7 x 4 trailer design questions?

[CRUSHU]

I am building a trailer out of a 2007 Crew Cab Hilux ute tub I have.

It is slightly less than 1200w in the tub, and it is just over 6' long. As it is a crew cab tub, it is a little short in the front, so I will be adding a 30 - 50cm wide toolbox to the front, to get it roughly in proportion.
It will work out to be about 7.5' x 5.5' outside measurements.

My question is, from the front of the Toolbox to the rear, should the Axle line be in the centre? Or slightly rearward? I have another trailer that is slightly rearward.

Also, how far forward of the Toolbox should the A frame extend?

[v6hilux]

The main thing with trailers is to have the majority of load including the trailer's weight on the tow ball side of the axle.

Then the next thing to consider is - The longer the trailer, (or axle from tow bar), the slower it reacts to steering input in reverse (slow is good).

Then you must consider the trailers maneuverability when you are moving it around by hand. When it comes to a box trailer, you don't want something that takes 2 strong men to lift and wheel around.

[CRUSHU]

I have 2 other trailers, 1 is 7x4 Camper, 1 is 7 x 6 tradesman trailer. Both are manouverable, but the good quality Jockey wheel and 4x4 size tyres makes it a lot easier.

I will be using a 4x4 tyre, and Jockey wheels, so it should be easy to handle.

The frame will be 50mm x 50mm rails, with 50mm x 65 or 75mm ends, to make it easier to mount to the underbody of the tub.
The A frame on my other 2 trailers is 50 x 75 or 50 x 100mm, so I will probably stick with that.

So will about 6" less rear overhang do it? The tailgate will add a lot of weight to the rear, offset by the weight and leverage of the A frame.

[v6hilux]

As long as the final weight, including full load is greater in front of the axle/s.

This is a safety issue as far as towing and loosing control is concerned.

There is no specific amount of distance!

[christover1]

I used this as a guide with my trailer build

http://www.angib.pwp.blueyonder.co.uk/t ... tear81.htm

http://www.angib.pwp.blueyonder.co.uk/t ... tear84.htm

http://www.go.jeep-xj.info/Trailers.htm

[CWBYUP]

Unless you have 100kgs plus it will be shiat to tow at 100 kph or over.

The only way we could do it was mount the generator on the front and the draw bar was 150 x 50 x 8mm.

Nick

[CRUSHU]

Most cars have a ball weight limit of 80kg's, so I wouldn't want to build a trailer with 100kg's, then load it.

My Camper tows like a dream, maybe I should weigh the jockey wheel, to get an idea.

[Bluefreak]

When I was looking at a build, I asked about at heaps of trailer places... I openly told them I was building it but would buy axles and other fittings from them... 2 of them told me the rule of thumb was to set the axle back from center 1 inch for every foot the draw bar was long...

My welder went to heaven and I ended up just buying one instead...

[chook05]

I think you will find to be legal its got to have more load space in front of the axle than behind. and a toolbox mounted on to the draw bar does not count as load space. there is plenty on the road but there not legal.

[jcclures]

I went to the Qld department of transport and got the national code of practice for building small trailers, this gave me all the information I needed to build my trailer.
I then had no problems getting it registered, I would think you should be able to get this info from your department, or it could be on the internet as well.
I found a lot of information I had been given was not correct. Once I read the code of practice I had no more problems.
This way your trailer is legal in most states as it is the National Code Of Practice, and it was applicable in Qld for a change as well.

[its aford not a nissan]

I went to the Qld department of transport and got the national code of practice for building small trailers, this gave me all the information I needed to build my trailer.
I then had no problems getting it registered, I would think you should be able to get this info from your department, or it could be on the internet as well.
I found a lot of information I had been given was not correct. Once I read the code of practice I had no more problems.
This way your trailer is legal in most states as it is the National Code Of Practice, and it was applicable in Qld for a change as well.

x2 i did the same when i built my 8x4 trailer ,all the info is on the paperwork , so as long as you stick to it you wont have any dramas

[ricky1970]

Acording to NSW RTA regs, axle must no be forward of CENTRE OF LOAD SPACE, in your case this is ute tub, not including toolbox.
Local registary office should be able to give you a current spec sheet/booklet for building light trailers.

[stokedapollo]

hi i build trailers for a living
every single trailer i build can be moved by 1` person
single axles of course
with using a ute body i have found leaving the axle in the excisting position is the best use a longer than standard drawbar and then put on a tool box works a treat
keep your axe chainsaw recovery gear camping gear in it keeps the weight up front enough
put
it this way if wen you build it without toolbox on ,it lifts way to easy lengthen your draw bar and use slightly bigger or thicker walled rhs for it
then once the tool box is on she will be just right
one other thing when you put your hangers on for your axles if you are using trailer springs make sure that you measure from one end of the trailer chassis only same end for drawbar that way your trailer will run true and square
if you measure say from back for springs and front for drawbar you more than likely will not end up pulling it along the road square as 99% of trailers are not the same measurement down each side of it
phew just wrote a novel lol
hope it helps

[frp88]

I went to the Qld department of transport and got the national code of practice for building small trailers, this gave me all the information I needed to build my trailer.
I then had no problems getting it registered, I would think you should be able to get this info from your department, or it could be on the internet as well.
I found a lot of information I had been given was not correct. Once I read the code of practice I had no more problems.
This way your trailer is legal in most states as it is the National Code Of Practice, and it was applicable in Qld for a change as well.

That is what I did and it give you all ratios that you need.

[RN]

If you keep it under 200 kg's unladen
It does not exceed the width of the towing vehicle as manufactured.
and the length of the draw bar and load does not exceed 3 metres.

Then you don't have to get it registered , unless you're using it for commercial purposes.

source

http://www.vicroads.vic.gov.au/NR/rdonl ... Pack07.pdf

[christover1]

Mine was planned to be within those specs, but came in at 220kg.
But I was going to reg anyway, in case I went interstate with it.