Steve928 Posted June 12, 2015 Share Posted June 12, 2015 There, I've said it! It takes quite some saying because it was pretty high on my shopping list this time around. Independent suspension instead of a beam axle, torsion bars instead of cart springs, German engineering. What was there not to like? However, it's been a great disappointment because the harshness of the ride so detracts from the driving experience. Given a glass-smooth surface and sweeping bends (not in the UK then..) it is superb, but it seems that every little bump is transmitted directly into the van's structure, which becomes exhausting on a long drive. I've had an Al-Ko chassis before, on a glider trailer. It was a 1000kg axle and the loaded trailer weighed c. 700kg. but watching it in the rear view mirror it was evident that there was almost no suspension travel available in the compression direction i.e. it was on its metaphorical bump stops. Plenty of suspension extension, yes, but the trailer was hopping around over bumps and getting airborne. Sadly it seems that the van's axle is the same, which makes it a very poor match to the languid Sevel front suspension. The axle is a 2000kg unit and our rear axle weight is around 1600kg yet there appears to be virtually no suspension travel available in the compression direction so every little bump transmits a shock into the structure. How do I know this? Well, the brake hose and wiring loom going to the the swing arm only clear the wheel arch edge by around 10mm so any upward movement of the swing arm in excess of 10mm would cause the hose to rub on the wheel arch - but it hasn't yet in 7000 miles. No wonder it's a hard ride - the tyres are the major component of the rear suspension! It's not particular to my van or axle by the way - they're all the same in the showroom. It seems very strange that they would design a system that doesn't allow the suspension to compress to absorb bumps at it's rated weight but that's how it seems to me. As I say, very disappointing and off my shopping list next time around. Link to comment Share on other sites More sharing options...
Guest pelmetman Posted June 12, 2015 Share Posted June 12, 2015 Heretic :D ........ Link to comment Share on other sites More sharing options...
Brian Kirby Posted June 12, 2015 Share Posted June 12, 2015 In view of what you say about rear axle loading (which seems surprisingly low, with nearly half a tonne spare), are you using the makers recommended tyre pressures? If so, I suspect that is at least part of your problem, and your rear tyres are over-inflated for their actual load. I don't think any conventionally sprung vehicle, whether cart, torsion, or coil sprung, that is based on commercial vehicle running gear, is ever going to have a "magic carpet" ride. Ours is similar in UK, but corners much flatter than its Transit based predecessor (until I added air rides to the latter, that is). I assume you must have visited a weighbridge, so how close to its maximum is the front axle? If the van is running close to the front axle limit it will be likely to seem more absorbant at the front. I'd suggest you investigate adjusting tyre pressures to those recommended by the tyre maker for the actual axle loads concerned (both axles), and see how that works. It should bring some improvement. That apart, your best option will be to opt for full air suspension on your next van (or a conversion on the present van), but it is a very expensive option! Link to comment Share on other sites More sharing options...
Keithl Posted June 12, 2015 Share Posted June 12, 2015 Steve, What tyres are you riding on, or more to the point are they 'C' or 'CP'? and what pressures do you run them at? Tyres are a very important part of a vehicles suspension system. Keith. Edit. Posts are like buses, 3 come along together :D Link to comment Share on other sites More sharing options...
markh1 Posted June 12, 2015 Share Posted June 12, 2015 I had the same until I reduced my rear tyre pressures form the ALKO recommendation of 80 psi to the tyre manufacturers recommendation of 65 psi, ride transformed! Link to comment Share on other sites More sharing options...
markh1 Posted June 12, 2015 Share Posted June 12, 2015 markh1 - 2015-06-12 12:40 PM I had the same until I reduced my rear tyre pressures form the ALKO recommendation of 80 psi to the tyre manufacturers recommendation of 65 psi, ride transformed! My axle loads are 2046kg front and 1646kg rear Link to comment Share on other sites More sharing options...
