F250 load leveller question

Nutta,
I see our local Holden dealer is selling new Dodge rams with the 6.7 cummins motor.

My dream rig!! If i only had 135k!!

Cheers

Break the piggy bank open. LOL.

Just because Holden says it doesnt need one doesnt mean it wouldnt benefit from using one. Anything with a large weight swinging a metre or so behind the rear axle will have its steering and weight distribution dynamics altered by that fact.

Whilst you may be happy with it there are a lot who arent and use them.

Perhaps you should borrow one and try it You may be pleasantly surprised.

I did actually borrow and try one, I couldn't stand it.

My ute tows quite comfortably and hugs the road nicely, the nose sits quite low so I'm happy with it overall.

In saying that I don't like towing 3 tonne with something that weighs slightly less than 3 tonne hence why I'm looking at an american truck, it annoys me that something that size still needs a wdh, hopefully the ram doesn't need a hitch, cheers.

One thing you must grasp is that these " big American trucks" are not as big as they seem and they don't have the load capacity they may appear to have.

In short they look bigger than they are ...... they may look big have a huge motor and in the US have massive towing capacities ....... but the truth is they have relativly low payloads and far more limited towing capacities under the Australian rules.

People think the F100 is a big thing ..... but it carries and tows about the same as a hilux of the same era. ... in fact its about the same size.

The same is true with ALL the "big american pick ups" ..... they carry and tow far less than a similar sized Japenese or Europen diesel truck

Compare any of the small just under 4.5 tonne ( pasenger licence ) trucks from Isuzu, Hino and the like .... they will have a curb weight around 2 tonnes and will have a payload around 2.5 tonnes (including body) and GCM of around 7.5 tonnes ... so unladen they will tow around 4.5 tonnes (in simplicity) ..... in the 4.5 tonne version.
Most of these are in fact a 5.5 tonne vehicles derated for passenger licence compliance.
In the 5.5 tonne version they will carry around 3 tonne in the tray including a 1/2 tonne body and tow well in excess of the 4.5 tonne that is permissable on a conventional rear hitch.
As far as I can establish the F250 only carries a little over a tonne in the tray, that is a pretty poor payload for the size and weight of vehicle.

The American Pickups, while they have big motors and look big ...... they are not real trucks, they do not have the load capacity or the stiffness in the rear suspenion that a real truck would have.

Remember the heavy transport industry does not use load sharing hitches the reason they are used in the caravan industry is, that the pig trailer caravans are fundamentally instable and the vehicles they are mostly towed with are too light and soft in the rear suspension.

cheers

I can appreciate that.

Surely having a vehicle weighing an extra tonne can only create a safer towing environment than the rg colly with the same tow weight.

Nutta, you are correct in what you say about weight, and the big engine in the F truck will do it easy.

With the foreword control light trucks, I would suggest you join the PBR and get some practice at riding bulls. They are not touring vehicles at all and are designed as round town delivery and service vehicles, which they are very good for. They are also noisy.

If you did buy one, I would suggest around a 6 tonner as a minimum, so you get a bit of horsepower and a bit longer wheel base.

I momentarily considered a cab over truck but thought just too rough.

Cheers

Thanks Roachie.

I remember you from the dual cab patrol days, good move going to a yank tank!

I would imagine with a spring kit or airbags the effy would be fine, it would seem load levelling includes any of the 3, but google keeps pointing to WDH. I am more concerned about legalities with insurance.

With the sheer size of the american trucks its hard to imagine the front end becoming light!

Yank trucks being imported the owners manual wouldnt mean much here i suppose.

I'm kind of thinking of upping my budget to 60 or 70k which gets into a little later models with a bit lower kays, theres a nice 2008 silverado and 2007 ram in my price range im now considering.

Your rig looks a beast mate! My dream rig!!

Thanks for your input, happy travels!

Nutta

There is a bit more involved in the use of a WDH than just lifting the rear to get a bit more weight back onto the front wheels.

How the car handles in corners has a lot to do with how much weight is on the outside front wheel and the outside rear wheel. As you increase the load on a tyre in corners you reduce its traction to the point where it lets go and slides. The one with the most weight on it in corners will be the one that lets go first.

Cars are designed with a little more weight on the outside front which makes the front of the car run out wider in corners when the car is getting along quickly. If you design it with more weight on the outside rear then it will go first and the car can spin out.

I would imagine light pickup up trucks with single rear wheels would be designed the same way.

An F250 with 350 kg on the tow ball will have over 500 kg on the rear axle due to the effects of leverage i.e the distance between the axle and the tow ball. Whatever you put in the back of the truck will increase the load. It will now be a lot higher than what is on the front. This is most likely why so many car manufacturers want the owners to use a WDH. They want some of that weight removed from the axle so it doesn't make a major change to the way the car handles.

