# Weighbridge Surprise! Mathematician Requires Please



## soundman (May 1, 2005)

We decided to weigh our outfit last week with surprising results. 8O 
I was expecting to be near or overweight which is what prompted us to do the check in the first place.
We carry a 250cc scooter on a rack (185kg) and according to calculations this would produce 285kg at the axle.
Incidentally the brochure for our vehicle indicates a total payload of 860kg.

So here are the results with the actual plate figures in brackets.

Front axle:1820kg (1800kg)
Rear axle: 2300kg (2430kg)
Gross weight:4120kg (4200kg)


From the results, in total we are under our gross weight but separately we have exceeded the front axle weight by 20kg.  

At the time of the check I had 3/4 tank of diesel and two full 13kg gas bottles, 2 adults with a moderate supply of food and clothing etc. and no fresh or waste water on board. 

To shed the required 20kg from the front axle to make things legal we are considering removing the overcab mattress together with the bed ladder which I feel should then bring us under the 1800kg limit.

Can any mathematician tell me what would be the effect on the front axle if we do either of the following:
1-Reduce the scooter weight by 30kg
2-Remove the scooter and rack altogether (185kg)

I know it would be best to visit the weighbridge again under different conditions but a clue beforehand would be an advantage.

No prizes given for correct answers only appreciation :lol: 

Soundman


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## cater_racer (May 1, 2005)

Impossible to calculate without knowing the overhang & wheelbase.


BTW it would also change with tyre pressure, it could be that you could overcome your front axle overload by increasing rear tyre pressure!


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## dikyenfo (Feb 16, 2008)

But where does all the wine fit in? my boxes are not fitted with anti-gravity units.


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## peribro (Sep 6, 2009)

If you go to SV Tech's website here and scroll down, you will see that you can download a program that calculates the effects on the axles of adding a bike etc. You can also use the same application to give you a good estimate of what you are trying to achieve. I'm pretty sure though that by reducing the weight of the scooter (assuming it overhangs the rear axle), then you will by increasing the loading on the front axle.


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## sallytrafic (Jan 17, 2006)

Removing the scooter would INCREASE your front axle weight, but we need wheelbase and overhang data.

Note 20kg only represents about 1% of your front axle loading, I doubt that the weighbridge is that accurate


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## 100127 (Jul 20, 2006)

Place the wife on the scooter, that would increase weight on the back and decrease weight on the front. Simples.


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## inkey-2008 (May 24, 2008)

If you increase the weight on the scooter rack it would reduce the front axle weight.

You still have over 100kg on the rear axle can you not move something back behind the rear axle like a gas bottle.

Andy


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## ralph-dot (May 10, 2005)

sallytrafic said:


> Note 20kg only represents about 1% of your front axle loading, I doubt that the weighbridge is that accurate


I think my friend who works at Trading Standards and who checks the Weighbridges would argue with that.


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## soundman (May 1, 2005)

sallytrafic said:


> Removing the scooter would INCREASE your front axle weight, but we need wheelbase and overhang data.
> 
> Note 20kg only represents about 1% of your front axle loading, I doubt that the weighbridge is that accurate


Does this mean that if we remove the scooter and rack we will be more over the front axle limit and therefore were supplied a vehicle that was overweight on the front axle in the first place?

On the 1% statement, how much tolerance if any is allowed?
I will post more info (wheelbase etc) soon

Soundman


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## DTPCHEMICALS (Jul 24, 2006)

So how much over are you when you and your good lady sit in the front.


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## ralph-dot (May 10, 2005)

soundman said:


> sallytrafic said:
> 
> 
> > Removing the scooter would INCREASE your front axle weight, but we need wheelbase and overhang data.
> ...


sounds like it, unless you have fitted something forward of the rear axle


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## Rapide561 (Oct 1, 2005)

*Weight*

Hi

I am a bit belt and braces with weights and so on, but I personally would not panic too much about 20kg. When my van was last weighed, it varied by as much as 50kg on two separate weigh bridges, only a few miles apart. The relevant thread is on here somewhere. I concur with Frank re the accuracy. A large plates that can weigh 60,000 kg probably would not even register me walking on to it. I stand to be corrected and will try this when I find a plate weigh bridge in my local area.