Steve928 Posted June 12, 2015 Author Share Posted June 12, 2015 Sorry, a typo on the rear axle loading which should have read 1800kg. but that doesn't change the point that the rear suspension is essentially fully compressed at a figure well below it's rated weight. Does that not surprise people? I'm not looking for a magic carpet ride nor to turn this into a thread about tyre pressures (225/70 C tyres at 53psi by the way), I'm just genuinely surpised that when I venture out onto the roads I have what is effectively a rigid rear axle with no ability for the wheel to deflect upwards over obstructions. That's not my idea of how suspension should work. The attached pic, taken level and static and with a fairly empty van (8 cases of wine just removed..) should illustrate my point. That swing arm cannot move upwards more than 10mm, only downwards. Hit an obstruction and the either the chassis must twist or the entire van deflect upwards. It just seems completely counter-intuitive to me. Link to comment Share on other sites More sharing options...
Brian Kirby Posted June 12, 2015 Share Posted June 12, 2015 I'm sure the trailing arms have greater movement than that on ours, so, how old is the van, and have the trailing arm pivots been regularly greased? There does seem to be a trace of exuding lubricant adjacent to the pivot. If not, the problem could be partial seizure of the pivots or, in view of the apparently low stance of the rear of the vehicle, a failed torsion bar. Have you tried jacking it up to see how far the trailing arms elxan when completely unladen? Might give a better clue as to what is going on. If the arm is almost fully compressed when relatively lightly laden, it would seem to indicate some sort of failure. BTW, did you take that rear axle weighbridge loading with the extra 60kg of wine included? :-D Link to comment Share on other sites More sharing options...
Steve928 Posted June 12, 2015 Author Share Posted June 12, 2015 The van is 6 months old and has covered 7000 miles, Brian, and I'm confident that it isn't suffering from any sagging, failure or breakage. It's as its always been, is as its designer intended, sitting level and at the normal ride height. Jacked-up the trailing arms drop smoothly and extend down through about 60 degrees (from memory). But then it would appear that when you put the weight of the vehicle back on them again all that 60 degrees gets used up by that weight, leaving nothing for bump absorbtion. Sadly air suspension or assistance isn't an option for the ultra lowline chassis either. Link to comment Share on other sites More sharing options...
Guest Joe90 Posted June 12, 2015 Share Posted June 12, 2015 The OP raises a question that has dogged me since our acquisition of an Alko chassis Rapido, we are currently in France and as ever when going through any areas where the roads are less than billiard table smooth, I.e pretty much every village and town the van crashes and bangs. A new set of Michelin Agelis camping green tyres before we came over has made little difference, and the requisite 6to8 strokes of grease in each nipple has been applied, in my case both Rapido and Michelin advise 5.5 bar rear pressures, and that's what I use being close to the maximum axle weights on the rear. May go back to a panel van for some peace. Link to comment Share on other sites More sharing options...
Guest Joe90 Posted June 12, 2015 Share Posted June 12, 2015 Edit, although not a large lady, I've just had the missus jumping up and down in the back of the van, the only thing appearing to flex are the tyres. Link to comment Share on other sites More sharing options...
Guest Joe90 Posted June 12, 2015 Share Posted June 12, 2015 Edit, although not a large lady, I've just had the missus jumping up and down in the back of the van, the only thing appearing to flex are the tyres. Link to comment Share on other sites More sharing options...
Steve928 Posted June 12, 2015 Author Share Posted June 12, 2015 I'm going to email Al-Ko and ask for some specification data. I would hope that they would be happy and able to provide compression measurements (the eye-to-eye dimension of the shock absorber would be ideal) for the axle at various loads and at full compression. This would allow me, and others, to calculate exactly how much suspension travel should have been used and how much should remain at a given load. I would be very happy to be proved wrong and for it to transpire that my axle is other than fully compressed at its running weight. I really hope that they will provide this data. Link to comment Share on other sites More sharing options...