Heavier springs or air bags lift the car but leave the weight on the axle. The car can look good and feel stable but who knows what will happen if something goes wrong.

Hi Splits, i can appreciate the purpose of the wdh, how do landrover d4 get away without wdh even though they have auto airbags, same thing?

how do landrover d4 get away without wdh even though they have auto airbags, same thing?


Never compare aftermarket air bags with factory designed air suspensions. There will be a big difference but you will have to go deep into suspension design and vehicle dynamics to see it.

The Landrover's suspension is the result of millions of dollars and years of research and development. So is the leaf spring suspension in a F250. You are not going to improve the Landy with a couple of aftermarket leaf springs any more than a few hundred dollars worth of air bags are going to improve the Effi.

A major difference between leaf springs and air bags is the leaf springs are linear and compress in proportion to the load. Double the load and you double the compression. Air bags are exponential just like a car's bump rubbers. The more you compress them the more they resist further compression.

Another issue with your leaf springs is they have been designed to change the angle of the rear axle in relation to the centre line of the car when loaded and going around corners. This link is on semi trailing arm suspension but the explanation covers all designs.

roll steer

A loaded leaf spring will be flat or very close to it and the front eye will be down lower than the axle housing. The axle will move up and forward in corners as per the centre drawing in those diagrams in the first section of the link. That feature of the design plays a major role in the stability of the car in corners.

Look at the little photo on the bottom of this page and read the third last and past post. The first link that I gave you gives you the best explanation


leaf spring

All I can say is don't play around with car suspensions unless you know how they they have been designed. There is always a lot more to the design than meets the eye. Alterations can give you what you want but there is a good chance you will get a few other things that you can do without, particularly with a big van tagging along behind.

I was kind of referring to the fact that the front end is still lighter with that weight, air suspension cant correct that.

Remember a few things
#1 a weight distributing hitch is a patch up, work around designed to treat symptoms of a combination of problems ..... they are not used in heavy transport or the military.
#2 the landrover is a vehicle specifically designed for military use. ..... most military users tow with ring feeder hitches and are expected to travel off road .... not compatable with WD hitches

The combination of problems I speak of are
A fundamentally unstable trailer format ..... they don't call it a pig trailer for nuthin'
Vehicles too light for the load towed
Vehicles too soft in the suspension for the load towed
Vehicles with a significant overhang from the rear axle

Adding bump steer from a soft leaf spring rear end does not help.

the landrover has two significant advantages
#1 little or no rear overhang ..... the wheels on landrovers have always been as close to the corners of the vehicles as possible, this accounts for many of the advantages of the landrover right back to day 1
#2 it has a factory designed active air suspension that produces far more stability than any passive suspension could and more stability at a given suspension stifness.

cheers

Hmm - Landrovers are not specifically designed as military vehicles. With the exception of the FC 101 all are just variants of civilian models and originally designed with the farmer in mind rather than the military.

That would be why so many of them a very large portion of the production are used in the military then ...... the primary design remains with military intent .... the primary design is not as a passenger car as most of its current competitors ...... the primary design is not as a commercial vehicle as pretty much all of the remainder.
It's primary design is military in nature that is clear and obvious.
The civilian variants are just that.

You need to research the marque a bit more - military variants come after the civilian versions not vice-versa.

The vehicles are designed as either with a commercial orientation - series 1, 2, 3 and Defenders or as offroad wagons at the luxury end of the scale.

Its primary design is civilian in nature that is clear and obvious.
The military variants are just that. :-)

It's original design comes from some left over jeep parts hardly a civilian product.
The supposed luxury versions are a pretty recent advent.
Back in the 60's and 70's there was very little difference between what was supplied to the military and the civilian market.
Th military versions pretty much had the military lighting spec and things like shovel and axe brackets and pretty mush no difference in the basic vehicle.

cheers

As I said - go and learn about the marque.

"I was kind of referring to the fact that the front end is still lighter with that weight, air suspension cant correct that."

Nutta

I have been looking through the net trying to find some detailed information on their air suspension but no luck so far. There is no end of basic info though.

The suspension is computer controlled with sensors at each wheel. When a load is placed on the tow ball and the rear goes down, extra air as necessary may be pumped into both ends. It could also be adjusted from side to side as necessary in corners but I am not sure of that.

The problem that is created by stiffening the rear suspension only when under load can be cancelled out by stiffening the front suspension to the same degree. You will end up with a harder ride but the manufacturer's original handling characteristics won't be altered. This is easy enough to do with leaf or coil springs but is not always possible with aftermarket air bags.

No doubt Land Rover's suspension engineers are well aware of all these things and have the suspension's computer programmed to sort it all out.

That is something that you can not do with a couple of aftermarket air bags in a location that was not designed for them.