Russell


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## soundman (May 1, 2005)

DTPCHEMICALS said:


> So how much over are you when you and your good lady sit in the front.


We are 20kg over on the front axle.
Doesn't like the idea of travelling in the garage or going on a diet!
Don't even suggest she sits on the scooter while it's on the rack either!


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## Rosbotham (May 4, 2008)

I hear what people say about "only" 20kg, but that's with no water on board.

Whereabouts is the gas locker? 2x13kg, full, is best part of 40kg - if that's near the front, may be worth looking at substituting a 6kg lite for at least one of them.

Paul


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## Fatalhud (Mar 3, 2006)

Your problem will get worse if you fill your fresh water tank

If its a 100 litres thats 100kg which will take you over your GVW

Alan H


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## GEMMY (Jun 19, 2006)

Correct me if wrong, I believe his water tank is in the garage which will have the effect of lightening the front axle.

tony


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## Fatalhud (Mar 3, 2006)

GEMMY said:


> Correct me if wrong, I believe his water tank is in the garage which will have the effect of lightening the front axle.
> 
> tony


Yes it would, but my point was that it is quite easy to exceed the Gross Vehicle Weight

On the figures given there is only 80kg spare overall

Alan H


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## Blizzard (Sep 21, 2009)

Soundman, 

Dump the missus  (In the nicest possible way of course).

I'm certain any official weigh includes the driver only,



Ken.


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## Penquin (Oct 15, 2007)

As far as I understand it it's all to do with levers......

what you have is the leverage at the back acting around the fulcrum of the rear wheels, this effectively lifts the front wheels somewhat.

Exactly how much would be an interesting calculation which I would not wish to attempt - it involves the distance of the load (scooter + rear overhang) c/w the distance from the rear wheel (the fulcrum) to the load point (front wheel).

Adding weight BEHIND the rear wheel will "lift" the front wheel around the fulcrum (rear) but will also increase the load on the rear wheel by an amount which also is affected by the distance from the rear wheel to the load.

So it is not a straightforward calculation IMO.

I would agree with Frank about the accuracy of weighbridges - anything greater than + 5% is considered accurate, and no weighing machines (balances) give accurate results - they all give differences rather than absolute values. Hence weighing the same thing on two weighbridges without changing anything would probably give two different results which may vary by up to 200kg for a 4000kg van (200 = 5% of 4000keg) so a 20keg difference is not considered significant.

As you can see it is not an easy problem to solve, but the key thing is to stay within your gross vehicle weight, which you currently are.

Hope that does not cause too much confusion (  ),

Dave


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## Chudders (Jul 5, 2008)

I also have a'friend ' who inspects and tests the weighbridges in this area
The following are laid down in law. 
Most weighbridges are now what they call 3 division weigh bridges
A division is 20 Kg,s (There are a few of an older type)
For weights under 10000 Kg,s weighbridges are expected to be within 1 division of inaccuracy. ie 20 Kg,s 
For weights for 40000 Kg,s for example could be up to 3 divisions of inaccuracy permitted (60 Kgs.)
A motorhome clearly being under 10000 Kg,s will fall into the former category with regard to accuracy. This can be either under or over.
However if a weighbridge is repaired it has to be re inspected and the law then only permits them at that stage to be half of 1 division inaccurate (10 Kg,s). (or 30Kg,s for higher weights)
It is clear from this that a motorhome could therefore weigh up to 20 Kg,s inaccurate.
Again however the majority of weighbridges are pretty accurate and unlikely to be too far out and should have a sump pump to prevent 'floating' of the mechanism. A nice clean deck is also recommended.
The above allowances would indicate the reason why when you weigh the weights come out in nice round figures. The old analalogue weighbridges could measure between the segments and give fractional readings but not necessarily any more accurate.
Dave

Edit, Just re read Soundman,s original post and this would also explain why his measured weights are nicely divisble by 20.


