Experience With Preparing ISUZU NPS Camper: Suspension

[Amesz00]

As a first step I have taken the third leaf out of the pack which has made the ride a lot softer but we have lost ~1" in ride height and we only have about 4" on up travel before the bump stop.

Man, my stock (and sagging) fuso suspension has about 30mm between the stops. what i would give to have 4" of up-travel!

anyways ill be curious to see how your new mods work out.
how did you go about fitting the much longer leaves to the front (ie was it very difficult with much rearranging)?

 

[IcedVolvo]

Update time: Well we have basically solved the front suspension issue. Its not perfect by any means but we did all of the things above:

1: fitted new low profile bump stops, as parabolic are OK inverting this gave us nearly 300mm of travel in each side with 150mm upward travel!
2: reset the remaining two parabolics to give more lift
3: blocked up the spring pack to regain the original height.
4: removed the front sway bar altogether

But I neglected to add one very important point; standard truck tire pressures are WAY TOO HIGH for this use. Each of the tires on this truck can almost carry the whole vehicle weight and the manufacturers Load Vs Pressure charts do not go anywhere near low enough to get down to the ~1250kg per tire we are running at. However after some technical discussions with ATW and the tire tech bods we dropped tire pressures to 55psi in the front and 60 in the rear (as opposes to the 80+ we were running). This also made a dramatic difference in the "softness" of the ride of truck. I do not even use the air seat most of the time now.

Basically the front is about as good as we can get it without going to a full coil/link conversion.

Now to the back suspension for the next instalment......

 

[IcedVolvo]

Well its been a while since we were here so I thought I would update the suspension to the final version.

The first pic shows the low profile bump stops on the front parabolics from a Volvo truck; not cheap @$60 each but we now have ~170mm+ of compression clearance on each front wheel. When I jack up the front chassis I get to 350mm of sag with the wheels still on the ground before my jack runs out


We did finally manage to get the rear suspension converted to standard grease-able 1" pins and full parabolics. The other pic shows the rear parabolics (from the F series ISUZU) and we had a 20mm override from Carrols fitted after we broke the standard 16mm one. You will also note the fitted adjustable shocks, note also the stone guards on the shocks as some twit design engineer forgot to realise that stones will obliterate the shocks in desert conditions and the shocks are in FRONT of the rear axle!!! This is the sort of design flaws you don't see on "real" 4WDs.



Although I have not done formal articulation tests we have at least 700mm of articulation before the concertina between the cab and house pops open. I am not really keen to go much further because this is a warning sign that the chassis is probably at close to its limit of twist as I want it to take it.

Anyway folks; that's about it: the truck rides sweet as and I don't even use the air seat on road; it handles brilliantly with minimal bump steer and with the shocks turned right up it doesn't need sway bars even at 100km/h+.

Now if only I could get the brakes working it would be perfect

 

[Alastair D(Aus)]

? fitting rear parabolics

IcedV,
I have a 2007 NPS, one of the last before the latest straight chassis and DPF models.

I am interested in what you had to do to fit the parabolics from the F series truck. Did it require major chassis work for the mounts? I have been looking hard for alternative suspensions but found little other than the ATW solution. I intend to shelve the suspension issues until my home build camper is complete so I know the real weights and distribution. I suspect that I will end up being much heavier than my original design as extra bits keep getting added.

Thanks for your thread it is most useful.

regards
Alastair

 

[IcedVolvo]

IcedV,
I have a 2007 NPS, one of the last before the latest straight chassis and DPF models.

I am interested in what you had to do to fit the parabolics from the F series truck. Did it require major chassis work for the mounts? I have been looking hard for alternative suspensions but found little other than the ATW solution. I intend to shelve the suspension issues until my home build camper is complete so I know the real weights and distribution. I suspect that I will end up being much heavier than my original design as extra bits keep getting added.

Thanks for your thread it is most useful.

regards
Alastair

Hi Sorry for the delay in replying;

Basically you just need to match five things:

1 spring length (around the curve!!)
2: spring width
3: pin position
3: load
4: eye/pin/bush diameter

My truck is simple and already matched the F series springs; here are the standard settings:

1300mm long x 70mm wide x 650mm-650mm load ~2100kg

I converted my chassis to standard "big truck" 1" greasable pins because you can get them anywhere!

As for parabolics well we broke our front ones .... and as there is a worldwide shortage of parabolics (they are only made in 4 factories in the world and NONE in the southern hemisphere!!) and this is the third lot of ISUZU springs that have failed we opted for Warrior ones which we changed bushes in to convert to my 1" pins. They are great springs and probably the best I have had in!!

here is a list of length/width/load compatible springs I found (dont know about pin centres....):

NPS 300
1300x70mm 2800kg

Other Truck with Matching Front Parabolic Springs

UD
MK5 3700kg
MK6 3700kg

MIT (fronts)
FIGHTER 6.0 FK61 7H/7K/7G/7L/FL/FM/FKW (9.4-10.4tonne, 4 leaf, 15mm) 3600kg
FIGHTER 6.0 FK61 FH/FL/FM/FLW (12tonne, 4 leaf, 16mm) 4500kg


HINO 500 (Fronts)
1018 3600kg
1022 3700kg
1024 3600kg
1027 3700kg
1227 4500kg

HINO 300 (Rear: 2 main 2/3 900 aux)
816 5500kg
716 5100kg
714 5100kg
616 4480kg
614 4400kg
916 6200kg
414 (2100mm!!!!) 4400kg



Duturo (Rear: 2 main 2/3 900 aux!)
5000 4400kg
5500 4400kg
6000 5100kg
6500 5100kg
7500 5500kg
8500 6200kg

You can see the largish set on the Warrior springs in this photo


Although the shackle set is not quite right the truck is unloaded and should be perfect when fully loaded!!

