Mercedes Twin Axle more stable than Single?

Discussion in 'Tech/Mech General' started by AndyJJDavies, Jun 5, 2016.

  1. AndyJJDavies

    AndyJJDavies Funster

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    Hi all
    I'm currently looking at a van that has a Mercedes twin rear wheel chassis (i.e four wheels on the same axle).

    I have heard that the single wheel configuration can be a bit unstable in cross winds, overtaking trucks etc. Does anyone know if the twin wheel configuration is more stable?

    Thanks
    Andy
     
  2. DuxDeluxe

    DuxDeluxe Funster Life Member

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    Logic dictates yes, but others will say for certain - the suspension will be beefed up as the whole axle will be able to carry a lot more - should be nice payload and much less getting stuck on muddy pitches with RWD
     
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  3. veevee

    veevee Funster

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    Had motorhomes based on the Mercedes 508D, Mercedes 609D, 410D and now the 416CDi, all with twin rear wheels. The amount of grip is astounding that includes for cornering and in the wet too (with good tyres). Have had two extreme situations, first with the 609D on the south side of the Atlas mountains in a snow storm on an unmade road going up a pretty steep incline. We got stuck eventually but managed about 100m further than a Landrover, and that's the God's honest, but were stuck for 3 days though.
    Second time a couple of days ago in central France in the 416CDi. As reported it is very soggy in central France, it has actually rained more or less consistently for 3 or 4 months, then a 2 day let up and rain again. On grass uphill with the top 2" - 3" with a consistency of blancmange, thought it would never get up this slope from a standstill but it did and no spin (had to go back and check the tyre tracks as I didn't believe it had spun the wheels), just a very slow uphill drive.
    In the very same place earlier in the year in drier conditions and partly loaded our works Ducato managed to bury the van up to the wheel rims and had to dig it out.

    Yes a fan of Mercedes twin rear wheels although 6 tyres to buy.
     
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  4. JeanLuc

    JeanLuc Funster

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    You are referring to a single rear axle with twin wheels, rather than a twin axle.
    My Hymer is based on a Mercedes 316 chassis with single rear wheels. You can feel it 'pull' off-line a little when a coach overtakes fast, or if a 40 tonne artic pulls alongside (I don't travel very fast on a motorway and sometimes trucks overtake me). Having said that, it's not a big problem and you soon get used to anticipating it. The improved traction of rear-wheel drive, compared with front-wheel drive, on poor surfaces more than compensates for any slight swaying in my opinion. Veevee puts the case very well above, traction being even better with a twin wheel set-up compared with my single wheels.
    If you want improved stability, I suspect you will need a twin rear axle with front-wheel drive, often called (incorrectly) a 'Tag' axle set-up in the trade. But then you will lose the benefit of better traction on poor surfaces, and there will be a tendancy for the rear wheels to scuff on tight turns (e.g. manoeuvring on a wet grass pitch). You may have noticed that on a true tag-axle arrangement, as seen for example on large coaches and bin lorries, the trailing pair of wheels pivots so that they 'steer' to follow the leading pair. You do not get this on a twin-rear axle motorhome.
     
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  5. DuxDeluxe

    DuxDeluxe Funster Life Member

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    There you go..... a compelling bit of experience and explanation above (y)
     
  6. AndyJJDavies

    AndyJJDavies Funster

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    Thanks for the replies. It looks like general concensus is that the Merc (particularly with the additional two wheels) has better grip than the Ducato but the Ducato is generally more stable (and more so with a 'tag' axle).

    I have experience of the single axle Ducato Alko (3500kg) so I guess what i'm really trying to get a feel for is if the addition of the extra two wheels on the Merc brings it closer to the Ducato that the standard Merc.

    FWIW, the twin wheel Merc I am looking at is a 2008 model, 5,300kg.
     
  7. JeanLuc

    JeanLuc Funster

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    I would not be too worried about the stability issue to be honest. It doesn't seem to affect a typical LWB Sprinter van driver! I have been in my Hymer when a German Mercedes mechanic took it for a spin to check the engine's turbo operation. I never realised just how quickly it could go round corners without losing grip!
     
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  8. DavidG58

    DavidG58 Funster

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    We have a twin rear wheel (four wheels on single axle) Mercedes, we have added air suspension to the rear to try and reduce the amount of body roll we get at low speed on rough ground, it has not stopped it as much as I would have liked, but I am not aware of any issues in normal driving, even in really strong winds apart from knowing it is windy it doesn't seem unduly affected.

    I don't really think the air suspension has made much difference to that, it has been excellent to avoid grounding our rear end on steep drives / ferries etc

    3.0 litre 5.5 ton, nice combination, have been stuck once, but we dropped into someone else rut that we hadn't seen
     
  9. Robin McHood

    Robin McHood Funster

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    My experience is very little, but driving RH back from Germany with Storm Katie earlier this year blowing across the Autobahn and RH being very slab sided I was really impressed by how little effect the sidewind had even with large trucks passing me. RH is the Sprinter 616 base with twin rears either side
     
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  10. jonegood

    jonegood Funster

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    Im no expert but have been in a few 416 based vehicles and found them to be bouncy both on the move and stationary. I pay particular attention because my wife suffers with inner ear problems.

    I have heard it suggested that the width of the rear wheels dictates that the point of contact between axle and chassis/body needs to be narrower than that of a single wheel.

    IMO Sprinters tend to have a softer ride quality ( so better on poor surfaces) than the Fiat equivalent but don't handle as well.

    I dont think traction comes into it for most people untill you get to difflocks ( much better) or Tags ( much worse).
     
  11. canopus

    canopus Funster Life Member

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    Our Concorde is on the Sprinter 616 single axle twin rear wheel drive and it sticks like to the proverbial to a blanket. Not been stuck on wet fields when others have and cornering is a dream, compared to some we've seen.
     
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  12. veevee

    veevee Funster

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    Just to add that I drive our 2013 LWB Ducato over long distances every month and our 416 Hymer twin rear wheel Mercedes frequently again over long distances. This Ducato has the best road holding of any of the 5 Ducatos I have owned but considering the physical size of the MH body compared to the Ducato van body the Mercedes is remarkably stable in cross winds and the like. The other side of that is comparing the Ducato which is used for long distance deliveries to the Mercedes, the Mercedes is more ponderous and not as nimble, just horses for courses.
     
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  13. DuxDeluxe

    DuxDeluxe Funster Life Member

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    As everything motorhoming........compromise is the key word.

    A tough decision but a really nice problem to have. If it were me, I might spend the extra on the Merc........
     
  14. AndyJJDavies

    AndyJJDavies Funster

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    Thanks all for the replies, very useful as always (y)
     
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