W220 Twitchy Rear

Discussion in 'Wheels, Tyres, Brakes & Suspension' started by ahd91, Feb 2, 2015.

  1. ahd91

    ahd91 New Member

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    I've recently purchased a 2001 S55 with a couple of niggles. The main one being that the back end is extremely twitchy going over anything more than a manhole cover at 30mph.

    The rear suspension is creaky, but I'm fairly sure that's just the old bushes that I'll be replacing soon, so I'm thinking perhaps that the rear wheels are out of alignment? Seems logical that if they were, they'd pull the car in a slightly different direction when one wheel lost some traction, which is what it feels like.

    Any other ideas? Can't see anything immediately amiss.
     
    Last edited: Feb 2, 2015
  2. DSM10000

    DSM10000 MB Club Veteran

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    Try the simple things first.

    Correct tyre pressures? What brand of tyre is fitted and how much tread is left?

    I have just changed the rear Michelin tyres on my C320 as they were feeling twitchy on poor road surfaces as you describe, they were both at just below 3mm
     
    Last edited: Feb 2, 2015
  3. OP
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    ahd91

    ahd91 New Member

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    Good point - can't believe I haven't already tried pressures.

    Continentals all round, with a good 5-6mm of tread left.
     
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  4. DSM10000

    DSM10000 MB Club Veteran

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    Not sure what sort of suspension you have (conventional or ABC?) but poor damping would also give similar symptoms.

    Hope it is a simple fix, when I got this car it was feeling unsettled at the rear although it had new Pirelli tyres all round, the pressures had been set too high.
     
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    ahd91

    ahd91 New Member

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    It is indeed the dreaded ABC system, but it appears to be OK in every other regard, with no warnings lights either.

    Fortunately I persuaded the dealership to give me 3 months warranty on all of the suspension system.
     
  6. Howard

    Howard MB Club Veteran

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    Are the 220's on abc ? I thought they were on air ?
     
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    ahd91

    ahd91 New Member

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    Definitely has ABC - there's an 'ABC Sport' button on the dash.
     
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  8. gIzzE

    gIzzE MB Club Veteran

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    Matched front and rears?

    Same model Conti?

    These don't like different tyres front and rear, if the treads are different the back end gets very twitchy.

    However, you say when you go over a manhole cover, which does make me think it is rear suspension. Have you had it on a ramp to check anti roll bar bushes and rear arms etc.?
     
  9. alexanderfoti

    alexanderfoti Hardcore MB Enthusiast

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    also check rear subframe bushes.

    55 and up (600 and 65) 220's come with ABC, anything underneath comes with Airmatic.
     
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    ahd91

    ahd91 New Member

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    Many thanks for all the help guys.

    Mere hours after posting however, the ABC system itself failed, and I expect the car to be a write-off.
     
  11. alexanderfoti

    alexanderfoti Hardcore MB Enthusiast

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    Ah thats a bit of a shame
     
  12. C43AMG

    C43AMG MB Club Veteran

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    Very Sorry to hear that :mad:
     
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    ahd91

    ahd91 New Member

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    A shame indeed; I knew her for just 48 hours.

    Dealer will be picking up the bill, but I'd imagine they'll just want to refund me and cut their losses.
     
  14. m2287

    m2287 Hardcore MB Enthusiast

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    What exactly happened?
     
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    ahd91

    ahd91 New Member

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    The car didn't settle quite right when I pulled up in the work car park after lunch. Tried raising and lowering to see if it would sit properly, and the front driver side simply gave out and lowered right down to the tyre. Red warning came on, so I got out and saw that the sytem had expelled most of its fluid out onto the tarmac underneath the strut that appears to have failed.
     
  16. DrFeelgood

    DrFeelgood MB Club Veteran

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    Is ABC a more expensive fix than Airmatic?
     
  17. m2287

    m2287 Hardcore MB Enthusiast

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    A leaking strut or pipe is pretty simple to replace, even if the pump is gone it can be rebuilt for under £100
     
  18. m2287

    m2287 Hardcore MB Enthusiast

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    I think they are pretty similar cost wise but ABC is harder to work with.
     
  19. OP
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    ahd91

    ahd91 New Member

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    Do you have any more info on this? I was under the impression we were talking a good £500 each for the struts and pump, with lots of labour on top.
     
  20. m2287

    m2287 Hardcore MB Enthusiast

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    Well you can get a second hand strut for around £200, pipes are around £50 to get made up at any hydraulic specialist and you can get a pump rebuild kit from Mercedes Benz ABC Pump Seal Kit MBZABCSEALKIT

    They deliver FAST, I ordered a kit on a Wednesday night at it was delivered to my door at 9am Friday morning.
    Labour wise, I have done struts in an hour and the pump takes me around an hour and a half to get out.
     
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