D40 Bending chassis

[Old.Tony]

On the subject of welding the chassis, I'm sure I was reading a VSI from the NSW RTA that said you could legally weld across and along the SIDE of the chassis but you could NOT weld across the top or bottom.

I can't find it now but if I spot it again I'll quote from it.

 

[Aussie Frontier]

Speaking of skull dragging
what would everyone say is the maximum weight the D40 can drag from the tow bar. No downward force and a properly connected snatch strap as in the eye of the strap into the hitch and onto the pin.Would dragging like this also put large strains on the chassis?

 

[KraftyPg]

Maybe a jet powered truck....but you'd have to be an idiot to do that

 

[Aussie Frontier]

Good thing the Bullet has a V16 Diesel then eh lol
shame about the busted uni joint his not mine

Only reason I ask is with towing the busted race cars they sometimes are really hard to drag. When a car gets beached in a sand trap is a damm heavy load. Never stopped to think what if any damage it might do to the chassis rails dragging a dead weight like that

 

[KraftyPg]

I thought the BB was the first jet truck in Australia, obviously my memory is shot to shit again.

 

[Aussie Frontier]

Nah both Bullets are Diesel powered. The fire show comes from gas and igniters in the exhaust stacks

 

[KraftyPg]

Looks like another trip to the shrink for me to get that medication increased.

 

[Aussie Frontier]

Nah its just OldTimers
you get to meet new and exciting people Every Day !
Now where am I again?

 

[KraftyPg]

The best bit IS forgetting what you did or didn't do yesterday.

 

[jayk]

very interesting comments on page 2 that is! i thought i was doing the right thing in airbags, but maybe not? ..... they company that fitted my suspension and bags suggested that the load leveling kit would cause damage to the chassis. i know tony does not agree, and looks like he may be right. i only got comfort springs so i could still go 4wding.
when i was looking at buying i was desperate to get a lux, but the tow limits where crap. one of my best mates is pretty high up at toyota, and i got him to look into why they rate their limits so much lower and he just said that they were more conservative, and that half the tradies in the country where driving with illegal limits on their utes... so they (manufacturers) do know what is going on. as a side note ive heard of farmers towing up to 7 tonne (not far) with patrols.

 

[Old.Tony]

I'm pretty sure that while our Navaras are RATED for 3T they're easily capable of more.

The problem with a bending chassis is simply because the wrong pressure is applied at the wrong point. Support plates welded to the side of the chassis around the point of impact of the air bag would probably remove that particular problem.

As for a weight distribution hitch (WDH) causing a failure ... it'd bend the thing the other way. The whole idea behind the WDH is to twist the rear of the chassis UP forcing the nose of the vehicle back down. If the WDH was going to bend the chassis, we'd see a bunch of photos of utes with the top of the tub rammed into the cabin. Instead, we see it the other way around - and to me, that spells two things:

1) Excessive loading behind the rear axle
2) Inappropriate pressure point at the point of bending caused by either
a) weak chassis or
b) device that creates a pressure point ie airbags incorrectly adjusted

You CAN use airbags if you adjust them right and don't overload the vehicle, but I would prefer to see some strengthening around the impact point - look at the section of chassis where the leafs connect. The load is spread around the point.

Jayk, I was looking at the Hilux as well, and the salesman told me my best bet would be to buy a Sahara ($100K) and spend another $30K at a chop shop getting the tail end converted to a ute.

 

[04SilverSTR]

I'm pretty sure that while our Navaras are RATED for 3T they're easily capable of more.

The problem with a bending chassis is simply because the wrong pressure is applied at the wrong point. Support plates welded to the side of the chassis around the point of impact of the air bag would probably remove that particular problem.

