johnlc Posted June 3, 2014 Share Posted June 3, 2014 I have an East Neuk (Fiat Ducato) 5 mtre long van conversion. I knew there was limited payload when I got it and am currently uprating (paper exercise) by 200kg via SVTech. They have told me I could get an additional 100kg on the rear axle with air assist suspension. I've read many previous threads about air assist suspension and the common view seems to be that the Dunlop system is particularly favoured. Whilst the 100kg would no doubt be useful it may not be essential purely for payload. I'm wondering whether anyone else has put air assist on a SWB PVC and what they thought of it. The issues I'm contemplating are 1. Increased payload on rear axle - probably essential if we want to fit a bike rack. 2. The East Neuk has two rear travel seats which can be made out of the back end of the two rear benches. These seats are based on steel frames with no springing built into them. The ride in these seats is firm and one tends to feel all the bumps in the road. The seats sit adjacent to the rear wheels. Improving the ride in these seats would be good, but I don't know whether the air assist would help here given the lack of springs in the seat/frame. 3. What people call crashing and banging occurs on potholes/poor quality roads. This seems to be at the back of the van more than the front. This gets tiresome and I wonder whether it is doing damage to the van. I don't know whether it is because the current bump stops are too close to the leaf springs, or whether the suspension units are not functioning properly, or whether it is simply unavoidable. I sent a picture of one of the bump stops to an air assist company who told me that air assist was "necessary". If I posted this picture would you experienced guys be able to form a judgement about things? 4. Whilst there is some body roll when cornering/going round roundabouts my wife says this is just because I am driving too fast! It does go away if one drives slower. 5. Ride height. I don't have any problems with the rear of the van "sagging", as there is no overhang. The van sits level and I want it to stay that way, not be elevated at the back. So, my key objectives would be too enhance rear axle payload/ help with using a bike rack:reducing crashing and banging, and improving rear seat ride quality. All advice appreciated - Thanks Link to comment Share on other sites More sharing options...
colin Posted June 3, 2014 Share Posted June 3, 2014 What you call 'bump stops' are not at all, they are spring assitors. Link to comment Share on other sites More sharing options...
pepe63xnotuse Posted June 3, 2014 Share Posted June 3, 2014 One of our previous vans was a swb X250 Peugeot CB.. and I fitted a pair of Grayston spring assistors to that. http://www.springassisters.co.uk/menu.htm Very easy to fit and they lifted the van clear of the original rubber("bumpstop") assistors ... To be honest, I can't recall their exact handling "characteristics" (it was 5-6 years ago)but I don't recall it being overly harsh and they did certainly take the "sag" out of the rear end .... and as yours is only a swb PVC, I would think that they'd be more than adequate for the job... (..but obviously, if they're not, they can't be "adjusted"...) Edit: Please ignore my twaddle :$ ...I've just realised that you're looking to go down the SVtech route... (lol) Link to comment Share on other sites More sharing options...
Archiesgrandad Posted June 3, 2014 Share Posted June 3, 2014 Before you make your decision it might pay to check how heavy they are and deduct that weight from any potential gain. AGD Link to comment Share on other sites More sharing options...
Guest JudgeMental Posted June 3, 2014 Share Posted June 3, 2014 I'm guessing its 3300 and your thinking of upgrade to 3500? For a start the X250 has a firm ride, cant see air assist helping much in this regard full air would. I would visit a weighbridge and find out the actual weight on those axles, once you know this you can adjust your tyre pressure accordingly before wasting money..I find it peculiar that a 5 meter van handles so poorly..... Link to comment Share on other sites More sharing options...
