Vehicle Engineers reports, 4WD Modification rules, whats allowed, what not...

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Originally Posted by Bacho86

Be interested to know why as I run 305"s off-road - I wouldn't think the additional width / rolling weight would have thrown things out that much?


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Yeah not sure mate. He was talking so much i wish i had recorded what he was saying. Haha.
Im sure that probably 90 percent of Patrol drivers running 305's wouldn't see any issues. Maybe its just a comparative between the two sizes and that 285s would be a better choice for the expert? Or someone who knows their shizz.
TD runs 305's and i know he doesn't see any issues etc etc.
Pretty impressive place too he's got. He must get real busy as i reckon there was 20 4wds in the car park there.

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It effects the geometry slightly. Different contact patches, even offsets will change what the vehicle does. But as you say for the most part most people wont really notice.

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Originally Posted by mudski

Pretty impressive place too he's got. He must get real busy as i reckon there was 20 4wds in the car park there.

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Ever since he did Simon's 80 series v8 conversion (featured on 4wd TV) it went full on. That was done out his old shop on high street, even then he always had a few parked up, but now it's like a full car park always.

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Originally Posted by jay see

Ever since he did Simon's 80 series v8 conversion (featured on 4wd TV) it went full on. That was done out his old shop on high street, even then he always had a few parked up, but now it's like a full car park always.

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Yeah i was a bit taken back by how many there was. Hes in a good spot too and theres another mech workshop and an auto elec shop(pretty sure it was) in the same factory lot. So its pretty much a one stop shop.

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Originally Posted by nissannewby

It effects the geometry slightly. Different contact patches, even offsets will change what the vehicle does. But as you say for the most part most people wont really notice.

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Agree but would add that width can (not always but can) have a strange effect.

Most people increase offset to deal with a wider tyre IE the inside wall stays about the same and all the width goes 'out'.
This means the track increases but the geometry does not.
That in turn means two things, one is a change in the load on the swivel hub bearings and more importantly a change on the scrub radius (well at least that is the term i am familiar with)

A change in scrub radius means rather than the wheel and tyre 'pivoting' when you turn it, now has to travel thru an arc as the track is no longer near the centre line of the king pin or whatever and has been effectively moved out.

This can give you some interesting new handling issues under brakes.
I can't recall at the moment whether was under or oversteer, my boy racer days are too long ago, but IIRC it was unpredictable understeer

I believe contact patch and offset can effectively alter your akerman angle. While only small changes they can alter the way the vehicle feels and drives. Akerman being geometry....

Would anyone know 1,, how the Police measure a 2" lift and 2,,,what parameters are they bound by,
As is there a magic number that cant be beaten.
Just saying cause there can be big differences in height with 2" lifts from brand to brand

Maybe someone with a 3" lift can measure from centre of front hub to under the guard to get a 3" number

When the police got me, they didn't bother measuring.. They just wrote it on the defect notice - 'lift not to be over 2 inches'.

I guess it would depend on what height specifications the manufacturers put out.. When I measured my lift, the specs I found for stock were from diff to bumpstop. My 3" was exactly 3", I was impressed haha.

This was what I used for heights.

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Originally Posted by threedogs

Would anyone know

1. How the Police measure a 2" lift?
2. What parameters are they bound by?
3. As is there a magic number that cant be beaten?

Just saying cause there can be big differences in height with 2" lifts from brand to brand
Maybe someone with a 3" lift can measure from centre of front hub to under the guard to get a 3" number

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Sorry, my OCD got the better of me there.

Very good questions and I do like Throbin mentioned.

I've just added two Youtube Vids on swerve tests. Just so you can see how its done.

The Hilux made it look easy. The Jeep looked sketchy as. Wonder how a GQ would go.

I have also added the current vehicle lift allowances for all australian states and jurisdictions.
If anyone can find the procedures for how your vehicle is correctly measured for GVM, please let me know so I can add this. I have been told one procedure, others have been told otherwise. Seems the more I look, the more I find different answers.

GVM is measure by either...
On a weighbridge as a whole vehicle
On a weighbridge as sum of axles (which lets them see if your individual axle weights or tyre ratings are exceeded)
On individual load cells where they put them on the ground and the vehicle drives onto them and all are digitally summed (which lets them see weight per wheel, weight per axle, weight per axle group and overall weight)

Thanks. This is where it gets confusing. Well to me atleast. I have been told that when they measure the GVM, they include the occupants. In My case its a seven seater, each person is calculated at 80kegs each, plus full tanks of fuel. You did mention otherwise yeah? That it was weighed without the occupants.

