Single axle vs tandem axle caravan. I need advice

One Word. TANDEM

There is always a lot of discussion about single vs twin axles. I offer the following comments...

1 A twin axle setup weighs a lot more than a single - at least 100 kg, b the time you add the extra axle, springs and wheels.
2 A dual axle setup will have slightly more drag due to friction in flexing the tyres. Yes - the tyres are nominally carrying less load than a single axle but there will still be more drag.
3 A lot of hoo hah has been put up about stability if you get a blowout on a single axle. My caravan is a 16.5 ft Jayco Poptop and I have done over 140000 km with it. In that time, I have had 2 blowouts, and the only way I knew was a rumbling noise which didn't sound right. The first time was on the Bruce Hwy on a Sunday afternoon - 2 solid lanes of traffic travelling at 100 km/h, just over the crest of a hill. Nowhere to pull off. I just kept driving until I could get off the road a bit. Other than noise, no dramas. The second time was on a narrow, winding road, double lines for about 5 km and I thought the car felt a bit sluggish. I heard a noise but then that went away. AA car behind me started flashing it slights and I knew I had trouble, but there was nowhere to pull off, so I kept going for about another 3 km until I came to a driveway and then pulled over. That little trip did wonders to the wheel rim... As for the caravan tipping over - not a chance. Incidentally, I now have a tyre pressure monitoring system which covers the van and the Pajero. Hopefully a worthwhile investment.
4 Reversing the caravan: The most critical part of reversing a van is the distance from the towball to the van axle(s). Obviously, a twin axle setup is going to scrub the van tyres as you reverse, but the amount of reversing yo do is minimal anyway, so there is no difference. For what it is worth, a rear kitchen van typically has the axles set further back (the centre of gravity if well back with a rear kitchen) and thus the length between the towball and the axles is greater. This means that you have to get the car at a wider angle to reverse the van into a spot and therefore it is much easier with the longer distance.
5 Manhandling the Caravan: You can manhandle a single axle caravan (n a level firm site) to position it in a site or a garage, but there is no way you can do this with a dual axle setup.
6 General Towing: A dual axle setup is probably better for towing, but the difference should be minimal if the van is loaded correctly. A dual axle van badly loaded is just as dangerous as a single axle one.
7 Caravan Length: More and more caravan parks are having problems with the size of modern vans. They are getting too large for their sites. A few years ago, we accidentally arrived in Alice Springs the week of the Finke Desert Race. We tried 3 caravan parks to get a site - all booked, but the 4th park asked us how big our van was. I told them and they said it was very tight but we could have the last site. It was tight but we fitted (just) and we had a fantastic week there.


So if you are looking at different vans and all things are equal, I would go for the smaller van - it will most likely be lighter, you will use less fuel and it may make the difference as to where you can get a site if that is your wish.

Had a Blow out on a single axle 16ft Pop top, while a B Double was passing me. Me doing 95 the B Double? The van kept swaying after it passed so pull over and checked the van. Tyre had only done 2500Km. Distributor was reluctant to replace free of charge until I threatened to go to the media. Van normally rock solid behind the Tug.

I like the larger living space so would go with the Tandem. Our Traveller is 21'6"

400Kg payload is not great, from memory ours is 650Kg.

Peter

Any big single axle trailer I've towed hasn't been as well behaved as a similar tandem on road. I've towed single and tandem boat trailers up Fraser Island. Both were OK. I like a single axle trailer but at the sizes and weights you are talking I would prefer a tandem.
A load sharing tandem should also have a lower ball weight than an equivalent single axle which will be a consideration with the Pajero.

I've owned 3 vans, first one 18 foot single axle independent . Had three blowouts in it, wouldn't have know unless I notice the van had a funny lean on it. Second one Tandem axle, 18 foot 6, towed well no major issues but as said above, dirt tracks could be a pain. Third one Single Axle independent, 18 foot 6, The best of them all, Off Road, owned if for 7 years or so. Did some outback roads and tracks. So my preference up to about 19 foot would be single axle. But of course if you want much larger then dual is the only way to go.

The big issue is to make sure it is fitted with High Load Carrying capacity tyres with plenty of leeway between their max capacity and the GTM. Don't under inflate them!

Well our experience with our AOR campers after towing the Q+ for over 40,000km around outback Australia is that it's been utterly reliable in the wide variety of conditions we have been. For example Tanami and GCR as well as sitting at a comfortable, safe and legal speed in the NT that would be illegal in every other place in Oz.

The only advantage, for our use, a twin axle may offer is a lighter down ball weight.

So you need to consider what places you intend to go and what you want form your camper. You have mentioned ball weight as a major consideration so unless you want to do a GVM upgrade on the Pajero I suggest the outcome is inevitable, tandem axle.

But without knowing where you tow a harder question to answer with any more detail

Rob

I agree with Erad's reply above. Most people who relate their experience and compare the towing of single and twin axle vans have towed vans of difference lengths, They have upgraded from a short single axle van to a long twin axle van. About 14 years ago a mate and I changed vans All four vans were about 19" body length. In both cases, we changed vans to get a more desirable layout. His had a floor to ceiling cupboard modified to get a longer kitchen bench. I changed from an L shape dinette in the rear corner to a cafe style one. In both cases, we went from a twin axle van to a single axle. Neither of us noted any change in the towing characteristics of our vans.

