The motion you describe is called "pitching"

You could try more tension on the WDH, but that is hard to determine without understanding your "starting point" more fully. For example, you should have 3 sets of reference measurements (from the bottom of the wheel rim to the wheel arch - for all 4 wheels on the vehicle):

1. Unladen (no van connected)
2. Van connected
3. Van connected and WDH tensioned.

By understanding the relationship between those figures, it is possible to firstly work out whether you have scope to increase the tension on your WDH (which, incidentally, would likely solve a large portion of the pitching you are experiencing)

Dave, which particular stretches of road have you encountered this on? What type of surface did you experience the effect?

I have encountered this on a few notable sections. It used to be bad along the river between Grafton and Maclean but this has gone with the road upgrade a few years ago. This was concrete road. Another was the Pacific Hwy going south just before you swung east to go around the Gold Coast Airport, this also has gone with the upgrade to a bitumen surface. The current one up there is through Sleepy Hollow ( after you swing away from the Tweed River and after you go through the tunnel.) There are a few other bits further south mainly on concrete. Is this a frequent occurrence or just occasional?

The cause is a wavy surface on concrete roads but can also happen on bitumen. With a van on behind one vehicle reacts with the other and causes this hobby horsing.  There is one bad bit of road that is not well laid that you would encounter, just after the Lake Munmorah foot bridge in the RH lane going north on the highway.

Generally the only way you can fix this is slow down. Adjusting the WDH can lead to strife. Once set up correctly, if you increase the tension on the bars you will most likely change the slight under-steer characteristics of the tug to severe over-steer. Just don't do it. It would not hurt for you to review the WDH set-up on your rig. I can't give you a link without upsetting Cindy, send me a PM with your email address if you would like the links.

Thanks guys there is some really useful stuff here for me to follow up on, I will get the reference measurements as per Anthony's suggestion to make sure the WDH is set up correctly because at the moment it has only been visual. If the WDH is set up correctly I may take it off and see what the effect is. Neil that Anderson hitch sounds interesting I will do some research on google to find out just how they actually work.

As you suggested Peter the section of road that was the worst was concrete near the Hexham Bridge which may be the result of harmonics but will also do it occasionally on bitumen roads on one off hills or dips. I haven't taken the van over it yet but there is another section of the Pacific Hwy before you get to Lake Munmorah just near Catherine Hill Bay that has a few dips and hollows as a result of mine subsidence (which no doubt you are familiar with) I may use this and the section that you suggested as my test track. I guess the last straw will be to fit the heavier duty shocks or springs as AK and John suggested but I'm reluctant to do it as the ride when not towing will be harsher. One of the reasons I bought the Sport rather than the crew cab was because when I test drove it it seemed to ride and handle better on the coils rather than the leaf springs of the ute - oh well you can't have everything.

Did anyone think that shortening the tang by 50mm on the WDH would have any effect or maybe even relocating the spare wheel from the back of the van to the front ?

Cheers BB

When I was shopping for a ute based wagon I took all contenders for a standard half hour round the block and up the freeway test to narrow the field.
I eventually had it down to the Pajero Sport & the Fortuner, so the next test was an off-road one in the Wombat State Forest and finally a tow test with my own van.

The PS was far more luxurious and high-tech inside and I really liked its looks (some don't like the crying tail lights) but there is a reason it is $10K cheaper, its suspension is generally agreed by all to be barely acceptable on the black top but absolutely woeful when towing.
That pitching even occurs without a van attached and the rock'n roll sideways motion means the PS gets terribly upset with the slightest hump or hollow and chicanes done over 20kph nearly have you tipping over.
Super soft suspension is great for 4x4 rock hopping but that is all.

I did however seriously consider buying the PS and spending the $10K saved on replacing the entire suspension, but Mitsubishi stated that doing so would void the warranty.
Additionally, I wanted a bulbar and winch and those options are NOT permitted on the Exceed due to the Crash Mitigation System.

I was left to buy the vehicle with the less refined interior (horrible colour scheme too) but having its feet designed right in the first place with the credentialed heritage of excellent road holding and handling that Toyotas are famous for.

So what I am saying is this. You can either trade the car or fix the suspension.

The damaged to chassis caused by air bags is usually caused by too high a pressure when they try to lift the sagging rear. The independent rear suspension of the Pajero allows you to install the air bags inside the coil springs, this area is well constructed as at is where it carries the total rear end load of the vehicle where as with leaf springs the load is designed to be carried at each end of the spring where the chassis is stronger. If you only put in 25 psi you will get rid of your problem without any impact on the chassis. Heavy duty shocks will do the same thing but you are stuck with them all the time , the air bags you can let down to say 10psi and have your normal suspension back when not towing. Our pajero was out of warranty but I would think if there was a problem Mitsubishi would try and get out of a claim, but if you are loaded right, have a WDH fitted and don't try and get the air bags to lift the rear end you won't have a problem. We did about 70k with our bags and had no trouble

Wassa

I don't for one minute suggest that this is the problem in this case but I just throw it in to the ring for interest sake.