Tracker Posted June 12, 2015 Share Posted June 12, 2015 We had an Alko chassis on our Autocruise Starlet but that was on the previous model Sevel X244 and may not compare with a new one for set up? We found it by far the most stable, smooth, and comfortable riding van we have ever had and I only wish we had one now - but not from what you are saying? I no longer have the handbook as it went with the van but the Alko suggested tyre pressures were around 50 psi as I recall, whereas Peugeot suggested much higher pressures. Overly hard tyres all round when we collected the van totally negated the intrinsically softer suspension of the Alko units and it was only when I let them down to what Alko said, along with the fronts which Alko also gave as lower than Peugeot suggested, that the ride improved to what it should be. As the lwb Alko made for a very long wheelbase the downsides were a massive turning circle and low ground clearance around the midpoint of the wheelbase, but as the rear overhang of the van was only about 3' the weight on the rear axle was less than with a longer overhang which made for much better better ride and handing. Tyre pressures may well be the solution? Link to comment Share on other sites More sharing options...
Steve928 Posted June 12, 2015 Author Share Posted June 12, 2015 As stated above, Rich, this isn't a 'my van's a bit uncomfortable' issue and genuinely has nothing to do with tyre pressures. Reducing tyre pressures (which I cannot do anyway when running at 53psi already) doesn't give suspension movement where no suspension movement exists. As Joe90 has also noted, the rear axle is just plain immovable, on it's stops, solid. I've just added almost 400kg very nearly directly above mine by filling both tanks and loading some handy nbags of cement and it hasn't budged one millimetre. Link to comment Share on other sites More sharing options...
Guest Joe90 Posted June 12, 2015 Share Posted June 12, 2015 Right at this very moment I'm looking at my Alko chassis handbook, for the maxi chassis the pressure given are 215/70/15c 5.0 bar, and for 215/75/16c tyres 5.5 bar, pressures stated are, quote, empty or fully loaded, go figure. But which would also lead to the conclusion the OP is running seriously under inflated, and I'm 0.5 bar over. Link to comment Share on other sites More sharing options...
Tracker Posted June 12, 2015 Share Posted June 12, 2015 Steve928 - 2015-06-12 2:43 PM As stated above, Rich, this isn't a 'my van's a bit uncomfortable' issue and genuinely has nothing to do with tyre pressures. Reducing tyre pressures (which I cannot do anyway when running at 53psi already) doesn't give suspension movement where no suspension movement exists. As Joe90 has also noted, the rear axle is just plain immovable, on it's stops, solid. I've just added almost 400kg very nearly directly above mine by filling both tanks and loading some handy nbags of cement and it hasn't budged one millimetre. My sincere apologies Steve I didn't read your posting properly. Sounds like a failure or manufacturing defect and I would be inclined to visit one of their service centres so they can check it out while you wait or with luck observe and comment on the problem? Link to comment Share on other sites More sharing options...
Guest Joe90 Posted June 12, 2015 Share Posted June 12, 2015 I have an extremely competent company that are well versed in Alko chassis motorhomes, they said my axle was as they would expect it to be, the only thing they can suffer from is a broken torsion spring which would be self evident, usually with a low ride height or listing badly to one side, mine has neither of these issues. Link to comment Share on other sites More sharing options...
Brian Kirby Posted June 12, 2015 Share Posted June 12, 2015 Steve928 - 2015-06-12 2:10 PM I'm going to email Al-Ko and ask for some specification data. ................ I have previously contacted their UK end by 'phone (01926 818500 - over what grease to use) and found them very helpful. I wonder if this may be a more productive approach initially, as folk are sometimes more inclined to be forthcoming (read mildly indiscreet :-)) in conversation than in writing (which may be an embarrasment to them if later quoted). BTW, ours is on an AMC35L, plated at 3,700kg. I can't find any mention of an "ultra lowline" chassis in the AlKo handbook, so assume this must be a van manufacturer's term. Autotrail, by any chance? Link to comment Share on other sites More sharing options...
