Brian Kirby Posted March 3, 2018 Share Posted March 3, 2018 I don't think any SEVEL variants used for motorhome conversion have (or possibly even can have) a rear ARB fitted (I think both the platform-cab and ladder-chassis variants lack the torsional rigidity to absorb the resulting forces). However, I think all have a front ARB which, if it were to have snapped or detached, would undoubtedly produce some very odd handling characteristics. Worth checking, definitely. Link to comment Share on other sites More sharing options...
Derek Uzzell Posted March 3, 2018 Share Posted March 3, 2018 My 2015 Rapido has a hefty rear anti-roll bar (ARB) and I believe that’s the norm for the Ducato X290 ‘camping-car’ chassis. I’m not sure about the Ducato X250 'camping-car’ chassis having a rear ARB as standard (photos don’t show it, though it’s evident that a rear ARB for Ducato X250s existed) and I’ve no idea whether the Boxer “Tempo Libero” chassis Ted’s 2012 Elddis was built on would have had an ARB. Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted March 3, 2018 Share Posted March 3, 2018 I am concerned about Roly. A RMI scan is in it self is heavyfor the dog. Hope he will recover. Maybe he get sick of the sway of your motorhome. Link to comment Share on other sites More sharing options...
snowie Posted March 3, 2018 Share Posted March 3, 2018 Brian Kirby - 2018-03-03 12:33 PM I don't think any SEVEL variants used for motorhome conversion have (or possibly even can have) a rear ARB fitted (I think both the platform-cab and ladder-chassis variants lack the torsional rigidity to absorb the resulting forces). I can understand and indeed would expect that Fiat would do a considerable amount of static and dynamic testing of their orn product variants, but who tests the dozens, maybe hundreds of coachbuilt variants? Are they “homologated, or given type approval for small production runs? I would be cautious about buying some makes having heard of some manufacturers inability to do carpentry, let alone vehicle engineering! Regards, Snowie Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted March 3, 2018 Share Posted March 3, 2018 What kind of mods were carried out on your rear axle. What was the original in the firstplace, and which parts were removed. Was the standard OEM ride height changed? What kind of air suspension, semi air or full air. And what make. Is it allowed by reg to drive whit. Did you do do it as DIY. Have you control of your airbags pressure. Is your rear axle overloaded, Have you passed a bridge to check the axle.Can you drive at which speed if you have inflated bags let say max 30 km/hr, how do you do this on the M roads. Your rear axle can be in two position either fully unloaded or at bump stop, the last one is the most discussed what it actually means. But i drive alko torsion bars and they have not a defined bump stop as a fiat which is viseable as a spring rubber, the same as fitted in their front struts. Link to comment Share on other sites More sharing options...
Brian Kirby Posted March 3, 2018 Share Posted March 3, 2018 Derek Uzzell - 2018-03-03 3:29 PM My 2015 Rapido has a hefty rear anti-roll bar (ARB) and I believe that’s the norm for the Ducato X290 ‘camping-car’ chassis. I’m not sure about the Ducato X250 'camping-car’ chassis having a rear ARB as standard (photos don’t show it, though it’s evident that a rear ARB for Ducato X250s existed) and I’ve no idea whether the Boxer “Tempo Libero” chassis Ted’s 2012 Elddis was built on would have had an ARB. Useful to know, and thanks. I imagine much the same would be true if there were a broken or detached rear ARB - though one would think the technician should have spotted that during his inspection. Link to comment Share on other sites More sharing options...
weldted Posted March 3, 2018 Author Share Posted March 3, 2018 With the greatest respect illusion doesn't come into it. I have owned this van from new and similar size spec ones before, having been an mot tester for many years, and as stated before the first 3,000 miles were fine. The solar panels and sat dish were fitted the first week I owned the van as was the second battery, loading has alway been careful to ensure even loading, heavy item down low between the axles or close to the rear axle. If the handling aspect changes with no alterations to load etc after 3,000 into the journey something is adrift. Link to comment Share on other sites More sharing options...
Tracker Posted March 3, 2018 Share Posted March 3, 2018 Whilst I always thought, but was unaware just how much, that you had considerable mechanical (and electrical) experience I do hope that my earlier posts, particularly when grasping at straws in the hope that something might help, did not offend you as I did try not to insult your intelligence!! Link to comment Share on other sites More sharing options...