Brian Kirby Posted June 3, 2014 Share Posted June 3, 2014 Question 1: have you weighed the van fully loaded (as in fully, including passengers etc.! :-)) and at the same time taken note of the load on each axle? If not, I suggest you do, as it is the logical starting point in deciding whether the rear axle load needs upgrading. Question 2: what tyre pressures are you using? In many cases the standard recommended tyre pressures are set to suit both axles at maximum load, a condition no standard van can achieve without being substantially overloaded. If you do 1 above, you will know the load on each axle, so will then be able to use the tyre pressures recommended by the tyre manufacturer to suit those loads. This can make a surprising difference to ride comfort and general road manners of the van, though no tyre pressure change is going to convert a crudely sprung commercial vehicle into a limousine! As above, what you are calling bump stops are not, they are part of the springing system, and are designed to assist the rear "cart" springs by compressing as load increases. Installing air assistance at the rear comprises removing the OEM assisters and substituting air assisters in their place. The original shock absorbers (dampers) are retained. Not all air assistance units are suitable for increasing axle load, but SV Tech will know which to use. Once fitted (especially if you fit the version that does not connect both units to the same inflation point) they generally have two benefits. They transmit less of the "crashing" from potholes etc., because the air units are more progressively compliant than the plastics units they replace. For much the same reason they tend to resist roll better. This is especially noticeable through roundabouts and on "S" bends. As to the extent to which these improvements will come through on a SWB van, I cannot say. I fitted them to our previous van, which was a 6 metre MWB Transit based coachbuilt, and they had the affects described above. However, my main reason for fitting was to eliminate tail droop on a longish rear overhang van that loaded predominantly onto its rear axle. FWIW, this they also remedied, and I was vary pleased with the result overall. I'm somewhat puzzled that you are running short on payload on a SWB PVC. I assume the MAM of the van must be only 3,300 kg, which would seem to me an economy too far. One might have hoped East Neuk would have recognised this, and specified a higher rated base vehicle, or made alternative provision in anticipation of the problem. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted June 3, 2014 Share Posted June 3, 2014 Although East Neuk's website data for a "Fifer Touring S" indicates that a 2013 model is built on a 3300kg chassis and has a stated payload of 500kg, I think a 2008 version (which is what John owns) may have a 3000kg chassis and a much lower payload. (No doubt John can confirm whether or not that's correct.) This is the type of technical issue that can be discussed learnedly at length, but the only way to find out how well fitting air-assistance will meet John's objectives is to fit it. I don't know off-hand what an air-assistance kit weighs, but it won't be more than 20kg. So, if SVTech say it can provide an extra 100kg of rear-axle load capacity, you'd still be well in 'profit'. I can't see fitting air-assistance (and I'd favour the Dunlop system) making John's motorhome any worse to drive and there's a more than even chance it will improve matters. If the cost can be borne, then go for it. Link to comment Share on other sites More sharing options...
johnlc Posted June 3, 2014 Author Share Posted June 3, 2014 Thanks for your replies. The van has a 3000kg MAM weight as specified by East Neuk hence the need to uprate it to 3200kg via SVtech, with the maximum weight allowed being 3300kg with air assist. I haven't weighed the van fully loaded since I bought it, and know I need to do that. Before I bought it - with driver, full 90 litres fresh water, gas bottle and half fuel tank, it weighed 2820 kg, hence the need to increase the weight to enhance payload. I do know the weight of what we travel with as I weighed it all before buying the van. That doesn't take us to the 3200kg figure. But in carrying two people in the back it would do. Also the "lever weight" effect of the bike rack would add to the weight at the back. Having said that, the washroom and kitchen are much closer to the front than the rear wheels on this van. I'm running the tyre pressures at what the Fiat manual, and East Neuk, say to do i.e. 4 bars front and rear. I didn't realise I could safely mess around with thiese to change ride characteristics. I wouldn't say the ride at the front is bad, and I (or my wife!) may have overstated the roll characteristics! Link to comment Share on other sites More sharing options...
