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Thread: Spring tension hose clamps

  1. #1

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    Default Spring tension hose clamps

    Hello everyone! It's been cold here in Nebraska and I've noticed small antifreeze leaks. I pulled the cowling off and noticed drips coming off the spring tension hose clamps. Does everyone use these or do you use regular hose clamps?? Thanks

    Patrick hintz
    Kitfox series 6
    Rotax 100 hp

  2. #2
    Senior Member jiott's Avatar
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    Default Re: Spring tension hose clamps

    I used regular hose clamps for the cooling system hoses I installed, but kept the spring clamps that came with the Rotax 912 installed hoses. I have never had a leak with the Rotax spring clamps, but have had a few small leaks with my screw clamps. Whenever I change a hose I will use the better Oeticker or fuel injection clamps next time around. Will keep the Rotax supplied spring clamps on those hoses.
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  3. #3
    Senior Member Dave S's Avatar
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    Default Re: Spring tension hose clamps

    Hi Patrick,

    Can't say that we have ever had any observation of drips at the small hoses with the Rotax spring clamps...I did swap out the hoses at the 5 year schedule and found that the newer Rotax brand small hoses were more pliable and a little larger on the OD than the originals - The spring clamps are one version of a constant pressure clamp which adjusts for material shrinkage in extremely cold conditions. The only thing I can think of is either the spring clamps are a little weak, or the hose is not as pliable as it should be - but they should work in normal conditions.

    I do not like the basic screw clamps at all....they are not smooth on the inside so the hose rubber tends to squeeze up through the slots; and, they are definitely not a constant pressure design. We replaced the 1" screw clamps for the radiator hoses with constant pressure clamps and found that solved the cold shrink/drip problem - the new clamps were smooth on the inside and wider than the screw clamps - this particular design utilizes a stack of small belville washers to accomplish the constant pressure.
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  4. #4
    Senior Member kmach's Avatar
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    Default Re: Spring tension hose clamps

    I had screw type hose clamps on most hoses before my five year hose replacement. Our climate has a big tempature swing from summer to winter, in the winter I had drips from the coolant hoses.

    At my 5 yr hose replacement I switched all coolant hose clamps to the spring type that apply constant pressure and have never had a drip ever since.
    Kevin,

    Kitfox Outback
    912 ULS
    Airmaster AP332CTFH-WWR70W
    Summit Aircraft Wheel Skis
    C-FOXW

  5. #5

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    Default Re: Spring tension hose clamps

    Quote Originally Posted by Dave S View Post
    Hi Patrick,

    Can't say that we have ever had any observation of drips at the small hoses with the Rotax spring clamps...I did swap out the hoses at the 5 year schedule and found that the newer Rotax brand small hoses were more pliable and a little larger on the OD than the originals - The spring clamps are one version of a constant pressure clamp which adjusts for material shrinkage in extremely cold conditions. The only thing I can think of is either the spring clamps are a little weak, or the hose is not as pliable as it should be - but they should work in normal conditions.

    I do not like the basic screw clamps at all....they are not smooth on the inside so the hose rubber tends to squeeze up through the slots; and, they are definitely not a constant pressure design. We replaced the 1" screw clamps for the radiator hoses with constant pressure clamps and found that solved the cold shrink/drip problem - the new clamps were smooth on the inside and wider than the screw clamps - this particular design utilizes a stack of small belville washers to accomplish the constant pressure.
    Hey Dave , Not sure what to tell ya, I will keep an eye on it for now but may change the hoses alittle early maybe and try again. I agree that the spring tension should be the best.

  6. #6
    Senior Member kmach's Avatar
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    Default Re: Spring tension hose clamps

    I just thought of this, make sure your spring clamps are on the hose just aft of the bulge on the aluminum fitting, not on it but just beside the flare.

    The rotax hose is very flexible and soft, I could see a leak potential if you use a hard composition hose.
    Kevin,

    Kitfox Outback
    912 ULS
    Airmaster AP332CTFH-WWR70W
    Summit Aircraft Wheel Skis
    C-FOXW

  7. #7
    Guy Buchanan's Avatar
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    Default Re: Spring tension hose clamps

    I really hate dealing with spring clamps during service. I know their worth, but hate them so much I replaced them all with screw clamps; much easier to install. So this begs the question, does anyone know of a constant pressure screw clamp?
    Guy Buchanan
    San Diego, CA
    Deceased K-IV 1200 / 912uls / 70" Warp 3cs

    gebuchanan@cox.net

  8. #8
    Senior Member Dave S's Avatar
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    Default Re: Spring tension hose clamps

    Guy,

    I agree the spring clamps are a PITA....ended up buying a pliers for them from the auto parts store - the pliers has a pair of anvils that rotate to get at the ugly angles a person deals with. I kept the spring clamps on the small hoses.

    I believe one of the other list members from Canada uses spring clamps for the 1" hoses - I couldn't find any the right size so went to an alternative style (which is a bit more costly @$7 each)

    There are several versions of constant pressure clamps - the ones I got from Fastenall are represented in the attached photo and I used them on the 1" hoses

    Others designs use small coil springs rather than bellville washers.
    Attached Images Attached Images
    Dave S
    Kitfox 7 Trigear (Flying since 2009)
    912ULS Warp Drive

    St Paul, MN

  9. #9
    Senior Member jiott's Avatar
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    Default Re: Spring tension hose clamps

    What about fuel injection hose clamps? They are screw type but I believe considered 360 degree const. pressure clamps?
    Jim Ott
    Portland, OR
    Kitfox SS7 flying
    Rotax 912ULS

  10. #10
    Senior Member jrevens's Avatar
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    Default Re: Spring tension hose clamps

    I'm using some of those using the belleville washers also, Dave - made by Breeze, all S.S. I found a really good deal on them on the internet in boxes of 10, but I've misplaced the info on that - it was a big truck supply place. I think they're a little large & bulky for the small coolant hoses on the engine, but I like them for the oil hoses that go to my oil thermostat especially. I decided not to use them on my silicone hoses... I think the surface of that hose is so soft & "conformable" that they won't be needed for a reliable leak-proof joint. I did use "silicone" type clamps with an all-smooth surface against the hose though. I got sizes for both the smaller & the larger 1" hose,but ended up not using the larger ones. I'd sell the constant pressure ones I have left over for $3 each. As I said, I've got some for the big & small hose sizes.
    John Evens
    Arvada, CO
    Kitfox SS7 N27JE
    EAA Lifetime
    Chap. 43 honorary Lifetime

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