On our 2000 trip round the block our traveling companion in a new Jackaroo and a dual axel Coromal on the back complained about the pitching action of his rig whilst my Jayco Westport was smooth as..  In the end he solved the problem by lowering his vaNtyre pressure towards the 200 that Jayco recommended for mine.

ps. I have since increased my tyre pressure up a bit from the spongy 200.

pps. The Westport doesn't have shockies .. only independent load sharing springs on beam axles.  Simple but effective on the blacktop. 

macka17 wrote:

---

SNIP~~~

I don't know about others. But my normal tyrepressures are 32lb all round. driving.
Load in tray . up 4 or 6lb on rears.
Towing.

Small (17\18ft) van. 32 fronr 34 rear.

Big van was 34 front\36\38 rear, depending on roads.

Dirt. ALL 28. and slow down to under 80 or so.

ALways got good longevity\even wear. from tyres.
Always GOOD grip to road
and comfortable ride. 10 PR Rated tyres ONLY. too.
Pay the little extra, you'll be glad.

I tried these 40\42\45 lb's.
Like driving on wooden wheels. No thank's.
I'd rather wear tyres a "little" quicker and ride softer.
I respect mine and Di's backs thank you.

---

Gday...

Good advice again Macka ... however, providing advice on what pressures to run in tyres is very dependent on many variables such as the make/model of vehicle, wheel/tyre size. tyre construction (LT, AT or H/T) and to some degree, the make of the tyre.

eg I have LT AT3 265 60 18 (on second set) on my Landy -

I run 36 front and 38 rear without van - 38 front and 48 rear when van is on. I get more than 55,000Km on the Landy. 

When I had H/T 265 60 18 on the Landy -

I used 32 front and 34 rear without van - 36 front and 46 rear when van was on. I got over 50,000Km on the Landy. 

They definitely do (or did) not feel like "wooden wheels".

I run the tandem van (2,600Kg) on LT 195 65 14 at 55PSI all round. I tried 45PSI initially, then upped to 50PSI but the wear suggested they were just little bit under-inflated. I have had four years on each set on the van and all wore evenly (only replaced as precaution).

And as you suggest, if on 'unsealed' roads I run 30 front/35 rear on Landy when towing and drop van to 30PSI and of course drop speed to 70>80Kph depending on conditions.

There are 'basic rules' for tyre pressures but often it is through trial and error that determine the optimum pressure.

Remembering, of course, that the manufacturer of the vehicle suggests a lower pressure for tyres - for a more comfortable ride - whereas the tyre manufacturer recommends higher pressures for better grip. Somewhere inbetween is often the optimum.

Cheers - John

macka17 wrote:

---

SNIP~~~
I normally found over the years specially in wet.
that harder tyres slid easier than softer, more profile on road tyres?.
Or did you get that wrong way round.

Skinnies were better way to go then.

~~~SNIP

---

Gday...

It is a bit like my earlier comment on giving advice on tyre pressures - the answer is 'it all depends' 

If you are talking about 'compounds' - how the tyre is constructed eg how they develop the black stuff (it used to be rubber) - some 'compounds' are softer - ie wear faster but grip in all conditions better ... some 'compounds' are harder - ie wear slower and grip well in most conditions but not at their best in the wet.

Hence some tyres are 'renowned/guaranteed' to do forty million Km some not.

When it comes to 'harder' (pumped up harder) or 'softer' (not pumped up as much) there can be a difference in their ability to grip in wet.

So, the problem. When determining what pressure to run in any particular tyre one needs to have some knowledge of the 'compound' and then decide on a pressure that gives the best 'compromise' workability.

Hence, my comment that giving advice to someone on what pressures THEY should run in THEIR vehicle/van can only be 'broad' rather than 'specific' - ie what I run in my tyres as a guide for their starting point.

You need to know -

• what make/model vehicle they have (and how they will use it) - it will have varying impact on what are 'ideal' pressures.
• what make of tyre they have fitted - and which 'model' tyre in a particular brand's range
• what construction tyre is fitted - H/T, AT, LT - or other 'non-highway' pattern/construction
• what pressure/s does the vehicle manufacturer 'recommend' - usually on a plaque inside the driver's door
• and quite probably what pressure/s does the tyre manufacturer 'recommend' 

Given ALL of that the final thing is to decide on a pressure that seems to be within all the above parameters - ie take a 'now-educated' guess.

Then, over a period of time/distance (eg 100km) -

• observe the wear pattern on the tyres
• observe the grip characteristics - on varying road conditions and at various speeds
• observe the ride obtained

Having done all that perhaps try some changes to the pressures up and/or down to get the best 'balance' of wear/grip/comfort.

Simple. 

People, like most on this forum I'd suggest, have now been doing all the above since they were knee-high to a grasshopper and have the experience to judge what suits them (and their tyres).

Damn that got long-winded  (I was nearly going to include a bit of a story about how I lived back in the 1920s but I thought I had gone on long enough).

However, I believe it shows that one cannot give 'firm' advice on what pressures to run in someone else's tyres - one can only give an indication of what their own experience has been and to offer a 'starting point' for someone else.

Cheers - John

Hi Cupie, I still have my Westport because I don't need or want any of the ton an a half of extra weight with all the mod cons they put into newer vans, however I had shocks fitted to mine and it makes a huge difference on undulating roads like you find in western Queensland and on corrugations when combined with lower tyre pressures.