ozzyfishaman
Adventurer
Thought I would share how much an Isuzu chassis twists without to much Effort.
Talk About Chassis Twist
- Thread starter ozzyfishaman
- Start date
4x4coaster
Adventurer
thanks John,
looks like about 100mm.
you've still got all wheels on the ground too!
this is the one with the 600mm chassis extension so it may twist slightly more than an original chassis.
looks like about 100mm.
you've still got all wheels on the ground too!
this is the one with the 600mm chassis extension so it may twist slightly more than an original chassis.
SkiFreak
Crazy Person
I am of the belief that the chassis on these types of trucks was not designed to flex freely. No-one drives these trucks around without some type of body on the back, be it a tipper, a tray or a pantec box etc.
The structural integrity of that body adds rigidity to the chassis, making it a more stable structure.
For most on road scenarios articulation would be quite minimal, meaning that a solidly mounted body would work just fine, and the proof of that is most truck bodies are mounted this way.
In an off-road scenario the best setup would be a suspension system that could deal with extremes of articulation, as this would significantly reduce stresses being transferred back into the chassis and body. If that is not possible, allowing the chassis to flex interdependently to the body would be beneficial.
My personal opinion is that an off-road body mounting system should allow some independent flexing, but restrict that flexing at the same time.
Unless the chassis has been designed specifically to allow free flexing, something like a 3 or 4 point mount may be more detrimental than beneficial.
The structural integrity of that body adds rigidity to the chassis, making it a more stable structure.
For most on road scenarios articulation would be quite minimal, meaning that a solidly mounted body would work just fine, and the proof of that is most truck bodies are mounted this way.
In an off-road scenario the best setup would be a suspension system that could deal with extremes of articulation, as this would significantly reduce stresses being transferred back into the chassis and body. If that is not possible, allowing the chassis to flex interdependently to the body would be beneficial.
My personal opinion is that an off-road body mounting system should allow some independent flexing, but restrict that flexing at the same time.
Unless the chassis has been designed specifically to allow free flexing, something like a 3 or 4 point mount may be more detrimental than beneficial.
I think that when there is no weight on the rear frame it would be less likely to twist and more likely to just pick up a wheel.
The more weight placed on the chassis the more the frame will twist to follow the ground contour.
At least that's been my experience with 2 FG's driven with and without a load.
The springs are stiff to carry the large payload and the frame is riveted / bolted together so it can flex to keep the wheels on the ground.
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gait
Explorer
we have different experiences.
If the vehicle in the picture were loaded evenly the leaf springs would compress. Front left and back right more than front right and back left. Which reduces chassis twist.
There is very little spring compression in the picture. The wheels are perpendicular to the chassis/body. There are heaps of pics in the sticky thread of loaded vehicles in action with springs compressed and axles/wheels at an angle to chassis to show the articulation.
Its all relative. How much of the terrain is accommodated by chassis twist and how much by spring movement depends on weight, spring rate, and how the load is attached to the chassis. And probably a few other things.
There's a point, different for loaded and unloaded, where one wheel will cease to be in contact with the ground. Where springs and chassis are sufficiently stiff for the angle and the load.
If the vehicle in the picture were loaded evenly the leaf springs would compress. Front left and back right more than front right and back left. Which reduces chassis twist.
There is very little spring compression in the picture. The wheels are perpendicular to the chassis/body. There are heaps of pics in the sticky thread of loaded vehicles in action with springs compressed and axles/wheels at an angle to chassis to show the articulation.
Its all relative. How much of the terrain is accommodated by chassis twist and how much by spring movement depends on weight, spring rate, and how the load is attached to the chassis. And probably a few other things.
There's a point, different for loaded and unloaded, where one wheel will cease to be in contact with the ground. Where springs and chassis are sufficiently stiff for the angle and the load.
You're right, with more weight on the truck the springs will compress and depending on whether the road surface is level or tilted, the springs on one side may compress more or less than the other.
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But as long as the plane of front wheels and axle are different than the rear and nothing has been done to change the stiffness of the frame like adding a rigid body or sub frame, the frame will flex.
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I was wrong, adding weight won't make it flex more, but adding weight alone shouldn't make it flex any less either.
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But as long as the plane of front wheels and axle are different than the rear and nothing has been done to change the stiffness of the frame like adding a rigid body or sub frame, the frame will flex.
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I was wrong, adding weight won't make it flex more, but adding weight alone shouldn't make it flex any less either.
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toylandcruiser
Expedition Leader
I think its sweet, whats wrong with chassis flex? I know on Unimogs, the more weight that is added, the more the frame flexes.
Czechsix
Watching you from a ridge
'mogs are specifically designed to utilize their frames as part of their suspension flexibility. They're designed not to be rigid, and to have a large degree of motion, relative to other trucks. Plus, some of the more flexy models of 'mog are specifically designed as off road trucks.
FG really isn't designed for "off road". Mildly rough terrain, sure. But the FG? The more that frame flexes, the more it work hardens.
gait
Explorer
Thanks. I think we are on the same wavelength.
Trying to find another way of saying the bit about weight and twisting. For a given axle twist increasing weight reduces chassis twist and increases spring compression. Twist the axles enough and eventually a wheel will leave the ground. More weight, more axle and chassis twist before that happens.
seems to be my week for different experiences.
Work hardening for me is a technical metallurgical term. Typically , increase in strength with plastic deformation. Any twisting is hopefully elastic deformation, not permanent. If we exceed the elastic limit in service we are in the pooh. Less than the elastic limit with gazillions of cycles and we may get fatigue.
For the Mitsu I suspect its one of those "some chassis twisting is ok, too much too often is not ok". The deigners forgot to tell u, or at least I've never found it if they have.
mog
Kodiak Buckaroo
Ahh, the recurring Fuso FGs are "not for off-road". While certainly they are not Unimogs (lets say old school Unimogs) in their prowess off-road, they seems to work well in Australia for the tour companies, mines and individuals. Ever around the world they have gone (yoda). While The Rubicon or Moab would surly challenge them (some have done Moab trails), they would seem to do fine operating with their design parameters.
Since most of the Fusos are set-up as campers and not "lets go wheeling" vehicles, how may smart operators want to do 'Hells Revenge' in Moab in their 'home' that still needs to take them another 10,000 miles on their trip.
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As I have posted elsewhere, the Fuso owner's manual sure seems to give it's blessing to off-road operations
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double-click to enlarge
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(note- Czechsix and I are friends, so he won't be offended, or will give me s##t off-line)
toylandcruiser
Expedition Leader
ok that makes sense
Czechsix
Watching you from a ridge
oooooooo
Gauntlet. Thrown. Down.
You and Fuso
Me and Haflinger
Calico.
Odessa and Bismark Canyon.
Let's do some real world testing.
MogFest 2015....be there.
:bike_rider:
And then newer FG's don't even have a low range xfer, right?
Which leads me to question....the FG has been around for quite a while. I haven't seen any adapted for Truck Trials, or pure off road use. I'm a noob at this though...I'd like to see what's been done.
mog
Kodiak Buckaroo
Not now;
2011-2015 "Transmission Standard equipment Mitsubishi Fuso DUOniC® 6-speed OD AMT with transfer case"
So it looks like 2010 and prior for "Transmission Standard Mitsubishi 5-speed OD MT w/2-speed transfer case"
(all data from Mitsubishi USA)
BUT maybe in the future (note a 2012 article, so were are they?)
http://www.carsguide.com.au/car-new...ter-4x4-dual-range-returns-20324#.VEhNtvnF9nU
