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Is there such a thing as a simple weight upgrade?


weldted

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Thank you for that, used them for processing upgrading my last van. That was a bit more complex needed semi air and larger tyres. It would appear a lot less involved with this one as the chassis plate gives the heavier weight but it's the converters plate that is less.
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if I remember correctly, the Ducato chassis on which your Burstner Ixeo I-736 motorhome is based was built by Fiat in late-2017 and Burstner completed the conversion in mid-2018.

 

For the 2019 model-year a UK-specification I-736 is said to have a Maximum Authorised Mass (MAM) of 4250kg

 

https://www.buerstner.com/uk/motorhomes/ixeo-i/technical-specifications/model/ixeo-i-736-uk-2/

 

whereas the following German advert for a ‘2019 model-year' Ixeo I-736 gives the MAM as 4000kg.

 

https://www.caraworld.de/wohnmobile/buerstner/ixeo/8909168/buerstner-ixeo-i-736-modell-2019-150-ps.html

 

It’s not that uncommon for a motorhome converter to revise downwards the weight-maxima on the chassis manufacturer’s data-plate. This might be if a low-power motor is specified as standard, or if the original chassis has had a rear extension fitted to it that restricts the amount of weight that can safely be towed. But if you wanted to know why Burstner has downrated the Fiat weight values, you’d need to ask them.

 

As your Burstner is built on a Ducato ‘heavy’ chassis, its present tyres should be OK for a 2500kg rear-axle loading, but adding semi-air might still be worthwhile if you plan to exploit that figure (or even the current 2400kg maximum).

 

I would have thought that uprating the MAM to 4250kg should not present any technical problems: it’s much more likely to be the rear-axle loading that would limit you if you really loaded up the rear garage or a tow-bar were fitted.

 

Presumably Burstner ‘downrated’ the Fiat weight values for good reasons, so merely because there are higher weight maxima on the Fiat data-plate does not automatically mean that altering the Burstner figures upwards to match the Fiat values should be easy-peasy or wise.

 

As has been advised above, contact SVTech about this.

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Derek Uzzell - 2019-11-11 8:55 AM

 

if I remember correctly, the Ducato chassis on which your Burstner Ixeo I-736 motorhome is based was built by Fiat in late-2017 and Burstner completed the conversion in mid-2018.

 

For the 2019 model-year a UK-specification I-736 is said to have a Maximum Authorised Mass (MAM) of 4250kg

 

 

.....interesting, that, given the discussion we had about the vehicle history and "model year".

 

However, the UK Tech Spec linked to above actually pertains (I think) to the 2020 model year, and the year has erroneously not been changed on the UK section of the site. (The German section flags 2020 for the equivalent page - and both versions configure 'vans on the new Euro 6D Temp Chassis). These 2020 models are definitely shown as shipping at 4250 as standard on the "Maxi" chassis.

 

Both the 2018 and 2019 model year pricelists (in German), however, show the standard MAM as shipped of the "Maxi" chassis version (pre Euro6D Temp) as 4000, which accords with the OP's experience.

 

The good news, however, is that these versions had a low-cost factory option on that chassis for a 4250 upgrade. (at a price commensurate with what many German manufacturers charge for just a paper exercise).

 

I suspect that an upgrade to 4250 will simply be "paper", and an enquiry of SVTech, or even Burstner themselves, should elicit a positive (and reasonably cost-effective) reply.

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This link may prove useful:

 

https://www.buerstner.com/uk/contact/vehicle-documents-admission-technical-changes/?

 

According to the original poster of the link:

"Burstner will confirm if you can up plate it without technical changes. They contact your nearest Burstner dealer and upon payment, they will issue you with a new plate. It cost me £119 eighteen months ago. You then fill out the changes section on the V5, sending photos of the old and new plates, copy of the documents sent from Burstner, certificate of conformity etc."

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pepe63 - 2019-11-11 8:58 AM

 

Mornin'..

 

I just wonder if Burstner have lengthened the rear subframe/overhang?.. and if they have, maybe their decrease from the Fiat weights is to prevent the rear axle from being overloaded?

 

Just a thought...

(sorry Derek, I crossed your post)

 

Good afternoon,

 

Just what I thought Pepe

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goldi - 2019-11-11 1:41 PM

 

pepe63 - 2019-11-11 8:58 AM

 

Mornin'..

 

I just wonder if Burstner have lengthened the rear subframe/overhang?.. and if they have, maybe their decrease from the Fiat weights is to prevent the rear axle from being overloaded?

 

Just a thought...

