Barter build - design advice please

[Mungus]

Hi All,
As the title suggests, I am having a trailer built for me as a trade off for electrical work done. I put power on to and fitted out a workshop of a boss of a mate. He has a trailer fabrication company up here in Darwin. I see many of his trailers around, as well as a few other companies that sell his. I have drawn on information here and on the web, as well as my mates suggestions. I need some advice as to what I should get built.


Purpose: Combination of a trailer for dump runs and use around the block, but; must also be able to carry our side by side ATV behind the D4 (when it arrives in July) on camping trips around Darwin and the NT in general. On these trips I would like to have a slide out kitchen in the front or back of the box. I don't require this to be a full blown off-road camper setup. That will come in time for longer trips and be something like a Kimberly Kamper/Karavan or something along those lines - no buggy required... fingers crossed!


Design: To carry the ATV and have something in front or behind it inside the box, it will have to be around 10'x5-6' (3000x1800mm).
My mate has agreed on my request for Chassis - 75x50x? Drawbar -100x75x? All HD Galvanised. Is it OK for the Drawbar to be under the main chassis section or should I go with the full frame in one plane where the drawbar continues into the frame? Advice please?
He has suggested an aluminium tub, 3mm maybe 4mm.
He has suggested Suspension - Tandem Roller Rocker, not the slipper type and a brief comment that the eye to eye often crack or break? I think independent would be a bit overkill for the purpose and as this is not a full blown job, I think the roller rocker is sufficient YES/NO?
I would want shocks fitted!
Axle - 45mm solid square (I think 50)?
We have discussed an will probably use Rims - 6 stud 16' Toyota rims. YES/NO?
I want these to be the same track as the D4 if possible?
He has said not to worry about electric brakes? I tend to agree this would be overkill> The trailer will be around 2t I think.
Hitch - Probably just standard 50mm ball, unless it makes it easier or more sense, to set the D4 up with a Mitch Hitch or similar now rather than later??
Other - I am thinking of designing my own and having him fabricate a Slide Out Kitchen in Stainless that slides out from front passenger side of box. The aluminium enclosure will remain in there at all times.

I would like to think I could somehow get a Roof Top Tent (like the Gordie ones) to sit upfront or behind the Moto (over the top would sit it up too high I think); otherwise it goes on the D4.


I have attached a bit of a sketch (in progress) of what I'm planning. I would like it smaller and single axle but if I have to lug that ATV then I have not much choice on size. I still want it to be solid, tough and fairly capable. Any comments or guidance is appreciated.


Cheers Mungus

[bee utey]

To keep it simple and light, don't bother with a tandem. I've owned a home built single axle car trailer for 33 years that weighs 400kg and safely carries 1500 kg on 195R14LT tyres. It is purely open frame without a floor as such. Wheels on the vehicle loaded go onto rungs about 6" apart. The load area is 12ft by 6 ft. If I need to carry loose stuff I install a sheet of mesh or corrugated tin or plywood. With a suitable axle and wheels I'd happily take it's design to 2000kg total weight. Above that you need breakaway brakes and other fancy stuff.

BTW drawbar fitted under the tray will put the hitch at a better height for a fourby towbar. That is unless you use a drop centre (cranked) axle to lower the floor but that would affect your ground clearance off road.

[Mungus]

Bee utey, I considered the Open frame style (like a plant trailer), but it would not suit as a block trailer carrying soil etc... Thanks for your input though! I thought a trailer that length would need to be (or be better) tandem? Now I think of it, there are some fairly big single axle off road caravans. Kedron, Kimberly etc...

[Xtreme]

Bee utey, I considered the Open frame style (like a plant trailer), but it would not suit as a block trailer carrying soil etc... Thanks for your input though! I thought a trailer that length would need to be (or be better) tandem? Now I think of it, there are some fairly big single axle off road caravans. Kedron, Kimberly etc...

Single axle are also far more manouverable.

[Mungus]

What type would suit single axle without too much expense

[bee utey]

You should look seriously at a slip on floor/bin, as towing the floor around when you don't need it is wasteful. The floor could be made in sections too. Having an open frame trailer is great as you have endless places to chain down your load. As for the single axle I wouldn't have it any other way. A single requires you to always balance your load so that your hitch gets 5% to 10% of the total but it's much easier to see with a single axle as the terrain never alters the load. I have occasionally towed tandems but hate the way they try to tear the back off the towing vehicle when you go off the dead smooth bitumen. My single axle has been all over the place, including vehicle rescue and firewood duties off road and you won't get me to own a tandem based on my experiences!

Oh and an open floor trailer makes a useful mobile vehicle pit too...

Axle capacity is the key, most el cheapo trailers were based on car wheels and four ply tyres. Of course you needed two axles of that kind for a 2T total mass. Nowadays there must be dozens of useful donor hubs/wheels for a 2T capable single axle.

