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Thread: Torque tube.

  1. #11
    Member jmorrical's Avatar
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    Default Re: Torque tube.

    Loctite 680 it is.

    On page 54 of the Fuselage Manual it tells you to test fit the rear mast on the torque tube with the rear block set in place. I thought since the rear mast came off once I could fit it on and off for the test. Wrong! The first fit got stuck and it took a while to get it off. Mitch suggested using some 320 grit sandpaper, not too aggressively as to keep a close fit, to take a little off the torque tube. I did that and tried again. It got bound up again after I pushed it on about 1/2" It was locked up, frozen, stuck... I was once again STUCK and frustrated! I'm just glad I hadn't used the Loctite yet. It bound up and I didn't have the hand strength to just twist and slide it off because of the position of the assembly and the cockpit floor.

    A friend suggested penetrating oil. Thankfully that worked. I guess I'll sand some more and try again. Any other suggestions.

    Troy how would you debur the inside of the holes on that rear mast? I have run my finger over the holes and they seemed fine, but I suspect that could be part of the problem.

    One other issue bothers me about my torque tube installation so far. When I got the front torque tube bushings and stiffener torqued in place it felt to me that roll movement force required to rotate the tube would be way too stiff. How do you tell if it's too stiff? Mitch suggested I might need to fabricate and install a very thin aluminum shim between the top and bottom bushing. Any recommendation?


    Jim Morrical
    Last edited by jmorrical; 09-13-2016 at 03:25 PM.

  2. #12
    Senior Member TroyBranch's Avatar
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    Default Re: Torque tube.

    Quote Originally Posted by jmorrical View Post

    Troy how would you debur the inside of the holes on that rear mast? I have run my finger over the holes and they seemed fine, but I suspect that could be part of the problem.

    Jim Morrical

    I have a tool that deburs holes on both sides. http://www.ezburr.com/products/micro_series.php+

    It's expensive but looks after all the holes you cannot get to on the inside of a tube.

  3. #13
    Member jmorrical's Avatar
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    Default Re: Torque tube.

    One other issue bothers me about my torque tube installation so far. When I got the front torque tube bushings and stiffener torqued in place it felt to me that roll movement force required to rotate the tube would be way too stiff. How do you tell if it's too stiff?

    Mitch suggested I might need to fabricate and install a very thin aluminum shim between the front top and bottom bushing. Any recommendation?

    Jim Morrical

  4. #14
    Senior Member ceslaw's Avatar
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    Default Re: Torque tube.

    Jim

    FWIW, it did feel a bit stiff when first installed. But try moving it from the end of the control stick - better judge of 'stiffness'. Also once the plane is rigged and with a bit of usage the 'stiffness' became a non issue. It is nice and smooth now.

    I would rather have it a bit stiff than loose.

    Also, worst case scenario, add the shim at the end when everything is done, if it is still an issue.

    Chuck

  5. #15
    Senior Member TroyBranch's Avatar
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    Default Re: Torque tube.

    I agree with Chuck. The rigging of the cables will cause more drag than that bushing ever will.


    Sent from my iPhone using Tapatalk

  6. #16
    Member jmorrical's Avatar
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    Default Re: Torque tube.

    Thanks Chuck and Troy. I appreciate a view of the results from you guys way down range of where I am now in the build. This forum is a great part of my tool box.

    Jim Morrical

  7. #17
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    Default Re: Torque tube.

    I had the same issue with the torque tube.

    It was slightly over the nominal diameter and was a tight fit in the mast and bearing blocks.

    I spent some time skimming it down with fine grit wet cloth, but ended up making a shim out of UHMW tape between the bearing blocks.
    There is still a bit of light drag on the bearing. Hoping that will reduce over time, but it's quite small and acceptable.

  8. #18
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    Default Re: Torque tube.

    Quote Originally Posted by jmorrical View Post
    Loctite 680 it is.

    On page 54 of the Fuselage Manual it tells you to test fit the rear mast on the torque tube with the rear block set in place. I thought since the rear mast came off once I could fit it on and off for the test. Wrong! The first fit got stuck and it took a while to get it off. Mitch suggested using some 620 grit sandpaper, not too aggressively as to keep a close fit, to take a little off the torque tube. I did that and tried again. It got bound up again after I pushed it on about 1/2" It was locked up, frozen, stuck... I was once again STUCK and frustrated! I'm just glad I hadn't used the Loctite yet. It bound up and I didn't have the hand strength to just twist and slide it off because of the position of the assembly and the cockpit floor.

    A friend suggested penetrating oil. Thankfully that worked. I guess I'll sand some more and try again. Any other suggestions.

    Troy how would you debur the inside of the holes on that rear mast? I have run my finger over the holes and they seemed fine, but I suspect that could be part of the problem.

    One other issue bothers me about my torque tube installation so far. When I got the front torque tube bushings and stiffener torqued in place it felt to me that roll movement force required to rotate the tube would be way too stiff. How do you tell if it's too stiff? Mitch suggested I might need to fabricate and install a very thin aluminum shim between the top and bottom bushing. Any recommendation?


    Jim Morrical
    well now I guess I'll join the club. Mine was very tight but after fitting it to the torque tube and drilling the rivet holes, it was hard but I got it removed OK. Now I installed it into the floorboard and applied the 680 Loctite and starting putting it on and with about 1/4" to go, it's stuck stuck stuck! Tried penetrating oil and it won't budge. I don't know if that Loctite hardens up or not but it's STUCK!

    I see the specs say it's suppose to be 30" +/- .020 between the 2 holes in the front and rear mast but I don't see where another 3/16" would be that big a deal?

    Loctite 680 sets up and hardens and it removeable by applying 250 degrees Loctite says but I don't think I can heat that up that much in that area without damaging the floorboard. I guess just have to cut it off and start over with a new part.
    Last edited by Daveembry; 09-11-2016 at 01:00 PM.

  9. #19
    Senior Member TroyBranch's Avatar
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    Default Re: Torque tube.

    The tube is cheap, I would cut it in two and get a new tube. You should be able to get it apart once it is out with heat. I would confirm with Mitch that the heat will not hurt the machined part.
    Next round make sure all burrs are off both sides of the holes. It's amazing how little will jam it up. The loctite is very thin and watery, so it shouldn't jam it.


    Sent from my iPhone using Tapatalk

  10. #20
    Member jmorrical's Avatar
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    Default Re: Torque tube.

    No fun Daveembry.

    I disassembled my front stiffener and torque tube bushing assembly after I finally got the aft mast free. Then I sanded the aft end of the tube and test fit the aft mast several times before I was confident I could do it with the tube installed thru the floor. I have not put the aft mast in place yet.

    Now that I have put the forward torque tube bushing assembly back together and torqued the AN4-24A bolt and AN365-428A nut to 90 IN-Lbs as specified on page #53 of the Fuselage Manuel I can hardly rotate the tube. Mitch suggested making a shim from scrap the same thickness of the outboard leading edge skins, about .016" thickness for one side of the blocks. Cutout scraps from the landing light trimmings from the wing build should work. I'll let you know how that works when I get back to it.

    I wondering if the specified 90 IN-Lbs torque is correct or has there been a change? I noticed at 70 IN-Lbs the tube rotated nicely. Any comments? As things change and sometimes don't get posted to the manual it's worth asking.

    Thanks

    Jim Morrical


    Last edited by jmorrical; 09-12-2016 at 01:50 PM.

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