(sorry Derek, I crossed your post)

 

Good afternoon,

 

Just what I thought Pepe

 

....can't see that. If the rear axle is capable of taking 2500kg, then it is capable of that whatever the rear overhang.

 

The overhang might certainly make it easier to exceed the max axle load, but it shouldn't in itself reduce it (indeed, there is an argument that says, because of that, the converter really ought to be shipping at the maximum technically possible, or even augmenting the capability).

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Just heard back from JR Consulting they can uprate to 4600kg with no alterations. £180. I am on 225/75 R 16 116Q rated tyres. I don't plan to run at that full weight but given the 120 litre water tank and our wild camping style it's better to have a bit in hand. But with the big garage and the rear overhang care must be taken on loading.
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A tyre load-index marking of 116 indicates that the tyre's maximum design-loading is 1250kg which, on a ‘single wheel’ axle (ie. one wheel on each end of the axle) translates to a msximum axle-loading of 2500kg.

 

I’ve no idea how JR Consulting has concluded that your motorhome’s Maximum Authorised Mass (MAM) can safely be increased by 600kg from the 4000kg specified by Burstner to 4600kg merely as a ‘no modifications’ £180 paper exercise, when Burstner itself only offers an upgrade to 4250kg.

 

But, if you drove your motorhome with its overall weight anywhere near 4600kg, there’s every chance that the present maximum rear-axle loading would be well exceeded, and that this would also be true for the 2500kg maximum shown on the Fiat data-plate.

 

I believe that a MAM increase to 4600kg would be pointless unless the rear-axle maximum of 2400kg were significantly increased (to over 2500kg) to match, and that would mean a tyre change and (probably) adding a ‘semi air’ kit too.

 

You’d be wise to check with SVTech as they are unlikely to use ‘By guess and by God’ calculation methods.

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Robinhood - 2019-11-11 1:48 PM

 

goldi - 2019-11-11 1:41 PM

 

pepe63 - 2019-11-11 8:58 AM

 

Mornin'..

 

I just wonder if Burstner have lengthened the rear subframe/overhang?.. and if they have, maybe their decrease from the Fiat weights is to prevent the rear axle from being overloaded?

 

Just a thought...

(sorry Derek, I crossed your post)

 

Good afternoon,

 

Just what I thought Pepe

 

....can't see that. If the rear axle is capable of taking 2500kg, then it is capable of that whatever the rear overhang.

 

The overhang might certainly make it easier to exceed the max axle load, but it shouldn't in itself reduce it (indeed, there is an argument that says, because of that, the converter really ought to be shipping at the maximum technically possible, or even augmenting the capability).

 

Reading back what I'd posted, and thinking on it again (although "again" would imply that I had actually "thought" about it properly in the first place, and I clearly didn't :$ ), you are quite clearly correct Robinh'.

 

 

I wonder why a converter wouldn't just rate it at 4250kg from the start..?

(I get 3500kg -UK license- thing but why 4000kg? Does it tally with restrictions in other markets?)

 

 

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pepe63 - 2019-11-12 10:23 AM

I wonder why a converter wouldn't just rate it at 4250kg from the start..?

(I get 3500kg -UK license- thing but why 4000kg? Does it tally with restrictions in other markets?)

 

 

The Ducato Converters Manual does indicate that, depending on the conversion type and final weight distribution both laden and unladen, the maximum weights stated by Fiat may not be fully available. This is due to the requirement on modern vehicles fitted with ABS/ESC that vehicle stability and correct operation of those systems can only be guaranteed if the ratio between the front and rear axle weights is kept within specific conditions.

 

So for instance, a motorhome conversion which causes most of the additional weight of the conversion and items loaded within it to be borne by the rear axle, may need to have the rear axle weight limited to that it does not exceed the ratio of total vehicle weight transmitted through that axle compared to the front axle.

 

Whilst the rear axle will be capable of bearing its specified weight whatever the rear overhang, a body with a longer rear overhang and the associated ability to distribute loads further back in the vehicle will both cause the centre of gravity to move further back than would be the case on a standard van and may therefore restrict the rear axle loading due to its ratio to the front axle load under all running conditions.

 

Restricting the rear axle weight to comply with those requirements will of course also affect the available MGW.

 

It seems to me that companies such as JR Consultancy have no way of determining whether and how those ratios will be affected on individual models of motorhome when they make up-plating calculations purely on the original (pre-conversion) stated manufacturers weights and proposed alterations to suspension and tyres, without carrying out weight testing of the individual vehicle subject of the application.

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I echo your final-paragraph views.

