Does Pajero Sport have the same issue as the Pajero (requiring airbags) when towing

[jared01]

Hello,

I used to own a NW Pajero, which had aftermarket OME suspension and airbags in the rear coils.

I believe the suspension type on that Pajero used to suffer from the rear inner or outer tyres wearing out and could be solved by running airbags in the rear coils, when towing heavy loads.

Our caravan has a measured towball weight of about 220kgs.


My question is, does the Pajero Sport suffer from the same issue, or because it has a different suspension type (or is it axle), not suffer and I don't need to consider airbags at this time.

Our Pajero Sport has quite expensive (to me) tyres (BFG T/A KO2) and I don't want to stuff them up. Still running standard suspension at this stage, but considering upgrading for better towing ability (although currently using a WDH) and ground clearance.

If there is a difference between Pajero and Pajero sport needing and not needing the airbags, can you please educate me as to why so I can try to understand further.

Thought I should double check this.

Thank you!

[nj swb]

Good question!

Pajero is much more sensitive to ride height, because the independent rear suspesion causes the camber of the rear wheels to change as the suspension compresses i.e. they go from | | to / \. This causes the inside edges to wear, as you noted.

Pajero Sport has a solid rear axle, so the wheels stay square to each other as the axle moves relative to the body, so camber change isn't an issue.

Either vehicle will still compress the rear suspension when the 220kg ball load is put on the tow bar, potentially leading to a "nose up" attitude. If your Pajero Sport sinks too much at the rear then air bags might help to keep it level, but it should be much easier to find the right spring to suit your needs without air bags - and OJ is the expert when it comes to that!

So - no, you don't necessarily need airbags to save your expensive tyres, but that doesn't mean you can't improve your suspension - either with air bags, or with new springs.

[Ian H]

I'm not sure why you'd want air bags when you have a WDH, in which case they aren't needed.

The WDH will basically take weight off the rear axle to the point where it's the same as if there was no van attached. Keep in mind, a WDH doesn't alter the fact that there's a ball weight, it just transfers a good portion of the weight on the rear axle to the front axle and some back to the caravan.

[old Jack]

Hi Jared,

The Pajero Sport has a live rear axle with trailing arm and coil suspension so it does not have the same change in wheel alignment issues that the independent suspension of the Gen 3 & 4 Pajero's have so no need to worry about uneven tyre wear when loaded.

The Pajero Sport has the same suspension as the Challenger, therefore the rear coils are very soft and do not carry weight very well. A common upgrade us to fit replacement rear coils and keep the standard front suspension, the replacement rear coils add a little firmness to the empty ride but stops rear end from wallowing and pitching when loaded. Fitting a set of King Progressive Rate rear coils KCRS-23 and replacing the standard rubber cone springs,that assist the coils in deep compression, is a better alternative than fitting airbags in my opinion. Replacement rubber cone springs are Peddar PN 5899. This is a tried and proven combination on both the Challenger and Pajero Sport.

OJ.

[ron2503]

Hi Jared,

Technically, no, you will not need airbags to prevent rear tyres scrubbing because there is no camber movement with a live axle. As to whether or not you need airbags for towing, well that's another story. There are a few schools of thought here. Personally I do not believe the factory suspension is up to towing a ball weight over 150kg, although there are some that would disagree. There are those that have installed airbags in standard suspension to stop it sagging. Others have upgraded the suspension and added airbags as well. Me personally I don't like airbags for towing as they lever extra weight from the trailer to the rear axle while making the front axle lighter. I'd prefer to upgade the rear suspension and use a WDH to distribute the extra trailer weight towards the front axle. This is just my personal opinion and as I said there would be many that would argue differently.

[Ian H]

Hi Jared,
I don't like airbags for towing as they lever extra weight from the trailer to the rear axle while making the front axle lighter.

I'm a bit confused by that statement. What do you mean by lever extra weight ?

As far as i know, all airbags do is change the spring rating and stiffen them up but do nothing about shifting any weight to or from the rear axle.

[Paul NT]

How do rear airbags transfer weight to the front axle??

[Ian H]

They don't.

[nj swb]

I'm a bit confused by that statement. What do you mean by lever extra weight ?

I'm confused too.

How do rear airbags transfer weight to the front axle??

They don't. Rear airbags alter the effective spring rate of the coil spring - more pressure = higher rate, reducing the sag from the ball weight.

With high ball weight, engough weight can be transferred from the front axle to have negative impacts on steering. A weight distribution hitch can transfer weight back to the front axle, helping to counter the effect.

Airbags don't do this.

Edit: Ian beat me to it!

[pharb]

I'm a bit confused by that statement. What do you mean by lever extra weight ?

As far as i know, all airbags do is change the spring rating and stiffen them up but do nothing about shifting any weight to or from the rear axle.

I think just wrong choice of words to describe how more weight comes off front axle, compared to using WDH instead of airbags.

[ron2503]

I'm not an engineer so I can't answer that effectively but this video explains it pretty well. https://youtu.be/XBZu39pQ8Gg

[old Jack]

Hi Jared,

When you hook your camper up and the full 220kg of ball weight is applied to the towball then roughly about 70kg of extra weight is transferred from the front to the rear axle due to the leverage factor of the towball being rear of the rear axle so the real extra load on the rear suspension is 310kg!

A correctly set up WDH should only transfer the 70kg back to the front axle, when this is done there is also a slight transfer of some ball weight back to the campers wheels, this weight is much harder to calculate especially if it is a dual axle trailer. If a WDH is used to transfer more than the front axle transferred weight then you are putting excessive loads on the tow coupling and towbar for which they are not designed for.

Convential WHD's should only be used on road and even then, care needs to be taken through spoon drains, driveway entry/exits or any road condition that will see the horizontal alignment between the rear axle, tow coupling and trailer axle change significantly.

I recall in other post you are considering towing on Fraser Island, obviously without a WDH so your rear stock suspension will not be happy with this.

OJ.

[Greg Grey Grumbly]

Quoting OJ:

‘Fitting a set of King Progressive Rate rear coils KCRS-23 and replacing the standard rubber cone springs,that assist the coils in deep compression, is a better alternative than fitting airbags in my opinion. Replacement rubber cone springs are Peddar PN 5899. This is a tried and proven combination on both the Challenger and Pajero Sport.’

This sounds like a really good mod for the PS for those towing, but just to clarify, I’m assuming that the rear ride height is unchanged?

Greg

[old Jack]

Quoting OJ:

‘Fitting a set of King Progressive Rate rear coils KCRS-23 and replacing the standard rubber cone springs,that assist the coils in deep compression, is a better alternative than fitting airbags in my opinion. Replacement rubber cone springs are Peddar PN 5899. This is a tried and proven combination on both the Challenger and Pajero Sport.’

This sounds like a really good mod for the PS for those towing, but just to clarify, I’m assuming that the rear ride height is unchanged?

Greg

Hi Greg,

There is a slight increase in rear ride height over the factory specification, I seem to recall it is about 10-15mm higher than standard. These coils are still very comfortable but greatly reduce the wallowing when cornering and pitching when on secondary roads particularly when loaded and or towing.

OJ.

[Greg Grey Grumbly]

Thanks for the response OJ, sounds exactly what I need as I did come across some of those rough roads with big dips coming back from S.A. where with the caravan on the back pitching was a bit more pronounced than I’d like.

Rear ride height of an extra 10-15 mm would be quite OK and probably lose that when loaded and hitched up anyway. Thanks for the advice.

Greg