Brian Kirby Posted March 3, 2018 Share Posted March 3, 2018 Pax vobiscum Rich! :-) I think Ted was reacting to Will being provocative, not you! Link to comment Share on other sites More sharing options...
weldted Posted March 3, 2018 Author Share Posted March 3, 2018 Correct!! No offence taken but some thoughtless comments are what may discourage people from posting. It does not matter how much or how little experience one may have, every day is a school day. Link to comment Share on other sites More sharing options...
weldted Posted March 3, 2018 Author Share Posted March 3, 2018 Re the fitting of the semi air, fitted by myself, prior to starting van van emptied of all non fixed equipment stood on flat level ground. Height from rear jacking point to ground measured both sides. Bump stops removed air bags fitted, air pressure sufficient to pressurise bags .7 bar took up slack but van still at starting height. Test run then all bolts and fixing checked and torqued where required. Van then loaded semi air pumped up to put van back to the same height as when empty. Test driven again all ok. Air bags have separate air lines but use a calibrated pressure gauge to check, no loss of air at any time. Two days before this was carried out van was mot'd. Been working on cars and light commercial vans since leaving school at 15, now 69. Mot tester for many years, still learning. Appreciate everybody's time with this problem. Link to comment Share on other sites More sharing options...
Tracker Posted March 4, 2018 Share Posted March 4, 2018 weldted - 2018-03-03 9:36 PM thoughtless comments are what may discourage people from posting. It does not matter how much or how little experience one may have, every day is a school day. Ain't that a fact - sorry two facts!! Link to comment Share on other sites More sharing options...
Derek Uzzell Posted March 4, 2018 Share Posted March 4, 2018 Ted In your original posting you said "Did wonder about shock absorbers but the van still over steers on a long bend by which time the absorber would have been fully compressed”. In (say) a left-hand bend a vehicle will tend to roll to the right and weight will transfer to the right. If there were minimal free upwards travel in the vehicle’s rear right damper, when the vehicle rolls to the right it might cause the damper to ‘lock’ and, with no further suspension movement possible, oversteer could well happen. You’ve been experimenting with the air-bellows inflation pressure and, when a high pressure was used, this should have raised your motorhome’s rear end well up and there should have been no likelihood of the rear dampers locking. However - as everything else has evidently been tried and checked without curing the problem - if the condition of the rear dampers has been ignored I believe the possibility of the dampers being knackered now needs to be explored. If the rear dampers aren’t damping (they are 6 years old and you’ve been giving them a tough time lately) then a wayward rear end could perhaps be predicted. If I couldn’t find anything loose or broken, I’d probably replace the rear dampers as, after 6 years and around 36k miles, the originals are not likely to be 100% perfect. (And the cost would not be that high...) I realise that you had our motorhome’s tracking checked before you left the UK, but you might want to have that done again. I’d see rechecking the rear geometry as very much a last-hope exercise. But if there’s no excessive weight well behind the rear axle and the dampers are OK, I can’t think of anything else that might provoke ’scary’ oversteer. Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted March 4, 2018 Share Posted March 4, 2018 Reading thru alko x2-x4 ,and Vb 2c-4c air suspension on a alko torsion bar axle they use calibration bars in steel. They are fitted in the fully unloaded condition of the axle while supporting the chassis. That bar has a calibration lenght. in that space the airbellow will be fitted. And end at the original ride height at ride height air bellow pressure .The shock absorber is teamed to it and very important. But we have here independed axle suspension wo take 90 percent of the load. In case of a fiat axle i read that a ARB is mandatory. In the type approval their is the Eland swing test.On semi air the same calibration. Is a wheel geometry and shock absorber test possible for your wheel base as a motorhome. Did you have sufficient load on your front axle. There must be a solution, but maybe not a simple one. Hope you will have result. Link to comment Share on other sites More sharing options...
Will86 Posted March 4, 2018 Share Posted March 4, 2018 Regardless of all previous comments and with no intention of provoking anyone perhaps someone will kindly explain (for ME only) what is oversteer' (when cornering) I see it as being derived from ... unaccustomed use of the type of vehicle being used, the individual skill of the driver when assessing their forward situation, proceeding around a particular corner at a speed faster than the corner can tolerate while keeping the vehicle upright and safe ... failing to assess the road camber and the calculated radius perceived on the approach. The actual road length of the corner and its surface condition, the weather conditions particularly wind speed and direction, the corner not being symmetrical for its whole length, the exit speed. I see this as a basic driving skill applicable to ME only. Link to comment Share on other sites More sharing options...