 

A few years ago in France it was agreed that a French driver who had obtained a ‘car’ “B” driving-licence entitlement before 20 January 1975 could legally drive a camping-car (motorhome) with no restrictions on the vehicle’s maximum overall weight. To permit this a footnote (Code 79) was simply added to the driving licence.

 

This prompted an enquiry in a French leisure-vehicle magazine asking about uprating the MAM of a 3500kg motorhome to obtain extra payload. The advice given was that this would only be permissible if the manufacturer of the 3500kg motorhome marketed in France a ‘carbon copy’ version of that model with a higher MAM. So a Rapido 640F like mine, and normally sold in France with a 3500kg MAM, could have its MAM increased to 3650kg because Rapido offered two identical 640Fs, one with a 3500kg MAM and the other with a 3650kg MAM. This approach has always made good sense to me.

 

Presumably JR Consultancy arrived at the 4600kg MAM figure by totalling the 2100kg and 2500kg axle-weight values on the Fiat data-plate. But if the MAM of an Ixeo I-736 with a Burstner-provided MAM of 4000kg were increased to 4600kg, not only would this be 600kg above Burstner’s 4000kg limit, but also 200kg above Fiat’s 4400kg limit.

 

I think the chances are nil that Fiat or Burstner would authorise a MAM increase to 4600kg, so - as weldted’s Ixeo is new - the question of potential warranty-related problems arises. If an ‘official’ Burstner upgrade to 4250kg can be obtained straightforwardly (as Robinhood refers to above) that should not affect the Burstner warranty and, as the result (probably) should not conflict with the Fiat weight figures, it’s likely that Fiat would be unconcerned.

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Just one further thought. I assume that your 2019 van must still be comfortably within its guarantee periods? That being so, I think it would be extremely unwise to have its MAM changed by anyone other than Burstner.

 

Even if J R Consultancy were to issue a revised plate that exceeded the limit values with which the vehicle was originally supplied and Type Approved, I'm inclined to think Burstner and Fiat would take the view that by doing so you had declared an intention to overload it beyond its authorised limits, and wash their hands of it.

 

So, I would definitely enquire via your supplying dealer what weight increase Burstner, as the final stage manufacturer under European Type Approval procedures, can offer without a) voiding their warranty, or b) exceeding their final stage T/A delegation.

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Derek Uzzell - 2019-11-12 2:22 PM

 

Presumably JR Consultancy arrived at the 4600kg MAM figure by totalling the 2100kg and 2500kg axle-weight values on the Fiat data-plate. But if the MAM of an Ixeo I-736 with a Burstner-provided MAM of 4000kg were increased to 4600kg, not only would this be 600kg above Burstner’s 4000kg limit, but also 200kg above Fiat’s 4400kg limit.

 

Fully agree Derek, and I am also of the opinion that increasing a vehicle's MAM to the sum of its permitted axle weights is ill advised and gives the driver a false indication of its capabilities in any case, since loading the vehicle to its MAM would almost certainly cause it to be overweight on one or other of the axles unless the load could be exactly distributed throughout the vehicle to achieve the desired balance between the axles, and this would change as soon as the vehicle was put into motion in any case. Manufacturers invariably design vehicles with axle weights which exceed the MAM when aggregated for a reason!

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Perfect Deneb. It is all about weight distribution overall. Point of gravity. Air Suspension keeps the standard ride height stable to their Max axle loads. The figures of fiat are correct for their phase one plate type approval. They provide their testing to the converters and guide lines. Phase two and final. What is including in phase two about testing you can read in the EC number on the COC. But they do not test every configuration. Weight upgrade rules differ per country in the EU. Belgium the worst. Burstner only works whit certain dealers about weight Not all of them per country market. On my fiat light- AL-KO 3500-3700-3850 was possible.New or later in time. And do not remove plates.
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Deneb - 2019-11-12 12:08 PM

 

The Ducato Converters Manual does indicate that, depending on the conversion type and final weight distribution both laden and unladen, the maximum weights stated by Fiat may not be fully available.

 

The manual certainly gives advice on loading, and the recommended proportions on both the front and rear. It also gives advice on maximum overhangs, and defines the limits within which ESC etc. is designed to function.

 

I can't however, find anywhere where it advises reduction in plated weights to compensate for anything (simply the advice on the "loading practice").

 

I suspect the reason for the rear axle MAM difference might be somewhat more prosaic than that.

 

Most "Maxi" versions have 2100/2400 F/R maximum axle limits ex-factory. I was therefore intrigued by the 2500 figure quoted for the Fiat plate. The 'van in question is built on the Fiat Maxi low-frame "camping" chassis, and on this version for the 150 and 180 engine option only the rear axle limit is increased to 2500. The 130 engine, however, remains rated at 2400, much like other Maxi versions.