I found on the Australian Government ADR website their definition on GVM....
https://www.legislation.gov.au/Details/F2012C00326

"GROSS VEHICLE MASS (GVM) - the maximum laden mass of a motor vehicle as specified by the ‘Manufacturer’."

This to me means measured with seven occupants and two full tanks of fuel included in the measurement.
My eyes are crosseyed at the moment. I just counted 26 tabs open in my web browser, all related to this and other things related. I have been reading page upon page for the last three hours, getting sidetracked and reading about other things etc etc and I don't know where Im at right now. Lol. Bout to give up for now and look again later.

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Originally Posted by mudski

Thanks. This is where it gets confusing. Well to me atleast. I have been told that when they measure the GVM, they include the occupants. In My case its a seven seater, each person is calculated at 80kegs each, plus full tanks of fuel. You did mention otherwise yeah? That it was weighed without the occupants.

I found on the Australian Government ADR website their definition on GVM....
https://www.legislation.gov.au/Details/F2012C00326

"GROSS VEHICLE MASS (GVM) - the maximum laden mass of a motor vehicle as specified by the ‘Manufacturer’."

This to me means measured with seven occupants and two full tanks of fuel included in the measurement.
My eyes are crosseyed at the moment. I just counted 26 tabs open in my web browser, all related to this and other things related. I have been reading page upon page for the last three hours, getting sidetracked and reading about other things etc etc and I don't know where Im at right now. Lol. Bout to give up for now and look again later.

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Mine has been engineered as a 5 seater..
One of the things that have to be done with gmv upgrade I've been told..
So maybe worth asking if that's something you need to do..

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Originally Posted by mudski

I found on the Australian Government ADR website their definition on GVM....
https://www.legislation.gov.au/Details/F2012C00326

"GROSS VEHICLE MASS (GVM) - the maximum laden mass of a motor vehicle as specified by the ‘Manufacturer’."

This to me means measured with seven occupants and two full tanks of fuel included in the measurement.

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Pls excuse the snip...

Yes, GVM is the maximum laden mass stated by the manuf.
Yes, it cannot be legally exceeded by any combination of load.
Yes, for the purposes of calculations it is assumed people averages 80 KG

Perhaps a 70 series Troopy is a good example.
The specs ex factory is GVM 3,200 KG, a payload of 880 KG and the max seating capacity is 11.

That means you can have any combo of people, accessories, cargo and towball weight you choose AS LONG AS you do not exceed a laden weight of 3,200KG

1 scenario - If you have 200 KG of roof load and 280 KG of Accessories (Winch, Bull Bar etc) and 4 x 100 Kg blokes for a total of 3,200 KG then you are OK even tho you are 7 blokes short of 11 IE you have 7 empty seats.

2nd scenario - If you have 11 people and they weigh 95 KG then 2 have to stay behind.

3rd scenario - If you have a Driver who weighs 140 KG and 10 empty seats you are under even tho 10x80 is 800 plus driver would put you over IE 1 fat dude driving an empty 78 isn't a GVM buster

4th Scenario - you add 240 Kg of permanent accessories (lets go for a roof rack, bull bar and winch), you do not have to reduce the plated capacity by 3 seats but you sure can't fill the truck with 11 adults.
You can still use all 11 seats but you better have a heap of kids or some really skinny adults.

Now, here is where the confusion is probably coming in.
For engineering testing etc. the tests are carried out at GVM because that is what you are legally allowed to load.
On a stock 78 this may require a simulated weight distribution of 80 KG in each seat.
This is so you can't cheat and put, say, a 880 KG lead bar on the floor so the vehicle will not roll during a swerve test or whatever to certify, say, a 4 inch lift

Bottom line is GVM is a physical measurement and the scale is the judge, jury and executioner you just need to stay under the GVM.

Please excuse my late night ignorance, honestly how does a vehicle get GVM weighed in at a stop? Driver & Kids in or out of the truck?


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Originally Posted by MB

Please excuse my late night ignorance, honestly how does a vehicle get GVM weighed in at a stop? Driver & Kids in or out of the truck?


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Everyone in that is travelling at that time as they are after the full mass of the vehicle at that time..

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Originally Posted by bigguwesty

Mine has been engineered as a 5 seater..
One of the things that have to be done with gmv upgrade I've been told..
So maybe worth asking if that's something you need to do..

