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#11
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Cobra Top Hinge Bolt Failure - Revisit
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Cobra Top Hinge Bolt Failure - Revisit
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#13
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Cobra Top Hinge Bolt Failure - Revisit
At 13:01 26 April 2012, John Sinclair wrote:
At 22:21 25 April 2012, wrote: On Tuesday, April 24, 2012 11:26:45 AM UTC-4, Steve Koerner wrote: The structure immediately under the handles had clearly collapsed. There is no such solid material between the inner and outer laminate on mine. The backing plate has resolved the problem quite well. I've looked at my hinge bolts a number of times, but can't detect any problems. Are there any symptoms that precede bolt failure, i.e. loose handles? TIA, Frank (TA) Check the hold-down clamps at the aft end of your trailer, If the top latch doesn't match up with the lower attach bracket like it did when new.....................that means the top has moved forward and may be setting up the failure mode with the hinge bolts. I found this condition on both aluminum and fiberglass tops and then found sheared off rivets in the hinge bolt bracket. Another item to remember; avoid opening the trailer when a 10+ knot cross-wind is blowing. An open top acts like a sail and can place tremendous loads on the hinge bolts. JJ As a contributory preventative measure how about doing something at the aft end to prevent forward movement of the trailer top during towing? For example, angle the aft trailer-top clamps at 45 degrees as viewed from the side with the lower fitment being to the rear. |
#14
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Cobra Top Hinge Bolt Failure - Revisit
It would seem that this problem is related to using the trailer on the
road. Steve Koerner's link above states "...lonitudinal loads on the trailer top hinge plate occur as the trailer and its tow vehicle pass over bumps on the roadway." This implies that if the trailer sits at a gliderport most or all of the time, you may never experience this failure at all. Correct? - John |
#15
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Cobra Top Hinge Bolt Failure - Revisit
John -
Subsequent to that writing, I think I really concluded that the biggest issue may be the open trailer top in a crosswind as JJ mentions here and as was discussed in the year ago thread on this topic. Lots of theories were put forth on the matter. As JJ points out, the crosswind issue is an avoidable situation although thermal winds and dust devils can present a surprise at times. |
#16
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Cobra Top Hinge Bolt Failure - Revisit
As a contributory preventative measure how about doing something at the aft end to prevent forward movement of the trailer top during towing? For example, angle the aft trailer-top clamps at 45 degrees as viewed from the side with the lower fitment being to the rear. There are some pretty strong forces at work here. Two struts that are strong enough to raise the top, are trying to move the top forward when it is down. Don't think the latches would last long tyring to fight the struts. If top mated over steel posts in the lower trailer sides at the rear, it might be strong enough to resist the forward forces. Spindelburger is always improving his product and I'm betting we will see a fix on his new product..........If anyone has enough money to buy one! I was told a new Cobra cost $40K. Can this be right? JJ |
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Cobra Top Hinge Bolt Failure - Revisit
On Thursday, April 26, 2012 5:36:53 PM UTC-4, JJ Sinclair wrote:
As a contributory preventative measure how about doing something at the aft end to prevent forward movement of the trailer top during towing? For example, angle the aft trailer-top clamps at 45 degrees as viewed from the side with the lower fitment being to the rear. There are some pretty strong forces at work here. Two struts that are strong enough to raise the top, are trying to move the top forward when it is down. Don't think the latches would last long tyring to fight the struts. If top mated over steel posts in the lower trailer sides at the rear, it might be strong enough to resist the forward forces. Spindelburger is always improving his product and I'm betting we will see a fix on his new product..........If anyone has enough money to buy one! I was told a new Cobra cost $40K. Can this be right? JJ JJ, According to my quick perusal of the 2011 price list on W&W, a 15-meter aluminum-topped trailer with some options was around $17K (abt 13-14,000 euros). TA |
#18
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Cobra Top Hinge Bolt Failure - Revisit
Hey Guys, I am noticing signs the top of my fiberglass Cobra is moving forward. I am going to replace the bolts as recommended by many, and may do the backing plate solution as well. The deformation of the fiberglass is worrisome. Can the clamping of the hinge plate and removal of bolts be done with the glider in the trailer? or is it recommended to empty the trailer first?.. for those who have done it.
BTW, I also see what JJ identified and that's the 4 rivets on one side are popped and gone. I wonder if I can realign the frame and get either rivets or small fasteners back in there? TIA, Darren |
#19
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Cobra Top Hinge Bolt Failure - Revisit
On Wednesday, May 15, 2013 1:06:10 PM UTC-4, wrote:
Hey Guys, I am noticing signs the top of my fiberglass Cobra is moving forward. I am going to replace the bolts as recommended by many, and may do the backing plate solution as well. Which will not help with the top migrating forward. The deformation of the fiberglass is worrisome. Can the clamping of the hinge plate and removal of bolts be done with the glider in the trailer? Yes, but BE CAREFUL. See below. I drafted a note for Spindelberger but didn't hear back, need to chase them... http://www.nadler.com/Antares/Cobra_...rcement_01.pdf Hope that helps, Best Regards, Dave PS: The part they made for me won't fit many trailers; there are different extrusions used at the lower edge of the top. |
#20
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Cobra Top Hinge Bolt Failure - Revisit
Wow, that seems like a good solution for me. Hmmm. I called one dealer yesterday and they did not mention this so I doubt they are aware of it. Let us know what you find. Anybody else able to get this part?
Thanks, Darren |
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