As for a weight distribution hitch (WDH) causing a failure ... it'd bend the thing the other way. The whole idea behind the WDH is to twist the rear of the chassis UP forcing the nose of the vehicle back down. If the WDH was going to bend the chassis, we'd see a bunch of photos of utes with the top of the tub rammed into the cabin. Instead, we see it the other way around - and to me, that spells two things:

1) Excessive loading behind the rear axle
2) Inappropriate pressure point at the point of bending caused by either
a) weak chassis or
b) device that creates a pressure point ie airbags incorrectly adjusted

You CAN use airbags if you adjust them right and don't overload the vehicle, but I would prefer to see some strengthening around the impact point - look at the section of chassis where the leafs connect. The load is spread around the point.

Jayk, I was looking at the Hilux as well, and the salesman told me my best bet would be to buy a Sahara ($100K) and spend another $30K at a chop shop getting the tail end converted to a ute.

well said tony about load point in the wrong place. That was the point i was making in my post. Although in sure that heaps of people have run air bags for years in dual cabs and not had any dramas. Just ones that over load the shit out of them!!!

But yeah best bet would be to strengthen it before he damage gets done!!

Bryan

 

[Aussie Frontier]

As I was getting at its not the chassis thats at fault its actually the placement of the airbag vs the geometry of the DC chassis.
Just because its the chassis thats bending doesnt mean its the chassis at fault.
The fact is simply as Tony said its overloading causing the issues.
Another thing to think about is the fact that nothing about bending chassis this was appears on either the US or the UK forums .It appears that the issue only appears to be here.
We are able to find any aftermarket unit and bolt it to the vehicle. Any damage caused by that unit is basically our issue not the trucks manufacturer.Possible the air bag lift kits should come with a warning that incorrect pressures will result in possibly bending the chassis.
Just because a Hilux SC can handle 50 psi doesnt mean that a Navara DC will take the same pressures.
Different geometry and design .
If your truck is running the recommended pressures and the ass is still sagging means your springs are too light or your load too heavy. Increased pressures will put the weight on a section of the chassis thats not designed for it. Something has to give.
Its all down to the driver not the truck.

 

[tweak'e]

Speaking of skull dragging
what would everyone say is the maximum weight the D40 can drag from the tow bar. No downward force and a properly connected snatch strap as in the eye of the strap into the hitch and onto the pin.Would dragging like this also put large strains on the chassis?

you won't bend break the chassis like the pics above by dragging.
the problem they can by using tow bar to pull from is pull the chassis inward. i guess you would actually bend the tow bar before that happens.

cuz had his tow bar break off from snatching 4x4's out. so just watch how strong your tow bar is.

 

[Aussie Frontier]

Sheesh
am hoping my poor old strap would break first

 

[tweak'e]

Sheesh
am hoping my poor old strap would break first

8 ton strap vers a 3 ton tow bar. tho normally tow bars are under spec, so they will handle 2-3x rated spec. but some are crap and barely withstand 3 ton.

 

[Aussie Frontier]

Ah I should be fine then lol
Mine is def worse for wear but when idiot race drivers drive over your strap your reluctant to replace them

 

[Prospector]

bending chassis

The plot thickens so to speak. Further research (getting underneath every D40 I see) reveals that the D40 STX Dual Cab has two different chassis. The Spanish manufacture chassis has the weak or flex point (mine is Spanish manufacture) but the Korean? manufactured chassis does not. Visually the stronger chassis resembles all other dual cab chassis I have seen with a sweeping thicker curved section where the Spanish manufactured chassis has the weakened section.

I cannot understand why there would be two such dissimilar designs of chassis in the D40 STX and I am stating to wonder if the Federal Government organisation that aproved the D40 for sale in Aust is aware of this. Also whether they aproved both designs for Australian conditions.

So my next step when I get out of the WA goldfields is to make some enquiries and to take my Navara to the relevant agency so that they can see the difference..... More to follow.

 

[Aussie Frontier]

The original D40 all came from Spain. There was 2 different Spanish Chassis in the 05/06/07 models but as far as I know it was only with or without camber .Later models come from 2 different plants. Dual Cab ST-X come from Spain and all other ST-X/other models come from Thailand hence the different chassis .

 

[twodogs]

i thought the bb was the first jet truck in australia, obviously my memory is shot to shit again.

wasn't that waltzing matilda??