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  1. #1
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    Default Home made U bolts Vs buying ready made

    Hey guys doing a aluminium trailer build on another forum and i was about to order 4x 12mm U bolts which cost a whopping $180 so i bought some 16mm round rod and used my hydraulic press to make the U bolt the test sample worked great but i have been advised not to use the home made U bolts because professional U bolt threads are rolled and not die cut or lathe cut as the rolled cut are far superior is this true?

    the U bolts are to attach the spring hanger assembly to the trailer, my test sample i bent has larger radius than i need but the die used was just a lathe off cut if i make the U bolts the die will be smaller for a tighter radius

    the steel is just regular Australian mild steel 16mm over the 12mm bought ones, if i can make my own should i step up the size 20mm or will 16mm be sufficient?

    cheers

    EDIT: Oops just reliased this should have been posted in the trailer section < edit: Did it for you - Grahame>
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  2. #2
    BobL is online now Member: Blue and white apron brigade
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  3. #3
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    Thanks Grahame

    Bob i took a look they dont sell the size i need i need a custom size IW:90mm, Hight: 165mm, When i got the quote of $180 or 4 pieces that was without mentioning the size i soe how think the price may increase due to the large'ish size of U bolts but more need to find out if homemade U bolts can work and if so what thickness would be sufficient

    The U bolts are for this aluminium boat trailer i have built from scratch its has been in the making for months now but slow progress i am chipping away the U bolts are for the spring hangers

    trailer is 7 meters long for a big boat i am also chipping away at rebuilding a once in a life time rebuild and make over custom boat
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  4. #4
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    Commercial bolts these days are rolled rather than cut which gives a tougher thread.

    I would suggest that you get commercial bolts even if that means adapting the trailer to suit. In terms of building a boat $180 is a pittance but if your home made bolts failed, you would have to show the insurance company (or if there was damage to property or people a court) that you had worked out these were strong enough, were of good quality material, were properly made and so on.

    Think of the mass of a 7m boat and trailer, and the damage it could do if the axle came loose even at 60kmh...

    Michael

  5. #5
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    Default

    Try somewhere that does truck spring and suspension work. U bolts that size are common on trucks and therefore you will get the best price you are likely to.

  6. #6
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    I have googled every where in oz the common size is 75mm or 100mm wide no 90mm so i have to get them custom made, the 100mm wide u bolts are $40 a set of 4 vs custom set of 4 for $180 its a bit of coin to be throwing away

  7. #7
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    A 16mm thread is going to be stronger then a 12mm thread, cut or rolled.

    Remember, steel nuts do not have rolled threads, they are cut..
    Gold, the colour of choice for the discerning person.

  8. #8
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    Quote Originally Posted by gazza2009au View Post
    I have googled every where in oz the common size is 75mm or 100mm wide no 90mm so i have to get them custom made, the 100mm wide u bolts are $40 a set of 4 vs custom set of 4 for $180 its a bit of coin to be throwing away
    You're not really throwing anything away, as you're getting specific U bolts for it.
    Besides, IF you made your own and something went wrong, you'd be up for a LOT more than $180.00.
    This way should something go wrong, you can blame the supplier, NOT yourself.
    You mightn't use it all that much, but if it's sold and the new owner has problems it could come back to you.
    Just as an aside comment we built a tri axle trailer with Timbren suspension, that kept breaking 16mm axle Ubolts.
    It was used on a very rough gravel road, but it still broke them. The suspension was changed to a roller rocker, which seems to have solved the problem
    Kryn
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  9. #9
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    I'll buy the propper bolts

    Kryn i set this trailer up with dual leaf springs with the spring on top of spring for the middle hanger i seen this was one recommended set up by ALKO the trailer sits a little lower than rocker and i will be running 9" wheels with truck tyres, trailer will be set up drive on drive off so it had to be the lowest height possibly for those really shallow boat ramps and solo launching

  10. #10
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    Quote Originally Posted by KBs PensNmore View Post
    You're not really throwing anything away, as you're getting specific U bolts for it.
    But are U Bolts anything special? Apparently they are grade 5 or 8 and bent out of blanks. https://www.youtube.com/watch?v=Fl-2TAYIoGA
    Gold, the colour of choice for the discerning person.

  11. #11
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    Instead of two U bolts, what about 4 bolts and two of the four hole plates.

    Hooroo.

  12. #12
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    Years ago I made a pair of U bolts to fit a sidecar, following a description on how to do it that I found somewhere.
    With the right material threaded, oxy-acet to heat and bend, then plunged in oil - all looked good.
    Installed, I made a cup of coffee before the first test drive.
    Sipping away and admiring my new vehicle, I heard two loud "pings" in succession, as the U bolts fractured at the bends - unlucky but really lucky.
    The article I worked from did not mention tempering.
    A little knowledge is a dangerous thing, sometimes.
    Last edited by nadroj; 13th Aug 2019 at 09:17 AM. Reason: More clarity

  13. #13
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    Nad watch that video RC posted the link to they specifically say not to use heat and to only cold bend the steel for the very reason u posted

  14. #14
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    Evidently U-bolts can be bent hot but they need correct heat treatment afterwards.
    Cold bending seems foolproof if you have beefy enough tooling.

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