Thread: Weighbridge Weight

To work out the effect of ball weight on axle loads - it increases the load on the rear axle and decreases it on the front axle:

To quote a post on the caravanners forum -

I suspect that you want to know what the effect on the tow vehicle axles will be, relative to ball weight?

You need to know three things to work this out:

1. actual ball weight
2. tow vehicle wheelbase
3. tow vehicle distance from centre of rear axle to centre of tow ball.

The additional weight applied to the rear axle using 1,2,3 above is calculated as - (3 / 2 X 1) + 1
(centre of axle to centre of ball divided by wheelbase multiplied by ball weight, then add ball weight).

The weight lifted from front axle is calculated as - (3 / 2 X 1)
(centre of axle to centre of ball divided by wheelbase multiplied by ball weight)


I make the distance from centre of rear axle to tow ball - or pin in my case as I use a DO35 hitch - to be 1.3 metres. My ball weight is usually around 130 kg. Wheelbase is 2.922 metres according to Land Rover.

So, in my case, 130 kg on tow ball means the increase in weight on the rear axle is:

( 1.3 / 2.922 x 130 ) + 130 = 187.8 kg

If you have a ball weight of 350 kg:

( 1.3 /2.922 x 350 ) + 350 = 506 kg added to the rear axle

The rear axle limit on a 5 seater is 1775 kg. My "tare" axle loads - car empty except me and a full tank of fuel are 1260 kg front and 1300kg rear.

Cheers
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Ok got it thanks. its a massive amount really. There has to be many setups running around exceeding their limit. I ask a few of my mates with vans any they had no idea and had not considered axel weights at all.

Are you happy with you disco.

What effect would using Weight distribution hitches make. Would that remove some of the excessive weight from the back to the front.

I love the Disco - it is a great touring and towing vehicle. My Sd6 has more power and torque than I need... I have a 5 seater SE. The 7 seaters have a higher rear axle limit, 1900 kg as opposed to 1775 kg and a 3170 kg GVM.

I tow things under 2 tonne and I am happy with that. I don't want what I am towing to be close to the weight of my car, let alone heavier.

Last trip my weights at the start of the trip - and I always try to weigh things at the start of a trip - were:

Front Axle = 1180 kg Limit = 1500 kg
Rear Axle = 1760 kg Limit = 1775
Car Total = 2940 kg Car GVM = 3050

Tow ball Weight = 140 kg
Trailer ATM - Axle Load = 1640
Total Trailer Weight = 1780 kg GTM = 1900 kg

GCM = 4580 kg

The Disco had two people - say 160 kg total, plus a medium load in the boot. And full fuel tank and AdBlue tank.

So, very close to my GVM and Rear Axle Limit. Way under my GCM and Tow Ball Mass Limit. Comfortably under my GTM.

I fear most people towing large caravans are way over their rear axle limits and don't even know what the limit is. Lots of them are over every limit, including static roof load. The huge American "pickups" often have a ridiculously low rear axle limit. I think on one of them it is 1500 kg.

Cheers
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This might help with weight distribution hitches:

Weight distribution & load levelling hitches for heavy towing (plus nuts) | Auto Expert John Cadogan - YouTube

HI Thanks for the info. i agree, many vans / cars will be overloaded.

As my caravan is 2900 loaded with a TBW of about 270kg I think I am stuffed. No 5 seater for me.


Thanks for all the info.

I don't know what others are finding but my car uses about 1litre of AdBlue per 100km while towing, which is an absolute pain in the butt. About 1litre / 800km when not towing. I am towing a 3.2T off road van at 90kph and not pushing things very much. I have had it checked by the dealer and there is nothing wrong according to them. However, with the 18l tank of Adblue that the Disco has you need to fill up before 1800km is done while towing. I now carry 20l of Adblue so that I can top up when necessary and fill that jerry up at Caltex truck stop servos around the country. Mine is the SD6 with 700Nm.

Another 20kg that has to be carried, which is not good, but you very quickly run out of Adblue and need to be able to fill it. Two days ago the range was 6700 with 10l remaining at the start of the day and 400km later is was at 2200km with 6l remaining, so the range it gives is meaningless when towing. The good thing is that the app tells you the range and refill volume on your phone so it is easy to keep track of.

Other than that, a perfect tow vehicle, particularly with the extra rear axle capacity of the 7 seater.

I found the same, my van weighs about 2.1T with 2 adults in the car, 3 dogs.
2,400km alert came on which has now dropped to 1,800km after 200km driving without the van, 150km with the van from Mudgee to Dubbo via Wellington. Going into LR Dubbo for a top-up this morning (I'm on a service plan).

Ron

I suppose going somewhere like Fraser island,where there is often a lot of soft sand,the vehicle would use quite a bit of Add-blue,even if not towing?

Something else to remember to take.

Originally Posted by dencat_54

Ok got it thanks. its a massive amount really. There has to be many setups running around exceeding their limit. I ask a few of my mates with vans any they had no idea and had not considered axel weights at all.

Are you happy with you disco.

What effect would using Weight distribution hitches make. Would that remove some of the excessive weight from the back to the front.

Do NOT use a WDH on a Discovery 3,4 or 5