Placement of chassis extension?

[corrupt]

Hi all I have sold my caravan and in 2 weeks I am picking up a 2009 NPS300 crewcab to start my camper project. Now seeing it has to sleep a family of 6 the shell ends up being 5.7 meters long. The problem is to fit that I need a 1.5 meter chassis (wheelbase) extension, this will give me a 43% overhang (which will be the 2 bunks at the end and the shower and part of the kitchen closer to the wheels).
Now I know nothing about extensions and I am a bit nervous letting someone that I nothing about make such a critical decision for me.
What I would like to know is the best way to do this eg placement of the extension itself. Do I put it up near the cab, back near the rear wheels or ********** bang in the middle. Is there something I should ask for or am I thinking to much into it?
The empty camper shell itself will be about 500kg and sit on top of its own 6" RHS steel chassis, fishplate mounted at the back and just guide plates at the front to allow for flex (mounted like a tipper).
The water tanks will be mounted to the truck chassis in between the rails and besides the second fuel tank on the opposite side it will be open storage again mounted off the outside of chassis.
No I know due to its size it will never be a 4x4 bush track rig but I am building it to get the family of the black top and in to the remote areas of this country which it should do with ease.
Any tips or recommendations will be greatly appreciated
Thanks Shane

 

[whatcharterboat]

Any tips or recommendations will be greatly appreciated
Thanks Shane

HI Shane,

My recommendation is >>> Start with a BIGGER TRUCK. This is my opinion only >>> A 1500mm extension is nuts on an NPS. Ive driven a few now with 750mm extensions and they felt VERY long and had a ridiculous turning circle.....still fine for dirt roads but somewhat limited rampover too. Yeah you can get away with 750mm or so (in fact I know a family of six with an NPS crew and 750mm ext that went from Sydney to Paris) but an extension twice that length is just incomprehensible to me. If you really need a body that long then starting with a 10ton or 13ton GVM chassis would be a better bet ...... or a single cab NPS with passenger seating in the rear camper module.
.

Hope you don't take this the wrong way.
'

........ and definitely get someone to do the job who knows what they are doing. By the way, Isuzu recommend an extension on an NPS not to exceed 500mm.

And to answer your first question >>>> extensions are usually done between the midpoint and the forward rear suspension hanger but there is more to consider for the exact location ......e.g.where to mount the extra crossmember with support for the new tailshaft centre bearing as the 09 NPS rear tailshaft is already long so any extension will require a new 2 piece setup.
.
I saw a really cool drawing at ATW last Saturday for camper to suit an NPS or FG crewcab. Mountains of room , even had a kingsize bed over the cab. Maybe you could get away with a shorter but smarter camper design.
.

Regards John

 

[corrupt]

Thanks John I had a look at bigger trucks but they jump in $$, have that air brake system, a even rougher ride, another 200mm higher and still have a large turning circle. With a single cab I could get away with a 500mm extension but I cant begin to imagine the logistics of having it approved with people sitting in the camper itself.
I think I have the design I want but I am going to the caravan show next week to see what others do, I would love to knock a meter off it but I want 6 beds.
My plans are based on the jayco 21ft basestation (shrunk down to just over 18ft) but with a queen bed that lowers down above the dinette. We just sold our 23ft basestation, we loved the layout but found ourselves not going down a lot of tracks because we didn't know if we would be able to turn around at the end, hence the truck idea, Which will be just over half the length of our last setup. I could knock it down to 1.3m extension but then I end up with 2.7m overhang

 

[selfy]

my single cab has a 1m extension (used to be a tour bus) it can get hard to turn around on tight tracks, just got to pick your spot
and do a 300 point turn

 

[corrupt]

Thanks selfy, can you tell me where they put the extension? pics?
I can handle doing multi point turns it a truck just dont like doing it with a 9 meter caravan.

 

[selfy]

as John said before the forward rear spring hanger
no pics sorry
try Ausquip in Bunbury they do truck mods and engineering (mod plates)
I used them for my mod plates they were good to deal with

 

[corrupt]

Thanks alot selfy I will give them a ring Monday. I will ask them about in camper seating aswell. Cheers

 

[selfy]

how did ya go ??

 

[corrupt]

Canned the deal ended up being a X exploration drilling truck. Im a exploration drill mechanic and work with drillers and I dont want one of them. Good thing is with a little re work I have the cab down to 4.6 meters and only a 1 meter chassis extension.

 

[Goldanfish]

So what's the deal now Corrupt ,
look for another truck of same dimension ?
John

 

[corrupt]

Yep still looking for a cheap crew cab Isuzu. I want to do the ATW springs and wheels straight up so between that and the chassis extension im up for about $20,000 straight up, hence the cheap truck. Im going to start going to the mining auctions, with the down turn there should be a few coming up.