Bessacarr Air assist suspension

[Motorhome Medic]

I have ordered a Bessacarr 957 and am considering having air assist suspension to the rear of the Alko chassis. This model has the low Alko chassis and a long rear body. My concerns are the rather steep angle of my driveway, high "speed humps" e.g. CC site, New Forest and the occasional undulating campsite.

Does anyone have any experience or advice on this subject.

 

Ian

[Derek Uzzell]

I think you mean Bessacarr 597 (not 957).

 

If that’s correct, the 2018-model 597 is a LONG motorhome (8.11 metres overall) with a long wheelbase (4.70 metres). Consequently everything points to it being worthwhile having the ability to raise the vehicle’s rear end when it’s apparent that grounding might occur.

 

Not a cheap option on an AL-KO chassis - but I’m sure you’ll know that.

[Motorhome Medic]

Oops! Yes it is a 597, thanks for the correction Derek.

[Robbo]

From the dimensions Derek has provided, the rear overhang works out at about 2.5m - not particularly excessive compared to some modern vans.

 

I assume your steep driveway rises up from the road and you will be driving the vehicle up the slope. Before you embark on expensive air suspension I suggest you do a bit of homework first.

 

You need to know what the unladen ground clearance is at the rear end. This could be measured at the dealer, assuming he has the same van currently in stock. Or you may need to contact Bessacarr direct. Deduct say, 50mm from the unladen ground clearance to give the laden ground clearance.

 

Carry out a level survey from the centre of the road and up the driveway for a reasonable distance. This can be done with a builders level and straight edge or you could employ a local surveyor. Plot the profile on graph paper at a suitable scale. Draw the critical vehicle dimensions on tracing paper at the same scale (ie. wheel base, overhang and vertical rear clearance). Overlay the tracing paper at various points on the driveway profile to check if you have a grounding problem.

 

This should give you a pretty good idea whether the significant cost of air suspension is necessary. A survey of your driveway would probably cost in the region of £150 whereas air suspension is probably at least £2k and possibly even more.

 

I have a low AL-KO chassis with a 2m overhang and never had a problem. Also, the rear end doesn't seem to drop very much when fully laden - although I've never measured it. Mind you, I don't have a very steep driveway.

 

PS. If you do go for air suspension, you need to find out by how much the rear end would be elevated. This amended vertical dimension could be checked against your driveway profile.

 

 

[Robbo]

I assume the OP is ordering the 597 with the 3850Kg chassis, giving a payload of about 500Kg. The rear lounge layout will possibly distribute the payload 40/60 between front and rear axles.

 

If so, the extra weight that could be permissibly carried on the rear axle won't be that much and hence the laden ground clearance at the rear end may well be less than 50mm.

 

Air suspension does normally give you the option of uprating the permissible load on the rear axle depending on tyre size, 16" tyres being the preferred benchmark. 16" tyres will of course give you greater ground clearance at the outset. Any uprating would need to be handled by companies like SV Tech or Bessacarr if this is a factory option.

 

Something else for the OP to ponder, especially if he's likely to have 4 persons onboard.

 

 

[monique.hubrechtsgm]

In case of the lowframe or highframe alko chassis the standard torsion bar axle is the same only chassis rails are different in height and their axle block. The high frame can have at the end a drop down extension chassis which you could have seeing the overhang. Air suspension is in first place a matter of comfort.At best you can raise the rear during parking up to max 5cm. But that is the axle travel of the air bellows. In case of the alko swing arm your air will be different as to the ducato axle. In case of alko buy new instead of retrofit.You are entering the alko axle world and at the same time i will be your companion to answer any questios you may have.

[Derek Uzzell]

The attached photo shows a side-view of a 2018 Bessacarr 599 (that has the same dimensions as the 597 model) and gives a good idea of the length of the rear overhang.

 

A significant difference between the 599 and 597 is that the latter has a very large rear garage that, if fully exploited, definitely won’t help with rear ground-clearance (see photos on following link)

 

https://www.caravanclub.co.uk/caravan-club-classifieds/motorhome/bessacarr/597/678246/

 

I note too that the two 597 models (and the two 599s) have - according to the layout - a maximum overall weight of 3500kg or 3850kg. Hopefully Ian has chosen the 3850kg variant as the 3500kg version’s payload is pretty dire.

