Thread: Can a Disco 4 tow a van with 350kg ball weight... I think not fit for purpose..

Originally Posted by tapda01

Hi, I am a little frantic and would appreciate some validation of my calculations please.... I purchased a single axle off road van with ATM of 2,700 kgs and a ball weight of 270kgs. I calculate when sensibly loaded with full water tanks that the ball weight will increase to about 320 kgs. I also purchased a 2013 SDV6 Disco 4 to tow the van with, assuming (wrongly I now believe) that it had ample power and as it was rated as 3,500kgs max tow weight and 350 kgs max ball weight it would handle the van with ease. If only I had done the calculations fully beforehand....

The Disco 4 has a Tare stated in the handbook of 2,546kgs.
The tank takes 82 litres of diesel. 10 litres I understand are included in Tare so the remaining 72 add 60kgs giving kerb weight of 2,606
The manual states the CGM of 3,240 is only valid with a ball weight of 150kgs or less. For every kilogram of ball weight over the 150, the CGM decreases by 1 kg. This means that the CGM if towing a 3,500kg van with a ball weight of 350KG will reduce to 3,040kgs.
This gives us a legal payload of 3,040 minus the kerb weight of 2,606 minus the ball weight of 350 equalling 84kgs!!!! Â… the wife and kids will need to stay at home and I will need to go on a diet to legally drive the rig... So, are my calculations incorrect, have I misunderstood the manual or did Land Rover have brain fade? Â…. you can tow a big van Mr customer,but you have to do so by yourself ....not fit for purpose I suggest....

I think my calcs are correct, but I would love them to be wrong...

With the van I purchased, I can just about squeeze in my wife and an esky... it has to be empty.. all recovery gear moved into the van.... Do I replace the car or the van?

Thanks

David

My apologies to all …. I have referred to GVM incorrectly as GCM in my original post... tardy of me... I see many have seen my error but others have replied based on GCM... too many acronyms!!!

Cheers

David

Originally Posted by Eevo

lighter isnt better from a stability point of view.

And too heavy is not good either. It is a Goldilocks thing.

Originally Posted by pop058

And too heavy is not good either. It is a Goldilocks thing.

yep, 10% is just right.

Originally Posted by Eevo

yep, 10% is just right.

Not always IMHO

Originally Posted by pop058

Not always IMHO

true, but the posted i quoted, made it sound like less was better, which it generally isnt.

IMHO, for stability, its better to be too heavy than too light on the towball.

The GVM, not Tare, includes all fluids, 90% fuel and 75Kg driver as per the Discovery 4 sales book.

Originally Posted by DiscoMick

I don't think you have a problem.

Top 10 towing vehicles

Mick, we all have the same problem...

3.5-tonne tow ratings: Busting the great 3500kg myths | CarsGuide

Originally Posted by Arapiles

Payload and tow ball weight aren't necessarily linked. The Euro caravans sold here, even the large ones, have very light tow ball weights - because the weight is centred around the axles and isn't over the draw bar. So increasing the weight in the van doesn't change the weight at 10%, which is what you appear to be presuming.

Edit: your numbers don't look right to me:

"Australia only: The nose weight must be a minimum of 7% of the gross caravan/trailer weight, up to a maximum of 250 kg. When using the detachable trailer hitch receiver, see FITTING THE DETACHABLE TRAILER HITCH RECEIVER (Australia only), the nose weight can be increased to 350 kg if the GVW is reduced by 200 kg."

GVW is 3,240 kg. Take away 200kg = 3,040kg.

At that point you can have a ball weight of 350kg - which in Australia typically means a tow weight of 3,500kg.

The D4 weighs 2,589kg, so 3,040 - 2589 = 451kg. Even if you take away another 70kg for fuel you still have 350kg of payload. You don't have to subtract the ball weight from that, it's already accounted for.

The GTW/gross train weight is 6,740kg. Take away the weight of the D4 = 4,151kg left. Take away the caravan weight of say 3,000 kg = over a ton before you hit the GTW. Even at 3,500kg of caravan weight you'd still be 651kg short of the GTW. And if your caravan and what's in it is more than 3,500kg you're breaking the law in any case.

"Fit for purpose"? I'd suggest that it was. And that's before you take into account the torque, the fuel economy and the stability when towing that comes from the weight of the vehicle.

Hi Arapiles, I was with you all the way until you said you don't subtract the ball weight. The second you connect that ball hitch to the D4 you have eaten into your GVM which you have correctly calculated as the reduced 3,040kgs.. the link below defines everything...

Vehicle weights explained | tare, kerb, GVM, payload and trailer figures | CarsGuide

In your example you need a driverless car if you connect a van with 350kg ball weight... hence my fit for purpose comment... I love my disco and it tows large vans like a dream with great economy... but I am now of the opinion that well over 50% of all rigs are not legal and feel car manufacturers need to come to the party and stop making these capacity claims that are not realistic and misleading....


Cheers

David