Payload, Axle Limits, etc.

[Robinhood]

Given the ongoing debate about payloads and axle-weights alongside the viability of a 3500kg MAM van, and the fact that I had the opportunity to weigh my 'van in Sweden in (virtually) full running order with contents for a reasonable length break, I thought I'd post my experience.

 

The current 'van was bought after the previous two being rated at 3850kg (albeit these without any uprating of axle-limits above the then Ducato maxi values of 1850/2120kg respectively).

 

Whilst it still wasn't critical from a licensing point of view (I'll still see a few more 'vans off before that happens ;-) ), I was getting more and more niggled by the increasing restrictions and cost implications of the over-3500kg rating. Coincidentally, future use was also likely to be (for the first time) in the main restricted to the two of us.

 

Much studying of potential 'vans took place, with my current Hobby Van TL500GESC coming out top of the shortlist (in the end, by a clear margin). It is nearly 6.8m long, but, being a "van" designated model (even though it is coachbuilt) is rather narrower than the norm at 2.18m.

 

(I would ideally have liked something just slightly shorter, but this ticked all the other boxes, so that was it).

 

It became apparent from studying many brochures that manufacturers in general seemed able to achieve better (quoted) payloads on the Ford Transit base (particularly the platform cab on which the Hobby Van is based) than they were on the Ducato. In addition the standard axle limits for the (3500kg) Transit are 1750/2250kg respectively - potentially a more useable balance for a vehicle with a decent rear-overhang.

 

MIRO is quoted by Hobby as 2870kg (with standard fit equipment, and including driver at 75kg (I wish!), 90% water and gas, etc.). This would lead one to believe there was a useable and very adequate payload of 630kg.

 

Having owned numerous 'vans in the past, however, my expectations were different. The quoted figure excludes any optional equipment, and would have been calculated using somewhat lighter German gas cylinders. Quite a bit of "Optional" equipment is fitted as standard for the UK market, and even before any additions of my own, this needed to be taken into account.

 

So, heavier gas, significant base-vehicle upgrades, upgraded heating, awning, bike-rack, etc. would all eat into that before such dealer-fit bits as an extra battery and TV aerial, etc.

 

My (admittedly back of fag-packet) calculations indicated that, even taking this into account, the payload was likely to be amply sufficient for 2, and a visit to a local weighbridge in (only) partially loaded state subsequently indicated that all was likely to be well.

 

From purchase I've run with the Continental Vanco (non-camping) tyres at the Ford "sticker" values, which coincide exactly with the Conti technical data for the respective maximum axle loadings.

 

Pulling up in Sweden for a tea-break just short of Halmstad gave me an opportunity to weigh the van in virtually full running order. I noticed that the lay-by we were in had a weighing "bridge", and an untended and locked cabin. On top of the cabin, however, was the digital read-out, and jumping on the platform showed that the system was active.

 

So, after tea, the 'van was manoeuvred onto the platform, and front axle, overall, and rear axle readings were taken. The approach and exit were both flat, (and there was only minor difference between the total of the two axle loads and the overall weight, which leaves me feeling rather confident about them).

 

So

 

Overall weight was 3395kg (as against an MAM of 3500kg)

 

Front axle weight was 1420kg (as against a max of 1750kg)

 

Rear axle weight was 1960kg (as against a max of 2250kg)

 

These readings taken whilst loaded for a 4 week holiday, and with 50% water (our normal travelling amount) and virtually full fuel.

 

In reality, the front axle is a bit-lighter than I would like (and may go some way to explain the - acceptable but noticeable - reaction to sidewind). The two electric bikes sit well out at the back, which will account for some of this via a cantilever effect, but I do also carry quite a weight of tools and odds and ends behind the rear axle (ironically, more often than not these have been used to fix someone else's problems) and I do have the opportunity to redstribute these a bit.

 

I'm now also considering reducing the tyre pressures at both ends a little to see if that improves stability.

 

So, given the right base vehicle, the correct construction and adequate distribution of the load, it IS quite viable to construct a 3500kg 'van with a quite adequate payload for reasonable touring. That is, at least for 2 people (though the figures also indicate that our use with 3 people (with less water and certainly lighter ancillaries) would also have been legal, albeit on the MAM margin).

