Cobra Trailer Jam-nuts (loose)

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Don't know why, but the last 3 Cobra trailers I have seen all had very loose wing spar jam nuts. When a wing is rolled in, it's spar passes under a horizontal cross bar and when the tip is lowered into the floor saddle, the spar rises slightly to firmly come to rest under the horizontal cross bar...............everybody still with me? OK, this cross-bar has 2 big wing nuts on top and the idea is to hand tighten these wing nuts so that the cross bar rests firmly on the spar butt. If not, the wing will sway side to side on the road.............Got the picture? What keeps your wing nut setting in place is the jam-nuts under the cross bar............and these puppies are loose .......all of them on the last 3 trailers I have inspected!
FIX, hand tighten all wing nuts so that the cross bar rest firmly on the spar butt AND then tighten the jam-nuts located on the under side of the cross bar. Let me know what you find and any reason why these jam nuts are loosening? I'm sure they were all tightened when the ship was originally fitted to its trailer? Or Were they?
JJ

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On Sunday, September 2, 2018 at 2:05:16 PM UTC-4, wrote:
> Don't know why, but the last 3 Cobra trailers I have seen all had very loose wing spar jam nuts. When a wing is rolled in, it's spar passes under a horizontal cross bar and when the tip is lowered into the floor saddle, the spar rises slightly to firmly come to rest under the horizontal cross bar...............everybody still with me? OK, this cross-bar has 2 big wing nuts on top and the idea is to hand tighten these wing nuts so that the cross bar rests firmly on the spar butt. If not, the wing will sway side to side on the road.............Got the picture? What keeps your wing nut setting in place is the jam-nuts under the cross bar............and these puppies are loose .......all of them on the last 3 trailers I have inspected!
> FIX, hand tighten all wing nuts so that the cross bar rest firmly on the spar butt AND then tighten the jam-nuts located on the under side of the cross bar. Let me know what you find and any reason why these jam nuts are loosening? I'm sure they were all tightened when the ship was originally fitted to its trailer? Or Were they?
> JJ

I have seen the same thing on several occasions.
After making jam nuts very tight, it has not happened again.
UH

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On Sunday, September 2, 2018 at 3:52:41 PM UTC-4, wrote:
> On Sunday, September 2, 2018 at 2:05:16 PM UTC-4, wrote:
> > Don't know why, but the last 3 Cobra trailers I have seen all had very loose wing spar jam nuts. When a wing is rolled in, it's spar passes under a horizontal cross bar and when the tip is lowered into the floor saddle, the spar rises slightly to firmly come to rest under the horizontal cross bar..............everybody still with me? OK, this cross-bar has 2 big wing nuts on top and the idea is to hand tighten these wing nuts so that the cross bar rests firmly on the spar butt. If not, the wing will sway side to side on the road.............Got the picture? What keeps your wing nut setting in place is the jam-nuts under the cross bar............and these puppies are loose .......all of them on the last 3 trailers I have inspected!
> > FIX, hand tighten all wing nuts so that the cross bar rest firmly on the spar butt AND then tighten the jam-nuts located on the under side of the cross bar. Let me know what you find and any reason why these jam nuts are loosening? I'm sure they were all tightened when the ship was originally fitted to its trailer? Or Were they?
> > JJ
>
> I have seen the same thing on several occasions.
> After making jam nuts very tight, it has not happened again.
> UH

More thought on this.
I expect most who adjust these spin the nuts up from the bottom, with the hold downs on the spar, and then tighten the wing nuts. It's hard to get the wing nuts tight enough. Gotta go in from the bottom afterwards and tighten more firmly.
I HATE when my nuts fall down!

UH

[Nick Kennedy[_3_]]

A naked man walked into the ER
The nurse looked at him and said " I can clearly see your nuts"!

[Charlie M. (UH & 002 owner/pilot)]

Your or you're?

For the first setting, maybe at least LockTite blue on the threads for the bottom nuts (would they be anywhere else?), set it up, tighten nuts (ouch), then let the LockTite set.

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There is a possibility that these nuts unscrew when the trailer is driven over rough roads without the sailplane inside. If so, some of our Trailers are much more vulnerable than others!
😝JJ

[Dan Marotta]

Your or you're?

On 9/2/2018 5:12 PM, Nick Kennedy wrote:
> A naked man walked into the ER
> The nurse looked at him and said " I can clearly see your nuts"!
>

--
Dan, 5J

[SF]

We Manufacture and ship large skidded Pump & piping systems with a couple hundred flange bolts on each one. All tight, with a successful hydrotest to prove it. Every now and then the combination of trailer suspension, road condition + transit speed = a very bad vibration frequency that loosens up the nuts, leading to customer questions regarding our competency. It's impossible to predict.

SF

[OHM Ω http://aviation.derosaweb.net]

On Sunday, September 2, 2018 at 7:18:20 PM UTC-5, Charlie M. (UH & 002 owner/pilot) wrote:
> Your or you're?
>
> For the first setting, maybe at least LockTite blue on the threads for the bottom nuts (would they be anywhere else?), set it up, tighten nuts (ouch), then let the LockTite set.

UH,

Yep, I use blue LockTite on both the lower nuts and (why not?) the upper wing nuts too. In case everyone is not familiar with LockTite it is a liquid applied to the threads that will "glue" the nut to the threaded rod and prevent inadvertent loosing BUT still will allow manually removal at a later date. DO NOT USE THE RED COLORED LOCKTITE as this requires the application of HEAT to remove the fastener!

PS - Why not replace the fasterners with metric nylock (nylon insert) nuts and be done with it?

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On Friday, September 7, 2018 at 9:05:03 AM UTC-4, OHM Ω http://aviation.derosaweb.net wrote:
> On Sunday, September 2, 2018 at 7:18:20 PM UTC-5, Charlie M. (UH & 002 owner/pilot) wrote:
> > Your or you're?
> >
> > For the first setting, maybe at least LockTite blue on the threads for the bottom nuts (would they be anywhere else?), set it up, tighten nuts (ouch), then let the LockTite set.
>
> UH,
>
> Yep, I use blue LockTite on both the lower nuts and (why not?) the upper wing nuts too. In case everyone is not familiar with LockTite it is a liquid applied to the threads that will "glue" the nut to the threaded rod and prevent inadvertent loosing BUT still will allow manually removal at a later date. DO NOT USE THE RED COLORED LOCKTITE as this requires the application of HEAT to remove the fastener!
>
> PS - Why not replace the fasterners with metric nylock (nylon insert) nuts and be done with it?

Nylok nut, to work correctly, would need to go on plastic first. Another option would be to take the top plate off, add a jam nut, then reassemble, locking jam nut against the lower nut after tightening the lower nut against the upper. Takes almost as much time to describe as it would to do.
UH

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Another Ship came in yesterday with Cobra...........yep, another loose nut! The rubber pad that protects the spar is also being compressed when the jam-nut is tightened, so UH's fix would be the best way to fix this issue. Jam-nut into another jam-nut. While we're looking things over in our trailers, it's not a bad idea to check all the adjustable fittings too. I have seen wing tip (assembly bar) adjustment so far out that the wing tip jumped out as trailer went down a rough road. Also found a scar on my root rib.............fixed it and next time I assembled the ship, the damned scar reappeared! Turned out the padding on the spar saddle, had compressed to the point the root rib started hitting the mid-span wing saddle, as the wing was pulled out.
Cobra is still the best trailer out there, thanks Spindleberger!
JJ

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On my last Cobra, I replaced all four with nylock nuts. It took a long time to turn them into position due to the limited space, but it solved the problem permanently.