Chassis Upgrading ATM on our 17.55-5SH OB.

achjimmy

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Jan 24, 2011
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Hi Max...

Well I'm nearly there too , increasing the ATM from 2006 kg to 2200 kg ...sent all the info off to the engineer and all i have to do is install breakaway brake system and he will certify it . Picked up the breakaway gear today , and started installing it ...easier than i thought .
Once have that done he will come over and check everything and give me the plate ..will keep you informed

Cheers Wally


How'd you get on @wally ? The 16' series on a single axle I would have thought the axle set is maxed at 2,000kg? I know the springs certainly are! Also watch your rims and tyres if fitted with 15"s we and others here cracked rims and had tyre issues on 16's when they were max loaded. The heavier 16's should never have come in 15" rims and there was one member who took Jayco to task over the tyre rating but never reported back here on his outcome. Least with ours they fitted a quality LT AT in place of the normal GT radials.
 

achjimmy

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Yes they were @Drover!! And completely frustrating because when the van was empty the ball weight on the weigh docket was 180kg and all the additional weight fitted to the van was all well behind the rear axle, not any where near the 146kg even if it had full gas cylinders it was still well off. In the end all worked out fine but I do need to be carful as the heavys will likely deduct 250kg from my ATM to work out an estimated GTM if I ever get checked, this is why I want to fully load the van and head to the weigh bridge again.

Cheers Max.


Yeah Jayco seem to have a "manic formula" for ball weights that they don't share with anybody :p
 

Drover

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I didn't realize it was a single axle would have to do some serious shopping for LT tyres with a load of around 1250kg and possibly bump the rims up to at least the same, as Jayco are fond of just using 1t rims on singles from what I've seen.
 

Herbertclan

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I didn't realize it was a single axle would have to do some serious shopping for LT tyres with a load of around 1250kg and possibly bump the rims up to at least the same, as Jayco are fond of just using 1t rims on singles from what I've seen.


If the rims are 1T then I would assume it is not legal. From what I understand over is over no matter how small the figure.
 
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twscoot

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Yeah Jayco seem to have a "manic formula" for ball weights that they don't share with anybody :p

Hi @achjimmy

The towball weight stamp is the off the production line towball weight.

The maximum towball weight we now see sometimes being stamped on our vans is that towball weight plus 10% of the load capacity of the van.

Eg.
Towball weight off production line may be 160kg.

ATM may be 2600kg (which by definition includes the payload capacity - in this example may be 475kg) so the equation for maximum towball weight is:

160 (Towball weight) + 47.5 = 207.7kg (Maximum towball weight).

Not a really helpful end result as many of us have written about before...
 

achjimmy

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If the rims are 1T then I would assume it is not legal. From what I understand over is over no matter how small the figure.

The problem with the 2010-12 era rims is they cracked so i wouldn't use em regardless on a van nearing 2t. The tyres will be near impossible to get. When I looked their was only one type of 15" bfg that had a high rating . Nothing else went above 1050kg loading and I can't recall the tyre manufacturers recommendation but your supposed to have something like 20-25% headroom for loading as well. It needs to be 16" wheels and tyres . But as above the also outback springs only went to 2t and I thought a 50mm sq axle was only good for 2t as well?
 

Drover

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On my old 14, I put on 6" ROH steel rims rated at 1140kgs I think and upped the rubber to 225 70x15 with a LR of 1120kgs, they are sitting in the shed, I swapped the original rims back onto it when I sold it.
You could go 16 rims with a 60 profile tyre so height shouldnt move much.
 

Herbertclan

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The problem with the 2010-12 era rims is they cracked so i wouldn't use em regardless on a van nearing 2t. The tyres will be near impossible to get. When I looked their was only one type of 15" bfg that had a high rating . Nothing else went above 1050kg loading and I can't recall the tyre manufacturers recommendation but your supposed to have something like 20-25% headroom for loading as well. It needs to be 16" wheels and tyres . But as above the also outback springs only went to 2t and I thought a 50mm sq axle was only good for 2t as well?

Yep you are correct!! I pushed my wife to agree on a tandem axle 17' van as I just knew we would always be on the edge of the weight and would be stuck with it. I know with doing my ATM upgrade that going to 16" wheels has a big impact on your suspension and brake ratings, in my opinion if the rolling circumference is the same it shouldn't impact on your braking efficiency and load rating is load rating on rims and tyers! Unless I'm. Missing something here??