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Yep. Mine will be engineered as a five seater. I also found in Section LH...
2.2.2
Vehicle Mass (Weight)
Where a conversion has resulted in an increase in tare mass, the modified vehicle must be
weighed at a weighbridge. Individual axle masses and total mass must be recorded separately.
Where the original GVM of the vehicle is no longer applicable due to the modifications
performed, a new GVM must be determined.
So I assume this is what they will be doing with mine as its had the motor changed which has resulted in an increase in weight. Something I will ask them for sure.

Thanks ET. You have cleared this up a lot for me atleast. Scenario 4 sorted my confusion well. Legend!
If they wrote something like you just said in the ADR's it would be helpful...

Getting closer now. We have school holidays the next two weeks so it will be going in sometime then.

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Originally Posted by mudski

If they wrote something like you just said in the ADR's it would be helpful...

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There would be a lot of lawyers and public servants out of work if that was the case Mudski :smiley_thumbs_up:

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Originally Posted by mudski

snip....
[/I]Where the original GVM of the vehicle is no longer applicable due to the modifications
performed, a new GVM must be determined.[/I]
So I assume this is what they will be doing with mine as its had the motor changed which has resulted in an increase in weight. Something I will ask them for sure.

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Nope... your GVM will still be the same.
Your Tare and Kerb Weight may increase and your Payload decrease accordingly but your 'original' GVM will only change if the Modification affects the GVM so the 'original' is 'no longer applicable' such as an engineered GVM upgrade

Think of it like a 20 litre bucket and for the example assume the bucket alone weighs SFA (tare).
The manuf says this bucket will only carry 20 litres of water equal to 20 Kg as any more and the handle will break (original GVM is 20 Kilos)
Sooo...

Ex factory it carries up to 20 litres (payload) and weighs up to 20 kilos (original GVM) = handle is good

Put in a 5 kilo brick (say an engine modification) this increases tare 5 Kg, bucket can now only carry 15 litres of water (payload) but brick plus water still weighs 20 kilos (mod doesn't affect GVM) and pick up bucket = handle is good (even tho there is still capacity in the bucket for more water)

Now, top the bucket up with some more water so bucket weighs, say, 24 Kg (GVM) and attempt to pick it up (get pulled over by scaleys) = handle will break (Scaleys give you a bluey for being 4 kilos over GVM)

Buy a stronger handle (a mod that does affect GVM ) rated to break at 25KG with a certificate for bucket. Now with brick and water it weighs 24 KG (1 Kg under the new 25 Kg GVM) and pick it up = Handle doesn't break (all is good and scaleys give you a hug)

P.S. where do I send my Consultancy Invoice?

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Originally Posted by gubigfish

There would be a lot of lawyers and public servants out of work if that was the case Mudski :smiley_thumbs_up:

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Yeah, keep the good ideas to yourself Mudski

Hands off the public service till after I retire please!!!

I get what your saying ET. So because of the Conversion, the motor is heavier that what was in there, the GVM on a factory fitted GU exactly as mine is 40kegs heavier. I would have thought because they are doing the engineering they would give the car a new GVM to that of factory spec. My original bucket and the new bucket with the brick are physically the same in every aspect, apart from the motor, I would have thought. The springs are the only thing I can think of that might be different out of the box. But having aftermarket springs in would make this null....

I am going to leave it and then see what the engineers are going to do. My head hurts.

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Originally Posted by mudski

I get what your saying ET. So because of the Conversion, the motor is heavier that what was in there, the GVM on a factory fitted GU exactly as mine is 40kegs heavier. I would have thought because they are doing the engineering they would give the car a new GVM to that of factory spec. My original bucket and the new bucket with the brick are physically the same in every aspect, apart from the motor, I would have thought. The springs are the only thing I can think of that might be different out of the box. But having aftermarket springs in would make this null....

I am going to leave it and then see what the engineers are going to do. My head hurts.

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You may have a new tow rating

Cheers man this was helpful

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Originally Posted by General

Cheers man this was helpful

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Glad we could help get ya to the big Two Five

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Originally Posted by the evil twin

Glad we could help get ya to the big Two Five

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Is that a literal comment or does it contain the merest hint of sarcasm?

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Originally Posted by Touses

Is that a literal comment or does it contain the merest hint of sarcasm?

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I'm gonna go out on a limb here and say it was loaded with sarcasm :049:

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Originally Posted by gubigfish

I'm gonna go out on a limb here and say it was loaded with sarcasm :049:

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Nah couldn't be, rules are 5k posts to qualify for sarcasm! 413 to go, keep your head down then!

