D40 STX V6 Diesel Towing Upgrades

The 3L V6 is an amazing engine and behind the 7 Spd auto will be a dream for towing. In terms of more power (If you need it) I would do in the following order: Catch can, block the EGR (if you can without throwing fault codes), 3" exhaust, intercooler/airbox piping upgrade and then finally either a good module or Ecu remap. If you do all this you will be pushing close to 300Hp/800Nm at the wheels if the car is tuned correctly.

Moving along

Thanks Guys for all the tips.

I have now taken delivery on the van and am yet to get it weighed. I took it for a run yesterday unloaded with the matteress out and the tug sags badly in the rear. It makes the steering very light which I realise can be dangerous. Supposedly the van ballwieght is only supposed to be 120kgs but it seems more. Could this be because it has no load?

Also the van sits up alot higher than the ball when level before I even hitch up. Could this also be because the van is unloaded? Will I neex to upgrade my hitch or turn the ball over? Is this legal?

I have decided to go with AUTB in Brisbane for the aluminium tray, canopy, drawer and racks. They were the cheapest by a long shot at $4500 and thier reviews seem good. I have no use for the well body so if anyone in Brisbane wants one this Friday, let me know.

My next task is the springs/lift upgrade. I have had heaps of quotes on heaps of different brands ans types. Airbags, leaf upgrades, etc etc. I am a bit overwhelmed. Looking for suggestions in the Hunter Valley/Tamworth area. I will try and get a package deal with the suspension upgrade, long range tank, snorkle and front roof racks.

Also I ended up buying a Waeco CFX 50 for the tug. Looking for suggestions for a drop down slide. I have seen the MSA and the Clearview slides which look good but are tough on the hip pocket.

Thanks again for all the help and suggestions.

Several things to note here.

1) The van's ball weight will be affected by how it's loaded but not remarkably so if you load the van correctly.

2) Suspension needs to cater for situations when you have the van hitched and when it's not, so it will be dual-rate springs on the back - anything less is a compromise. Thankfully ARB sell these (should be available for your model) - I have the Dakar springs on mine and they're fantastic even after a few years.

3) Lightness of the steering is the problem you need to tackle first, do NOT tow without fixing this. Thankfully this problem AND the ball height problem are solved together. Get a Hayman Reese Weight Distribution Hitch. This twists the back of the car upwards via the two spring bars, forcing the weight back onto the front wheels. Because you have to assemble the receiver head, the ball height is adjustable.

4) Airbags CAN be considered but I personally recommend against them. They reduce the flexibility of the rear of the car - where once you would traverse some uneven ground with both wheels down, the airbags can interfere with flex and prevent the higher wheel's springs from compressing enough, which will lift the lower wheel and without lockers fitted, you become stuck (until someone teaches you that light application of the handbrake can assist here).

Other issues: turning the ball mount over is perfectly legal, they're designed for that. Don't tow for long distances with the nose down at too steep an angle - the van's suspension should be kept as even as possible, vans are designed to be towed level or with a VERY slight nose-down attitude. This is more so for Cruisemaster or Simplicity suspension, the roller-rocker isn't as badly affected. I can't advise on the fridge lift.

AussieKane said:

Thanks Guys for all the tips.

I have now taken delivery on the van and am yet to get it weighed. I took it for a run yesterday unloaded with the matteress out and the tug sags badly in the rear. It makes the steering very light which I realise can be dangerous. Supposedly the van ballwieght is only supposed to be 120kgs but it seems more. Could this be because it has no load?

Also the van sits up alot higher than the ball when level before I even hitch up. Could this also be because the van is unloaded? Will I neex to upgrade my hitch or turn the ball over? Is this legal?

I have decided to go with AUTB in Brisbane for the aluminium tray, canopy, drawer and racks. They were the cheapest by a long shot at $4500 and thier reviews seem good. I have no use for the well body so if anyone in Brisbane wants one this Friday, let me know.

My next task is the springs/lift upgrade. I have had heaps of quotes on heaps of different brands ans types. Airbags, leaf upgrades, etc etc. I am a bit overwhelmed. Looking for suggestions in the Hunter Valley/Tamworth area. I will try and get a package deal with the suspension upgrade, long range tank, snorkle and front roof racks.

