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Thread: Brake Cylinders and Torque Tubes

  1. #1

    Join Date
    Oct 2017
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    Whitefish, MT
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    Default Brake Cylinders and Torque Tubes

    I've installed my adjustable rudder pedals and cables, and the brake cylinders that attach to the pedals. The inside brake cylinders (pilot right/copilot left) significantly limit the rearward rotation of the rudder pedals when the bottom of the cylinder makes contact with the torque tube. (Photos below.) Between the firewall limiting the forward movement and this limitation of rearward movement, the total distance is about seven inches, which seems short to me. But I'm a first time builder, so maybe this is the right amount?

    While searching the forum, I came across John Pitkin's suggestion to move the entire rudder assembly back a couple of inches, which I think would also address this issue by allowing more forward rotation. I'd be interested to hear the experience of anyone who made this modification.

    Outside rudder pedal swing
    Outside.jpg

    Inside rudder pedal swing
    Inside.jpg

    Limiting contact between brake cylinder and torque tube
    Contact.jpg
    Jeff Kendrick
    Building an SS7
    EAA Chapter 102

  2. #2
    Senior Member efwd's Avatar
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    Default Re: Brake Cylinders and Torque Tubes

    Jeff, your rudder stops are going to limit the travel of your pedals. What you have goin on is normal.
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  3. #3

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    Default Re: Brake Cylinders and Torque Tubes

    Thanks, Eddie. It's quite anxiety-reducing when someone who's already built one tells you things are going as they should be!
    Jeff Kendrick
    Building an SS7
    EAA Chapter 102

  4. #4
    Senior Member
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    Steilacoom, WA
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    Default Re: Brake Cylinders and Torque Tubes

    Isn't there a diagram in the build manual showing where you may need to grind that corner off the master cylinders?
    Kitfox 5 (under construction)
    Commercial SE/ME, CFII

  5. #5
    Senior Member efwd's Avatar
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    Default Re: Brake Cylinders and Torque Tubes

    Alex is onto something. I didn't have to adjust anything as my master cylinders worked as installed. There is in fact mention that you need to check the clearance between the "inboard" master cylinders and the torque tube and modify as needed. As with many things on these kits, some people have issues where I had none. Nice that this one should be an easy modification. Thanks Alex. This is how this forum becomes most valuable.
    Eddie Forward
    Flying
    SS7, 912iS, Garmin G3X

  6. #6

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    Default Re: Brake Cylinders and Torque Tubes

    Quote Originally Posted by alexM View Post
    Isn't there a diagram in the build manual showing where you may need to grind that corner off the master cylinders?
    Yes, I found the note (as did Eddie):

    Fit the inboard master cylinders and check the clearance between them and the torque tube. Modify them, if necessary, in accordance with figure E5.

    (That's my emphasis.) But--there is no indication of any potential modifications in that figure. Since the manual said they can be modified, I went ahead and ground the corners back a bit with a Dremel sanding drum and find the situation much improved.

    In the online manual (but not in my vintage 2011 manual), figure E5 has another bit of information that may indicate the source of my issue. There is a note that the space between the cylinder mounting bracket and the torque tube should be 0.125 (1/8"). In my kit, the brackets were placed by the previous owner/builder almost right up against the torque tube. I even had to remove one of them and file it back a bit because it was rubbing against the torque tube causing binding and removing the powder coat from the tube. I can now slip a piece of paper in the gap, but it's nowhere near 1/8 inch. This positioning causes the interference between the cylinder and torque to occur with less pedal deflection.

    As usual, the forum has come through again! Thanks everyone!
    Last edited by JeffKinMT; 09-03-2021 at 09:20 PM.
    Jeff Kendrick
    Building an SS7
    EAA Chapter 102

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