 

I suspect that either:

 

- Burstner have simply standardised on a plate that could be used across all "Maxi" engine options (since all are valid options), or

 

- The change to the higher rear axle rating on the larger engines happened sometime after initial build runs of the model, and Burstner simply haven't caught up, or

 

- They've erroneously "badged" it as if it were a 130 engined model.

 

;-)

 

Whatever, there is no way I would want to replate that vehicle at 4600, and ever since JR consultancy appeared in this space, I've had concerns about the advice provided and any methods of verifying the vehicle in question. I would certainly be more happy with advice from SVTech.

 

FWIW, whatever the final replated MAM, I don't think 100kg difference in the max rear axle weight will make any difference. Even 2400kg on the rear of such an A-class, with the loading characteristics such vehicles have, would, I think, make the front end so light as to be virtually undriveable.

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Robinhood - 2019-11-12 3:52 PM

 

The manual certainly gives advice on loading, and the recommended proportions on both the front and rear. It also gives advice on maximum overhangs, and defines the limits within which ESC etc. is designed to function.

 

I can't however, find anywhere where it advises reduction in plated weights to compensate for anything (simply the advice on the "loading practice").

 

"To ensure constant and correct set-up and peak capacity, even on low grip road surfaces, safe dynamic behaviour reliability and the required performance, weight distribution

must be within the following limits (that must not be exceeded) in all load conditions:

- Front axle: weight at ground always between 70% and 40% of the total vehicle ground weight

- Rear axle: weight at ground always between 30% and 60% of the total vehicle ground weight.

According to the weight distribution, the total ground weight and/or maximum admissible weights on the axes may not be fully saturated."

 

Whilst that doesn't say that the weights must be reduced, it does indicate that it may not be possible to achieve the maximum admissible weights whilst retaining the required axle weight ratios to MAM according to the type of conversion carried out and its weight distribution.

 

FWIW, whatever the final replated MAM, I don't think 100kg difference in the max rear axle weight will make any difference. Even 2400kg on the rear of such an A-class, with the loading characteristics such vehicles have, would, I think, make the front end so light as to be virtually undriveable.

 

Which in itself suggests that the recommended weight distribution ratios might not be achievable at the original MAM. By reducing the permitted rear axle weight and MAM, Burstner may be mitigating that undesirable behaviour and preventing the end user from overloading the back end as per the design configuration of the conversion.

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Deneb - 2019-11-12 4:37 PM...……………….

- Rear axle: weight at ground always between 30% and 60% of the total vehicle ground weight.

According to the weight distribution, the total ground weight and/or maximum admissible weights on the axes may not be fully saturated."...…………....

4,000kg x 60% = 2,400kg: 4,250kg x 60% = 2,550kg, so I think that is probably the answer. Loading the rear axle to 2,500kg requires the vehicle to be heavier than 4,000kg to avoid an increased risk of wheelspin or instability due to the front axle being sub-optimally loaded.

 

It seems Burstner are recognising that the rear overhang and internal layout are liable to lead to high rear axle loads relative to front axle load, and seeking to reduce the chances of this causing driving roblems.

 

I wonder if Ted has yet taken his van to a weighbridge unladen (useful for UK to check whether it exceeds 3,050kg, where the lower permissible speed limits come in) and at its maximum foreseeable load, to check how the load actually distributes? There may not be any need to re-plate at all unless either the MAM, or the permissible (presumably) rear axle load, is flirting with disaster at the existing plated values.

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This is what AK-Ko said to their Converters now phase 3, in case of their bolted on chassis. Weight distribution: To be sure of correct roadholding, velocity- and brake power even on low grip roads can only be guaranteed at the borders of: front axle on the ground between 40-70 percent of total weight. Rear 30- 60. Front axle should be min 1250 kg. Uneven load (hanging one side) max 10 percent of wheel load..Max overhang 65 percent of wheelbase Or 2.7 mtr. Max height of gravity point of 70 percent of wheel track is advisible. At load. The convertor is responsible for all the rest of negatives.
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Thank you for all your replies, hence the original question? I would find it hard given the design of my van to be able to get anywhere balancing the quoted uprated loading, this van although a bit late now we have bought it has a very limited storage anywhere other than the large garage area well to the rear. It would be very easy to overload the rear axle and take weight off of the front axle so effecting stability and front wheel grip. My original enquiry was to take it up to 4250 kg as the latest models have on the same chassis.

 

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