Guest Joe90 Posted June 12, 2015 Share Posted June 12, 2015 A quick Google search provided this post below,.............perhaps our expectations of a Citroen like suspension is misguided, and there's bugger all wrong with our axles, lol. Just returned from a short trip to France with the grandchildren and spent a time in the back of the motorhome and didn't realise how harsh the Alko suspension is. Having fitted Vredestein tyres with a much lower pressure than the original Michelins the ride overall is better than it was but travelling over the poor road surfaces that we have makes you realise just how harsh travel in the rear is. I am happy with the overall handling of the vehicle, just want a more comfortable ride but I don't want to go to the expense of air suspension if it is not going to give a smoother experience. Any advice from those who have gone down this route would be appreciated. Link to comment Share on other sites More sharing options...
Steve928 Posted June 12, 2015 Author Share Posted June 12, 2015 Joe90 - 2015-06-12 3:18 PM I have an extremely competent company that are well versed in Alko chassis motorhomes, they said my axle was as they would expect it to be, the only thing they can suffer from is a broken torsion spring which would be self evident, usually with a low ride height or listing badly to one side, mine has neither of these issues. Indeed and as I've said I'm confident that mine too is as it is designed to be - I just don't like how it's designed to be, so anyone thinking that 'Al-Ko = supple ride', as per Rich's experience with his old van, needs to make sure that they are happy with what appear to be the characteristics of the current generation of lowline chassis. I'm no engineer but presumably a torsion bar axle doesn't have actual bump stops but just stops moving when the bars can twist no more? Thinking back 30 years I had a succession of wonderful Peugeot cars (205GTi was the best!) with torsion bar rear suspension and although beautifully supple and compliant unladen they were useless at carrying any weight. Sit 2 adults in the back and the headlights would point skyward. Perhaps supple suspension with the ability to carry weight is simply outside of the torsion bar envelope and cart springs are the way forward! :-D Link to comment Share on other sites More sharing options...
Guest Joe90 Posted June 12, 2015 Share Posted June 12, 2015 Perhaps if as he suggested he was running at 50psi instead of nearer the recommended 80 psi it would have been considerably softer.........at the risk of frequent blow outs lol. However, must go the missus is getting techy, on the forums and supposed to be on holiday. Link to comment Share on other sites More sharing options...
Steve928 Posted June 12, 2015 Author Share Posted June 12, 2015 Brian Kirby - 2015-06-12 3:18 PM BTW, ours is on an AMC35L, plated at 3,700kg. I can't find any mention of an "ultra lowline" chassis in the AlKo handbook, so assume this must be a van manufacturer's term. Autotrail, by any chance? Bailey, Brian, and yes possibly it is the converter's term. They used to refer to the Approach SE range as being on the lowline chassis and the subsequent Autograph range as being on the ultra-lowline. There is a note on the Al-Ko website that the 'frame can be lowered by 144mm upon request' so perhaps this is the route they went down. It is certainly a very low chassis! Link to comment Share on other sites More sharing options...
Steve928 Posted June 12, 2015 Author Share Posted June 12, 2015 P.S. axle is marked as a BTR5 2000kg, made in FRANCE. German company, axle made in France, chassis assembled to a French-badged Spanish cab by the Brits. You couldn't make it up! And my Michelin tyres were made in Poland. It truly is an international vehicle.. Link to comment Share on other sites More sharing options...
Brian Kirby Posted June 12, 2015 Share Posted June 12, 2015 Steve928 - 2015-06-12 3:48 PM............... There is a note on the Al-Ko website that the 'frame can be lowered by 144mm upon request' so perhaps this is the route they went down. It is certainly a very low chassis! I'm guessing, but I wonder if that may be a clue. If the chassis is dropped, and if the van floor sits fairly close to the trailing arms (as seems the case from your photo), it would seem necessary to restrict suspension travel to prevent either the chassis grounding, or the arms striking the van floor on full bump. I just wonder if they are using a stiffer torsion bar to achieve that, and it is that which is resulting in the harsher ride. Law of unintended consequences? Might be worth asking if they can comment. Link to comment Share on other sites More sharing options...
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