[Blknight.aus]

and have it built with a tipper A frame that has the tub pivot on the rear spring perch...

You're going to love that for tip runs and for loading the ATV's

you can use a simply hydraulic lift to tip it OR a winch on a pedestal bar... IF you go the winch on the pedestal bar with some clever rigging the one winch can be used to both tip the trailer for loading as well as pulling the ATV up.

IF it was me I would be building it as a tandem.

If you go with leaf springs and swing shackles you wont need shockies. to Keep it manouverable dont go load sharing suspension but do watch the balance. My tandem is easy to move around when its balanced just right because I can just kick down the A frame and the back axle lifts clear of the ground, Punt the A frame around and keep on pushing. A landy isnt going to notice the extra drag if you're driving even remotely sensibly (and Ive jack turned mine with 3t of firewood on it on sand which is no where near sensible, reccomended or even advisable if you want a long life from the trailers springs, and bearings).

Fit good electric brakes and have the vehicle wired up at the same time. Ensure they include an over ride brake system (it wont always be on your car) and a manual locking hand brake. Fit a beeper to the hand brake actuator that will operate whenever there is power to the brake lights, aux power or tail lights from the vehicle and the hand brake is applied)

spec the same tyre or at least a compatible dimensions as your vehicle preferably the same rims, studs and nuts.

fit a battery tray and 4 jerry mounts in place 2 front 2 rear, sometimes balancing the trailer can be as simple as filling or emptying 2 jerries and it makes the difference between a floaty front end or a waggy trailer.

TIe down points.. Lots of em.

[Mungus]

OK! I agree and would much prefer single axle, so I'll start researching single axle set ups at around 2t. I really don't mind the extra sheeting for a full box, considering it will most likely be ally and most of the time it will be carting soil etc. for the block (hardly ever rocks as it would damage the ally)

[Mungus]

Sorry Dave, didn't see your post before my last. Yes, I have seriously considered the tipper option as I have had the privilege of this on my tray back cruiser (pic attached), but I didn't want to push the boundaries of fair barter. Maybe, I will consider the frame being built to suit and fit electric/hydraulics myself later.
When you say 'swing shackles' do you mean eye to eye or roller rocker?
Same rims, studs & nuts as a D4 is difficult to achieve I thought?
I will be going GOE 18"s later on as well, so sounds like the right way to go, but am unsure of how or how much extra $?
Are you meaning the beeper would be on the trailer and be a warning to you that the trailer hand brake is on? I don't get this bit?
I will be making sure I can have as many tie downs as well as jerry/gas/tyre or water tank options.
Nearly every trailer I look at on the net over 8x5 seems to be tandem.

[Blknight.aus]

Sorry Dave, didn't see your post before my last. Yes, I have seriously considered the tipper option as I have had the privilege of this on my tray back cruiser (pic attached), but I didn't want to push the boundaries of fair barter. Maybe, I will consider the frame being built to suit and fit electric/hydraulics myself later.
When you say 'swing shackles' do you mean eye to eye or roller rocker?
Same rims, studs & nuts as a D4 is difficult to achieve I thought?
I will be going GOE 18"s later on as well, so sounds like the right way to go, but am unsure of how or how much extra $?
Are you meaning the beeper would be on the trailer and be a warning to you that the trailer hand brake is on? I don't get this bit?
I will be making sure I can have as many tie downs as well as jerry/gas/tyre or water tank options.
Nearly every trailer I look at on the net over 8x5 seems to be tandem.

its not that much extra to build it up as a basic tipper, build the trailer chassis as per normal till it gets to the back of the spring, then cut it off.

weld on a pair of inch pin mounting plates and theres the basis of the tipper.

Build the tub on a smaller sub chassis and essentially drop it on drill the pin holes in then weld on a couple of tabs for the lock downs at the front.

Ive seen one done that used a highlift jack up the front as the tipping mechanism.

talk to them, the worst they can say is "no"

swing shackles as per ye olde series landrover setup.

the beeper on the trailer lets you know when the trailer is hooked up and the handbrake is on... saves you from setting fire to your trailer brakes. they probably wont do it for you but it is easy enough to do.

theres a reason why 8x5+ are generally tandom, its cheaper and easier to build it than it is to engineer up a single heavy axle trailer. the added bonus is offroad you get some redundency and depending on how long you make your draw bar you have a better departure angle and breakover angle on the trailer because of the space the wheel assemblies take up in relation to the front and rear of the trailer. Theres a guy who collects firewood round here who has something like a 2 foot gap between the front and rear wheels (measured between the tyres) on his 8x5 tandem, its murder on driveways and tyres but tracks wonderfully and is very hard to hangup.

[Mungus]

OK. I've decided tandem best suits usage. Two questions;
1. Other than height, what advantage/disadvantage is there between axle on top of springs or below?
2. How do I work out the optimal drawbar length?
pdf attached
Cheers Mungus.