 

[whatcharterboat]

As for parabolics well we broke our front ones .... and as there is a worldwide shortage of parabolics (they are only made in 4 factories in the world and NONE in the southern hemisphere!!) and this is the third lot of ISUZU springs that have failed we opted for Warrior ones which we changed bushes in to convert to my 1" pins. They are great springs and probably the best I have had in!!

View attachment 190323

Hey Jon.

Thanks for the comments. At least you have an insight into what we went through to develop these conversions !!!! Those bump stops of yours look a little harsh but the 1" pins should be a winner.

How's that smokey orange bike going?

Kind regards
John.

 

[Goldanfish]

Icedvolvo[/B
With regard to the shocks you used what are they and are you happy with them.
I have recently bought Isuzu NPS 300 camper with ATW Parabolics and Boss Adj. shocks and 19.5 singles. BUT the bounce is still there , travelling on undulating Bitumen roads.
An help appreicated.
John

 

[whatcharterboat]

Icedvolvo[/B
With regard to the shocks you used what are they and are you happy with them.
I have recently bought Isuzu NPS 300 camper with ATW Parabolics and Boss Adj. shocks and 19.5 singles. BUT the bounce is still there , travelling on undulating Bitumen roads.
An help appreicated.
John

John,

ATW stopped using Boss shocks over a year ago. I bet yours are dead. There are a couple of good alternatives. Have you called them?

Regards john.

 

[Goldanfish]

Thanks John,
when you say have I called them, being ATW or Boss
John

 

[whatcharterboat]

Thanks John,
when you say have I called them, being ATW or Boss
John

ATW

 

[Goldanfish]

Thanks John ,
I'll ring probably 2014 when their back on deck. Which shocks would you recommend?
Thanks for your help.
John.

 

[IcedVolvo]

Icedvolvo[/B
With regard to the shocks you used what are they and are you happy with them.
I have recently bought Isuzu NPS 300 camper with ATW Parabolics and Boss Adj. shocks and 19.5 singles. BUT the bounce is still there , travelling on undulating Bitumen roads.
An help appreicated.
John

Hi,

I use the Robo Shocks by Boundless Rider (http://www.roboshock.com.au/) which are handmade in Yandina. However I think that the company or at least some part of it has been sold and is now called Red Roo Shocks (http://www.redrooshocks.com.au/). You will have to ring them to find out what is happening with retail sales. The original owner/designer Graham still looks after his original customers for refits etc.

• Firstly I cannot tell you whether they are the best shock for this truck but I can tell you they are better than any of the major truck brands (Monroe/Powerdown/etc).
• Secondly they are not cheap @ $500 each shock
  
• Thirdly although there have been some reported issues with seals (Whatcharterboat may have something to add to this) but mine have lasted ~100,000km before a rebuild although also note that the rebuild wasn't cheap @$200 each shock!
  
• Thirdly you really need to have the shock linked to the airbag or have individual in-cab adjustment fitted. Especially because you want very different characteristics at 120km/h on the expressway than you do hopping a rocky creek crossing. The in cab adjustment adds about $500-1000 to the price.
  
• You need to make sure the valving is suited for your springs especially if you have parabolics (Graham is v. good for this)!
  
• You need to watch the mounting of the shocks to protect against rock damage (see my earlier photos). My rear shocks could not be mounted "upside" down doe to fouling of the chassis but ideally you want to mount them with cooling chambers at the top i.e. upside down.
  
• Finally if money is no object I would investigate the electro magnetic Koni option but @ ~$1800 per shock + fitting it's a VERY expensive option but probably the ultimate in reactive shock technology (less than 0.1ms reactive change to valving!!!) because you can program each shocks compression and rebound curves individually and change "on the fly" from "performance" to "off road" to any one of your pre programmed curves.

Other than that if anyones got any other info be glad to hear it.

 

[Goldanfish]

Thanks Icedvolvo,
You've given me a bit to chew over there, I'll be doing a bit more research and thinking. Yes these shocks haven't lasted long either, from the date they were fitted to now.
Thanks again John

 

[Goldanfish]

New shocks to Isuzu NPS 300

Well took some worth advise, contacted ATW re new Powerdown shocks all round ,they sent them down to Victoria quick smart and I have fitted them and trailed them locally on some pretty rough corrugated roads. Much better than the old shocks.
I'll give them a work out in a couple of weeks, heading up the Binns trk and Gibb river rd for a few months touring.

 

[alan]

Well took some worth advise, contacted ATW re new Powerdown shocks all round ,they sent them down to Victoria quick smart and I have fitted them and trailed them locally on some pretty rough corrugated roads. Much better than the old shocks.
I'll give them a work out in a couple of weeks, heading up the Binns trk and Gibb river rd for a few months touring.

I'm surprised they recommended powerdown shockers, in the 4wd industry they don't have a great reputation.