That last paragraph sounds like a plan
To tow a swb Terrano would I need twin axle then ? What about brakes etc.
I suppose I could just beef it up by welding some 50x50x3 box across it ? And form some tracks for the wheels to run on out of angle or sommit rather than covering the whole thing, but I could cover it with 18mm ply ... Would that do ?
I would think 18mm ply would be Ok with enough extra support, as the main chassis rails are between the caravan wheels, and that would mean the off roader would be sitting on the unsupported outside edges of the wood.
The person who adapted mine, had added several extra cross bars and like you said, tracks for the car to run along. The actual tracks were made from angle welded across the tracks, like the old style car ramps. The result with doing it that way was, plenty of places to attach tie downs too, the car had natural "wedges" to stop it moving as the wheels tended to sit in the gap between the welded cross angles, as these were about 6 inches apart, and jet washing off was a dream, as no mud stayed on the trailer. Not only that, but because the middle bit was open, it also made a great ramp for getting under the car to replace the gearbox and clutch when I needed to.:lol
You will definitely need brakes on any trailer that could carry a car, most vehicles, regardless of size can only tow up to about 1/2 a tonne of unbraked trailer legally, which is fine for a little box camping trailer, but anything else and you are asking for VOSA to pull you over if they see you on a major road, and make your life hell, also make sure you only get a chassis where all the wheels are braked, as it in now against the law to only have a part braked trailer. It is scary how many illegal trailers there are out there, especially boat trailers, and adapted caravan chassis trailers.
Oh and one other thing, read up on the law about towing and using the outside lane on a motorway... I am amazed at how many people do not know they have restrictions on it's use, and a Customs friend of mine got 6 points and a £100 fine in the summer, as she did not know, and was caught in the outside lane of the M20.
You can find caravan chassis that can carry that sort of weight on only 1 axle, but most will be twin. Your main thing is to check out the chassis ex-caravan rating before you buy. There are pro's and cons to both single and double axle, and really you have to go with what suits you.
Obviously, twin axle means a bigger wheel base to bridge for the off roader. 4 tyre and sets of brakes to replace (although the tyres are cheaper as they do not usually need to be reinforced), and it is more likely to go through wheel bearings, and scrub the tyres out than a single axle.
But it has far better stability when towing, will sink less when you tow it onto an off road location to unload, and if you have a puncture, is less likely to go unstable, snake and cause untold damage... Personally, I also prefer reversing twin axles as well, as intrinsically they want to go in a straight line, and you have to steer it off of that, where as a 2 wheel trailer wants to go where ever it likes and you are forever correcting it.
The main things for a Single axle, is less wear and tear on bearings and tyres (But they must be "Van" tyres), plus if you want to be able to manoeuvre the trailer by hand, rather than the car, it it a lot easier to turn, as turning a twin axle by hand is a pig.
