Frame height on late model Isuzu NPS

Sandexplorer

New member
Is the height of the straight frame Isuzu an issue for builders?

I had a look at a 2013 NPS for sale (graysonline lot 0001-9007585) with the ATW suspension upgrades but it appears to sit very high at the rear.

Are the parabolic springs compliant enough to level it up with a bit of load. If not is there any downside to reducing the height of the spacer block between the rear diff and the spring pack?
Would obviously need to match with new shocks plus ensure the driveshaft has enough travel and the wheel clearances are sufficient at full articulation. It already has the modification plate for the ATW parabolic upgrade and I assume there are no compliance implications unless I removed or changed a leaf which impacted GVM?

Any comments appreciated
BD
 

SkiFreak

Crazy Person
With the right weight the body should sit level.
Be mindful that leaf springs, no matter what type, are matched to suit the weight of the load. If they are not, the ride will not be optimal.
As has been mention here quite a few times... when building a camper, one of the last mods should be the suspension.
If you plan on buying a truck like you have mentioned, finish the camper build before making any modifications/adjustments to the suspension.
 

Sandexplorer

New member
All noted SkiFreak, I arranged to have it looked over this morning and was told the same thing “it will be fine with a bit of weight on it - the ATW parabolic is a good (and expensive) option to have”. I was told not to even think about a GMV downgrade to 4.5t because even with the lightest construction there may not be a lot of usable payload left.


My main concern was really the overall height of a straight chassis but looking at a couple of other builds over the weekend it doesn't appear to be an issue.. There is no way around the extra height gained by super singles and suspension upgrade. The straight chassis at 850mm wide has advantages and the extra wall thickness over an older FG is an added bonus. It's all going to depend on the final design (and when I can sell my old truck to fund another one like this). Unfortunately timing is all wrong.
 

SkiFreak

Crazy Person
Unfortunately timing is all wrong.

Ain't it always the way...

I would not be too concerned about the height of the Isuzu chassis. As an example, my build is probably as high on a FG84, because my subframe is flat and goes to the top of the frame step, which would be similar to the height of an Isuzu.
The trick is where you place the notable weighty items. I have all of my fluids below the subframe (water and diesel), which lowers the COG.
 

unkamonkey

Explorer
Just keep everything with weight as low as possible. I was on the way to camp and got run off the road by a logging truck and I had to hit the ditch. Figured I was going to flop it but It stayed on it's wheels. Now, how do I get out of this ditch? Actually I stayed in the ditch until I found a better spot to climb out and then cleaned the grass and stuff from my camper door and bumper later. Yeah, it still has the scars but it earned them well.
 

Sandexplorer

New member
Ain't it always the way...
.

Story of my life. Not many NPS's come onto the market already fitted with super singles and parabolics. They are the biggest expense after the cost of a truck. Some people must spend more on these two items than the value of their truck (before the body build that is).

Now that I have decided that the later model NPS is the type of truck I will go for I can start collecting ideas for the mounting of heavy items. Unfortunately most of the builds on here are FG's but there are great ideas here and your build site SkiFreak. Hope there is no IP or royalty fees applicable:)

Unkamonkey; glad you survived your brush with a logging truck. Raises another question - do people incorporate any way of righting a vehicle that has ended up on it side? Most bodies would probably disintegrate if used to lift a vehicle.
 

unkamonkey

Explorer
Good question about getting a vehicle back on it's wheels. I would have just called a tow truck and let them figure it out. (I don't even know if I had a phone signal there). I was busy doing other things like getting my butt out of the ditch. Once a tow truck hooks on, it is their show. I didn't know my Mitsu frame could flex that much but I drove it out in 4X4 low range when I found a better spot.I haven't flopped a vehicle, yet...
 

Sandexplorer

New member
The height is not as bad as first thought.
I checked the spec sheets and the chassis height on the new straight NPS chassis is 950mm and the older 2006 step down version is 820mm so only 130mm difference. I went out to the Grays Auctions to have another look at the NPS300 for sale there and the rear chassis height with 19.5 Super singles and ATW parabolic springs is 1060mm (no load). The parabolic suspension and 19.5 wheels adds over 100mm (4") to the height on their own. I didn't measure clearance to the bump-stop stop but it looks like it would have plenty of articulation. You can feel climbing into the cab that the suspension is a lot more compliant than a stiff conventional leaf spring setup.
Hope another one like this comes up in a couple of months time when I will be ready.


I did see another truck that had the ROPS (Roll over Protection System) frame and I notice the mounts on the chassis had a full plate reinforcement along the chassis for 710mm (28"). It would certainly beef up the chassis at that point and you could probably 'right' a truck with it without causing further structural damage (maybe?). They are used a lot in the mining industry here. The ability to right a truck that has 'flopped-over' or even just to prevent a truck from going over when caught in a precarious position on some tracks would be a nice to have.
 

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