I am currently looking at Caravans in the 16'- 18' size. Brands, Jayco, Coromal, Supreme. Aiming for 2000kg ATM. I am leaning toward the tandem for the payload & axle rating.
In your travels,
- For the majority of national park & fire trail roads do you find you really need an "offroad van"? (Ground clearance, driving to conditions, tyre PSI etc)
- For those that have tandem, how often do you find it restricts in selecting locations/sites vs having a single? (Wiki, National park, free camps etc)
- For early 2000 Jayco's were the chassis made by Jayco? Thoughts on the c-section vs box?
- For the Coromal offroad tandem non load sharing suspension, has anyone had or heard of issues?
My preference is tandem rocker leaf springs (most independent systems need realigning after gravel and corrugated roads). Leaf springs are much easier to repair out back and can limp on, tied up with fencing wire. Abandoned Overland telegraph wire is easiest to work with plenty of it out there.
Never had any troubles parking 6.5 metre van in free camps. Big 4 at Tamworth we had to unhitch and manager place van (with his little tractor).
Caravan doesn't need any greater clearance than tug - if plumbing is protected.
Meranti framed vans seem to handle rough roads better than aluminium frames.
Box section chassis is preferred (if Australian built chassis) - some Asian chassis very inferior steel and minimum wall thickness. I believe Jayco always made their own chassis.
__________________
Possum; AKA:- Ali El-Aziz Mohamed Gundawiathan
Sent from my imperial66 typewriter using carrier pigeon, message sticks and smoke signals.
My son recently purchased a single axle 17ft Jayco Expanda for an extended trip with his family of 4. It had an ATM of about 1.8T (from memory), but weighed almost that empty.
He removed the axle, wheels, 14" tyres and short slip springs and replaced them with a 3T axle, Old Man Emu after market springs designed for a 79 Land Cruiser and 17" wheels and tyres compatible with this Paj.
This improved the ride dramatically, increased the clearance a little and increased the ATM by about 700kg (from memory).
It is now a totally different van.
Cheers,
Peter
I am currently looking at Caravans in the 16'- 18' size. Brands, Jayco, Coromal, Supreme. Aiming for 2000kg ATM. I am leaning toward the tandem for payload and axle rating.
In your travels,
- For the majority of national park & fire trail roads do you find you really need an "offroad van"? (Ground clearance, driving to conditions, tyre PSI etc)
- For those that have tandem, how often do you find it restricts in selecting locations/sites vs having a single? (Wiki, National park, free camps etc)
- For early 2000 Jayco's were the chassis made by Jayco? Thoughts on the c-section vs box?
- For the Coromal offroad tandem non-load sharing suspension , has anyone had or heard of issues?
Look forward to the responses. Cheers.
Hi Mick, and welcome to the forum.
Always I have towed tandem-axle vans but I have never found any restriction in selecting locations and sites etc, although I do spend most of my time "in the bush".
Can't really think of any circumstance where tandem would be a disadvantage, but others may offer advice there?
My preference would be box section because of its inherent strength.
Coromal non-load sharing suspension is the ONLY suspension system where you will get no axle steer, which is a major cause of caravan accidents. This system has been in use since 1975, and is actually called Symons Knee suspension, with the agents now being Melbourne Trailers.
As with all non-load sharing independent suspension systems it is imperative that the caravan be level when travelling, and that the tyre pressure in the front axle be about 2-3 pound less than that in the rear axle.
This allows the front axle to "scuff" on turns and helps to prevent the van from pivoting on the front axle, and effectively steering the axle group, when travelling, making it tow a lot better, and being much safer.
The Coromal suspension is strong, simple, needs no maintenance and is great off-road or on rough roads. Just run the correct tyre pressures, but you may need to buy a suitable towball shank to get the van level.
Good luck with your search, but please feel free to ask any questions you may have.
Remember, the only silly question is the one you don't ask! Cheers
-- Edited by yobarr on Monday 5th of February 2024 07:41:19 AM
@ Possum3 Point noted regarding the clearance relative to the tug. Looks like I need to confirm what the intended travel goal & destination is, to determine what is really needed.
@Peter Looks like I will need to confirm weights & any mods prior to purchase.
@Yobarr Seems the consensus is for the tandem setup & box section for strength. To confirm, axle steer is the cause of accidents? Thanks for the info relating to suspension. Good to know the history & use of the system.
Cheers!
-- Edited by Ondway2grey on Monday 5th of February 2024 10:09:45 PM
@ Possum3 l Point noted regarding the clearance relative to the tug. Looks like I need to confirm what the intended travel goal & destination is, to determine what is really needed.
@Peter Looks like I will need to confirm weights & any mods prior to purchase.
@Yobarr Seems the consensus is for the tandem setup & box section for strength. To confirm,axle steer is a cause of accidents ? Thanks for the info relating to suspension. Good to know the history & use of the system.
Cheers!
Certainly is, and all suspension types except Symons Knee suffer from this.
Complicated subject, but I don't presently have time to devote to drawing pictures etc to show, but you may be able to find something by using the "Search" function above, as I have posted details and diagrams in the past. Cheers
Hi I have a 20 ft6 coromal tows well don't go offroad but that's our choice van is very capable the coromal suspension bogie set up is very good,tyre wear excellent no scrubbing and handle corrugated condition well again personal choice in relation to setup,have spent a bit part of my life towing things tag alongs, pig ,dog, semi trailers
Another couple of questions that have come to mind.