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Originally Posted by Touses

Nah couldn't be, rules are 5k posts to qualify for sarcasm! 413 to go, keep your head down then!

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412 now...

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Originally Posted by the evil twin

412 now...

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How do you not have 5000 posts???

Heres something I have just found out. I was looking through the factory specs of the Y61. I had them emailed to me from Nissan when doing the TD conversion. The DX Patrol came out with split rims from factory. The tyre size is 7.50 R16. In the old money, the rolling diameter is 33inch. Give or take a bit depending on tyre brand.
Section LS 4.2.4 Overall tyre diameter states "The overall diameter of
any tyre fitted to:.....Must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the vehicle manufacturer for that vehicle. "

Does this mean that if you have a DX you technically can get away with 35's?

I would think that if it is allowed for the DX then it would be allowed for any model, because the 33" is an option on the Y61 Patrol.
Is there a limit on increase in tyre width?

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Originally Posted by Winnie

I would think that if it is allowed for the DX then it would be allowed for any model, because the 33" is an option on the Y61 Patrol.
Is there a limit on increase in tyre width?

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According to the spec sheet I have from Nissan. 33" in not an option on anything but the DX.
https://drive.google.com/open?id=0B9...l9MZ1Z0c3FMUEU

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Originally Posted by bigguwesty

How do you not have 5000 posts???

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Because I exercise judicious restraint and tolerance only replying with coherent, relevant, thoughtful, incisive posts that are always 100% on topic...
aaand...
the $#%^%$ Mods deleted the other 15,000

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Originally Posted by mudski

snip...
Section LS 4.2.4 Overall tyre diameter states "The overall diameter of
any tyre fitted to:.....Must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the vehicle manufacturer for that vehicle. "

Does this mean that if you have a DX you technically can get away with 35's?

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'That vehicle' means that vehicle not a model or series run... so if you have a DX placarded by the manuf for 33's then cut sick.
As a point of interest I know of the odd case of people attempting to swap DX tyre placards onto ST's etc

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Originally Posted by Winnie

I would think that if it is allowed for the DX then it would be allowed for any model, because the 33" is an option on the Y61 Patrol.
Is there a limit on increase in tyre width?

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Yes, sort of...
While not specifically tyre width there is a limit in allowable track width (1 inch in NSW and 2 inches in other States for live axles or at least that is what it was a couple of years back)
Sooo...
As you increase tyre width you usually have to start changing rim offset so the inside of the tyre will clear the guards etc on full lock
Each inch of increased -ve rim offset will increase track by an inch (2 rims per axle/2)

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Originally Posted by mudski

Heres something I have just found out. I was looking through the factory specs of the Y61. I had them emailed to me from Nissan when doing the TD conversion. The DX Patrol came out with split rims from factory. The tyre size is 7.50 R16. In the old money, the rolling diameter is 33inch. Give or take a bit depending on tyre brand.
Section LS 4.2.4 Overall tyre diameter states "The overall diameter of
any tyre fitted to:.....Must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the vehicle manufacturer for that vehicle. "

Does this mean that if you have a DX you technically can get away with 35's?

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If thats the case it must be pizzing off every ST,,,ST-L and Ti owner.
By the letter of law an increase of 50mm is legal eh,,,lol

Would make a good case to run 35"

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Originally Posted by mudski

Heres something I have just found out. I was looking through the factory specs of the Y61. I had them emailed to me from Nissan when doing the TD conversion. The DX Patrol came out with split rims from factory. The tyre size is 7.50 R16. In the old money, the rolling diameter is 33inch. Give or take a bit depending on tyre brand.
Section LS 4.2.4 Overall tyre diameter states "The overall diameter of
any tyre fitted to:.....Must not be more than 50mm larger or 26mm smaller than that of any tyre designated by the vehicle manufacturer for that vehicle. "

Does this mean that if you have a DX you technically can get away with 35's?

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No. Because technically 2" is more than 50mm

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Originally Posted by nissannewby

No. Because technically 2" is more than 50mm

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Might need the metric diameter of a 7.50 R16 AND the proposed '35's'. Not saying they would, but it's possible they might just scrape in under the ruling?

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Originally Posted by Cuppa

Might need the metric diameter of a 7.50 R16 AND the proposed '35's'. Not saying they would, but it's possible they might just scrape in under the ruling?

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They are only 32" roughly.

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Originally Posted by nissannewby

They are only 32" roughly.

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So maybe tyre manufacturers need to bring out 34" tyres? :D