Caravan swaying from 85klm/ph

I shall get back to you but at the moment the tow ball weight is300kg van weight 2680 when fully loaded it was 2950, cant give any other weights as it is not loaaded for travell as yet still sorting out other issues with the manufacturer.
I shall get bak to all when it is fully loaded and ready for travel, if that is ok.

Hi Macca,
the water tanks ar in the forward half of the van but set back far enough to not interfere with the suspension. The grey water tank is in the rear along with the washing machine and shower and toilet. I need to get the van weighed agian now that we are home, and I have the time to get some more investigation done on the why????. so first I have to get the water leak seen to and also the dust issue. Although we havent been down many dirt roads as yet we need to get these things addressed.
As for the road test it was a beauty, we picked the van up in Melbourne, and instantly found the sway,just by going from where we picked the van up to our overnight stay which turned out to be a 4 day stay. I didn't pay to much attention to the sway as [its a new van] it must be the wind. Anyway before leaving the caravan park I filled the water tanks to the brim and off we set for Brisbane,four days free camping all the way up, tried to sit on a hundred and nearly flipped the van, scared teh crap out of me that was day one on the trip Northrang a few friends here in perth they gave me some advice so every night I wa under the van checking, then I found out about tyre pressures not only on the van but the cruiser too[200 series]that worked wonders but at 90 the sway was back with a vengance. It wasnt until after the wedding and a service in Gympie, that we got some more informationfron the service bloke he did a great job, that 's another story, we moved up to Mckay spent a week up there and put 70kg of wood in the A frame and emptied the rear tank closest to the front wheels. traveled like that four four days heading south we had to be home by the 20th of may, so it gave us three weeks..the van traveled ok so I took a gamble on the third day and filled both tanks. and travelled like that all the way home if trucks came toward us I would slow down same when they came up behind us. So to answere your Question we tested the whole system with some tweeking of the way we travelled, and it still sways the wood is still there and full tanks all the time. the van is level on the hitch, which is a do35. thank you very much for your response

Hi Broodie H3,

From your answers to my questions and the extra information you have provided, it sounds like there is something inherently wrong with the balance of this caravan. If you do not have a lot of weight behind the rear axle, and it still develops sway, something else is causing the sway to be induced.

Wheel alignment could be the issue, the best place to have your wheel alignment checked and adjusted is at a place that either specialises in caravans or truck wheel alignment. Car wheel alignment centres quite often are not set up to do caravan wheel alignments accurately. Whilst you say it has had a wheel alignment and it is better, I would certainly have it checked by someone who specialises in caravans. Were the wheels balanced at the same time?

Another thing to consider is if the axles are not “true” to the chassis, they should be at 90 degrees to the chassis rails.

Is the chassis “true”? In other words, are the chassis rails parallel? Is the caravan frame true to the chassis? Was the chassis manufactured in Australia, or is the chassis and caravan a fully imported “flat pack” and just assembled here?

A well designed and manufactured caravan should be able to travel with full water tanks and be stable on the road. If not, and you have not inadvertently added weight behind the axles upsetting the balance, then the van definitely is not fit for purpose. If you go online and search for reviews from other owners of this brand of caravan, you might get some information as to whether this is an inherent problem with this manufacturer, or if it is just specific to your caravan.

As to Tyre Pressures, whilst every set up is different, and what works for one person, may not be suitable for another, even with an identical caravan and tow vehicle, it is important to have the correct tyre pressures for the load they are supporting. The recommended pressures on the Chassis/Trailer plate should give you a max cold inflate pressure, similar to what is also on the sidewall of the tyres. It may also give you a “running” pressure based on the ATM of the van, or maximum axle load. If the van has been weighed correctly, you should have the individual wheel/axle weights that can be compared to the manufacturers recommended weights. Tyre pressures should be adjusted to suit the actual weight they are supporting along with the recommendations of the tyre manufacturer.

As to a WDH, a WDH is not designed to inhibit or control caravan sway. It is a Band-Aid to a symptom of rear axle sag on a tow vehicle. Whilst there are manufacturers that produce anti sway bars, and combination anti sway and Weight distribution bars, they are still a band aid to a symptom, and not a solution to a problem.

Macca.

I suggest that the primary purpose of a Weight Distribution Hitch is to restore weight to the front axle in order to maintain steering control which is lost due to the overhung hitch.
I caught this on my dash cam. The front wheels came completely off the road. It does not take much imagination to work out the result if this had been halfway around a corner.

Cheers,
Peter
OKA196 motorhome

Peter, that is scary. I would not want to be on the same road as that bloke!