Also I ended up buying a Waeco CFX 50 for the tug. Looking for suggestions for a drop down slide. I have seen the MSA and the Clearview slides which look good but are tough on the hip pocket.

Thanks again for all the help and suggestions.

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Sounds like your rear end is in a bad way to begin with. I've got the same canopy and tray you are getting with the internal frame. The weight of this is about 370kg, as Tony suggested you'll need to have suspension capable of managing that alone as well as the vans ballweight.

Wow 3k at pedders! That's a bit rough, not even for good gear!

There's plenty of options for gvm look around mate.
Call John at ZORDOS for suspension
Call aaa exhaust in qld for gvm advice ( no one knows d40's's like them)

Then as above, egr catch can, exhaust retune etc

Hi Guys,
Thought Id let you know what I decided to do so far.

I ended up getting a new lift kit from ultimate suspension in Sydney. They used thier own dual rate springs in the rear that are rated to GVM of the tug. Lovells coils in the front. I was a bit worried about how rough it would feel at first but turned out excellent. Van now tows like a dream.
I bought a aluminium canopy and tray from AUTB in brisbane. Price was way better than anywhere else and the finish is good. Only issues I have had with it, is that the latches/lock mechanisms are cheap crap and keep failing. It has been difficult contracting AUTB to sort out what we will do about it. But all in all I happy with the result.
I have the EGR plate and looking for advice on if the hole should be drilled or not.
I have started the dual battery setup and am using a dc to dc charger that allows for the solar panel I have installed on the roof of the canopy to charge the aux battery as well. I am going to keep the van and the tugs batteries seperate, as I have found the van doesnt need the extra charge from the alternator.
I found a second hand set of clearview mirrors which once installed are great to use.
Also installed a MSA fridge slide which I havent used too much yet as the battery system isn't finished but it works well.
Still got alot to go but will post some pics soon.

JLA said:

In my case the extra 240Kg means being able to carry water, food and some recovery gear.
As it is when I remove everything that isn't bolted down I can only carry 250Kg. Being able to carry another 240Kg with a GVM increase is vital.
I installed an Old Man Emu 2" suspension lift kit (no GVM increase) but for a bit more I could have had the same thing provided by Pedders with a GVM increase that would double my carrying capacity from 250 to 480 Kg.
It's not spending $3,300 - it's just spending a few hundred over the cost of Old Man Emu.
I just wish I had known about it earlier then I would have gone with the mob that provided the best GVM solution with the suspension kit. So far that is Pedders.

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JLA,
I weighed my STX550 will full camping gear setup (everything I have excluding food bags and my wife/daughter). This included me, full disel, a full water tank 48lt, chainsaw, portable toilet fridge and slide. dual battery inverter, swag, sleeping bag, stove, drawers and all my accessories, tables, chairs, and of course side/rear awning and shower awning, gas bottle, compressor and portable shower.

Came it at 1940kgs.
For all 3 of us to go with extra rv4 tent food and bags, I would be over GVM. My current old man emu are worn/overloaded was considering the pedders GVM upgrade. Did you end up doing this? Are you happy with it? How much lift does it give?

Andrew.

Hello JLA just wondering how you have found Old Man Emu Suspension? How long has it been installed?

I had the Old Man Emu lift fitted about five years ago. I keep the bushes greased. The steering was heavy until I later had an adjustable upper ball joint fitted. Since then I have had no issues. I keep the speed down partly to reduce flexing on the chassis rails. I had Superior Engineering fit the chassis strengthening plates on the chassis. Towing a camper on Western bitumen roads, I keep my speed down to 80klm/ as the sudden dips are a surprise and just one decent one at 100klm/h can bend the chassis.

It would be high risk driving on western roads without a bull bar because of the roos and cattle. I fitted an ARB bull bar and winch. In the rear I fitted a fibreglass canopy and drawers with fridge slide etc. Also fitted a standard tow bar.

