Outer Limits 4x4 Board

Hey, looking at buying either a second hand - max couple year old trailer or new trailer, mainly for towing bikes on but still has to be a box trailer so it can be used for moving houses and so on.

Will have to fit 3 fullsize 450's etc at times so I'm guessing the smallest you could go would be a 7 x 5.

What I'd like to know is for offroad towing , beaches and something a bit bumpy, is the minimum clearance you would want with a 7 by 5 trailer, what duty you'd recommend - light medium heavy extra heavy ( keeping in mind it'd be used maybe 6 times a year offroad)

What designs to look out for, tilt trailers etc and experiences with taking a say close to 7 by 5 heavy duty trailer offroad , vehicle towing it etc, the more info the better so i can make an informed decision on my next purchase aaaaannnndddd if anyone wants to sell one that could be helpful to

out of 70 people who've seen this none have taken a trailer offroad or have had any experience with them ?!

I would say that off roading persay doesnt really hurt trailers as it is moslty low speed work, it's higher speeds & corrogations that causes issues. Especially when loaded.

I would buy the heaviest you can afford with a decent spring pack (given you will probably have leaf springs being a box trailer) and heavy duty mounts. What I have seen with trailers is the spring mounts break & light duty springs fail. Most of them come with Holden or Ford wheel bearings which are more than stron enough for box trailer loads.

You will also need a hitch that allows articulation, a 50mm tow ball wont cut it for angles of articulation.

I also personally think you dont need an "off road" trailer with 31" tyres to go off road. Most people wont take trailers rock hopping & a 7x5 wont really drag its arse while off road on normal fire trails. You might want wider tyres on the sand but if you look at how big the boats were that people used to launch off the beach on Fraser Island in the Toyota fishing comp then you will see what I mean. Most trailers wont carry enough weight to warrant a 31x10.5 for off roading.

That is all I can add, a well built trailer will give you good service provided you dont knock it about.

mkpatrol wrote:You will also need a hitch that allows articulation, a 50mm tow ball wont cut it for angles of articulation.

Went camping with my father last week. Heavy rains had affected the track to our normal camping spot - we didn't actually make it all the way in, but I bent my towbar dragging our trailer of firewood.

Interesting, didnt even think of the articulation factor ! Im guessing most "heavy duty" 7 by 5's you see new for sale would at least have decent springs packs but whats the best way to tell , number of leaf's , length or ???

Im going to have a look at a few this week just to suss out the different designs from each trailer place till i find something solid, any idea on what you put a minimal height at?

How about something like this.



7x4 high sides
Tipping (greasable pins made from spring hangers so VERY strong)
75x50x3mm extended drawbar
100x50x3mm chassis
3mm checkerplate floor
2ton axle with 1500kg rated springs (eye to eye of course with greasable pins)
6 stud hubs using landcruiser bearings. (ie super heavy duty, no tiny ford bearings here)
waterproof LED lights
Preinstalled wiring for Elec brakes (easy upgrade)
Heavy duty side steps and guards (will support full weight when standing on them)
Heavy duty adgustable spare mount. (changing tyre sizes means you can still fit the spare. most trailers have a fixed spare mount.
Room for drawbar toolbox
Can upgrade to camper trailer with a tent (bolt on and go)
Powdercoated not spraypainted.
Sheet is all zinc plated so no rust
Tradesman's top is lockable, secure and has gas struts.
Waterproof interior (trailer will float rather than fill up)
31" tyres but 33" will fit. (not fitted in photo)

BTW, most 7x5 off road trailers will have the tyres outside the track of your car. Thats why most camper trailers are 7x4.

Disclaimer: Trailer isnt for sale (kinda reads like an ad, it isnt). I made this one for myself. Ive also made this type



This was a 7x4 with 13" rims i upgraded to 32" tyres, new guards, extended the draw-bar and added the spare carrier and jerry cans. (ive since added a cage too)

The best springs have a shackle, most trailer springs do not, most are slippers, that means they have the fixed end(PIN) and the other end sits in a bit of RHS and slips inside the RHS as the axle articulates. Slippers are satisfactory(cheap) but not ideal.

Need the poly block or any of the 4wd hitches. although i dont have one and have done general getting to camp sites 4wding with my trailer with no issue yet. Certainly if i was purchasing a new hitch, it would be a 4wd one.

I am going to disagree with mkpatrol on the 31" tyres. I think a normal 7x5 or 6x4 trailer drags its arse alot when dragging it through general trails and even on trails on fraser island.

Having 31's gives much needed height under the arse of the trailer. When you climb over a ledge thats only even 500mm, as the arse of your vehicle climbs up, it forces the rear of the trailer down and then drags its arse hardcore.

Alot of box trailer designs use a C150 as the rear deck support(CHEAPPP!!), this is handy for the design and builders as it gives a nice little spot for your number plate and tail lights, even on a trailer that sees normal house and bitumen work, its very common that these get dragged off gutters and smacked into things as they are just too low. THey usually end up bent and farked and the lights get smashed in there anyway from hard hits on gutters etc.