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## Chudders (Jul 5, 2008)

Coincidentally with this topic I have been to our local weighbridge today and was pleasantly surprised. Full tank of fuel, about 50 ltrs water, myself and her indoors.
Front axle 1840 Kg,s (max allowed 2000)
Rear axle 2600 Kg>s (Max allowed 3000)
Overall weight 4440 Kg,s (Max 5000)
I,m happy as the van is loaded ready to go away and still have plenty of weight to spare. (Note my measured weights with regard to them falling neatly into 20Kg,s divisions. mentioned above)
Dave


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## Rapide561 (Oct 1, 2005)

Dave

Is your Eura a TAG axle model? If so, how did you weigh the rear axles? When I tried to weigh my rear axles individually, this was not possible as the axles are too close together, and so I got one reading for the two. 

I am hoping this week to visit one of those large plates that weighs the whole lot in one go. 

Russell


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## Chudders (Jul 5, 2008)

Hi Russell,
No you are right I could only weigh the back axle as a whole. Both together but I understand that that is what is expected on a TAG axle. It would be very difficult if not impossible to weigh separately I would have thought. Also the axles being so close together I think would share the load almost identically
May be wrong though, I usually am
Dave


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## Rapide561 (Oct 1, 2005)

*Weight*

Hi Dave

Here is a link to my original "first time to a weigh bridge with a tag axle."

http://www.motorhomefacts.com/ftopict-35748-harrogate.html

The weigh bridge in question was one large plate. Drive on and weigh the lot, then again with the front axle on, and again with the rears.

I also weighed at trading standards in Leeds, this one was like a panel a foot wide and I drove over it slowly. I do not think it was very accurate for doing the rear axles.

I agree with you though that the rear axles are probably sharing the load, unless the rear locked was extremely heavily loaded, thus more downward pressure on the rear most axle, but the closeness of the two axles should minimise the differentials.

Russell


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## sprokit (May 1, 2005)

soundman said:


> We decided to weigh our outfit last week with surprising results. 8O
> I was expecting to be near or overweight which is what prompted us to do the check in the first place.
> We carry a 250cc scooter on a rack (185kg) and according to calculations this would produce 285kg at the axle.
> Incidentally the brochure for our vehicle indicates a total payload of 860kg.
> ...


As others have already stated, if you take weight off the rear axle it will transfer weight to the front axle - in this respect it's like a see-saw.

Don't worry about 20 kg - most weighbridges (well, plate weighbridges) have a tolerance of + or - 50 kg and dynamic weighbridges (used for weighing in motion) have a tolerance of + or - 150 kg - all in accordance with the Code of Practice for Weighing.

Be aware that for practical purposes, 1 litre of water or diesel weighs 1 kg, and no doubt your fuel tank is at the front of the vehicle!(either above or immediately behind the front axle)

I always advise any motorhomer who comes to my office to enquire about weights to make sure his vehicle is loaded as it would be when touring at maximum weight before I weigh it - that way I can advise him/her properly.

I've attached a weight calculator - just put your own figures in the yellow boxes.

Russell - if you look at http://tinyurl.com/6d6pux8 in the downloads section, you'll see the correct way to weigh a tag axle (in fact any vehicle) on a plate weighbridge. Tag axles (twin rear axles) are classed as one axle for enforcement weighing purpose as they are considered to be "compensating axles" i.e. they share the loading.

The 'foot' wide plate is in fact a dynamic weighbridge, which can be used in either a static mode or 'weigh in motion' mode.

