by angib » Thu Jan 03, 2008 9:38 am
I think it's worth saying that you can widen an axle in the middle quite safely - just make sure the new bit is as strong as the original axle and that the joints are also as strong. When you widen the axle in the middle, the springs move further apart, so this only works if you widen the frame as well.
What you can't do is widen the axle at either end as that would need a much stronger axle - the wheels are now much further from the springs than before and that is critical. It would be easier to buy a new axle than to try to widen an existing axle at either end.
However, if you want the wheels outside a 60" body, you will need a hubface measurement of 70-72" and with a 48" wide frame (ie, 46" spring centres), that gives you an overhang each side of 12-13". That is more than most axles will allow you to have, though you might be able to get a special axle made - something like a 3500lb axle but only rated to carry a 1500lb load.
A 11-12" overhang (it is measured slightly differently for torsion axles) is also too much for most standard torsion axles, though a Dexter #9 is close enough at 10.9" max overhang.
So it would be a lot less work to either buy a 5x8 trailer, or build over the wheels of a 4x8 as many people have done, than to think of widening the axle of a 4x8.
Andrew