Tracker Posted March 4, 2018 Share Posted March 4, 2018 Oversteer is hitting the wall with the back of the car, Understeer is hitting the wall with the front of the car. Not hitting the wall at all is skilled driving. Link to comment Share on other sites More sharing options...
weldted Posted March 4, 2018 Author Share Posted March 4, 2018 Fair comment, counter with, Owned this van from new 6 years, owned our cottage near Chalus 5 years. Made the same journey from Roscoff to cottage at least 3 times a year, same route each time. Have been motor homing for over 20 years, this type and weight of van since 2002. Steady moderate driver like to minimise fuel used, travel within speed limits and road conditions. Adjust speed according to weather. Care taken to be within load capacity, have free used of local weigh bridge to ensure even load. If you drive the same route a number of times then suddenly van acts different some is amiss but unlikely to be the driver or his driving. Link to comment Share on other sites More sharing options...
weldted Posted March 4, 2018 Author Share Posted March 4, 2018 New shocks on order!! Link to comment Share on other sites More sharing options...
Tracker Posted March 4, 2018 Share Posted March 4, 2018 Sounds like a nut loose at the wheel to me Ted!! Link to comment Share on other sites More sharing options...
Derek Uzzell Posted March 4, 2018 Share Posted March 4, 2018 Will Information on oversteer and understeer is here: https://en.wikipedia.org/wiki/Understeer_and_oversteer Someone reasonably familiar with vehicle design and dynamics should know the difference but, more to the point, any motorist who has any sort of ‘feel’ for driving should realise when his/her vehicle is behaving oddly. Ted is an experienced driver and mechanically literate. Depending on the vehicle being driven it is certainly possible to provoke massive understeer or oversteer, but Ted has described his motorhome’s behaviour when being driven normally as ‘scary’ and quite different from how it behaved until recently. Even if Ted provided fine detail exactly how his motorhome ‘oversteers’, as the vehicle has been checked over and the unusual behaviour demonstrated, I can’t see remote advice via this forum helping him further. I’d like to drive the vehicle myself to see what it’s doing (though I’d probably regret that if it’s as scary as Ted says) but obviously that’s not giong to be practicable. As Monique has said, there must be a reason for Ted’s motorhome to do what it’s doing. But if it is not been ‘over driven’ by Ted, and it’s not over-loaded, and the tyre pressures are sensible, and there’s nothing obviously mechanically wrong with it, what’s left? It should not be doing this, but it is. Fitting new dampers might do some good and won’t do any hard - sometimes one gets lucky. Link to comment Share on other sites More sharing options...
Will86 Posted March 4, 2018 Share Posted March 4, 2018 Wonderful Link to comment Share on other sites More sharing options...
Derek Uzzell Posted March 4, 2018 Share Posted March 4, 2018 Explain Link to comment Share on other sites More sharing options...
Tracker Posted March 4, 2018 Share Posted March 4, 2018 That's easy Derek - wonderful means something full of wonder - a bit like Will's grasp of vehicle dynamics! Link to comment Share on other sites More sharing options...
monique.hubrechtsgm Posted March 4, 2018 Share Posted March 4, 2018 About any remote advice on this forum, Having full air suspension on a alko high frame chassis i can count any bolt where it sits. And any airline, height sensors,compressor box, fuses, etc, No one else of the fitters who tell you this. i can fit full air suspension my self whit some axle stands. So this forum is capable to solve the oversteer if Ted really said what he has done on his suspesion front and rear. Sorry derek we are not a bunch of ass holes beside you. Link to comment Share on other sites More sharing options...
Archiesgrandad Posted March 4, 2018 Share Posted March 4, 2018 From my motorsport experience of many years ago, I recall that if the roll centre on the rear axle is lower than the roll centre of the front axle it will provoke oversteer, and the other way round it will provoke understeer. If the back is dropping lower than before it could have this effect so maybe Tracker is on the mark when he says look at refitting the bump stops. AGD Link to comment Share on other sites More sharing options...
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