David Grason wrote:I see at least 3 "no I don't want thats" with the individual torsion axle ends.
David, I'd encourage anyone to go with the suspension system they prefer but that's not the same as saying other systems don't work. For example, there still seem to be plenty of people who don't trust torsion axles and want to have a tube axle on leaf springs.
In general, a one-piece torsion axle will be the easiest suspension system to use and probably the cheapest, but some of the points you've made need to be looked at:
#1. Yes, you do need to fit independent torsion units with the tires facing forwards. This is dead easy - you clamp the units to a straight piece of tubing (actually wood will do) while you tack weld their mounting plates in place. Anyone who can line up a one-piece axle will be able to line up individual units.
My experience is that the individual units generally seem to be more solidly made than the one-piece axles, but I don't think the difference is significant - both are plenty strong enough.
#2. Yes, a one-piece axle becomes a part of the frame - but I've not seen anyone here build a trailer that actually needed that - the axles's always an addition to existing frame cross members, so why is it needed?
A one-piece axle can't serve as a floor support so it's not actually a very useful part of the frame - unlike the cross member connecting independent units.
#3. Yes, you do need to make mounting plates - rectangular flat plates with holes made using the suspension unit as a drilling jig - not rocket science! I'm surprised that the supplier doesn't offer these plates ready-made (as they do here). Because the brackets are so adaptable, many of the restrictions of using a one-piece axle disappear - for example, you can mount the suspension to a transverse frame member.
#4. That's a spindle you're looking at - it's what the bearings and hub mount on.
The method to fit independent units is to make the mounting plates and bolt the units to them. Clamp the units to a straight tube or piece of lumber while you're lining them up. Tack weld the plates to the frame, unbolt the suspension units from the plates and then fully weld.
The main reason for using these independent units is if you want to build a lightweight trailer, for which they are invaluable.