Caravan pushing my Pajero side to side, will air suspension fix this

[old Jack]

The springs should settle no more than 5mm within a few kms. Since your rear ride height has changed 25-30mm it would be best to get a rear wheel alignment fairly soon. Cost of a wheel alignment is small compared to wearing the outside edges of the tyre's out over a few thousand kms and having to scrap the tyres.

OJ.

[bsperka]

Hello All



We have a 2018 Pajero & we’re towing a dual axle 2.8T caravan with 150kg on the ball



At 90km/hr on the highway we get shaking of the car side to side.



Have had caravan wheels balanced & aligned, hasn’t stopped the shaking. Caravan manufacturer says it’s because of the independent suspension of the Pajero



Will fitting of airbag suspension help with this?



Cheers



Ken

Late to the party. Have you also considered fitting electronic stability control to the caravan? (As well as sorting out suspension etc).

Sent from my SM-G930F using Tapatalk

[Peterng]

"At 90km/hr on the highway we get shaking of the car side to side. "
What you seem to be describing is a yawing effect...
In regards to the caravan manufacturer..
1/. .I would be quite sceptical of their explanation at this stage until proven otherwise...
2/. I would document all meetings / conversations...names/ job description etc... just in case in the future you may find yourself undertaking a warranty claim with them.
I agree with many of the comments. installing air bag suspension to your vehicle without finding out what is causing the problem in the first place, is throwing good money away.
It seems from your initial explanation, that it may be the design of the suspension of dual wheeled coupled with the van"s design shape that MAY be the problem..
Have other purchasers of your model of van had the same problem as you when towing over 90kph?
Why I say this, as you are increasing speed..over 90kph..the air velocity around the van is applying forces to the Van's structure..that is being transmitted through the chassis /suspension and if the suspension/ wheels is not aligned properly..this can create an unstable Van.
It could a very simple fix..adjusting the vans tyre pressures for that matter or more complicated..hence points 1 & 2
I would get the van's chassis dual suspension alignment checked by a reputable experienced professional who knows what they are doing.....until then..nothing over 90kph.
Good luck.

[gas55]

Many years ago, when I had a Prado, I unwisely put a water container and small tool box on opposite ends of the rear bumper bar on our caravan.
The effect was immediate; a very noticeable 'shimmy' from side to side in the car, due to the extra leverage or swaying of the caravan. Most 'van manufacturers don't recommend adding too much more to the bar.
Nonetheless, our latest 'van has had an extra support added, and with the spare, a box for the occasional use of a Honda 2gen. and a hi-lift jack, I always make sure that every thing is centred as much as possible to the middle of the 'van. Made a bracket for the jack so that it sits in-between the tyre and box on the inside of the bar.
So far have had no problems with our NW.
It is a great, gutsy car for a 4 cylinder.
Greg.

[redbruce]

Good article on why we and US use 10% towball weight rule and Euros use 5-6%.

https://outbacktravelaustralia.com.au/driving-towing-towing/towball-weight-and-trailer-stability/

[Ian H]

Interesting that the author states ..

"Some makers, like Subaru, limit the permissible towball load to a set figure (90kg for most models) and insist that if a Subaru is coupled to a trailer or caravan with a heavier towball load the owner must fit weight-distribution bars, to pull the towball weight back to 90kg."

Wrong. I know what he is trying to say and that's to take weight off the rear axle, which it does but a WDH does not reduce ball weight.

[old Jack]

Yes it is a good article that clearly explains the effects to the static centre of gravity and the impact on towball down loads. Also not worthy is the mention of the trailers suspension, tyre's and coupling.

I am yet to find an article that looks at the dynamic centre of gravity based in both the yaw and pitch axis's that looks at the shifting centre of gravity due to load placement. Also I am yet to see any reliable information on the aerodynamic effects of the frontal drag, lift or down force due to the shape of the caravan, the effects of turbulence at the rear of the caravan and the effects of extremal forces when applied to the side sections of the caravan.
Aerodynamic forces are low at speed below 80kph but once you are doing 90kph or more they start to have an increasing effect on the caravan and the tow vehicle.

If the trailer has dual axles then if it designed and loaded correctly then the weight distribution should be the same across all 4 wheels with the drawbar level.
How many dual axle trailers/caravans would meet this criteria?

If the tow vehicle is pitching up and down due to undersized rear springs then this will also have an effect on the aerodynamic and dynamic stability.

All caravan should have to go through a dynamic stability test in both the unladen and laden conditions.
New vehicles should also have to go through unladen, laden and towing dynamic stability test. I suspect many vehicle would not be able to maintain minimum legal ride when at max rear axle loads if they have standard suspension.

Also worth mentioning, is that WDH's should only be used to transfer the weight back onto the front axle that was transfered to the rear axle by the application of towball downloads and not to compensate for undersized rear springs.

OJ.

[Dicko1]

6 pages and have not heard from original poster who started the thread....some people.

[old Jack]

6 pages and have not heard from original poster who started the thread....some people.

It does matter Dicko, the Op is missing out on a good discussion.
Amazing how some people want to bury their heads in the sand and deny there is a major problem with towing in Australia.

OJ.

[Ian H]

Agree with you guys 100%

Especially about people not wanting to face up to the problem.

[Hill]

At times owners are not at fault.

Attached judgment re a caravan that wasn’t the weight that it was meant to be. A few more findings like this might start the move to tidy up the caravan industry.

http://www8.austlii.edu.au/cgi-bin/viewdoc/au/cases/vic/VCAT/2020/418.html

Credit; ExplorOz forum for this article. (via AOR forum)

Hill

[Ian H]

I don't think they are blameless even in that case. They should load up the van, fill the tanks and head to a weigh bridge to check.

[BruceandBobbi]

They are totally blameless. Compliance stated 2,700kg. Rego papers stated 2,700. There is no reason to think that isn't correct. It also stated they had a 800kg payload. To way in 660kg overweight empty is nothing short of scandalous and disgrace.

You would have to think this wasn't the first time it's happened.

The system is wrong allowing caravan manufactures to weigh one of a type and use that weight for the rest of the same type with added accessories. Each van should be individually weighed for compliance.

[old Jack]

It is the Caravan manufacturers and resellers, vehicle manufacturers and resellers and those in charge of the legislation that are mostly to blame. Combine this with uneducated consumers that believe everything the sales people or sales brochures tell them and you have a recipe for unsafe tow vehicles and trailer/caravan combination.

OJ.

[Mundy55]

This link I have just received is relevant, I think. You've probably seen the first part before but the demonstration in the latter 2/3 is very interesting, imho.

https://www.caravansplus.com.au/guides/caravan-sway-crash-a-115.html?ci=152156&ni=43