 

I think the 597 model is based on a Ducato ‘light’ and has 16”-diameter wheels as standard. There seems to be no indication that Bessacarr offers rear air-assist as an option and (because the vehicle has an AL-KO chassis) I’m doubtful that SVTech would authorise uprating beyond 3850kg. Adding air-assist would have a potential impact on the motorhome’s Fiat/AL-KO warranty, but there’s not much that can be done about that.

[monique.hubrechtsgm]

It is not only the slopes. This was the situarion today at an international chelty dog festival in hulst NL. We needed tractors to get out of the parking. see the picture, heavy rain fall and ice cubes. I left flwg Brian method :-D

 

[Brian Kirby]

I hate to say it, but this seems another example of where the heavy chassis you pay. Is this an option? It won't assist the back end ground clearance, but the 2,400kg rear axle limits would allow the "garage" to be exploited. For the air assistance, an AlKo approved or branded installation would seem highly desirable, for the reason Derek cites.

[Motorhome Medic]

Thank you all for your replies.

Yes I have ordered the 3850 chassis.

I failed to state that my driveway slopes DOWN from the road.

 

Food for thought!

 

Thanks again.

[Robbo]

I strongly recommend Ian checks which chassis is being provided.

 

He should be getting the AMC 38H (35 Heavy) with 2100/2400Kg front/rear permissible axle loads.

 

It has been known for manufacturers to provide the AMC37L (35 light) with 1850/2000Kg front/rear permissible axle loads and claim a MAM of 3850Kg, ie. 1850+2000 = 3850 ??? I would imagine this is a legitimate interpretation of the AL-KO chassis design but it does mean you lose the extra 400Kg which could be transferred to the rear axle. This could be critical, especially if your van has a large rear garage.

 

You mentioned your driveway slopes downwards from the road. This is a better scenario but with a long wheelbase you could still have potential problems of grounding between the front and rear axles, depending on the severity of the change in slopes. And, what happens at the end of the driveway where it presumably levels out ?

 

PS. I subsequently note that Derek has indicated that the chassis may be based on the Fiat Ducato light and not the AL-KO chassis. The plot thickens 8-)

[Derek Uzzell]

The 2018 Swift-Bessacarr brochure (available on-line) indicates that there are three Bessacarr model-numbers (596, 597 or 599) with those motorhomes having the same external dimensions.

 

597 and 599 models with the twin-settees “Lounge” layout are offered with a 3500kg maximum overall weight. When the 597 and 599 models have the alternative ‘half dinette’ layout, they have a 3850kg chassis maximum. The 596 model - that has a 'twin-dinette’ layout - is offered only on a 4250kg chassis.

 

The brochure reveals the thinking behind this policy, as 597 and 599 “Lounge” models have just two belted seats (the cab seats), 597 and 599 single-dinette versions have four belted seats, and the 596 model has six belted seats. So the 3500kg, 3850kg and 4250kg chassis-weight variations are directly linked to the number of people that the model can transport in seats fitted with safety-belts.

 

As I said earlier, there appears to be nothing in Swift’s documentation to suggest that a 597 or 599 model is available on the 4250kg chassis, though there seems to be no ‘technical’ reason to prevent this being done.

[Derek Uzzell]

Historically, ‘European’ motorhomes over 8 metres long would normally have been built on a FWD base (usually Fiat) with an AL-KO tandem rear-axle, or on a RWD base (usually Mercedes or Iveco) with twinned rear wheels.

 

As Robbo has highlighted, combining a FWD Ducato with an AL-KO ‘low frame’ chassis, a single rear-axle and a really long wheelbase risks grounding mid-way along the motorhome. I recently saw a Bailey motorhome reversing on to a pitch that sloped slightly downwards off a level campsite roadway, and the underside of the Bailey’s chassis looked perilously close to the ground as the vehicle traversed the ‘hump’ where the pitch met the roadway.

 

Another good reason to be able to raise the Bessacarr’s rear, as doing so would also increase the ground-clearance between the axles.

[crocs]

What is described here is one of the key stats in off-roading ie break over angle. How to calculate it can be found here: https://www.vcalc.com/wiki/KurtHeckman/Breakover+angle

[monique.hubrechtsgm]

On the fiat light chassis cab, or chassis cowl for the integral their is an alko pdf. in case of large overhang and garage the builder chooses a chassis. Also depending of the drop down or going up of the chassis. I have a 38L. And the full lay out in dimensions. But not the ride height. That is the irretating mystery of their swing arm settings in degrees to a particular chassis.

