Trailer Frame Ideas - Wadda ya reckon??

[gav74]

Hi to all at Expo,

This is my first post. I have been lurking in the forums studying and appreciating all the awesome trailer builds people have done. I have been wanting to build a purpose built off road camper-tent trailer for a while now and its time to start planning. I'm building this trailer to take it to Cape York (Aus) about this time next year, 6000k+ round trip. Its the last 1000k's that is the real killer. The terrain on this trip will be extreme. Apparently the road to The Cape is littered with broken trailers and I don't want mine to be one of them. It would be absolutely heart breaking to leave a fully equipped trailer on the side of the road to be picked over by passers-by. Anyway I have plenty of time to build the trailer between work and paying bills.

I have been working on frame plans for a week or so and they have already changed many times but this is what I have so far. I gained inspiration from Box Rocket and Mike's Trailer Build as you can see.

Steel and weight of frame should come to @
12m(39ft) - 75x50x3 (3x2x.120) = 65kg(143lb) main and outer A frame.
2.7m (9ft) of 65x65x3 (2.5x2.5x.120) = 15kg - inner A frame
3.6m (11ft) of 65x65x5 (2.5x2.5x3/16) = 31kg - tongue
total weight of trailer chassis 110kg (240lb)

So do reckon this design going to be strong enough for hard core off road adventuring?
How does the weight sound?

Any comments, advice or recommendations are welcome as its easier to change the design now.

Cheers,

Gav.

 

[FlatlinesUp]

Frame looks nice, but I'd bet a dollars worth of donuts that most of the trailer litter that was left wasn't due to frame issues, but something smaller.

When you build, pick the best out of your options and don't sacrifice on strength/reliability on the small details. I'd pay particular attention to the tongue/hookup, suspension/axle, and would consider a brake axle even

 

[Spudy]

i agree. i would assume most trailer that would brake down would normally be an axle or suspension problem. If not that it then maybe the trailer lookup its self.

BTW frame design looks great.

 

[gav74]

Thanks for the replies.

I'll probably weld some fish? plates on the tongue where the A frames meet up and under the four corners of the box for extra strength.

The axle and suspension I would like to use is by Huntsman (Aus). The kit has a 45mmx1700mm (67") axle, 7 leaf 1600kg eye to eye leafs, 10" electric brakes with handbrake, 6 stud cruiser hubs and all the hardware to put it together. Just have to work out what the final loaded weight will be. Also looking at a Treg Hitch.

I'll be towing it with a BJ74 so I think a 67" axle will work well to keep the trailer tyres tracking the same as the Cruiser's. Does that length axle sound right for a 70 series footprint?

Cheers, still working on my welds.

Gav.

 

[UK4X4]

That double V and such narrow angles you will have problems welding , unless your using stick and not mig

and all that steel is also just being supported by the front single tube, if its 3/16 then its failure prone,but I'mguessing its a mispell and its 5/16"

Most on here use a full 2.5" X 1/4" tounge - to double as a 2" reciever

at both ends.

Your cross members could be smaller wall if you wanted as they won't support much actual weight

when I made mine the outer steel 3"'s were notched and bent and then welded, rather than cut and welded.

 

[R_Lefebvre]

The double Vee is overkill. And not in a good way. It's wasteful. Your two center transverse frame members should be positioned at the same fore/aft location as the spring hangers, assuming you're using leafs.

 

[gav74]

Thanks for the feedback Rob and UK4X4,

After reading some of your posts a respect your opinions. I'll lose the the double A frame idea. Its extra weight and to much weld on the front tube I was worried about with that design. I'll keep researching and come up with something better.

In regards to the A Frame, the designs I like have a long single tube as the the draw bar to help in jack knifing situations on a narrow trail. Does the single tube compromise strength and would it be better to run a longer A Frame closer to the coupling down to the front spring hangers?

I'm new at this but hoping to build a solid off roader.

I will be using stick for the frame and get a mate with a mig to do the sheet for the box.

Cheers.

 

[Windaroo]

Your design would fail I believe with all your welds at the front of your box area. You need to have an A frame design going as far back as possible.

Look at a design like something along the chassis design on this site http://www.trailerplans.com.au/?page_id=405

You can build whatever sort of top/box on the top you need but the chassis frame is critical to survive the trip north

 

[R_Lefebvre]

You can absolutely have a single tube draw bar design. Lots of trailers are built that way. You just need the right piece of tube. Somewhere around here, I think maybe NTSQD posted a link with some guidelines for doing that. I think a lot of us (myself included) are really overbuilding these things compared to the weight of the trailer.

Another reason why most of us are using a triangular tongue is because we can mount stuff on top easily.

If you are really worried, maybe what you could do would be to build a good single tube tongue, but then have bolt-on side braces. In the rare case you need to fully jack-knife, just unbolt the braces.