 

Any more people than 2 or possibly 3, however, would I suspect, be problematical. :-(

 

 

[rupert123]

Interesting. I doubt the cantilever effect was very much as regards the front axle weight. On our 2008 Swift Sundance when we added a scooter plus rack this put 200kg on the rear axle, scooter plus rack dead weight was 140kg, but only took about 25kg off the front axle. Fiat give a minimun front loading as a percentage of total, which we only just made, I guess other makers do the same. With our current van, which has Al-ko chassis, adding the scooter had no effect at all on the front axle, although the rear overhang is pretty small by C/B standards.

[Robinhood]

With a 1.9m overhang on the back, and the heavier stuff as a necessity to the rear of this, I beg to differ.

 

Even the front of the "garage" is 1m behind the rear axle, so all the loads in here are going to lighten the front axle..

 

Simply removing the (push) bikes will make something like a 40kg difference on the front axle.

 

....and I'm afraid that, for me at least, your maths and physics for your Sundance (and new van) just don't add up! ;-)

 

 

 

 

[rupert123]

Robinhood - 2013-06-28 5:52 PM

 

With a 1.9m overhang on the back, and the heavier stuff as a necessity to the rear of this, I beg to differ.

 

Even the front of the "garage" is 1m behind the rear axle, so all the loads in here are going to lighten the front axle..

 

Simply removing the (push) bikes will make something like a 40kg difference on the front axle.

 

....and I'm afraid that, for me at least, your maths and physics for your Sundance (and new van) just don't add up! ;-)

 

 

 

Add up or not that is what the weighbridge showed.

[Robinhood]

rupert123 - 2013-06-28 10:07 PM

 

Robinhood - 2013-06-28 5:52 PM

 

With a 1.9m overhang on the back, and the heavier stuff as a necessity to the rear of this, I beg to differ.

 

Even the front of the "garage" is 1m behind the rear axle, so all the loads in here are going to lighten the front axle..

 

Simply removing the (push) bikes will make something like a 40kg difference on the front axle.

 

....and I'm afraid that, for me at least, your maths and physics for your Sundance (and new van) just don't add up! ;-)

 

 

 

Add up or not that is what the weighbridge showed.

 

 

In which case, the weighbridge (or your figure for the combined weight of the rack and scooter) must be faulty :-(

 

....if you add 140kg to the weight of your vehicle (by fitting the above), the net effect on axle weights must total 140kg, the respective effect on each axle (+/-) being determined by the geometry.

 

You say you added only 140kg, but the net effect (total increase in axle-loading) from the figures you quote is 175kg.

 

Unless Newton got it wrong, that just ain't right. ;-)

 

[bolero boy]

2010 Bolero 680FB in race trim........including bikes on rack, fuel, water, gas, clothes, food/drink supplies etc.

 

Total mass 3300kg, MAM 3500kg, spare 200kg.

Front axle 1520kg, allowed 1850kg, spare 330kg,

Rear axle 1780kg, allowed 2000kg, spare 220kg.

 

As we have huge storage under both lounge sofas between the axles, any booze run retains the proportional balance and axle loads which is the bain of most rear garage models with little orher large internal storage space.

[Robinhood]

bolero boy - 2013-06-29 8:01 AM

 

2010 Bolero 680FB in race trim........including bikes on rack, fuel, water, gas, clothes, food/drink supplies etc.

 

Total mass 3300kg, MAM 3500kg, spare 200kg.

Front axle 1520kg, allowed 1850kg, spare 330kg,

Rear axle 1780kg, allowed 2000kg, spare 220kg.

 

As we have huge storage under both lounge sofas between the axles, any booze run retains the proportional balance and axle loads which is the bain of most rear garage models with little orher large internal storage space.

 

....I must admit that, with (AFAIK) a quoted MIRO of 3150kg, I find the above figures quite surprising!

 

I carry somewhat more than 150kg over the MIRO in mine (in fact, my "excess weight", Mrs H, and the bikes alone would just about eat that ;-)).

[Derek Uzzell]

Robinhood - 2013-06-28 2:18 PM

 

...I'm now also considering reducing the tyre pressures at both ends a little to see if that improves stability....

 

 

Your "Van", although longer than my own Hobby, is built on the same length wheelbase Transit platform-cab chassis as my T-600FC model. I believe the suspension differs on your vehicle (my Hobby has double rear leaf-springs) and I don't know what tyre pressures you use.

