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RV-7 Tire Wobble on Rollout...

donmtt

donmtt

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Any suggestions on how to solve a pretty serious tire wobble/shimmy on rollout after landing in my new RV-7? I have tires with tubes (not sure of brand but can find out tomorrow if needed) that were replaced in July 2020 per the logs.

I'm thinking maybe a balance issue? Or maybe just a need for some new skins?

It seems worse in cooler weather, but that just my be coincidence. I have about 20 hours in the plane so far and want to make her right...

Thanks!
 

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You can vary air pressure to see if that helps. I found that most of my problems went away when I raised pressures on my -6 from 25 to 35 PSI. Your mileage may vary. Tire balance and tire roundness are issues. I've found that older tires (probably with uneven wear) are contributors. Finally, the addition of gear leg stiffeners is helpful on many aircraft.

There's a ton of discussion of this topic if you search the site.
 
Kyle Boatright said:
You can vary air pressure to see if that helps. I found that most of my problems went away when I raised pressures on my -6 from 25 to 35 PSI. Your mileage may vary. Tire balance and tire roundness are issues. I've found that older tires (probably with uneven wear) are contributors. Finally, the addition of gear leg stiffeners is helpful on many aircraft.

There's a ton of discussion of this topic if you search the site.
Click to expand...
Thank you! FNG here - and working out the minor issues on my new plane.
 
Quotafiller said:
having a camera under the plane helps a lot to see what is happening
Click to expand...
Ah! OK. Never would have considered that. I have several GoPros from my P210. And I think there's a mount on the wing already. I'll give it a shot tomorrow. I'll post and look for expert insight. (Will also try increasing the tire pressure as well.)

Thanks.
 
You may be running the wrong profile tire.... Goodyear Fight Special II tires work well on RV gear due to it's need to "scuff".
 
gasman said:
You may be running the wrong profile tire.... Goodyear Fight Special II tires work well on RV gear due to it's need to "scuff".
Click to expand...
Thanks. Can you help me understand the need to "scuff"? Not familiar with that...
 
gasman said:
You may be running the wrong profile tire.... Goodyear Fight Special II tires work well on RV gear due to it's need to "scuff".
Click to expand...
Plus one on the Flight Special II. Make sure you orient the tire in relation to valve stem in accordance with the fine print on the placard stuck to the tire. If it still shimmys I wou;d try balancing next.
Jack one side.
Remove the brazke caliper, loosen the axle nut slightly and spin the wheel. Make a chalk mark on the low spot and repeat. If the results are the same add a half of a motorcycle stick on weight opposite the heavy point .
Next step would be the gear leg stiffners. I would just bond the stiffners to the gear leg as recommended by Vans.
 
Aircraft like a Piper Warrior have landing gear that travels straight up and down. They can use tires that have a flat tread looking at the top of an inflated tire.
RV's have gear made of spring steel. The gear tucks in several inches during flight. As the weight of the aircraft is lowered on the tires, the tire must scuff on the ground as the spring gear expands.
 
jrs14855 said:
Plus one on the Flight Special II. Make sure you orient the tire in relation to valve stem in accordance with the fine print on the placard stuck to the tire. If it still shimmys I wou;d try balancing next.
Jack one side.
Remove the brazke caliper, loosen the axle nut slightly and spin the wheel. Make a chalk mark on the low spot and repeat. If the results are the same add a half of a motorcycle stick on weight opposite the heavy point .
Next step would be the gear leg stiffners. I would just bond the stiffners to the gear leg as recommended by Vans.
Click to expand...
This the correct tire? https://www.aircraftspruce.com/catalog/lgpages/gy_tire6.php
 
donmtt said:
Any suggestions on how to solve a pretty serious tire wobble/shimmy on rollout after landing in my new RV-7? I have tires with tubes (not sure of brand but can find out tomorrow if needed) that were replaced in July 2020 per the logs.

I'm thinking maybe a balance issue? Or maybe just a need for some new skins?

It seems worse in cooler weather, but that just my be coincidence. I have about 20 hours in the plane so far and want to make her right...

Thanks!
Click to expand...
Tire/wheel brand and recommendation very important. Beringer recommends 4 bar on my Michelin tire (almost 60 psi) and runs very smooth on landing.
 
Describe your wheel bearing preload procedure. This will help us determine if the wheel shimmy is related to roll resistance.
 
gasman said:
You may be running the wrong profile tire.... Goodyear Fight Special II tires work well on RV gear due to it's need to "scuff".
Click to expand...

jrs14855 said:
Plus one on the Flight Special II. .......
Click to expand...
Tried the Flight Special II one time on my -6 (from recommendations on VAF) and those were the absolute worst-balanced and most-shimmy-prone tires I've ever had. Horrible.

The best were the Michelin Pilots (although they are heavier): https://www.aircraftspruce.com/catalog/lgpages/michpilot_06-03068.php

The takeaway is that "Your Mileage May Vary".
 
I thought I had the wobble issue, as I could feel something. Turns out is NOT the wobble. See the video below.

vimeo.com

Nose Wheel

This is "Nose Wheel" by FPV Australia on Vimeo, the home for high quality videos and the people who love them.
vimeo.com
 
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