at Desser Tire, ~$15.

I just replaced all my tires before OSH and used Desser Recaps (with Michelin Airstop tubes) for the mains and a new "Lamb" tire & tube from Van's on the nose.

My nose tire took 1oz, one main took 3oz and the other took 4.25oz, the original tires took about the same amount.

The results are impressive - I have no noticeable shimmy at any speed.

See this page http://www.desser.com/mounting.html for more info about balancing.

[n2faith2]

I experienced the same maingear shimmy and, like Vic, had someone watching when I landed. The right main looked like a basketball being dribbled down the court. I removed it and it took almost 4 oz of weight to get it close to being balanced. The shimmy is all but gone now.


Bill Stegemann
RV10 N545RV
116 hours

[vic syracuse]

Thanks, guys. I will get new tires on order and balance them and let everyone know the results.

Vic

[Geico266]

There is a certain taxi speed when I get a shimmy. Faster and it stops, slower it stops. Any ideas? Is the nose gear like the other RVs needing a certain "break out" value for wheel tightness? I did not build this plane.

[doctornigel]

I'm sure you checked the obvious, bearing torque and wheel balance.

Almost all nose wheels have a speed where some vibration is more apparent, kinda a harmonic thing, but it shouldn't be severe. Has the vibration gotten worse over time?

[Mike S]

This has been addressed a few times already in this forum, use the search function, or just scroll through old posts.

There seems to be 3 main causes------tire balance/out of round, loose bearing crush/pre load, and fork breakout force.

The Matco wheel provided is not too tolerant of things being out of whack.

Here is one example http://www.vansairforce.com/communit...ad.php?t=17878

Good luck,

[ddddsp]

Larry,

Did you buy an RV10? Fill me in on the details..........gonna be at the next York Breakfast with it? Inquiring minds wanna know.................

Dean 805HL

[Geico266]

Thanks to all who posted. I'll work on all of the "Big 3".

I sure do like this site when guys who have 'been there, done that" help out. I really appreciate it guys.

Yes, I did buy the KC 10, no I won't be in York, family stuff weekend. It needs alittle more "dressing up" to get to the level of your 10. That is one FINE aircraft you built.