1. Overslung vs underslung on tandem live axle. Concerns / issues / Preference?
2. Can rocker be direct replaced by rocker roller?
Thanks.
You may be unaware, but "Underslung" and "overslung refer to the position of the SPRING. Not the axle.
Underslung if you're at all concerned about what would happen if the U Bolts break, as if underslung the axle is confined in the area between the spring and the chassis. No big deal.
However, if it's overslung and the U Bolts break the axle is free to travel to places distant, with disastrous results. RSup.
Probably not worth worrying about if decent sized U Bolts are used, but worthwhile being aware of. Cheers
P.S Have you learned about the dangers of axle steer?
@ Yobarr Thanks for the confirmation. I did come across the point that the u bolts needed to be uprated when overslung. I will read up about axle steer. If you have any specific links to share would be great.
@ Possum 3 Main reason was getting some extra ground clearance. Might do travel first & see if it is actually really needed. It seems the rocker is preferred with good maintenance.
@ Mike g g Thanks for sharing your experience. Only thing I can find is some Coromals have internal tyre wear which appears to be a result of spring sag.
@ Yobarr Thanks for the confirmation. I did come across the point that the u bolts needed to be uprated when overslung. I will read up about axle steer. If you have any specific links to share would be great.
@ Possum 3 Main reason was getting some extra ground clearance. Might do travel first & see if it is actually really needed. It seems the rocker is preferred with good maintenance.
@ Mike g g Thanks for sharing your experience. Only thing I can find is some Coromals have internal tyre wear which appears to be a result of spring sag.
Cheers!
VERY briefly, when a caravan's suspension compresses the distance from the van's axle to the hitch point increases because the suspension on that side swings upwards through an arc.
This means that the axle is no longer at 90 degrees to the caravan's chassis, so the van will tend to change its direction of travel.
This is a temporary situation, but when the suspension on one side compresses, the suspension on the other side does the opposite.
Very quickly a rock-and-roll situation develops, with the axle's angle relative to the chassis changing regularly and unpredictably. Rsup.
VERY brief description but I'll TRY to find time to draw some diagrams to help you understand.
Could be a few days away though, as I'm doing big hours on the Roadtrain at present. Cheers
Can someone please give an explanation of what is meant by "axle steer" as I can't find anything on the www that relates to caravans. Any info appreciated. Cheers Free to Fly
Can someone please give an explanation of what is meant by "axle steer" as I can't find anything on the www that relates to caravans. Any info appreciated. Cheers Free to Fly
Hi Rob, because I am working long hours I can't devote time to explain properly. However, in the past I have posted explanation, along with diagrams. You may be able to source that by using the "search" facility on top of the page.
VERY briefly, when a spring compresses the axle swings upwards in an arc, meaning that it is no longer at right angles to the caravan chassis.
This causes the axle to steer the van to the left ( or the right, depending on which side spring has compressed). At the same time, because of "bounce" there will have been weight removed from the opposite side wheel, and very quickly a rock-and-roll situation will develop, where the van steers left, then right, then left until it all goes RSup.
Simple physics, but probably not well explained as I am very tired.
IF I can find a couple of hours spare on Sunday I will try to re-create my diagrams, but in the meantime you may like to try the "search" function to see if you can find them.. Cheers
Can someone please give an explanation of what is meant by "axle steer" as I can't find anything on the www that relates to caravans. Any info appreciated. Cheers Free to Fly
Following on from what Yobarr wrote, but taking a different approach to the explanation ....
A leaf spring is curved, but when compressed as in going over a bump, that curve flattens somewhat, and may become negative. That means the straight line distance between the ends of the spring (the mounting points) constantly varies as you travel. So at least one of the mounting points needs to be free to move.
Usually, the front mounting point is fixed to the chassis and the rear one is on a hinged arm that can swivel backwards and forwards. There are other arrangements but this is the common method.
So, when a bump compresses the spring, the rear mounting point swivels backwards. As a result, the axle which is securely mounted to the spring at about the centre does not travel just vertically. As the spring straightens, it moves slightly backwards. If the bump is on one side, the axle is now slightly angled fore/aft, resulting in it steering to one side or the other.
I am currently looking at Caravans in the 16'- 18' size. Brands, Jayco, Coromal, Supreme. Aiming for 2000kg ATM. I am leaning toward thetandem for the payload & axle rating.
2,000kg ATM? Stay with single axle. Adding another axle will cost considerably more weight. Having a useful payload and being under 2T ATM is unlikely with a tandem. From our perspective, how long we can free camp is determined by our water capacity. Your water capacity will be very low with a 2T ATM tandem.
There is no difficulty from an axle perspective at any weight that you can imagine.
This chipper has an axle group capacity of 4.5T and an ATM of 3.5 Ton on a single axle.
Tandem axle vans are not permitted to drive into the Bungle Bungles.
Cheers,
Peter
OKA196 motorhome
-- Edited by Peter_n_Margaret on Thursday 15th of February 2024 08:12:23 PM
-- Edited by Peter_n_Margaret on Thursday 15th of February 2024 08:13:20 PM