[lennyhb]

Motorhome Medic - 2017-11-05 7:31 PM

 

Thank you all for your replies.

Yes I have ordered the 3850 chassis.

I failed to state that my driveway slopes DOWN from the road.

 

Food for thought!

 

Thanks again.

3850kg is the Al-Ko light chassis with a van of that size I would have thought you need the heavy chassis if for no other reason than getting a decent load allowance on the rear axle.

Also 500kg is about the absolute minimum payload for two people and Swift don't include water and only a 6kg light gas bottle in their MIRO.

We only have a 7.5m van but it's on a 4500kg chassis.

[monique.hubrechtsgm]

Nice link. Promobil in germany provide these angles in all their individual type motor homes. Nice, but what in practise? Only remember the 15 degres on the rear My motorhome is not the same as my range rover whit air suspesion. But the flair on the end of the picture based on iveco has no problem whit traction.

[Brian Kirby]

Brian Kirby - 2017-11-05 6:51 PM

 

I hate to say it, but this seems another example of where the heavy chassis would pay. Is this an option? It won't assist the back end ground clearance, but the 2,400kg rear axle limits would allow the "garage" to be exploited. .......................

Sorry to repeat myself, but I realised the above typo (underlined - which I've now corrected), reduced the sentence to nonsense. Unless this van is based on the heavy chassis, as others are implying, it is liable to have very compromised usability. Simply stated, with the layout and long rear overhang of its design it is liable to overload its rear axle before its already meagre payload is realised, meaning that its calculated MAM is purely academic.

 

I think Ian would be well advised to explore whether this upgrade can be provided by Swift, and if it cannot, to consider cancelling his order in favour of an alternative van with realistic payload/rear axle max load.

[Derek Uzzell]

There is a model in Swift’s 2018 Kon-Tiki range - the 635 - that is slightly (5cm) shorter than the Bessacarr 597 and on a 4.60m wheelbase AL-KO chassis (rather than the 597’s 4.70m) and with a roughly similar interior layout.

 

However, the Kon-Tiki 635 is built on a 4250kg chassis. The standard specification also differs - 150bhp motor instead of the 597’s 130bhp powerplant - and (for some reason or other) the quoted Mass in Running Order is significantly higher than the 597’s.

 

Another difference is that the 635 has a factory option of "Premium air suspension from AL-KO for rear axle or 4 corners - increases in ride comfort with automatic self-levelling”.

 

In standard specification there would be similar potential ground-clearance issues, but at least the (optional) rear air suspension could be fitted to a Kon-Tiki 635 before delivery to the buyer occurred, plus the suspension option would be warranted from the outset.

 

[Robbo]

Brian Kirby - 2017-11-06 6:50 PM

 

Brian Kirby - 2017-11-05 6:51 PM

 

I hate to say it, but this seems another example of where the heavy chassis would pay. Is this an option? It won't assist the back end ground clearance, but the 2,400kg rear axle limits would allow the "garage" to be exploited. .......................

Sorry to repeat myself, but I realised the above typo (underlined - which I've now corrected), reduced the sentence to nonsense. Unless this van is based on the heavy chassis, as others are implying, it is liable to have very compromised usability. Simply stated, with the layout and long rear overhang of its design it is liable to overload its rear axle before its already meagre payload is realised, meaning that its calculated MAM is purely academic.

 

I think Ian would be well advised to explore whether this upgrade can be provided by Swift, and if it cannot, to consider cancelling his order in favour of an alternative van with realistic payload/rear axle max load.

 

Agree Brian. It's possibly, Ian doesn't realise that NORMALLY the addition of the front/rear permissible axle loads exceed the overall permissible weight (MAM). This is done for a purpose, to allow a degree of flexibility in distributing the load within the vehicle.

 

The 3850Kg chassis with a front/rear permissible axle load of 1850/2000Kg doesn't allow for any flexibility in loading configuration. So, unless one can distribute the load exactly within the van to take advantage of both permissible axle loads, the meagre payload of 500Kg won't be achieved.

 

As an example, the 4250Kg chassis has a front/rear permissible axle load of 2100/2400Kg. So, you could conceivably load the rear axle to the maximum 2400Kg and still run the front axle at 1850Kg. Furthermore, any load placed behind the rear axle has the effect of reducing the load on the front axle, so it's very unlikely the permissible front axle load will be exceeded. Similarly, the reduction in load on the front axle is transferred to the rear axle + the actual load imposed behind the rear axle.