Keith (Sprokit)


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## JockandRita (Jun 1, 2005)

Rapide561 said:


> Is your Eura a TAG axle model? If so, how did you weigh the rear axles? When I tried to weigh my rear axles individually, this was not possible as the axles are too close together, and so I got one reading for the two.
> 
> I am hoping this week to visit one of those large plates that weighs the whole lot in one go.
> 
> Russell


Hi Russell,

My last weigh in was just before leaving the UK to join the MHF 2010 German Rally, and after officially upgrading from 4.5 tonnes to 5.0 tonnes. 
It was done by invitation from VOSA, at their roadside weighbridge near Sawtry, just off the A1 in Cambridgeshire. Even without the official plated upgrade in GVW, I wasn't over weight with all services fully replenished. The front axle was weighed first, and then I was asked to move forwards so that the middle axle could be weighed.
The next instruction was to drive forwards off the plate completely, and then reverse the rear axle back onto the plate. This then completed the weighing of each axle in turn. 
Upon receipt of the weigh ticket, the VOSA operative could not believe that I had all tanks full, (except waste), and he was suitably impressed with the vehicle's payload. I still had about 130Kgs spare, and that was before the upgrade to 5.0 tonnes was officially plated onto the vehicle.

I have been informed by VOSA, (who were instrumental and supportive in the upgrading), that I am welcome at any of their weighbridges any time FOC, but preferably by appointment.

What can one say about that level of service other than..........absolutely superb. :thumbleft:

Cheers,

Jock.


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## grizzlyj (Oct 14, 2008)

Hi

As others have said, the weighbridge can be + or - 20kg, so you could well be 40kg overweight on the front, and also be 20kg higher on the rear, leaving you with only 40kg spare payload for the remaining diesel, full tank of water, and all the other odds and sods that may well travel with you on a trip!

Perhaps this is "near enough" to the manufacturers figures to not worry unduly, but rather than trying to move a bit here and there, would it be better to have a full rethink of what you always carry, see how much you don't need and can easily leave behind, ensuring you are always well within your maximum? We've done this quite often, and are always amazed at what weight we can lose and a few months later can't remember any of the stuff we don't have any more!!!

I know VOSA "allow" 5% over, but I've yet to discover wether that 5% is still going to cost you a fine per offence, and over that gets you impounded, or is 5% realistically permitted, perhaps with a warning, and over that fines etc start?

Maybe the forum members should club together and buy some of those scales used to measure corner weights for race cars? Or just hire some at an event?

Links below are an idea of what I mean, I can't find any for sale with a suitable weight capacity, or to buy with a price in the UK!

http://hawkleygroup.com/hawkleyint/portablevehicleweighing.shtml

http://www.scaleline.com/truck_scales.htm










Jason


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## MyGalSal (Dec 8, 2008)

Soundman, I may have missed it but what is your van plated at?
Sal


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## GEMMY (Jun 19, 2006)

Sal, page 1 item 1

tony


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## MyGalSal (Dec 8, 2008)

Thanks Tony. I saw the figures in the OP but I wondered if Soundman was adding the maximum permitted front and rear axle weights together and using that total figure as his maximum weight. If he is plated at 3850 or 4000....... :roll: but perhaps he is plated at 4200. I thought the platings above 3500 or 3850 were usually say 4000 or 4250 or even 4500. Although I say 'plate' I should be saying log book because when we were stopped and checked in France they were only interested in our log book (or V5C Registration Document or whatever fancy title it has these days).
Sal


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## soundman (May 1, 2005)

MyGalSal said:


> Thanks Tony. I saw the figures in the OP but I wondered if Soundman was adding the maximum permitted front and rear axle weights together and using that total figure as his maximum weight. If he is plated at 3850 or 4000....... :roll: but perhaps he is plated at 4200. I thought the platings above 3500 or 3850 were usually say 4000 or 4250 or even 4500. Although I say 'plate' I should be saying log book because when we were stopped and checked in France they were only interested in our log book (or V5C Registration Document or whatever fancy title it has these days).
> Sal


Hi Sal, yes the plate says 4200kg which I believe has already been uprated by Hymer AG.

