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Thread: Parking Brakes?

  1. #1
    cubman's Avatar
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    Parking Brakes?

    I am building a Javron cub and have the Grove brakes, master cylinders and pedals. I am installing the plywood floor right now and am close to drilling holes for rudders, brakes, etc. Before drilling holes into the floor for the brake lines, I need to decide whether to install parking brakes and if so, which product. Any advice?

  2. #2
    Steve Pierce's Avatar
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    Does the Javron come with just blank floorboards? The stock Piper floorboards accommodate the factory brakes and parking brakes. Not sure what Javron uses. I have seen Groves master cylinder that looks similar to factory with Steve's or North River booster. Can you post a picture of what you have? I think Robie Grove makes a parking brake like the Scott that Piper used. It is nice to lock the brakes in the wind or on an incline so you can get out. I have seen simple on/off valves, you just have to remember to turn them off. The originals kick off when you push the brake pedals.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

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    Don't run the lines through the floor. Run them out the side of the fuselage with a bulkhead fitting that keeps the lines above the floor. That way everything is easy to get too. Downside of this advice is now you need to weld tab on side tube.
    DENNY

  4. #4

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    I have seen problems with parking brakes on Cubs. Four different aircraft, two different systems - inadvertent brake lock. Only damage so far was a broken tail wheel. Usually the owner is not aware of exactly what the problem is.

    My old friend Don Marks said "get those things outta there."
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  5. #5
    cubman's Avatar
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    Parking Brakes?

    Thanks Steve. The floorboards come from Javron cut for the rudder pedals, brake pedals, etc., but not for the 3/16 bolt holes to fit the clamps and straps. Also, there are not holes for the L/R hoses through the floor and out to the gear. Not having the holes to the gear makes sense because where you drill the holes for the L/R brake lines depends on where parking brake fitting is located.

    I've discussed pros/cons of parking brakes with others, and have decided to install them. I assume not all designs are the same. It appears the Scott L/R master cylinders and parking brake valves extend forward with a 45 degree elbow coming out of the bottom and a flexible line coming out of the elbow.

    I called Robbie and he sent me a drawing of his solution. I looks like it will clear the airframe substructure just fine if I have the hoses come off the fittings at about a 45 degree angle. See attached drawing and pictures.

    It seems best to wait until after I receive the parking brakes to drill the holes for the hoses.

    Randy
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  6. #6
    stewartb's Avatar
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    Had this valve in my old certified -12 and now again in my exp Cub. Simple. Works great.


    http://www.matcomfg.com/PARKINGBRAKEVALVEDUAL-idv-3579-8.html
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  7. #7
    Steve Pierce's Avatar
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    This is how Piper did it and the lines exited out just behind the front gear fitting and down the gear leg. I have been using these parts with a single braided line all the way from the master cylinder to the caliper.
    https://www.summitracing.com/parts/AER-FBM1101
    https://www.summitracing.com/parts/AER-FCC0420
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    Steve Pierce

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    Will Rogers
    Thanks cubman thanked for this post

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    There was another thread on this a while ago. Parking brakes are a good idea, you will need them eventually, but I made a couple of “safety” clips to keep the parking brakes from being deployed unless I deliberately take them off. Checking that the clips are on is part of my pre-flight.
    Likes hotrod180, PerryB, tedwaltman1 liked this post

  9. #9
    Bearhawk Builder's Avatar
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    Looking for this parking brake if available. Doesn't seem to be a Scott unit, or maybe it is but there are no markings. This one has a crack at the thread area. Better off to just buy a new Univair unit?.Click image for larger version. 

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  10. #10
    Steve Pierce's Avatar
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    Looks like a Huff, I will look at what I have.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  11. #11
    Bearhawk Builder's Avatar
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    Thanks Steve, I ordered one from Univair already. The other side is fine but may replace that one to match.
    Do these Huffs kick off with brake pressure?

  12. #12
    Steve Pierce's Avatar
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    I am not sure. I have found theminstalled in mismatched sets as replacements for the Scotts on several Super Cubs.
    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

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  14. #14
    Steve Pierce's Avatar
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    Must be a Scott 4200 not a Hoof. I only have one that has marking on it with the rounded cast body.
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    Steve Pierce

    Everybody is ignorant, only on different subjects.
    Will Rogers

  15. #15

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    ive tried to figure out the story on the round ones and still havent been able to do it. years back wag was selling some for about 20 bucks apiece. heres a scott 1954 catalog.https://www.univair.com/content/1954-scott-catalog.pdf

  16. #16
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    I just pulled 2 of the round ones out of my Cub and tore them down to clean. No markings, but I'm assuming 4200s. Does anyone know if the o-rings for the square 4200 will work? If not, does anyone know what the sizes are?

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  17. #17
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    Have enough thrust and mediocre brakes, and taking off with the parking brake engaged, especially on dirt or turf, is not a real breaker. You WILL wonder what the hold up is on lift off though: been there/ done that.Matco for me, hard to imagine a scenario of engaging it prior to landing, even I haven't done that yet.
    Last edited by courierguy; 06-27-2021 at 08:10 AM.

  18. #18
    WWhunter's Avatar
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    Personally I would install one. My RANS has the MATCO one, similar to the example Stewartb linked. The plane is so light that when on any incline or with a bit of breeze, it is hard to exit without the plane getting moved around in the wind. Reaching for chocks or tiedowns can be like watching a monkey on a jungle gym at times. The unit is a simple design and works great. I don't have parking brakes on the Rebel, Was flying last week in some gusty winds and when I landed and exited, it was a demonstration like I mentioned above. I actually just put the unit on my wish list yesterday so I can purchase one at Oshkosh.
    Don't take life too seriously ... no one gets out alive!

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