Author Topic: Question About GVM Weight - Are We Under Or Over?  (Read 2936 times)

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Offline edz

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« Last Edit: October 03, 2019, 11:14:06 PM by edz »
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Offline #jonesy

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #26 on: October 04, 2019, 06:20:15 AM »
What the dealer said was wrong.
Yes you have towball weight, so GVM is decreased. Yes you still have to include that weight in the total weighed GVM.

Weighbridge accuracy is 20kg, because of the increments it can show, i.e 20, 40, 60 etc.
It can't show 50, 55, 56

Even if you ball weight is 180, and you reduce GVM by 210 instead of 300, you are still over.

To suggest it is 170/180 without weighing or seeing it is fraught with danger. The 200 as calculated by the weighbridge is the most accurate you have at the moment.
The best way would be to have a post the same height as the towball (when loaded) put that on the scale and lower the coupling on.

Also looking at you car specs for axle load, their total is only 65kg, (< 1 person) over GVM.  so you would have to get your load fairly well balanced.

As GBC said your rear axle weight, is what I'd be looking at if you to do anything. Put front axle on plate, trailer attached and subtract that from your GVM as weighed.


Towball scales aren't great. I've got one and can get reading between 90 and 190 kg for exactly the same setup, depending on how I use it.

I know you said you can't, but anything out of the car to the rear of the camper will help more than its weight.  10 kg out of car is -10 off GVM. Add it to the rear of the trailer, and it will also reduce ballweight, and GVM even further.

In reality you should be fine, I'd keep in mind rear axle Weight for next time.
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Offline Redback

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #27 on: October 04, 2019, 08:35:46 AM »
I agree with Jonesy, once you find out what your rear axle max weight  is, go from there, I wouldn't stress too much a few kilos over won't be a problem if you do get pulled over, which I doubt you will, as long as your setup looks nice and level it shouldn't be an issue.

Unlike some of these grey nomads that drive around with the arse of the car dragging on the ground >:D
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Offline Fizzie

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #28 on: October 04, 2019, 09:10:54 AM »
Not meant for any other purpose.....like snatching, pulling over trees, hanging the 4wd upside down from a cliff or any other stupid idea that a human could think up !!   ;D ;D

Thanks, Gronk - makes sense! :-[
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Offline Merts

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #29 on: October 04, 2019, 01:40:53 PM »
Towball scales aren't great. I've got one and can get reading between 90 and 190 kg for exactly the same setup, depending on how I use it.

100kg variance? They are just a spring inside a couple of tubes and the spring will compress at a known rate for any given load. Unless the tubes are binding or something like that it's simply not possible for the readings to vary that much. I've used mine a few times and whilst I don't know exactly how accurate it is, it reads the same each time unless I alter the weight in the camper.
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Offline Bird

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #30 on: October 04, 2019, 01:53:21 PM »
Quote from: Merts
100kg variance? They are just a spring inside a couple of tubes and the spring will compress at a known rate for any given load. Unless the tubes are binding or something like that it's simply not possible for the readings to vary that much. I've used mine a few times and whilst I don't know exactly how accurate it is, it reads the same each time unless I alter the weight in the camper.

it should be simple...
but its not unusual which is what I was saying earlier.. 50kg diff in weighbridge and towball scales.. 2 people in my club with towball scales.. both give massive reading differences.

'He then went home, and used a tow ball weigh scale from somewhere like BCF, no change to the load, it comes in at 110kg. How would you account for a 50kg difference, and which one would you trust?'

http://www.myswag.org/index.php?topic=56655.0
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Offline #jonesy

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #31 on: October 04, 2019, 02:04:47 PM »
100kg variance? They are just a spring inside a couple of tubes and the spring will compress at a known rate for any given load. Unless the tubes are binding or something like that it's simply not possible for the readings to vary that much. I've used mine a few times and whilst I don't know exactly how accurate it is, it reads the same each time unless I alter the weight in the camper.


http://www.myswag.org/index.php?topic=56655.msg996294#msg996294

Has how I managed to achieve wildly different readings.  I couldn't and get it to bounce up and down like a normal spring type bathroom scale.
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Offline Merts

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #32 on: October 04, 2019, 02:17:53 PM »
http://www.myswag.org/index.php?topic=56655.msg996294#msg996294

Has how I managed to achieve wildly different readings.  I couldn't and get it to bounce up and down like a normal spring type bathroom scale.