Broodie,
Macca makes a good assessment and advice.
I would only add…..
1) Take it back to the manufacturer fully loaded and insist that he takes it for a highway drive and attend to revealed problems.
2) Sell it and buy a new van of proven reputation.
3) Do the above before you feature in a news story.

Quote " It is a Band-Aid to a symptom of rear axle sag on a tow vehicle"

That is a furphy propagated by the suspension aftermarket suppliers. They maintain that caravan stability can be restored by making the individual vehicles 'level.' Peter_n_Margaret is on the ball. If your tug is not stable then jacking up the rear suspension with a stiff suspension will not restore the stability of the rig. Jacking up the rear of the tug does nothing to restore the steering control of the front wheels. You need to restore some of the weight back onto the front wheels that was removed when you hitch up the van. You have two ways to restore the steering effort, unload everything behind the centre of your rear axle or use a WDH.

When you stiffen the rear suspension all you do is to upset the slight under steer effect in the vehicle that is carefully built into the vehicle by its manufacturers. That is more likely to cause problems than fix your current instability problems

The change in understeer created by stiffening only the rear suspension is real. To reduce this effect, the front suspension also needs to be stiffened, otherwise we are making the tug more difficult to control, just when you need the exact opposite.
Now we are redesigning the tug to do a job that it was not designed to do.
Buying a more appropriate tug would be a better solution, or don't tow a pig trailer that is so big.
Cheers,
Peter
OKA196 motorhome

Peter D,

A WDH does not remove the weight of the caravan/trailer tow hitch, that weight is still there behind the rear axle of the tow vehicle. A WDH pushes the front of the vehicle down and lifts the rear of the vehicle back up.

A suspension upgrade applied to both front and rear suspension is a better option. Yes, a suspension upgrade also does not remove the weight or downforce applied by that weight of the tow hitch, but it enables the tow vehicle to better cope with that weight, and is not restricted to smooth bitumen roads like a WDH is.

Macca.

north 200,
we didn't take the wdh with us no room, we had the car fridge tools anand other parafinalier.
we have a 220vx landcruiser, wheel alingment for the van is require, the vehicle had one done in horsham on the way over along with new tyres. shocks on the van are brand new, and belong to the cruisemaster suspension coil.

I hate WDH but you might not have any choice but to use one. If the landcruiser has had a lift you might need to change the control arm to get the front wheel alignment camber correct. If the tug wonders slightly this can be a problem. Empty the water tanks in order to keep the weight as close to the axle as possible.

In my opinion towing anything over 3000kg with a landcruiser is a risk unless you keep the speed down.

Yes as detailed in the article linked to the post.

Weighing will not tell you anything about its yaw inertia.
Cheers,
Peter
OKA196 motorhome

It will not tell you about its yaw inertia but it will tell you if it's legal. It will also tell you if it can be bettered for towing which will see the yaw taken out. Yaw inertia is mainly caused by poor weight distribution, poor tow ball weights, poor suspension set up, tyre pressures and then of course external factors like crosswinds and to a lesser degree wind turbulence from large trucks. A good weighing company knows all about factors affecting your towing set up and will advise appropriately...they are professionals doing it for a living.

No single item is going to provide a solution.
Adding more tow ball weight can/might add to the yaw inertia, plus transfer more weight off the steer axle. Neither will reduce instability.

Just for "fun", ........

I have a Dutch friend who tows this 32ft caravan behind his Porche Cayenne.
He claims to have towed it non stop from Holland to southern France (1,100km) at an AVERAGE speed of 100kph (cruising at 130kph).
We 'like' ball weights of 10% in Oz. The Europeans like 5%. Caravans are relatively rare in Europe, many more travelers use motorhomes.


This is my pig trailer.
It probably weighs about 2T in this configuration (lots of fuel and water onboard). The tug weighs 6-6.5T. Note that....... :)
It has low yaw inertia and a longer than usual draw bar. Ball weight is about 20kg (I can lift it on and off the hitch), that is 1%. I tow at whatever speed I would use if I was not towing.

Cheers,
Peter
OKA196 motorhome

Brodie said "We have purchased a new caravan from a long standing reputable manufacturer in Victoria"

He has done all the simple initial tests. These did not reveal the root of the problem. The van needs to go back to the supplier, It's not fit for the purpose at present. The supplier should be able to rectify the problem.

Hi RMD thank you for your reply, it is one aspect that had not been drawn to my attention to have checked out. I shall get the caravan yard to check it out on the 16th of next month. Thank you very much as I never would have thought of the shockies being an isssue. Regards