Derek Uzzell Posted June 4, 2014 Share Posted June 4, 2014 John I assume the tyres fitted to your Fifer are 215/70 R15C size and 'white van' type rather than 'camper' type (eg. Michelin's "Agilis Camping" or Continental's "VancoCamper" patterns). For those tyres (and for the size/weight of your vehicle) a 4.0bar (58psi) inflation pressure for front and rear tyres is likely to be on the high side, but not excessively so. If you weigh your motorhome fully-loaded and obtain its axle-loadings, you may well be able to safely lower the pressure to match the measured loadings. However, if you reduce the pressures to the safe absolute minimum you should anticipate the vehicle's handling to be affected, with increased roll during spirited cornering being a strong possibility. It should be expected that a short-wheebase X250 Ducato-based PVC will be fairly pitch-prone and, if the rear travel seats are ergonomically unsophisticated, unsprung and near the rear axle, people occupying them will not have a de luxe travelling experience. You could simulate the effect of fitting air-assistance by removing the 'bump stops' (spring assisters) and see what that does to handling and ride quality when the motorhome is normally loaded. If there were no significant change, installing air-assistance (unless you just wished to comply with SVTech's requirement in order to gain an extra 100kg) would have questionable value. If ride quality noticeably improved, then air-assistance should be worth the cost. As has already been touched on, the advantage of air-assistance is that its 'spring rate' can be adjusted easily. I don't think reducing your 4.0bar tyre pressures well down would produce magical improvements and I believe you'd be better to experiment with adjusting the pressure in air-assistance units while retaining a reasonably high rear-tyre pressure than to run your tyres at minimum safe pressure. I'm not sure how SVTech operates but, if it's a 'single shot' uprating procedure where you can choose to uprate from 3000kg to 3200kg without air-assistance, but would then have to pay SVTech for a second helping if you subsequently wanted to go from 3200kg to 3300kg via adding air-assistance, then you'd probably be better to take the 3300kg route to begin with. If you stick with a 3200kg uprate I consider air-assistance would be nice to have but not essential. If you opt for 3300kg, then it seems you have to fit air-assistance. I believe it's probably worth fitting, but I ain't paying... Link to comment Share on other sites More sharing options...
pepe63xnotuse Posted June 4, 2014 Share Posted June 4, 2014 ...and then, when you've got your rear spring assistors/axle weights/ tyre types/tyre pressures all sorted, you can then start with all the fun of "...Which bike rack?".... (lol) Link to comment Share on other sites More sharing options...
derek pringle Posted June 4, 2014 Share Posted June 4, 2014 Hi Johnlc, I have Air Suspension Assistance fitted albeit my van is longer than yours. I must say the ride is a great improvement and even fully loaded the van sits nice and high. On my experience I would recommend. cheers and good luck derek Link to comment Share on other sites More sharing options...
johnlc Posted June 4, 2014 Author Share Posted June 4, 2014 Thanks again for the helpful replies, particularly Derek and Brian. I don't know how you guys find the time to write such detailed responses to so many of the posts on this forum, but I'm grateful that you do. Derek - yes the tyres are Pirelli Chrono which I assume are "normal" tyres and are the size/rating you mentioned. (There is a Pirelli Chrono Camper tyre as well apparently). SVTEch do allow a further free uprating if air assist is fitted within a year of the initial uprate. As it costs over £300 they should do this! That's an interesting suggestion of removing the current rubber spring assisters to simulate the air assist. I'm not technical enough to do this but it might be worth a try, rather than spending hundreds of pounds on air assist to find it makes little difference. The next time the van will be fully loaded is when we go away for a few days later this month, and for the first time, will have 2 people in the back as well when the van is full. I'll get it weighed then, and make a decision about air assist after that. I'm sure from my calculations that we will be within (just) the new 3200 kg limit. But should I remove the rubber stops for that trip or not? Decisions, decisions! Link to comment Share on other sites More sharing options...
Derek Uzzell Posted June 4, 2014 Share Posted June 4, 2014 johnlc - 2014-06-04 2:22 PM ...But should I remove the rubber stops for that trip or not? No! This is something to try when it doesn't much matter what the effect is and definitely not when you will have a full complement of people onboard and everybody is out to enjoy themselves. I'm not advocating operating the vehicle without the spring assisters as a long-term solution to your ride-quality criticisms, just as an experiment that might indicate whether fitting air-assistance might be worth doing. If it were concluded that air-assistance might be worthwhile, the spring assisters would be replaced and remain in place until the air-assistance system was installed. It's spring assisters OR air-assistance - dispensing with the spring assisters is not on the menu. As SVTech won't charge extra for re-uprating from 3200kg to 3300kg within a year I suggest you hang fire regarding air-assistance until after the motorhome has been weighed. If it's under 3200kg and the axle-loadings are OK, you might find that adjusting the tyre pressures will improve the ride sufficiently to dissuade you from forking out for air-assistance. Link to comment Share on other sites More sharing options...
johnlc Posted June 4, 2014 Author Share Posted June 4, 2014 Derek - thanks for the warning! What you say makes perfect sense and reflects my thinking after all the helpful comments John Link to comment Share on other sites More sharing options...
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