Now with more awareness of overloading, I have been backing out some of these mods to reduce weight. I removed the drawers, fridge, battery and put the vehicle over the weighbridge with two people in the front and a full tank of fuel. No cargo anywhere.

Front axle. 1.60Tmeasured, max allowed 1.530T (70Kg overloaded)
Rear axle. 1.18T measured, max allowed 1.717 (537Kg freeboard)
BUT
The gvm is 3.010T and the sum of my axle loads is 2.78T
This means the max payload can only be 230kg.
I tow a 2T trailer, means a tow ball weight of up to 200kg
200kg on the tow bar means the payload is derated by 60kg.

This means I am overloaded by 30kg when I am towing, that’s all you get when you spend $60,000 on a three tonne vehicle.

I intend to remove the winch, then the front axle is only overloaded by a few Kgs which would be lost due to caterleaving when rear load is added.

It seems all dual cabs and many recreation vehicles are just the same, only people are not aware of it. This issue is not confined to Nissan only.

One I like are the makes that advertise 3.5T towing vehicles and have a combined max mass of 6T. The vehicle weighs 3T, combined max mass of 6T, therefore it can only tow up to 3T and not 3.5T. How do they get away with this?

What to do? vehicle is not usable as is. If I remove the bullbar then there is a huge cutout hole left in the front that would cost heaps to have repaired.

Option 1.
ARB do not offer a gvm upgrade for the D40s
Pedders do have an gvm upgrade, details:
This upgrade makes the vehicle useful, but is not great.
Rear axle 1720 to 1960 (+240)
Front axle 1530 stays the same
GVM 3010 to 3215 (+205)
Cost $4,500

Option 2.
But what if you already have heavy suspension fitted eg. with my D40 with ARB components.
Pedders will only do the upgrade if they fit their own gear.
There are Auto Engineers who will assess the safe load carrying capacity, braking etc of the existing eg. ARB suspension and raise the gvm and axle loading.
Lindsay Stone of Livingstone Automotive in Townsville is a good example.
Professional auto engineers are difficult to locate because every mechanic calls himself an engineer.
In my case this will probably be the way I go now. Does anyone know of any (professional) Auto Engineers in the Sunshine Coast area? Although hundreds come up in Google, none do gvm upgrades.
Cost, hopefully less than Pedders because they don’t have to replace any hardware.

Option 3.
Fit a lay-axle. A mob in Toowoomba will add an axle behind the rear drive axe. It becomes a six wheeler. Will need to remove the tub and add a tray.
Gvm 3010 to 4200kg
Add a tray, canopy etc and you are left with about 600kg payload capability.
Cost, just over $20,000 for the axle, for the tray add another 6 or $7,000 then there is a canopy and boxes. Let’s have a guess of $35,000+ all up.
While this may seem expensive, the alternative may be to spend $200,000 on a different capable vehicle.

please do your own research, no guarantees that info is correct.

Don’t know if it’s been mentioned previously.m, but if you are getting a try built make sure it is designed to take s much load as possible forward of or above the axle. Anything rear of the axle shortens the lifespan of the chassis

GunMentalGrey said:

Don’t know if it’s been mentioned previously.m, but if you are getting a try built make sure it is designed to take s much load as possible forward of or above the axle. Anything rear of the axle shortens the lifespan of the chassis

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All true, but with option 3 above it uses a walking beam to equalise the two axle loads equally. The axles attach to each end of the walking beam and the centre of the beam is attached and pivots on the chassis between the two back axles. The chassis is also strengthened. It’s a good strong system and a tray could go on anywhere without too many concerns due to the chassis strengthening.

Hello JLA I just found this on the Arb website... also I have heard about people achieving greater GVM by installing airbags. But I haven’t reserch it.
5 years carrying that kind of weight is awesome... you know what they say hehehe grease is cheap parts are dear.
hope this helps

As JLA pointed out, the GCM is a vital figure too, and modifying the GVM will NOT modify the GCM, so even if you gain a 300-400kg buffer on the GVM, you're still limited to 6T total.

I'm not sure if that's changed by fitting a second rear axle, I've never even considered doing that!

