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Robart giant Corsair / Hellcat retract problem

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Robart giant Corsair / Hellcat retract problem

Old 02-04-2020, 07:51 PM
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MaJ. Woody
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Default Robart giant Corsair / Hellcat retract problem

My new Robart Giant Scale Rotating Retracts are getting stuck in the up position because the latch that locks them up won't release. I had another set of these years ago in my Top Flight Corsair and they always worked great but I may have removed the locking latch on those. I can't remember. Has anyone removed the locking latch and spring? I have to think that the air pressure will hold the gear up. I I think I am going to remove mine for reliability sake before the maiden. Worst case is they dont stay up but having them stuck up can have dire consequences.
Old 02-06-2020, 11:26 AM
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Chris Nicastro
 
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Nooooo!

I had issues with the brand new Hellcat retracts too. I took them completely apart and made sure the scissor links were smooth and free. After close inspection the scissor links were bound up so that was a big improvement right away. Then I took apart the air cylinders and cleaned out the factory lube and replaced it with thick silicone oil for RC buggy differentials. Put it all back together and checked them and now they are perfect. This gear operates at 10psi down and 23psi up and no locking issues. Make sure align the locking pin and lever and when you put the retract back together you must double check the mechanism is free and correctly assembled.

I posted about this fix before, let me see if I can link it here
Old 02-06-2020, 12:09 PM
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Default Retract Fix

















Old 02-06-2020, 12:10 PM
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More explanation than photos to get the point across but let me know if you have any questions.
The main thing to look for is binding in the main scissor link assembly and between the frame and the pivots and solve it. The lower scissor links were fine on this set of gear but checked anyway.
Grease the spring with heavy grease like Bellray waterproof grease, it’s very tacky and works well in this case.

Last edited by Chris Nicastro; 02-06-2020 at 12:17 PM.
Old 02-06-2020, 12:21 PM
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In the photos with the red Allen key holder I’m showing how the stamped link end is not parallel. This was the source of the binding. I had to make the parts more parallel so they would be free.
Old 02-06-2020, 03:09 PM
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Maj. Woody,
I had the same problem with the up lock not releasing in the Robart gear for a H9 giant Corsair. I never could figure out the problem, but removed the latch and spring as you are thinking of doing. I did not have a problem with the gear sagging out of the well even when pulling out of loops.
Chuck
Old 02-06-2020, 03:43 PM
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Hi guys.
Thanks for the replies! I too completely disassembled the gear, cleaned it, painted the upper and lower links white, reassembled it with the links facing forward as is appropriate for a Hellcat ( they come Corsair style facing rearward) and used locktite on all the screws. I lubed the key areas as Chris points out. The gear operate very smoothly but it's that darn locking lever. My theory is that the retract cylinder (which can float a bit on the pin) is jamming the lever against the retract frame. Although the lever is tapered, it still can get wedged in there. Glad to hear removing the lever causes no harm. I did not think it would and am almost certain that's what I did on my TF Corsair.
Old 02-06-2020, 06:58 PM
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HI ALL.
Thank you for starting this thread the information here is a real help to anyone with retract issues..ive got a top flight GS corsair and a hanger 9 60cc corsair both with Robart elec retracts so far so good but will check for binding in the future..

cheers raaf
Old 02-06-2020, 07:47 PM
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Ive had several sets over the years. I always just bend the latch out of the way.
Old 02-07-2020, 05:06 AM
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Awesome! Thanks!
Old 02-07-2020, 06:15 PM
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My TF Corsair is over 10 years old and the gear have never had an issue since new. I use silicone oil both light and heavy and the gear operate smoothly and at lower pressures. I add light oil to the air lines each season or so and that keeps things lubed for a while.
As for air I use as much capacity as I can put in the airframe. Usually that’s a large tank and medium tank or like in the YA P-38 it has two large tanks for gear and one medium tank for brakes. You cannot go wrong with more volume, it only improves performance and reliability in these retract systems. I also use air line restrictions for both up and down circuits so they don’t slam up and down to lock.
As far as the locking arm goes I have seen them misaligned but the main thing is that the air cylinder can move freely to actuate the locking arm. I suggest before someone removes the arm they make sure the cylinder does what it’s supposed to do and the arm is able to lock and unlock as designed. None of my Robart gear, Corsair, P-51, Hellcat, etc, have ever had a locking problem in the last 15 years. The most recent Hellcat gear are the first to be poor from the factory and I fixed them so maybe these count as the first bad set I guess.

Side note: I still have a full set of electric actuators and controller for the large Robart gear new in bag. I’m never going to use them so if you need a set let me know.

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