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

[Coolrunning2009]

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

[nj swb]

Despite what a few people will tell you, the Gen 4 Pajero is a popular towing vehicle, and I have a severe doubt that it would be so popular if all the owners are being shaken from side to side by their caravans. I suspect that the cause of your problem is not simply the Pajero's IRS.

Are your quoted figures (2.8T / 150kg) measured figures (i.e. weighbridge) or manufacturer's specification? Is that 2.8T ATM or tare? I don't subscribe to the "10% ballweight" mantra, but a 2.8T van with 150kg ball weight is getting to the light end of the spectrum. To troubleshoot this properly, it would be good to know we're dealing with actual figures. In addition to simple centre of gravity, the actual distribution of weight in the caravan will also affect performance - a lot of weight a long way from the axles is less stable than having that same weight over the axles. Where are your water tanks?

A 150kg ball weight on its own shouldn't bother the Pajero's rear suspension - what else is loading your rear suspension?

Some photos might help - a side shot of your rig loaded and ready to roll, and perhaps an "upskirt" photo of your caravan suspension.

[old Jack]

Agree with NJswb something is not right.

1. Do you use a WDH?
2. What are front and rear ride heights when the caravan is attached, measured from centre of the wheel hubs to the underside of the wheel arch in a vertical line. Do this measurement with and without the WDH connected.
3. What are the front and rear ride heights when the caravan is not connected?

OJ.

[Coolrunning2009]

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

Thanks for the responses

1) Ball weight has been measured using a ball weight scale

2) 2.8T is ATM & we haven’t had a weighbridge check but the van currently weighs 2.6T (scales used to check). The Tare weight is 2.2T (checked by supplier on weigh bridge)

3) We have a Hayman Reese Weight Distribution hitch but there’s no room on a frame for dual cam sway breakers. When WDH is engaged it levels the Pajero where front is 5 mm higher than back

Will do photos when we hook up tomorrow

[Bessiejan]

Stiffening rear suspension

Hello and I hope the brains here can help. We have a 2018 Pajero which is used to tow a caravan with an ATM of 2800. We experience pitching and yawing of the Pajero when towing. Hayman Reese towbar and WDH installed by ARB. We tow on blacktop only.

The caravan manufacturer recommended getting a sway control system as the independent rear suspension of the car will always cause the movement. We do not have room enough to fit the Hayman Reese dual cam system without e tens I’ve reconfiguration of the a frame on the caravan (again!)

A random person suggested that airbags fitted to the rear suspension would reduce the yawing and pitching.

Has anyone had any experience with the problem we have and how did you fix it without selling the car 😸

Jan

[nj swb]

Hello Jan,

Are you related to Ken?

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

[Bessiejan]

Yes I am.

I did not know he had posted here, but still no response to our similar questions. ����

[nj swb]

Welcome to Jan & Ken.

Rather than have two threads running for the same issue, I've merged them into one. I've left it in the "Bolted on Bits" sub-forum, as it's more likely to reach a wider audience here - the NX, while being the latest iteration of the Gen 4, has roots tracing back to 2000, so we may have many members with relevant experience who won't necessarily look in the NX sub-forum.

As previously posted, it's unlikely the Pajero would be as popular as a towing vehicle if its rear suspension was inherently susceptible to sway - or we'd all know a lot more about the problem. I don't believe your caravan manufacturer is correct to blame the vehicle, and we'd like to help you get to the bottom of the issue. The previously discussed photos would be a good place to start, along with some more information about weight distribution. There is more to caravan stability than simple "centre of gravity" - having the bulk of the weight closer to the axles is better for stability than having two big lumps at either end of the "see-saw".

[old Jack]

Hi Ken and Jan,


As "Njswb" has stated, we cannot offer accurate assistance without accurate information.
We ask specific questions for specific reasons what will become clear as the information is processed. Your problem is most likely caused by numerous factors and just spending $500 on fitting a set of airbags is unlikely to fix your handling problem and could be a waste of money.
Most business are in the business of selling something, even if it is not what you really need. We see this all the time, where forum members spend their hard earned cash, trusting a sales person form XYZ only to still have the problem so they go to the next expert at WXY only to be told and sold something different that still does not fix the problem.


Regards,


OJ.

[nj swb]

Thanks OJ.

