by angib » Sat Oct 22, 2005 9:17 am
flyfisher,
There are quite a few things about your plan that I don't understand:
- Because the track bar is angled so far from the horizontal, the axle will move sideways 1" for every 2-1/2" it moves up and down. If the tires don't hit the body as a result (they would, as drawn), this may work OK off road but I would expect it to cause the trailer to do some bad swaying on bumps on the road. An alternative would be to run a diagonal bar from the front mount of one control arm to the axle end of the other arm. That would give you pure vertical movement on that side of the axle, but you would still need to increase the body-to-tire clearance a lot.
- There's nothing holding the axle from twisting around with the wheels, until it pops the spring seats off the springs. You could attach the axle end of one control arm to the axle in two places to prevent this twist, though you'd have to use rubbers or ball joints in the control arm so as not to overload it.
- I can't see any reason why twisting the axle tube 45deg is a good idea - for example, it doesn't improve its strength. As far as I can see, it would just make it harder to fabricate.
- I can't see why the axle wants to be so far back. While it gives a superb departure angle as shown, it makes the breakover angle really poor.
But I think the main question is why use a coil-sprung axle at all? For a four-wheel vehicle, coil sprung axles are used to give good axle articulation so that all four wheels can be on the ground, getting traction, all the time. But the trailer has only three 'wheels' (two wheels and a hitch), so it can always keep both wheels on the ground all the time, whatever suspension is used.
So for an off-road trailer, I can't see why traditional leaf springs won't work just as well as a coil spring system and they're certainly much easier to build.
Andrew
Fred 