The difference in apparent stability between long and short van is due to the length. A longer van will appear more stable because of the yawing resistance. The longer van resists yawing more than a short van. Just like long arrows fly straighter than short ones. It has nothing to do with twin axles being more stable than single axles. Don't let people feed you with all the BS regarding the superior stability of a twin axle.

I have been involved in shifting vans around caravan sales lots by hand. There is no way I can spin a twin axle van on its axis. However, once we had the vans travelling at a walking pace I could easily steer a van by myself. If a van loses its resistance to turning at walking speed, consider how much more turning resistance is lost ah highway speeds. Again I say, don't fall for all the BS about twin axle stability.

The big question will be what's your travel plans & how well will the pajero tow a 19.5 tandem ?

Agree with not so , I'm in the same boat .Picking up a 17,10 off road crusader at years end and have a Nw pajero , little light in the ball weight so i'm upgrading to a dmax . Moving from offroad camper to my first Van so I;m no expert , however I tow our 3 .4 tone vessels around at work and they are hard on tyres etc .
I think a lot people go a bit overboard with there van size these days, most are travelling with just two people and spend a lot of time outside when camping etc .

G/Day Alister p

I've owned both single and tandem axle vans and have not had many problems with either.

I do think depending on drawbar length the tandem always felt a little bit more stable.

The only thing with tandem axle vans, the axles have to be perfectly inline or they will chew tyres like no tomorrow.

Cheers.

Tare at 2100kg and max weight at 2500 means only 400kg load. Doubt if you will make it . 180kg ballweight on Paj is also a limiting factor. I,m buggered if I know why people want bigger vans. I,d go for a single axle van with a tare of around 1900kg...give you more room to move as your Pajeros tow ball weight limits you. I have a Paj and tow 2100kg. In all honesty thats as much weight as I would like to tow. Why/ Because I can safely sit on 100kph not holding up traffic and I also have power left to overtake if need be. Hell of a lot less stressful pulling that weight as well...both on me and the vehicle. Choose carefully mate as there are many out there who tow overweight illegal rigs . Dont join the club. Good luck with your search...you,ll get a million opinions..lol.

A couple of years ago I upgraded from a 750kg 5m single axle 'van to a 1350kg 5.5m dual axle 'van. The suspension on the dual axle is all fully independent (not load sharing) and it's horrible on concrete freeways because the wheels are independently going over the undulations from when the road surface was poured and it shakes the car around uncomfortably. If I was going dual axle again, I'd be trying to get a load-sharing arrangement which should behave better.

No one seems to have mentioned it yet, but a dual-axle 'van has higher maintenance costs (and time if you're not afraid to get a bit of grease on your hands) - twice as many tyres, twice as many bearings and brakes to service.

Others have also mentioned this, but the biggest difference I notice is when trying to move it on the driveway or site - when backing the car up to the 'van to connect them, near enough is good enough with the single-axle, but with the dual-axle it'll be hard work to push the drawbar sideways if you haven't lined up the towball exactly on centre.

All else being equal, your decision could come down to where you can park your van at home, and whether you need to manually manoeuvre it into that spot.

A number of years ago I was in then Flinders Ranges, the camp spot they gave us was at the end of a long driveway, the only way was to reverse. A big crowd gathered, fortunately I was quite good at reversing a tandem so there was no entertainment for them.

Backed up nicely straight, but I wonder how it would have been with a single axle. Does a single axle track like a tandem in reverse or can it be a bit sensitive and twitchy?

Thanks for you comments so far everyone, appreciate them a lot.

Be interesting to know how often blowouts occur. Towed a single axle for 15 years out in WA and never had one. Mind you I did have Bridgestone Duelers
fitted and not Goodyear.
Dave.

If you have the option, dual axle, they are not as easy to reverse, but are more stable, less pitchy, better brakes if both axles have them, less towball weight compared to single, and a better ramp angle....now all ive said is dependant on setup, but generally true. Your GVM will be more with a dually aswell. Do your homework, there are lots more police out there checking weights and measures, keep it legal and enjoy.

Gday, what I meant was the carrying capacity of a dual van is higher than a single, so you can legally carry more stuff in a dual axle than a single. I should not have mentioned GVM, it’s like what tyre is best or model 4wd. This is all subjective, not always the case, so a 4wd single axle may have close to a std dual axle. Then there is load sharing vs independent to consider. The best van I have ever towed was a full shower toilet golf van with dual independent, 4 wheel brakes. Didn’t know it was there.

I've owned a 30 foot single axle 'van, three 27 foot triaxle 'vans, three tandem axle 'vans, two single axle 'vans and two, twin axle, turntable type 'vans.

A tandem axle van copes with rough roads, dips, potholes and sunken culverts better because of its load-sharing suspension.

A tandem axle van is more resistant to sway than a single axle, because the four wheels provide the resistance, and there's less overhang behind the rear axle.
Excessive overhang is a primary cause of sway (as well as poor design and poor 'van loading)

A blowout at speed is easier to control on a tandem axle 'van. You only lose one quarter of your rubber on the road, not half.

I would choose a tandem axle 'van every time, unless it's a only a small 'van.

Cheers, Ron.