A much better design uses 50x50RHS(or the same as the rest of the deck construction, 40x40?) as the rear deck support which gives 100mm more clearence, and can take a beating alot better than the c150 crap.

But then you need your number plate on the tailgate, wiring the number plate light becomes a challenge as it is attatched to a moving tailgate, or on a bracket beside the rear of the box etc.(usually they stick out too wide and look odd here) and lights must be either side of the box at the rear, which is alot better spot for protection anyway.

LED lights are great because you dont need to worry about them ever again (well almost lol). Most are 100% water proof so every creek crossing isnt going to start rusting them out etc etc. one less maintenance problem.!

There are 2 bearing sizes you can use, ford or holden, I think the fords are the bigger ones and recomended for 31" tyres.

You can go bigger and parallell bearings etc, but its not necessary unless you want a 2tonne trailer.

45mm solid round axle is a good idea as it will take alot more of a beating from rocks etc underneath.

my trailer doesnt have shocks but watching it in my mirrors on bumpy trails sometimes i wish it did!

Voodoo you sure they are landcruiser bearings? that bearing cap looks way too tiny to get a landcruiser bearing in there.

infact, im 99% sure thats just a regular trailer hub with Ford bearings.

Shadow wrote:Voodoo you sure they are landcruiser bearings? that bearing cap looks way too tiny to get a landcruiser bearing in there.

infact, im 99% sure thats just a regular trailer hub with Ford bearings.

im 100% sure. you can see the cap where the nut is not the hub which is huge. Ill take a photo toomorow and show you.

Edit: whoops, your right, my 2 ton axle is on the cage trailer. i have too many trailers

Thanks for the replies lots of good info here !!

Yeah the general design I'd be after is like the above photo, given the lower sides on a 7 by 4 would you be able to fit 3 bikes in 2 forward one backwards?

As having the same or smaller wheel track would be good to avoid hitting obstacles in tight spots.

Thats a tidy tradie trailer and yes you do have too many trailers, wanna make some space ?!

I'm also looking at mounting a toolbox ( would fit in the frame of the ute tray trailer ) at the same spot as the frame, what length draw bar would you have to avoid jarring ?

Whats involved with the electric brakes as an upgrade at a later stage and would they be necessary , pros/cons ?

And how much would you expect to pay for the above trailer new from say a trailer mob , second hand in decent condition or to make yourself as my mates a welder and does side projects ( would be mates rates labour )

I had cape York trailers in cairns build me a 7x5 to put my 700 grizzly on. Running 35s on 10" rims, independent coils, dual shocks, electric brakes, fully galv dipped. Great trailer, pretty heavy tho.



Quad makes the trailer look smaller than it is due to its 28" tyres and 2" lift.

I dont see the point of independent on the trailer when all serious 4x4s have beam axles front and rear.

If you're building from scratch and you REALLY go bush:
Treg hitch is a must.
Hydraulic brakes overide for smaller ones and electric over hydraulic for bigger ones but its expensive.
Electric brakes are for caravans, the dirt and red dust wreck them off road.
serious springs, if you have a leaf sprung tow vehicle you may wish to use the same springs on the trailer. You can buy duplicates of most factory spring hangers from superior etc.
Match the wheels to the tow car, just so you have more spares even if you dont need them that big.
put shock absorbers on it. again match your tow car for spares reasons. they will be a bit stiff to use your old flogged out ones on the trailer, its better than nothing if you rip the end off one on your tow vehicle out bush.
put a pipe rack on it, that you can also put a roof-top tent on.

long drawbar, much easier to reverse. and tows nice at speed, I used to take my Pioneer camper up to 140kph.

dont put checker or propeller plate in the floor no matter how cool you think it looks, over corrugations it shreds your plastic crates and is a real bitch when trying to shovel sand or mulch out.

Don't use ford or Holden bearings unless using ford or Holden sized rims and tyres. Also don't use heavy duty hi load springs if you don't carry the weight. 750kg trailer uses 750kg springs anything else will be harsh. Use eye to eye Aussie springs and they I'll last forever.

The softer you can get the trailer to ride the longer it will last.

MikeH wrote:I dont see the point of independent on the trailer when all serious 4x4s have beam axles front and rear.

Completely different scenario.

With a "serious" 4x4 articulation is important to keep all four tyres on the ground, to maximise traction and help keep the body level (which equals improved stability). The type of trailer we're discussing here doesn't need articulation in the suspension, as it should have an articulating hitch to allow both trailer tyres to remain on the ground (and keeping the trailer level isn't really an issue).

So we're interested in ride, for the benefit of both the trailer and its contents. If you need ride, and articulation isn't important, it's independent suspension all the way.

Plus, as crankycruiser's photo shows, an independent setup doesn't have a beam axle to create clearance issues over large rocks or through deep ruts.

supazuk wrote:Don't use ford or Holden bearings unless using ford or Holden sized rims and tyres. Also don't use heavy duty hi load springs if you don't carry the weight. 750kg trailer uses 750kg springs anything else will be harsh. Use eye to eye Aussie springs and they I'll last forever.

The softer you can get the trailer to ride the longer it will last.

This!