I pull a 2t boat with my 550 and swear by my airbag rear suspension boosters. The big advantage is I can drop the air bag pressure when not towing the boat so the rear suspension isn't rock hard. And when loaded up I just increase the pressure to level the vehicle.

Andyjo said:

I pull a 2t boat with my 550 and swear by my airbag rear suspension boosters. The big advantage is I can drop the air bag pressure when not towing the boat so the rear suspension isn't rock hard. And when loaded up I just increase the pressure to level the vehicle.

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That’s a good logical approach but I have heard of chassis damage caused by airbags fitted to D40’s because they shift the chassis stress points. It may come down to how the vehicle is driven though? Have you had the chassis strengthening plates fitted? I don’t know if the plates would solve the alleged airbag damage problem though.

JLA said:

That’s a good logical approach but I have heard of chassis damage caused by airbags fitted to D40’s because they shift the chassis stress points. It may come down to how the vehicle is driven though? Have you had the chassis strengthening plates fitted? I don’t know if the plates would solve the alleged airbag damage problem though.

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It's not just D40s, it's any ute with leaf spring suspension and there's a reason for the failure that the strengthening plate only marginally alleviates.

Normally, the distance between the rear weight support (the rear leaf spring mount) and the towball (that holds the extra weight) is relatively short. This distance is increased by effectively moving the leverage point from the rear leaf spring mount to the centre of the axle. Now, there's an exceptionally long lever for the towball mass.

Under normal driving (flat roads, uphills, downhills, parking etc.) this wouldn't be a problem. It's when you find a causeway and don't slow for it, or those railway tracks on the Bylong Valley Way, or that cattle grid ... where the load behind bounces opposite to the way the ute is bouncing, greatly increasing the ball weight which - without airbags - would normally be of little consequence. With the additional leverage afforded by the airbag taking the load, you're overloading the chassis at a point where it's not designed to take the load.

This issue has been discussed numerous times across lots of forums. Driven with care it's not a problem, but the simple physics of it dictates that without due care, and with excessive loading, disasters happen and often a long way from home.

I didn't choose airbags (I was given the option). I chose dual-rate heavy duty springs instead, where more leaves are engaged with increased weight, thus providing more comfort when unloaded, and more support when loaded.

That’s right great information Old Tony. I Have seen the photos of utes Brocken most between the cab and the tray from corrugated roads causing fatigue due to airbags, as you said the distance of weight is now from the diff not the rear shackle To the tow bar. (All the broken chassis I have seen are from towing )
I chose airbags on factory suspension to retain comfort. This didn’t work because the airbags had to be pumped right up to stop them bottoming out grrr suggested and fitted by Arb Healesville, anyway now I have a 40mm lift old man emu 400kg rated rear suspension with the same airbags and it works a treat. Specially for a heavily loaded ute on top of towing, if I had my chance again not sure which way I would go, the duel springs sounds safe, strong and fool proof, but being able to finely adjust the airbags is very nice. mmm decisions

Old.Tony said:

As JLA pointed out, the GCM is a vital figure too, and modifying the GVM will NOT modify the GCM, so even if you gain a 300-400kg buffer on the GVM, you're still limited to 6T total.

I'm not sure if that's changed by fitting a second rear axle, I've never even considered doing that!

Click to expand...

As you suspected the extra axle does not increase the GCM.

apk47 said:

JLA,
I weighed my STX550 will full camping gear setup (everything I have excluding food bags and my wife/daughter). This included me, full disel, a full water tank 48lt, chainsaw, portable toilet fridge and slide. dual battery inverter, swag, sleeping bag, stove, drawers and all my accessories, tables, chairs, and of course side/rear awning and shower awning, gas bottle, compressor and portable shower.

Came it at 1940kgs.
For all 3 of us to go with extra rv4 tent food and bags, I would be over GVM. My current old man emu are worn/overloaded was considering the pedders GVM upgrade. Did you end up doing this? Are you happy with it? How much lift does it give?

Andrew.

Click to expand...

hello Apk47 I wondering if you made a mistake 1940kg is stx550 kerb weight ? Did you mean 2940kg ?