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  1. #1
    Join Date
    Jan 2008
    Location
    NSW
    Posts
    11

    Default Box trailer suspension lift

    Hi guys,

    I have a heavy duty box trailer that I take onto some steep and fairly rough building sites behind my 4WD.

    I would like some more clearance under the box trailer for passing obstacles and avoiding dragging the tail on steep gullies etc. The towball on the truck is also a fair bit higher than the trailer so it drives a bit 'nose-up'.

    I was thinking of moving the axle from on top of the leaf springs to below the springs. I believe it is called a spring-over conversion in the 4WD world.

    Looks like a very simple process - just remove the wheels, remove the 4 U-bolts, flip axle over and reassemble.

    Is there any saftey or rego issues I haven't considered?

    Thanks in advance.

  2. #2
    Join Date
    Mar 2008
    Location
    Newcastle West Australia
    Posts
    197

    Default

    Been there done that had no problems.

    www.solidwoodfurniture.com.au

    A good edge takes a little sweat!!

  3. #3
    Join Date
    Jan 2008
    Location
    NSW
    Posts
    11

    Default

    I read that some trailer axles have camber or castor or whatever built in. Is my garden variety trailer likely to have this and can I stuff it up by flipping the axle?

    Now I am wondering... should I flip the axle 180 degrees, or keep it in the same orientation and just drop it below the springs?

    Cheers.

  4. #4
    Join Date
    Mar 2008
    Location
    Newcastle West Australia
    Posts
    197

    Default

    You would be very lucky if it is straight let alone have camber built in.

    www.solidwoodfurniture.com.au

    A good edge takes a little sweat!!

  5. #5
    Join Date
    Apr 2008
    Location
    Southern Riverina
    Posts
    24

    Default

    Just swapping spring-under for spring-over is cheap but it will only buy you a couple of inches.

    Maybe think about replacing the hubs too so they take the same rims as your 4WD (you can find 6-stud trailer hubs in Supercheap for not much), then pick up a couple of steel rims to suit from a wrecker. Bigger wheels will make a much bigger difference off road, and being able to interchange your spares is a real bonus.

    Personally I'd probably replace the springs with some higher, heavier ones while I was at it - they aren't particularly expensive.

  6. #6
    Join Date
    Dec 2004
    Location
    Northen Rivers NSW
    Age
    57
    Posts
    131

    Default

    Hey

    No worries with putting the axle under the springs. Just remember that there is a small axle pad with a hole in the middle that is welded to the axle that the spring bolt (holds spring together in middle) head locates in to locate the axle. You may have to remove this bolt and turn it around so its round head fits the pad. If so you will need to clamp the springs together before you remove the bolt.

    Camber or castor is not an issue in a trailer as the car effectively tells it where to go.


  7. #7
    Join Date
    Feb 2006
    Location
    Central QLD
    Age
    61
    Posts
    21

    Default

    If it were me Iwould swap the axle as said before. The extra couple of inches should make enough difference for good clearance.

    The bolt that dazzler is talking about is called a center bolt and may have to be replaced with a new one as they have a habit of seizing up over time.
    Cheers,
    Buzzer :)

  8. #8
    Join Date
    Apr 2006
    Location
    Brookfield, Brisbane
    Posts
    0

    Default

    just remember you wil gain no clarance under the axle by doing this it wil stay the same distance from the ground. otherwise there will be no pronblems.

    www.carlweiss.com.au
    Mobile Sawmilling & Logging Service
    8" & 10" Lucas Mills, bobcat, 4wd tractor, 12 ton dozer, stihl saws.

  9. #9
    Join Date
    Jan 2008
    Location
    NSW
    Posts
    11

    Default

    Thanks for the info everyone. Will give it a go this weekend.

  10. #10
    Yonnee's Avatar
    Yonnee is offline Trailer Bloke & Mild Mannered Moderator
    Join Date
    May 2007
    Location
    Tooradin, Vic.
    Age
    52
    Posts
    1,318

    Default

    Camber is only put into caravan axles that are on their upper weight limit. It helps a little with tyre wear.

    The centre pin/bolt through the springs will be your only hiccup. The head of the bolt is at the top of the spring, so putting the axle underneath, the 'spring pad' (the little square spacer usually welded to your axle) wont be thick enough to clear the thread of this bolt. You can either shorten the thread with the grinder, or clamp the spring, remove the bolt and poke it through from the bottom.

    Easy enough to do otherwise and will gain you more than some think. Even with only 4lf springs you'll go up 3", and that's a fair bit of extra departure angle.

    Yonnee.
    Too many projects, so little time, even less money!
    Are you a registered member? Why not? click here to register. It's free and only takes 37 seconds! Doing work around the home? Wander over to our sister site, Renovate Forum, for all your renovation queries.

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