Custom built roof rack - engineering advice please





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  1. #1
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    Default Custom built roof rack - engineering advice please

    I need some advice please

    I own a Jimny as you can see and as you know it doesn't have a lot of interior space. So on the roof I have a Thule box which is sufficient packing space for my needs.
    I need to carry extra fuel and a gas bottle though. These things need to be outside the vehicle. Especially the fuel because of the smell.

    The materials I intend to use is Aluminium angle-iron and slats/strips. All welded together. The roof rack will be attached to the Thule bars with U-bolts (green arrows in pictures)

    The first option is to place the roof box forward and carry the fuel behind it. This is the neatest solution. Pleasing to the eye and less wind resistance.
    But I am concerned that corrugated roads and potholes will shake such a roof rack apart.
    It will be bolted onto the Thule bars with U-bolts (green arrows in pictures) and have a rubber bung (blue arrows) to reduce some of the flex in the frame.
    I am not certain that my design will be strong enough to survive Africa.

    The second option is to move the Thule box off to the side and placing a very simple rectangle alongside it. The layout doesn't look nearly as good as the first option but it is stronger and safer. It also disperses the weight over the roof better and will have little or no flex.
    I can allow a few centimetres between the box and the fuel so that the Thule's lid can still hinge open.

    What do you engineers think? Can I go with the first design of am I right in thinking that it'll break?
    Alternative suggestions are most welcome.
    Thanks
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  2. #2
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    With a good Jerry can you get no petrol smell inside the vehicle.

    YES, I know of the dangers of petrol inside the vehicle.

    BUT, That kit is way over the weight limit for the Jimny.


    PS - I have done a few thousand kilos with the jerry can inside my Jimny.

  3. #3
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    Quote Originally Posted by ChrisF View Post
    BUT, That kit is way over the weight limit for the Jimny.
    okay thanks. I didn't know that. I feel a bit like a moron...

    obviously the jerry will be completely empty except for that one day I know I will be driving further than the range permits. Only then will I fill it at the last garage. So most of the time it will be empty containers on the roof

  4. #4
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    Sadly the Jimny has a VERY low carrying capacity on the roof, 30 or 50 kg.

  5. #5
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    I can't really help much with your roofrack but can't resist commenting on your signature pic.

    Fear and Loathing, yay! Bats! Bats!

  6. #6
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    "As your attorney, I advise you to take a hit out of the little brown bottle in my shaving kit. You won't need much, just a tiny taste"

    Quote Originally Posted by ChrisF View Post
    Sadly the Jimny has a VERY low carrying capacity on the roof, 30 or 50 kg.
    I looked it up. 40kg
    I'm hoping the box plus contents will weigh no more than 30kg. That leaves 20kg for 25litres of fuel but only for a few hours and I will try to take it easy whilst there is fuel on the roof. I'm sure the pillars can handle brief and infrequent overloading. Wishful thinking?
    The No.7 Gas bottle can go inside.

  7. #7
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    Quote Originally Posted by ChrisF View Post
    Sadly the Jimny has a VERY low carrying capacity on the roof, 30 or 50 kg.
    Sadly the Jimny has a low carrying capacity full stop.
    360kg according to the licence disc. If you are carrying 4 people this does not leave one much weight for luggage

  8. #8
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    Quote Originally Posted by LuckyStriker View Post
    I looked it up. 40kg
    I'm hoping the box plus contents will weigh no more than 30kg. That leaves 20kg for 25litres of fuel
    Not by my maths! 40-30=10, and you haven't allowed for the weight of the roofrack. Furthermore, I'd be surprised if the box and contents will weigh only 30kg........so why not get rid of the box? Strap a bag up there with light but bulky items such as sleeping bags.

    One jerry can, 20 litres, weighs 20kg (petrol) or 22kg (diesel)....and about 4kg empty.

    Mike
    "A poxy, feral, Brit architect who drinks bad beer and supports the wrong rugby team." Tony Weaver

    "Mike for President" Freeflyd

  9. #9
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    Quote Originally Posted by Woolf View Post
    Sadly the Jimny has a low carrying capacity full stop.
    360kg according to the licence disc. If you are carrying 4 people this does not leave one much weight for luggage
    but let's not forget, when carrying 4 people there really is not much space left for luggage ...

  10. #10
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    With a Jimny you have a choice; 2 regular sized people or 4 midgets.
    If midgets then you will have plenty of carrying capacity left over. They wear small clothing and eat tiny morsels

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