Soundman


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## soundman (May 1, 2005)

I have had a lengthy chat to the people at SV Tech in Leyland today (what helpful people they are).
It appears what I thought was going to be a problem (scooter and rack) could well end up being our saviour.
If I remove the rack and scooter they calculate the front axle weight will go up to around 1932kg which puts us well over the rated 1800kg.
The only accessories are the ones fitted by the dealer since the van arrived in the UK are:
5m Omnistor (between the axles)
2*11kg gaslow bottles (near to front axle) 
1*85 amp battery ( between axles but nearer to front)
1*towbar (naturally on the back)
Apparently the front axle cannot be upgraded and the plate is now at maximum for the gross weight.
I intend to weigh the van again without the scooter and rack to confirm the speculated front axle weight.

Nothing more can be moved rearwards other than the overcab mattress which we don't ever intend to use so we are considering removing this to make things legal for time being.

How many vans are out there not carrying scooters etc. are over weight on the front axle right from the start without the owners ever knowing.

Soundman


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## Fatalhud (Mar 3, 2006)

I think I would go to a different Weighbridge as well, just in case the first one did it wrong

Its hard to understand how it can be overweight on the front axle
especially with all the weight hanging off the back

Alan H


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## Rapide561 (Oct 1, 2005)

*Vosa*

Hi

Where are the VOSA weigh bridges listed? Local private ones want £15 in this area. Not paying that!

Russell


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## Fatalhud (Mar 3, 2006)

*Re: Vosa*



Rapide561 said:


> Hi
> 
> Where are the VOSA weigh bridges listed? Local private ones want £15 in this area. Not paying that!
> 
> Russell


If you don't want a ticket my local one does not charge, I usually leave them a fiver for a drink to keep them sweet

Alan H


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## soundman (May 1, 2005)

Fatalhud said:


> I think I would go to a different Weighbridge as well, just in case the first one did it wrong
> 
> Its hard to understand how it can be overweight on the front axle
> especially with all the weight hanging off the back
> ...


We used the one at Trading Standards at Gildersome Spur near Leeds.
It's a self weigh dynamic system which is free.

Soundman


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## Chudders (Jul 5, 2008)

I have weighed at 3 different plaaces here in Cornwall.
Vastly different prices
One charges £7 per weigh which means when you weigh each axle separately and the gross weight equals £21 so I don,t go there.#
The second charges nothing if you just want the 3 weights written on a piece of paper.
The third and is the one I use charges £2.20 for all 3 axles. The reason I go is because its clean and easy to access.
I don,t begrudge £2.20 for a proper printout.

Dave


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## Rapide561 (Oct 1, 2005)

*Weigh*

Hi

Fatalhud - Where is the free one please?

I have used the trading standards bridge at Gildersome, but difficult to weigh a tag axle.

I have never weighed this van though, only the previous one

Russell


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## Fatalhud (Mar 3, 2006)

As I said there was no charge providing you did not want a printout of the weights
It was Wastecycle Ltd, Private road no 4. Colwick industrial estate, Colwick, Nottingham
Tel: 0115 940 3111
Its a good 9 months since I was there, so it may be worth a call to make sure nothing has changed

Alan H


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## JockandRita (Jun 1, 2005)

*Re: Vosa*



Rapide561 said:


> Hi
> 
> Where are the VOSA weigh bridges listed? Local private ones want £15 in this area. Not paying that!
> 
> Russell


Hi Russell,

I spoke to a VOSA inspector at the local HGV testing station, who told me when he and his colleagues would be operating at the nearest VOSA weighbridge, and off I went.
Tags are easy to weigh on the axle plates.

Cheers,

Jock.


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## JeanLuc (Jan 13, 2007)

The calibration and use of a weighbridge seems to be a pretty complicated area. I have downloaded the testing and calibration document from the VOSA website and without boring everyone with all the details, the extract below is from the section on using an axle weigher in dynamic mode: as outlined in Soundman's original post. You will see that it implies a wide margin of potential error.

