Isuzu NPS 300 camper build

Alastair D(Aus)

aging but active
2007 - 2008 models

I have one of the last 2007 NPS300. Mine has an access hatch in the cab which is very little use if you have added sound proofing and a custom centre console. It is quicker to tilt the cab which after I adjusted the tension, is now quite easy. I understand the hatch was deleted in the new model due to the changed geometry of the chassis and engine location.

I purchased the 2007 model because of the reduced pollution gear - no DPF etc which made changing the exhaust and building the sub frame far easier. The new model definitely has a better suspension and extra creature comforts which was an attraction to my wife. The main attraction to me of the new model was the flat chassis rails as can be seen in one of the earlier pictures. The prior models all have the curve behind the engine which makes for extra issues. I also had a comment from one of the sales folk that the DPF can get very hot and this is not something one wants when off road on grassy spinifex tracks. I found my truck with a known history, 12mnths warranty, only 40K on the clock and half the new price - that swung the balance.
 
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4x4coaster

Adventurer
As mentioned I have fitted a second fuel tank the same as the original but before I fitted it I had to get the exhaust modified slightly. The exhaust hung out to pretty much the same line as the outside of the chassis so would have been very close to the tank and also the solenoid arm of the exhaust brake would have hit the tank. So the exhaust shop cut the pipe, rotated it to give better side clearance, shortened the pipe in front of the exhaust brake to move it forward and then added a piece to the rear to close the gap.

I thought about the pro’s & cons of having the tanks on the same verses opposite sides, and while from a weight distribution perspective opposite would be better, it meant filling both would be a pain and trying to run a filler from the passenger side to the driver side also had its share of challenges. So they are on the same side; the other thing is that I probably would not have both tanks in use all the time. I would use both on extended trips or to take advantage of discounted fuel but most of the time would only use one tank anyway.

While the tank is fitted, the plumbing is not done yet. I’m waiting till the camper chassis is done just to see where the best place to mount the change-over device is. Prefer to have it somewhere with easy access but well protected.

The wrecker that I got the tank from has got another 8 of the same tanks that I saw and they came with the chassis brackets but no sender and they came off new trucks and have been in dry storage since, so they are like brand new.

The tanks are 140L versions and are 400mm high, 500mm wide and 820mm long excluding the hangers.

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4x4coaster

Adventurer
I did give everything a good pressure wash once the tray was off, it will never be that easy again!



I noticed that the euro4 NPS doesn't have the pre-filter setup like the euro5 version of NPS so I decided to add the additional filter. I priced an OEM one and it was rediculous, over 500au, so I picked one up at the same wrecker that had the fuel tanks for 50au. While the assembly was from a different and older truck, the housing body looked exactly like the one Isuzu were using. I cleaned it up, got 2 new fuel connection pieces for my size fuel lines, picked up a new Fleetgaurd filter FS19551 which is the equivalent of the Racor filter isuzu uses and mounted it to the chassis in the place where the priming pump was. I moved the priming pump up on to the support for the cab mounts and it was a pretty simple install. So now I have the same filtration as the new euro5 standard setup.



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4x4coaster

Adventurer
Here is my ‘Interpretation’ of how to make flexible mounts for the camper chassis;
The channel bolted to the truck chassis is 100x50x6 PFC, the section to be welded to the camper chassis is 75x75x6 SHS, the flat which separates the two is 75x8 and the bolt is 9½ inch by ¾ inch UNF HT of course. The spring is 150 long by 50 diameter with 12mm rod.

The side clearances between the moving parts is about 2mm, I actually used 2 pieces of thin laminate as the feeler gauge to set up the gaps. Once I had the mounts mocked up, I tested the clearance by removing the springs and lifting one side of the camper chassis at a time to make sure nothing would bind and it was fine.

Between the camper and truck chassis I am using 65x25 cast polyurethane for the full length of the truck chassis, and the same material as the spacer in the mount.
The vertical clearance between the moving parts is at least 12mm or roughly half the thickness of the polyurethane, I figure it will never be able to compress anywhere near that amount.

Skifreak, no plans for DPF at the moment.


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dlh62c

Explorer
The mount looks good to me!

The design allows for the body and frame to separate, yet there's some guidance to aline the two as they return to a resting position. You've addressed forward, backward and side-to-side shear forces on the bolts as well.

Great Job!

One down five to go?

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4x4coaster

Adventurer
Before I could fit the Polyurethane to the chassis and spring mounts I had to drill lots of holes so I just set up a temporary bench with planks, trestle ladders and my drill press and used wood and clamps as a guide.
To attach the poly to the underside of the camper chassis I pre-drilled clearance holes for metal thread screws and a washer to increase surface area. The washers were 16mm diameter so I bought a 16mm 4 bladed cutting bit but it was too tight, the poly tends to stretch while drilling and then shrinks back to a smaller hole size, so then I got a 19mm bit which was perfect.
The 19mm hole was 10mm into the poly and then a clearance hole went right through the poly for the metal threads. I also drilled 1” holes in the square blocks for the spring mounts to clear the ¾” bolts.

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4x4coaster

Adventurer
I'll post some pics of the finished mounts and first layer of the camper chassis.

There are 6 mounts and as usual the front and rear are at the ends of the chassis wherever it is convenient to mount them. I wanted the middle pair to be as close to center as possible but the fuel tank made it too difficult to mount on the outside of the chassis, so, I have mounted the middle pair inside the chassis.

They are still attached to the vertical face of the truck chassis but they are spaced out to get around the flanges.

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RHS middle

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LHS middle

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right rear

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right front

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left front with additional filter and batteries moved forward

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SkiFreak

Crazy Person
I had to on my FG84 Fuso, but, as I see it, it's really a "suck it and see" scenario. If the blinkers flash normally without a load resistor then it's kinda pointless adding one.
 

4x4coaster

Adventurer
One thing I forgot to mention about the steel I’m using for the camper chassis is that I cleaned the insides of all the metal dust that tends to accumulate and painted the clean surface with Penetrol which is an additive to improve adhesion in paint. When used undiluted it gives a clear coat finish that gets into the pores of the steel and will act as a rust preventer. I also used it on the outside surface over welds and mixed it with the black gloss enamel paint I’m using for the finish coat (Killrust).

The method I used to clean inside the steel and also to apply the Penetrol was to use some plastic tongue from sheet flooring. I drilled a small hole in one end so that I could tie some nylon rope to it and tied a loop in the other end to secure a piece of sponge. The rope only needs to be a couple of metres long. I pulled it through each piece of steel twice to clean the inside then twice again to apply the Penetrol.

I used a new piece to apply the Penetrol as the piece used to clean ends up very dirty.

When doing the 75x75 SHS I cut a block of sponge about the size of a 90mm cube and for the 50x50 SHS about a 60mm cube. I just soaked the sponge in the Penetrol and squirted some inside the steel before squeezing the sponge inside and pulling through from the other end. By doing it twice I got very good coverage, when you look through the end you can see the shining surfaces.
 

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