Lengthen Toyhauler
Steve, you are correct - the KZs have a large 10-12" I-beam main frame, then step down into the garage area on a smaller box or c-channel frame. That is why I said the frame would have to be extended and gussetted. Per the Engineering departments, when they extend the garage areas at the factory while building the coach, they move the axles back 1/2 the distance of the extension.
Admittedly, they said the axle placement in a Toyhauler was merely an educated guess (makes you feel really safe doesn't it?), but this is what they generally did when custom lengthening Toyhaulers. These particular models are tri-axles. And yes, this is the problem with Toyhaulers is that unloaded, you have a heavier pin weight vs. the same length conventional 5th, and then loaded, it may even be lighter than a conventional 5th. Obviously, Toyhaulers are more sensitive to load and weight distribution than a conventional 5th.
I would look at two things (mainly because I don't know).
How are the frames constructed? Would it be feasible to weld 4-foot extensions to the existing frame? Do you have a solid frame to start with, you know, to tie into?? Most large trailers I have seen start witha stout toungue and frame to the axles, then change to a lighter frame/different frame design from there back.
And instead of moving the axles back, I'd leave them where they are. I'd just add another axle of similar capacity behind the existing axles. You get a safer towing rig in the end as long as the pin weight would be ok. And this is assuming the trailer is a tandem now, and not already a triaxle. If it were a triaxle, I'd simply move the front axle behind the other two... you are only adding 4 feet of length... how much would that actually affect your balance (how much of that would be loaded and how heavy would it be loaded)?
steved
Steve, you are correct - the KZs have a large 10-12" I-beam main frame, then step down into the garage area on a smaller box or c-channel frame. That is why I said the frame would have to be extended and gussetted. Per the Engineering departments, when they extend the garage areas at the factory while building the coach, they move the axles back 1/2 the distance of the extension.
Admittedly, they said the axle placement in a Toyhauler was merely an educated guess (makes you feel really safe doesn't it?), but this is what they generally did when custom lengthening Toyhaulers. These particular models are tri-axles. And yes, this is the problem with Toyhaulers is that unloaded, you have a heavier pin weight vs. the same length conventional 5th, and then loaded, it may even be lighter than a conventional 5th. Obviously, Toyhaulers are more sensitive to load and weight distribution than a conventional 5th.