 

I've had first hand experience of members on my "owners forum" purchasing MH's based on a 3850Kg chassis. Some have returned the MH to the dealer, on the basis that the payload is unworkable and they weren't given sufficient advice by the sales team. They re-ordered the same MH but based on a 4250Kg chassis. Overall, an expensive mistake.

 

 

[derek pringle]

hi Ian,

Whilst my Bessacar was not as long as yours,it was a 660 model, I had suspension fitted for benefit of payload but the difference to the drive and handling made it a great investment so I don,t think you would regret the purchase.

good luck

derek

[Derek Uzzell]

derek

 

I think the Bessacarr E660 model was built on a non-AL-KO Ducato ‘maxi’ chassis (4005kg?) and, consequently should have had a reasonable amount of payload to begin with given the vehicle’s dimensions.

 

Ian’s Bessacarr 597 is a lot longer than an E660, with a lot longer wheelbase and an AL-KO chassis that is much closer to the ground. It has a Ducato ‘light’ 3850kg chassis with (apparently) no ability to opt for the ‘maxi’ 4250kg chassis instead. Adding rear air-assist to an E660 would be a relatively simple (DIY) and cheap task, but adding air-assist to a 597 would be more complicated and expensive.

 

It’s not just the limited payload with a Bessacarr 597; there’s the limited ground clearance under the rear and beneath the chassis to consider (as Ian mentions in his original posting). Irrespective of whether adding rear air-assist would improve a 597’s ride and handling, driver-controlled rear air-assist would help with the ground clearance issue.

[Steve928]

As Derek mentions adding air-assist to the lowline Al-Ko chassis is not particularly cheap and is not a DIY job. I believe that the only 2 firms offering this option are Glide-Rite and AS Air Suspension - at least that was the case when I researched it a while back.

The cost from both is (was) around the £1600 mark and it's a full day job.

No original components are removed, unlike with VB Full Air where one torsion bar per side is deleted and the swing arms are changed, so the full weight of the kit at around 25kg will detract from payload.

 

The Bessacar in question has similar dimensions to the current Bailey 79-x series which is also on the 4700mm wheelbase low-frame chassis, as were the previous 750, 760 and 765 models although at 7500mm overall they had a shorter overhang. Groundings are a fairly common occurrence among the owners on the Bailey Facebook group.

 

My own low-frame van is on the shorter 4102mm wheelbase chassis but we still ground more than occasionally; on a recent 6 week France+Spain trip we did so 6 times, twice between the axles and 4 times at the rear of the overhang. Between the axles it's usually just the silencer box or tailpipe while at the rear the chassis continues at full height to the rear of the van (thankfully offering good protection to the bodywork itself) and it's fairly common to have to drag this slowly out of supermarket car parks and aire exits etc. Route Barree and Deviation signs always raise the heartbeat as often the alternative route or the roadworks themselves are on the limit for such a low-slung van. I would love to fit air-assist but as I prefer to keep below 3500kg MAM for simpler use abroad I don't have that 25kg to spare.

 

If opting for such a large van on the low-frame 3850kg chassis then personally I'd see the VB Full Air system at around £6000, no weight penalty and the ability to raise both front and rear as essential (mandatory even!).

 

[monique.hubrechtsgm]

I had the full alko and vb air suspesion study X2/x4-alko and vb 2C/4/C on paper.But upload is a problem on this site and also pdf drawings. also real built on pictures for the low frame which you can see on the internet, and the high frame which you can not see on the internet, but now received from adria on their supreme. We are talking of torsion bar axles here on which the airbag takes 90 percent of the load. This is done by two weak torsion bars in the axle tube for the other 10 percent and keep the swingarm to the wheel. Also another shock absorber is fitted because of different load and travel. The standard ride height is not changed during travel in case of air.

[Derek Uzzell]

Replacing the original torsion bars of an AL-KO AMC-chassis axle should only be necessary for the more sophisticated ‘air suspension’ systems that permit a motorhome’s rear end to be lowered as well as raised, and it’s unlikely that an owner of a motorhome having the low-frame AMC chassis would want to lower it even further.

 

DIY kits still seem to be available

 

https://dunlop-systems.uk/product/al-ko-chassis-ducato-relay-jumper-and-boxer-kit/

 

though this reasonably recent MHFun discussion suggests that a professional installation might not cost that much more.

 

https://www.motorhomefun.co.uk/forum/threads/which-air-suspension-kit-diy.148826/