 

However, if your Van is 'twitchy' in sidewinds (and this might perhaps be anticipated with its longish rear overhang) I suggest you err on the high side regarding tyre pressures rather than soften them, particularly where the rear tyres are concerned. I'd be tempted to inflate the rears to their design maximum (70psi?) to see if that makes any significant improvement. If high tyre pressures don't help, I think you'll find lower pressures will just make matters worse (at least that's my experience with my Hobby) and the next step (assuming you haven't already taken it) would be to follow Brian Kirby in fitting air-bellows to stiffen up the rear springing.

[Robinhood]

Derek Uzzell - 2013-06-29 9:58 AM

 

Robinhood - 2013-06-28 2:18 PM

 

...I'm now also considering reducing the tyre pressures at both ends a little to see if that improves stability....

 

 

Your "Van", although longer than my own Hobby, is built on the same length wheelbase Transit platform-cab chassis as my T-600FC model. I believe the suspension differs on your vehicle (my Hobby has double rear leaf-springs) and I don't know what tyre pressures you use.

 

However, if your Van is 'twitchy' in sidewinds (and this might perhaps be anticipated with its longish rear overhang) I suggest you err on the high side regarding tyre pressures rather than soften them, particularly where the rear tyres are concerned. I'd be tempted to inflate the rears to their design maximum (70psi?) to see if that makes any significant improvement. If high tyre pressures don't help, I think you'll find lower pressures will just make matters worse (at least that's my experience with my Hobby) and the next step (assuming you haven't already taken it) would be to follow Brian Kirby in fitting air-bellows to stiffen up the rear springing.

 

 

.....as above, the rears are already at 70psi (alright, nominally 69.5 ;-)) the "book" figures for 2250kg.

 

The projected experiment was purely in the interests of testing - three years of use hasn't invoked anything that was over-frightening, but sidewinds on big bridges (ref. Scandinavian tour) can be mildly exciting. If anything, I was more interested in dropping the fronts slightly, previous experience on different vans having been positive in this respect.

 

My previous experiences with air assistance (fitted as standard on a Benimar) were mixed.

 

The overall "ride" on the Transit, as it is, is considerably better than any of the Ducatos I've run. ;-)

[rupert123]

Robinhood - 2013-06-28 10:23 PM

 

rupert123 - 2013-06-28 10:07 PM

 

Robinhood - 2013-06-28 5:52 PM

 

With a 1.9m overhang on the back, and the heavier stuff as a necessity to the rear of this, I beg to differ.

 

Even the front of the "garage" is 1m behind the rear axle, so all the loads in here are going to lighten the front axle..

 

Simply removing the (push) bikes will make something like a 40kg difference on the front axle.

 

....and I'm afraid that, for me at least, your maths and physics for your Sundance (and new van) just don't add up! ;-)

 

 

 

Add up or not that is what the weighbridge showed.

 

 

In which case, the weighbridge (or your figure for the combined weight of the rack and scooter) must be faulty :-(

 

....if you add 140kg to the weight of your vehicle (by fitting the above), the net effect on axle weights must total 140kg, the respective effect on each axle (+/-) being determined by the geometry.

 

You say you added only 140kg, but the net effect (total increase in axle-loading) from the figures you quote is 175kg.

 

Unless Newton got it wrong, that just ain't right. ;-)

I admit my figures are from a year old memory so may be a bit out so if I added 150kg, this is the max it could be with fuel in the bike, the effect on the front axle is not much. My current van only has a rear overhang of 1.2mtrs and torsion bar rear suspension, the wheelbase is also a much larger percentage of the total length so effect on front axle is even less. Just looked up the actual figures and I had plus 190kg on the rear and minus 35kg on the front. So my guess at the front was a bit out, sorry about that, but still not much effect. I found in the driving you did notice the scooter on the rear but not much on the steering, it was mainly 'rear swing' and a little bit more sway, air bags cured it and added 100kg to rear axle permitted load. I did take 5lbs out of the front tyres but found this made no difference I could detect.

[Brian Kirby]

If it is of interest, this is where we finished up with our 6.0 metre long Hobby "Van".