Cheers Max.
 
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Drover

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The change from 15 to 16" rims may have an effect on paper but not so much in the real world as the brakes and suspension would all be the same if you ordered it with 16's, the change that would effect things would be height, so doing the math before buying tyres is very important, otherwise you end up with a can of worms getting the hitch position right.
 
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BruceD

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I have found this thread interesting as I recently upgraded the ATM of my Retreat Macquarie. When we purchased the van we had a Ford Territory AWD diesel which had a towing capacity of 2700. Retreat matched the caravan ATM to this, ie TARE 2222, ATM 2700. We quickly realised that with the van and car loaded up we were right on the limit of the car, if not over the GCM. Also just doing some weighing of items when loading the van we were very close to the 2700 maximum of the van. We upgraded to a Jeep GC diesel, towing capacity of 3500, and then asked Retreat if we could upgrade the caravan ATM to 2900. They came straight back and said as the axle rating was 3200, and the ratings for rims/tyres were ok as well, then they had no problem with the increase. Paid the $80, as it was my choice for the change, and the new compliance plate was stamped and posted same day.
 

achjimmy

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Jan 24, 2011
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I have found this thread interesting as I recently upgraded the ATM of my Retreat Macquarie. When we purchased the van we had a Ford Territory AWD diesel which had a towing capacity of 2700. Retreat matched the caravan ATM to this, ie TARE 2222, ATM 2700. We quickly realised that with the van and car loaded up we were right on the limit of the car, if not over the GCM. Also just doing some weighing of items when loading the van we were very close to the 2700 maximum of the van. We upgraded to a Jeep GC diesel, towing capacity of 3500, and then asked Retreat if we could upgrade the caravan ATM to 2900. They came straight back and said as the axle rating was 3200, and the ratings for rims/tyres were ok as well, then they had no problem with the increase. Paid the $80, as it was my choice for the change, and the new compliance plate was stamped and posted same day.


Yep that was because you down rated your van. It's a little diff if your van was never designed for the higher load originally. Hence why I suggest when people are starting off check the regs you had no reason to down rate your van in the first place you just had to keep to 2700 loaded. :D

But in reality what gets most starting out (including us) is they have no idea how much crap weighs and adds up! The average family with 2-3 kids needs a clean payload of 500 kg min in the van I reckon ? Unless all your dong is towing to a van park empty and going grocery shopping when there?
 

BruceD

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@achjimmy Not sure I understand what you mean by down rating my van. Even though the caravan was manufactured to allow a greater ATM, if it had been stamped higher than 2700 I couldn't tow it with the Territory, even if I stuck to 2700 when loaded.
 
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Herbertclan

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I have found this thread interesting as I recently upgraded the ATM of my Retreat Macquarie. When we purchased the van we had a Ford Territory AWD diesel which had a towing capacity of 2700. Retreat matched the caravan ATM to this, ie TARE 2222, ATM 2700. We quickly realised that with the van and car loaded up we were right on the limit of the car, if not over the GCM. Also just doing some weighing of items when loading the van we were very close to the 2700 maximum of the van. We upgraded to a Jeep GC diesel, towing capacity of 3500, and then asked Retreat if we could upgrade the caravan ATM to 2900. They came straight back and said as the axle rating was 3200, and the ratings for rims/tyres were ok as well, then they had no problem with the increase. Paid the $80, as it was my choice for the change, and the new compliance plate was stamped and posted same day.

Its nice when the manufacturer is happy to assist and hats off to them for helping you :)

Unfortunately Jayco weren't as forthcoming in my instance but the end cost was similar.

Cheers Max.
 

achjimmy

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Jan 24, 2011
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@achjimmy Not sure I understand what you mean by down rating my van. Even though the caravan was manufactured to allow a greater ATM, if it had been stamped higher than 2700 I couldn't tow it with the Territory, even if I stuck to 2700 when loaded.


You sure can Bruce. You can have a van stamped with a 27,000kg ATM and as long as it only weighs 2,700 kg when you tow it with your territory it's legal! The ATM is figure you can't exceed regardlesss of your tow vehicles capacity that's all. Quite a misunderstood rule .