Thread: Building a trailer, a question about Springs

Yes it is possible , years ago a few guys around toowoomba built trailers to carry cars to the local speedway. The big drawback is that without suspension it will shake the hell out of whatever you are carrying.

If you are carrying a vehicle on the trailer with susspension that will act as the susspension for the trailer,empty it will bounce around.

You can... But it's pretty harsh on whatever you load onto the trailer, other than a vehicle that has its own suspension, but it's pretty harsh on the trailer too. Things like light globes and welds get shaken about a bit.

Actually, let me look at my Reg's sheet when I get home and see...

I have the National regulations in front of me, it seems that the simple answer to your question is; Firstly, it depends on how far apart your axles are, and Secondly, the Aggregate (Trailer & maximum load) weight of the trailer and your axle capacities.

Section 15 of the Vehicle Standards Bulletin for building small trailers states that; "All axles in a group must be interconnected by a loadsharing suspension except in a close coupled axle group provided that the load carrying capacity of each axle in the group and the wheels and tyres fitted to it is:

• at least 120% of the load on that axle with the trailer at its ATM."

What this means is that your axle capacity for a 2000kg trailer, including load, needs to be 1200kg. And 2000kg is your maximum limit for over-ride brakes.

The drawbacks for doing this are;

• Increased stress on your axle stubs and bearings.
• Increased tyre wear as the tyre itself is doing all the work of your suspension, particularly when cornering.
• Increased stress on the trailer chassis, including all welds.
• Increased stress on your towbar and tow vehicle due to increased vibrations.

There are only two advantages I can think of at present for not having springs;

• Cost saving on purchase of trailer spring set.
• Lower trailer ride height...

But this lower ride height can be acheived with 4" drop axles, but can also give you trouble with clearance on driveways.

Another option for getting a low ride on a trailer is using these axles from ALCO

I have seen these used on car trailers for cars the have very, very low clearance and these allow the car to get on the trailer a lot easier. They do cost a bit but are worth it.

http://www.alko.com.au/vehicle/axles/irs.html