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RV6A Nosewheel Breakout Pressure

Ddegange

I'm New Here
I purchased my RV6A 2 months ago and it flys an performs amazing. The nosewheel shimmy upon landing is another story. I have read much on the problem and finally took the route of starting with doing the antisplat nosewheel bearing mod and balance and adjusting the breakout force. I found that breakout force was at 15 lbs with my fishscale. I tightened the nut 1/6 turn to the next alignment point for the cotter pin and now I'm at 40 lbs. Do I go with it and see if it eases off or drill more holes? Any help would be appreciated. Thanks
 
Did you disassemble, clean, and grease, or just tighten the nut? I do not see that kind of a leap with 1 flat. If that is indeed the case I would re-drill. 40 is going to put too much force on the gear leg retaining bolt.
Have you verified that the washer arrangement is per Vans assembly instructions?
 
Nose wheel

You could try taking the nose gear fork off and cleaning/relubing the swivel area. That may change your breakout force. Nothing wrong with trying it at higher breakout settings and see if it loosens up.

Make sure you use proper technique with the nose wheel. The nose wheel can be elevated on takeoff almost immediately as the power is applied. The nose can be held off on landing roll until a fast taxi speed. If I have to taxi fast on a runway, I do it with the nose in the air. The nose wheel is easier to hold off during landing roll if you retract the flaps.

-Andy
 
I second what Keith and Andy are saying. Disassemble and clean/grease the axle at every annual or more often. You would be surprised how much rust and dirt accumulates there.

 
There is a wave washer that creates the preload gradually when the nut is tightened. If that washer has been crushed to the point that there is no wave anymore, then the breakout will increase quickly. Make sure the wave washer still is in good shape, and if in doubt I would suggest replacing it.
 
Actually, two (2) compression washers

Top one is concave up, the bottom one concave down, so that they compress as the nut is tightened, the flat washer is next to the nut ---- I have found those washers "nested" (because they fit so nice) --- also found one airplane where the compression washers were missing.

Ron
 
Top one is concave up, the bottom one concave down, so that they compress as the nut is tightened, the flat washer is next to the nut ---- I have found those washers "nested" (because they fit so nice) --- also found one airplane where the compression washers were missing.

Ron

Of course, yes they are conical washers, not wave washers- I had another application in mind. My bad:(
 
Make sure the two Bellville washers are facing one another with the curves facing away from one another. DO NOT USE ANY LUBE BETWEEN THE WASHERS. A little higher breakout force is OK. It will loosen up after a couple of flights. Be sure to clean and grease the post. I used Aeroshell 5 bearing grease.
 
I've not had to adjust mine ever in 1500+ hours. Using fine emery cloth on a flat surface, I put small flats on the belleville washers like this:

5d3TJ_sznOIJpK1TkjytqJMkdKaJITiDeLkoCeQJEsqkLwEzwq47kav8mpM6-7xjxTx6kNTmTWPAMmOqTJFOLUbhUNMFIsdJsR0uPKsNE62eGGq-XF-cKP85aLk84DsRuUPwCgC96-2eNy_mOgF1PnptOXXm2YjnlKr4F9PEsPGY-5TnAjx63F6R5vRvMpLLmRGQL43bp2-OxOvrMObgy2FSyJds2dVSrPufkvxS4tfc8XulPh26voDb2O2hRCqcyAq_KNVfPsKr2b3vZd9zKKdXmdM0sOeUfDJYbrrUXgyYPvLTKXl2lqnoPWb0VotTapLOTx2ji4dAiig89EIZ5badFLl5e5fLdtZ6Yu4vWQIZLuU84hXnzh6ILTtvffdPXJ26HGc3T3L6SJYApKC7_hk8ZkQ-X_7pbH4cwVXnYL1rNgCHCCnU3tK6whK_p5XnCUGeBXbXyov41hvbhT8p6PlmT1cjOpRHpaKSqCjSsIQYB4uyiQR6MBanBWud14U0kG4lReLcsuAUE8Q-CEjmBfMw1JwnAjpmbUPVxoV_oADEp_FVIyempzNBs7XLe-RLdgqYBkOclWu0m_P_mK-_xT9SBvAIoDPgPEVKHI4l7ngkG7nqQkfm=w330-h371-no


These flats give a much better, and larger, bearing surface than the line contact that would normally occur. The sharp edges before this modification will quickly chew into the bronze bushing otherwise. I recommend using grease on these to make the friction predictable, and to prevent rust.

Also, to be clear, the concave sides of the washers face each other. Meaning, the large faces of the washers contact each other. I think this was perhaps misstated in an earlier post.
 
I've not had to adjust mine ever in 1500+ hours. Using fine emery cloth on a flat surface, I put small flats on the belleville washers like this:

5d3TJ_sznOIJpK1TkjytqJMkdKaJITiDeLkoCeQJEsqkLwEzwq47kav8mpM6-7xjxTx6kNTmTWPAMmOqTJFOLUbhUNMFIsdJsR0uPKsNE62eGGq-XF-cKP85aLk84DsRuUPwCgC96-2eNy_mOgF1PnptOXXm2YjnlKr4F9PEsPGY-5TnAjx63F6R5vRvMpLLmRGQL43bp2-OxOvrMObgy2FSyJds2dVSrPufkvxS4tfc8XulPh26voDb2O2hRCqcyAq_KNVfPsKr2b3vZd9zKKdXmdM0sOeUfDJYbrrUXgyYPvLTKXl2lqnoPWb0VotTapLOTx2ji4dAiig89EIZ5badFLl5e5fLdtZ6Yu4vWQIZLuU84hXnzh6ILTtvffdPXJ26HGc3T3L6SJYApKC7_hk8ZkQ-X_7pbH4cwVXnYL1rNgCHCCnU3tK6whK_p5XnCUGeBXbXyov41hvbhT8p6PlmT1cjOpRHpaKSqCjSsIQYB4uyiQR6MBanBWud14U0kG4lReLcsuAUE8Q-CEjmBfMw1JwnAjpmbUPVxoV_oADEp_FVIyempzNBs7XLe-RLdgqYBkOclWu0m_P_mK-_xT9SBvAIoDPgPEVKHI4l7ngkG7nqQkfm=w330-h371-no


These flats give a much better, and larger, bearing surface than the line contact that would normally occur. The sharp edges before this modification will quickly chew into the bronze bushing otherwise. I recommend using grease on these to make the friction predictable, and to prevent rust.

Also, to be clear, the concave sides of the washers face each other. Meaning, the large faces of the washers contact each other. I think this was perhaps misstated in an earlier post.

Thanks for clarifying this. After reading this thread, I was beginning to doubt the way I assembled mine. I like the idea of making a flat surface and wish I had done that. I may do it at my next annual.

Larry
 
This thread is a perfect example of why builders / owners need to be discerning when using / following info or advice provided here in the VAF forums (it should also show you why Van's tech support seems to have some (small) level of disdain for the forums).

The two belville washers do get installed with concaved portions facing each other.
They will always require some adjustment after initial installation (usually at about 15 hrs and again at 75 or so) After that the adjustment usually stays constant for many hundreds of hours (even if you don't do any modifications to the washers).
The plans recommended breakout value is the recommended value.
Much less and there is a high chance of shimmy (castor). Any more than that and you just make the airplane harder to steer during taxi, which will require a much higher brake usage (and pad/disk replacement) than what is required with proper technique, along with increased load on nose gear components.
 
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