Max rear axle load fully laden (obviously varies, but weighed with everything full) about 2,000kg, unladen 1,500kg, pressure 4.5 bar/65 psi. (limits 2,250kg, 4.75 bar/69 psi)

Max front axle load about under the same conditions 1,330kg, unladen 1,300kg, pressure 2.5 bar/ 36psi. (limit 1,750kg, same tyres front and rear).

Until the air assisters were fitted there was noticeable rear sway, especially on roundabouts, and noticeable steering affect when overtaking HGVs or in gusty winds. There was also and ever present grounding risk, mainly because the lightly laden front rode high relative to the more heavily laden rear. After the air assisters were fitted the sway was pretty much eliminated, the van was much less susceptible to slipstreams/crosswinds and, because I adjusted the air assister pressures to give the same ground clearance at the rear valance fully laden as when unladen without the assisters, the grounding issue was also eliminated. This improved resistance to crosswinds was amply demonstrated during our trip to Croatia in autumn 2008, when we had the Bora for company all down the magistrala from Krk to Split! Mistral, what mistral? :-)

[bolero boy]

Robinhood - 2013-06-29 9:26 AM

 

bolero boy - 2013-06-29 8:01 AM

 

2010 Bolero 680FB in race trim........including bikes on rack, fuel, water, gas, clothes, food/drink supplies etc.

 

Total mass 3300kg, MAM 3500kg, spare 200kg.

Front axle 1520kg, allowed 1850kg, spare 330kg,

Rear axle 1780kg, allowed 2000kg, spare 220kg.

 

As we have huge storage under both lounge sofas between the axles, any booze run retains the proportional balance and axle loads which is the bain of most rear garage models with little orher large internal storage space.

 

....I must admit that, with (AFAIK) a quoted MIRO of 3150kg, I find the above figures quite surprising!

 

I carry somewhat more than 150kg over the MIRO in mine (in fact, my "excess weight", Mrs H, and the bikes alone would just about eat that ;-)).

Robin, yes I was pleasantly surprised. I wanted it weighed as I was aware of the lowish quoted payload. Possibly two factors help. Firstly, manufacturers figures are +/- and we might be lucky.

Secondly, the wife and I only weigh 120kg (or just under!) together, wringing wet!

Also, we normally have a half tank of water but generally like to keep the fuel up.

[Robinhood]

...thank you Brian (and a result not too dissimilar to my own).

 

It encourages me to experiment with reduced pressures (at least for a bit, and especially on the front!).

 

I can't remember whether your 'van was fitted with the Ford factory spring assisters or not (the ones which have caused some confusion at MOT time). Mine is, and there is little "sway" as you term it, simply more reaction to strong crosswinds than would be ideal. The rear overhang on mine is slightly longer than yours (though with a different, longer wheelbase), but I haven't noted any risk of grounding (the 'van having neither a tail-up or down attitude).

 

In reality, (though different), I find it all no more disturbing than my previous van (Alko-chassised, with differing front and rear track) which had a tendency to tramline badly on the "spurinnen" found on most motorways.

 

 

[Brian Kirby]

No, not that much difference, as you say. The front axle load was below Conti UK's technical regster when I asked them for appropriate pressures. In the end I took the pressures from the Tyresafe booklet, checked that Conti were BTR members (they are) and quoted that information to them. They then agreed the pressures should be fine, although the axle load was still off their technical reference scales.

 

The effect was to considerably reduce the wander induced by irregulatities on the road, not just the usual tramlining, it would even wander if I drove over a longitudinal accident scar on the surface. On narrower secondary roads, with variable surfaces and uneven camber, it would invariably try to make friends with any truck it saw coming the other way! Needed quite subtle correction to leave the truck enough room without taking to the ditch.

 

Both the air assisters and the reduced pressures improved directional stability no end, so that avoiding main roads again became the pleasure it should be. However, as you say, shorter wheelbase, so probably inherently more "twitchy".

[Robinhood]

...yup! It's off my Conti documentation as well, the lower point on that being 1590kg at 43.5psi.

 

Though I can also see where you derived the lower pressure from, in the first instance, I'm going to try reducing to 43.5 from the current 51psi, and see if it makes a noticeable difference.

 

I'm not over-worried, having just had a rather relaxing 3000 mile plus drive around Scandinavia, I can't plead that things are not acceptable!.