That is pretty bad. It seems like it's binding between the two sections that are supposed to move smoothly. I'd take it back for a refund.
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Offline weeds

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #33 on: June 17, 2020, 08:57:26 AM »
Off for a weigh in today...after new fitout


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Offline NZMarkb

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #34 on: June 17, 2020, 09:07:23 AM »
This is well worth watching
Very good explanations

https://www.youtube.com/watch?v=Gv394M0ZMqo

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Offline Wazza999

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #35 on: June 17, 2020, 09:46:37 AM »
Something to keep in mind is that all errors are additive. This means that a weighbridge with an accuracy of +/-20 kg is effectively useless to calculate a ball weight. If each measurement is +/-20 kg, the calculated ball weight will be +/-40 kg. A result of 200 +/-40 kg is not really a useful figure. Even if measured directly on the weighbridge you get 200 +/-20 kg, again not terribly useful if 200 kg is an important value.

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Offline Fizzie

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #36 on: June 17, 2020, 10:24:25 AM »
This is well worth watching
Very good explanations

https://www.youtube.com/watch?v=Gv394M0ZMqo

Thanks for that Mark!

Might have to give them a call ???

Another link to when the two of them had their own weight checked

https://youtu.be/T_DNf0v1zMQ?t=867
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Offline weeds

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #37 on: June 17, 2020, 01:26:25 PM »
Something to keep in mind is that all errors are additive. This means that a weighbridge with an accuracy of +/-20 kg is effectively useless to calculate a ball weight. If each measurement is +/-20 kg, the calculated ball weight will be +/-40 kg. A result of 200 +/-40 kg is not really a useful figure. Even if measured directly on the weighbridge you get 200 +/-20 kg, again not terribly useful if 200 kg is an important value.

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In my experience, most public weigh bridges go up and down in 20kg increments...therefore the weight displayed can only be +/- 10kg....I’m not sure how your getting 40kg as a total error.

I’d say that’s pretty good for doing axle weights, tare, GVM and GCVM.

For towball weights on a weigh bridge which I ’ve done this many time, again not 100% accurate as your not measuring from the tow ball, it’s either at the jockey wheel or rear axle.

Either way, if your within +/- 10kg off your max. weights on a weigh bridge than it’s time to maybe monitoring things.


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Offline weeds

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #38 on: June 17, 2020, 01:33:42 PM »
Just rolled over a weight bridge...free as I didn’t want a docket although it helps when we use recycle steel with them.

Just picked the car up with new fitout, empty apart from driver at 100kg and full tank of fuel

1200 front axle
1440 rear axle
2640 tare

3050 GVM

410kg pay load available......hmm, be interesting to see Touring weight.



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Offline Fizzie

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #39 on: June 17, 2020, 02:17:48 PM »
Either way, if your within +/- 10kg off your max. weights on a weigh bridge than it’s time to maybe monitoring things.

I agree, but I noticed that the people in those videos ^^, mentioned an "80kg tolerance" ???

Anybody heard of that before ???
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Offline Wazza999

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #40 on: June 17, 2020, 02:46:54 PM »
G'day weeds, The original poster quoted the weighbridge operator saying +/-20 kg. I agree it's most likely +/-10 kg. The point though is the additive nature of the errors, so for a 200 kg difference you would get +/-20 kg or 10%. Then if 200 kg triggers  a step change in capacity it is still problematic.

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Offline weeds

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Re: Question About GVM Weight - Are We Under Or Over?
« Reply #41 on: June 28, 2020, 12:46:37 PM »
An option on the north side of Brisbane.....at least they advertise a price.

http://www.aussieescapecaravans.com.au/page/weigh-to-go/

Think they have a special @ $100 at the moment


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