Defender 130 Towball Load question

[Claire]

Hello all,
Has anyone any advice or explanation to help me navigate the low Towball weight limit on my 1996 Defender 130 dual cab?
Towing capacity is 4000kg, towball limit is 120kg only!
All towing specialists and vehicle engineers I've spoken to are surprised at the low limit, but nobody can explain why it would be, or if there's any hope of upgrading it. Some suggest it might be about axle loadings, but they seem reasonable at 1580kg and 2200kg respectively.
My husband has admitted to towing all sorts of heavy things back in the day (with no regard to towball weight) with his similarly aged Discovery, ditto my husband's son, with his 2010 Defender 110 wagon.
Visually, the chassis and towbar of my vehicle are far more heavy duty than some (most?) of the new things driving around with a towball limit of 350kg.
I guess im missing something.
Does anyone have any thoughts?
Thanks!

[shack]

Hi Claire,


Where are you getting the figures from that you are quoting for your Defender?

The towbar, the manual or somewhere else?

[Claire]

Hi Shack,
The GVM, GCM, axle max loads etc are both in the manual and on the compliance plate.
Towing limit is in the manual and on the towbar plate.
Towball limit of 120kg is on the towbar plate. In the manual is says 75kg!! But I just cant even get my head around that, so im not even going there!
If the Aus compliance were happy to increase the limit by 60% from the manual to the compliance plate - what is it based on? 🤔

[350RRC]

Hi Claire,


Where are you getting the figures from that you are quoting for your Defender?

The towbar, the manual or somewhere else?

193469

This is an image of the genuine towbar on my POS. Spec'd by real engineers.

There is absolutely NO science behind the '10%' rule that I can find anywhere on the net.

DL

[scarry]

193469

This is an image of the genuine towbar on my POS. Spec'd by real engineers.

There is absolutely NO science behind the '10%' rule that I can find anywhere on the net.

DL

That is "static ball load",120KG.
Maybe operational is 75KG.

Seems rediculous to me,but i do remember my Brothers D1 having something similar.

[TonyC]

James,
My 95 130 is the same, as is a 96-7ish Disco.
That is the factory numbers, in the owners book, workshop manual and on the tow bar.

Claire,
If it can be changed, it would be through an engineering process, the first step would be to talk to an appropriate engineer in your state, I'm not sure How the system works in NSW.
Roads and Maritime will point you in the right direction.

The 130 has a high rear axle load compared to most vehicles, but be aware that the load that is placed on the rear axle is higher than the towball load due to the rear overhang.

Keep us informed with how your go, I've always puzzled over this as well.

Tony

[Claire]

Thanks everyone.
I'll let you know how I go.

[350RRC]

That is "static ball load",120KG.
Maybe operational is 75KG.

Seems rediculous to me,but i do remember my Brothers D1 having something similar.

The 10% rule is ridiculous IMO, seems to be based more on popular belief than real science.

Originally my 74 had the HD towbar that was rated to tow 6t, but at a reduced speed with an uprated ball from memory.

Imagine putting 600kg on the bar, front wheels would be almost in the air.

DL

[MLD]

I ran a case about a horse float not long ago on this issue and i researched the laws, ADR, VSB14 up to my eye balls. In summary:

The towball load capacity is set by the OEM manufacturer. Ford Ranger has a tow ball rating of 350kg but other manufacturers set their own. Only the OEM or a secondary manufacturer can increase the tow ball weight. Engineer does not have discretion to increase the tow ball weight.

Tow load rating is set by the OEM manufacturer. Only the OEM or a secondary manufacturer can increase the tow ball weight. Engineer does not have discretion to increase the tow rating.

to acheive 4,000kg load rating you need to use a 70mm tow ball. 50mm is limited to 3,500kg.

axle loading is taken into account in tow capacity and tow ball weights but is not determinative (ie can't reverse engineer the logic and say my rear axle rating is 2200kg, therefore i should be able to tow X). The axle load distribution changes based on the tow ball weight of the thing being towed. In a balanced set up the front carries its fair share of load of the tow weight. Increase tow ball weight, the weight balance shifts to the rear axle. Lighten the tow ball weight, weight is distributed to the front axle.

As for the 10% rule, there is no rule, law, guideline, Australian Standard or other document in Australia that states 10% of tow weight for tow ball weight is a standard to be applied. I looked into it for my case. My lines of enquiry i found linked the 10% to USA material that was in circulation 40 or 50 years ago. For some reason, that made its way to Australia and then cemented itself into folk law. It's absolute bullocks and any person that quotes it to you should be ignored.

As a comparison, my MY11 130 I have a GVM rating of 3,850kg (engineered increase) with a 2.5T rear axle rating. I have a GCM of 7,350kg and my tow rating is 3.5T. I asked the engineer if i can use the extra in the GCM to increase the tow rating and was told no. Petty sure my Haymen Reece tow bar is rated higher than 120kg tow ball weight. It's been a while since i looked at it.

[350RRC]

.....................

As for the 10% rule, there is no rule, law, guideline, Australian Standard or other document in Australia that states 10% of tow weight for tow ball weight is a standard to be applied. I looked into it for my case. My lines of enquiry i found linked the 10% to USA material that was in circulation 40 or 50 years ago. For some reason, that made its way to Australia and then cemented itself into folk law. It's absolute bullocks and any person that quotes it to you should be ignored.

...............

A few years ago I searched the net for a whole day to see where this 'rule' originated and the only thing I found was a reference to an off the cuff comment by an engineer at a RV show in the US decades ago when asked about ball / tow weights.

DL

[p38arover]

Is that towbar placard correct? It says, RangeRover/Discovery, not Defender.

[Claire]

MLD... Thanks for taking the time to share all your prior research. Much appreciated and great info.

Ron.B.... My original 130 placard is the same as the one shared, so perhaps its standard on both vehicles.

[Slunnie]

193469

This is an image of the genuine towbar on my POS. Spec'd by real engineers.

There is absolutely NO science behind the '10%' rule that I can find anywhere on the net.

DL

Personally, I think the 10% rule is a massive smoldering load of bull****. 350kg on the ball is only great if you want to destroy vehicle dynamics and have a crash.

However, good luck buying a Caravan or horse float (or many other trailers) where at the higher weights doesn't have a massive ball weight. Its totally ridiculous.

[TonyC]

Is that towbar placard correct? It says, RangeRover/Discovery, not Defender.

That's because it's a picture of RRC350's Range Rover tow placard, not a Defender one.

Tony

[TonyC]

Claire,
What does you caravan weigh?
What is it's coupling weight?
Can you move things to reduce this?

Tony