GU GVM upgrade

[mudski]

It's worrying just how little weight most 4X4s can tow and carry legally. It's even more worrying how difficult it is to understand all the rules and acronyms they use when explaining why such a large vehicle as a Patrol can only tow and carry so little in weight.

There would not be many Patrols out there towing reasonably large vans that are doing it legally.

Agreed. I threw mine over the scales last week, empty, and got a bit of a surprise.

[Hodge]

Agreed. I threw mine over the scales last week, empty, and got a bit of a surprise.

Where did you go Mark ? I desperately need a scale to go to.

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[mudski]

BP Western hwy outbound about 5k before the turn off to 4x4 Obsession. Cost $18 from memory.
I think its just after the Caroline Springs overpass. Cant miss it anyhow. It even says weigh bridge on the sign as you enter.
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[Cuppa]

Just out of interest ........... what does 'laminating' a dif involve, & how does allow for a GVM increase? I'm guessing it is a method of strengthening the diff(s) to allow for a greater. axle weight, but given that a GVM increase also involves things like suspension, tyres & brakes I don't get how strengthening just one component could get the GVM increased?

I recall the place who fitted my GVM upgrade telling me they could fit springs to increase weight carrying capacity to whatever was wanted within reason, but it wouldn't increase the GVM. I was shown an older Volvo station wagon which had had all bar the front seats removed & the full back floor area was filled with big batteries. I don't know what the purpose was, nor how many batteries, but at a guess there would have been at least 40 batteries - and a weight of at least a tonne & quite possibly 1.5 tonnes. The car was sitting level, from the outside it would never have been apparent it had that sort of weight in it.

[taslucas]

Here's a photo of a laminated diff cuppa


>>>tappin from tassie

[BigRAWesty]

Spot on Cuppa. . Laminating is welding strength plates to the diff..
My rear is done under the diff from pumpkin to outter edges..
When I did my gq front I placed it onto to radius arm plates and then some knuckle gussets..
My gu also has the superior tower braces in..
But as mentioned only rated to 3.495T.
I'm wondering if they can't get 3.5T out of a coil wagon..

[BigRAWesty]

This is the kit for the front..
Of course only one side is done due to off set center..
But the rear has the box both sides

[BillsGU]

The reason the rear diff is laminated on a coil sprung vehicle in order to carry more weight is because the pivot / contact point where the spring connects to the diff housing is a fair distance inboard from the wheel bearing (unlike a leaf sprung car where the bottom of the spring contacts the diff housing closer to the wheel bearing). The laminations strengthen the housing at that point by transfering the down weight along more of the diff rather than the small contact point.

I hope I have used the correct terminology.

[BigRAWesty]

The reason the rear diff is laminated on a coil sprung vehicle in order to carry more weight is because the pivot / contact point where the spring connects to the diff housing is a fair distance inboard from the wheel bearing (unlike a leaf sprung car where the bottom of the spring contacts the diff housing closer to the wheel bearing). The laminations strengthen the housing at that point by transfering the down weight along more of the diff rather than the small contact point.

I hope I have used the correct terminology.

Yep. Totally agree..

[JoeG]

Hi Kallen and Bill
Yes I totaly agree how ever my certifying engineer will only certify the leaf spring axel not the coil as the lamination modification is not a Nissan job so would need to find another engineer to certify before lamination.
Other wise it's find a complete rear leaf spring assembly from the wreckers and then cary out the mod under the engineers supervision to get the upgrade.
He has agreed to this so looks like the way to go as the only other way is 6X4 and as I'm 7.2m long now I definitely don't want that (how ever a GVM of 4.9t and 3 sets of disc brakes makes it atractive)
Regards
Joe