Philip


•	the vehicle to be weighed is stopped a minimum distance of 6 metres from the weighbeam; 
•	the driver of the vehicle is instructed to drive across the weighbeam at a steady speed not exceeding walking pace; once at a suitable speed the driver must not accelerate, brake or change gear; 
•	the vehicle is observed at all times during the weighing procedure to monitor that a consistent speed is maintained and that all wheels pass over the weighbeam; 
•	if at any time during the weighing a driver accelerates above the permitted speed, thus causing an invalid printout, or no printout to be registered, or if the driver brakes to cause a sharp deceleration, the weighing must be disregarded and the vehicle weighed again until a satisfactory weighing and printout is achieved; 
•	the recorded weights should be assessed in the light of accuracy limits of +/- 150 kg per axle, with a consequent accuracy limit on gross/train weight of +/- 150kg, multiplied by the number of axles. Compensating axles should be assessed as a combined weight, applying the +/- 150 kg for each axle included.


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## soundman (May 1, 2005)

JeanLuc said:


> The calibration and use of a weighbridge seems to be a pretty complicated area. I have downloaded the testing and calibration document from the VOSA website and without boring everyone with all the details, the extract below is from the section on using an axle weigher in dynamic mode: as outlined in Soundman's original post. You will see that it implies a wide margin of potential error.
> 
> Philip
> 
> ...


Hi Philip
Thanks for your input to this thread.
+/-150kg sounds an awful lot of tolerance when other people seem to think 20kg was a problem!

The van has now been weighed again without the scooter and rack and we weighed in on the front axle at 1930kg (130kg above max)

Soundman


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## peribro (Sep 6, 2009)

soundman said:


> The van has now been weighed again without the scooter and rack and we weighed in on the front axle at 1930kg (130kg above max)


It's reassuring (in a way!) that this reading is consistent with the one you had done a few days ago. You previously said that the scooter and rack weighed 185kg but the load on the rear axle had been calculated at 285kg. This implies that the negative load on the front axle of the scooter and rack is 100kg. Your front axle weight without the scooter has apparently increased by 110kg so that is pretty close to what would have been expected. Just means that you can't go anywhere without the scooter!


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## soundman (May 1, 2005)

peribro said:


> soundman said:
> 
> 
> > The van has now been weighed again without the scooter and rack and we weighed in on the front axle at 1930kg (130kg above max)
> ...


The guy's at SvTech calculated our front axle weight to within 2kg when the rack and scooter were removed. I think I have found my "Mathematician"
This now means it's back to the dealer who supplied the vehicle for some answers!


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## sallytrafic (Jan 17, 2006)

With respect Soundman if you had given us the details we asked for on page one of this thread we would have calculated it for you.


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## soundman (May 1, 2005)

sallytrafic said:


> With respect Soundman if you had given us the details we asked for on page one of this thread we would have calculated it for you.


Not wanting to feel ungrateful for all the advice given on this thread, we had to be precise and be weighed again rather than work from predicted figures.
SvTech actually did calculate the the predicated figures from the details in the first post!

Soundman


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## sallytrafic (Jan 17, 2006)

soundman said:


> sallytrafic said:
> 
> 
> > With respect Soundman if you had given us the details we asked for on page one of this thread we would have calculated it for you.
> ...


That's because they already knew your overhang and wheelbase. :roll:


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## soundman (May 1, 2005)

sallytrafic said:


> soundman said:
> 
> 
> > sallytrafic said:
> ...


I did say they were clever people! :lol:


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## longhorn (Apr 30, 2009)

*max veh weight*

you will find that your max gross 4100 Kgs & train weight 5500 Kgs

regards longhorn


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## soundman (May 1, 2005)

*Re: max veh weight*



longhorn said:


> you will find that your max gross 4100 Kgs & train weight 5500 Kgs
> 
> regards longhorn


The vehicle is plated at
4200kg Gross with a trainweight of 5880kg
Where have you got your figures from Longhorn?

Soundman


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