Jan & Ken, have you read this article on ExplorOz?

https://www.exploroz.com/Vehicle/Caravans/Caravan_Dynamics.aspx

The article's author is well known across the industry, and has been known to attract his share of controversy - we prefer not to post his name on this forum. Personally, I'm not one of his biggest fans, but I believe the linked article is a good introduction to caravan stability. Hopefully that article may help you to understand why we're asking these questions.

Ultimately, stiffer rear suspension may be your answer - but we'd prefer to confirm that there isn't an underlying issue that we can address first. And (without knowing the brand of your caravan) you can't necessarily trust that the manufacturer has designed your caravan well.

[Dicko1]

Just to add. There are many thousands of Pajeros hauling caravans across Australia that have no towing issues whatsoever...once set up correctly. Many have suspension upgrades to assist with the weight of the van. In Europe the ideal ball weight was proven to be about 5-6%. This test was carried out by a European University study. In Oz we tend to talk about 10% which I also think is too high. As the above forum members have posted...knowing the exact weights will help tremendously...as will tyre pressures, ride height and van weight distribution. I an sure that there is a relatively simple answer. Old Jack and nj-swb are very knowledgeable and with years of experience will offer sound, sensible advice.


Good luck. Dont forget that you have a very capable towing vehicle in the Pajero.

[Greg Grey Grumbly]

Agree with all the above comments, start with the basics such as tyre pressure, loading front and rear.

Having towed our 2.5T van all over Australia with my NT Paj I can confirm that they are a great tow vehicle. I have never felt the need to modify the rear suspension and mine was left stock.

When being passed by trucks etc the van can get pushed around, but sensible techniques like backing off improves the results. Dicko’s comment re ball weight is also good, 10% of van weight is too much IMO.

Two things that I think cause poor handling are excessive weight at the back and tyre pressures -I never run less than 45psi. Rear weight can be helped by loading the heavy things over the axles - wine, air compressors, etc.

But overall the Paj is a great tug and there are plenty put there to prove it.

[Merts]

Hello All

Caravan manufacturer says it’s because of the independent suspension of the Pajero

That's a bizarre assertion. Did the manufacturer explain why they believed independent suspension would cause your problem (a problem that the multitude of people who tow with IRS vehicles don't have)?

[erad]

It sounds as if the balance of the caravan itself is not correct. Does it have a rear kitchen or a rear ensuite? If so, there is a fair bit of weight at the rear of the van, and this can then cause the van to start wagging the tug. You would have to try to load more stuff towards the front of the van (this in turn increases the towball loading).

First things first - check tyre pressures on the van and the tug. Rear tyres on the tug should be about 36 to 40 psi, and at a guess I would put 40 psi in the van tyres as well.

Then check your driving habits. The steering will become lighter when the van is hooked up. You have to use a very light touch on the steering until you get used to it.

Then I would go somewhere else other than the dealer who told you about Indepenant Rear Suspensions causing these problems. That guy was sprouting Bovine Excreta and knows nothing (or he knows there is a problem with the design of the van and is trying to deflect attention from this issue). If you walk through a caravan park, you will probably find at least 40% of the tugs are Pajeros and I doubt that many, nay any of them have sway problems in towing.

Airbags will help with pitching up and down, but ultimately in the pitching situation, it is the dampers (shock absorbers) which will control the pitching. The airbags simply give the dampers more stroke to operate over, and thus work more effectively. Load levellers will do an even better job at controlling pitching up and down, and depending on the design of them, they also help in reducing lateral sway.

[nj swb]

That's a bizarre assertion. Did the manufacturer explain why they believed independent suspension would cause your problem (a problem that the multitude of people who tow with IRS vehicles don't have)?

This is a very good question.

My best guess is that the caravan manufacturer knows that independent suspension on a van can have more stability issues than a solid axle (note that I wrote "can have", and not "will have"), and they have assumed the same issues apply to the towing vehicle. They don't.

The article on Exploroz makes a reasonable explanation of some of the differences between solid and independent van suspensions, but I think he has written "above" in one spot where he should have written "below" - otherwise it doesn't make sense to me.

The more I think about this, the more I suspect that the van manufacturer has modified the weight distribution to reduce the ball weight (to suit Mitsubishi's specifications) without understanding the impact that has on the van's stability. Then, because this same model van (with original weight distribution) has never caused problems behind "other vehicles", the problem must obviously be the Pajero's fault.

I'm guessing.