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C Class Changed Gearbox Characteristics after Service

Discussion in 'Engine, Drivetrain, Fuel and Exhaust' started by cumbriasport, Aug 4, 2011.

  1. cumbriasport

    cumbriasport Guest

    Twice after service my 08 C Class gearbox has had changed characteristics: changing up later and down earlier with an increase in diesel consumption. Car also seems noisier – but this could be due to higher revs.

    At first service it was returned to main dealer garage and fixed by "adjusting electronic settings". Second annual service at main dealer caused no problems. After recent third service a similar situation was created but when returned to M-B specialist who carried out this service they could identify no problems on their M-B diagnostic machine.

    Is this common and what is the fix?
     
  2. Steve@Avantgarde

    Steve@Avantgarde Forum Supporter Authorised Forum Supporter

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    There is nothing done at any service that could change such characteristics. Even plugging it into star and clearing fault memories wont change performance of your gearbox in anyway unless you had a fault with it to begin with.

    The adjustment settings mentioned could be the adaptations in the gearbox that were reset by the dealer. There is nothing else you can adapt electronically on these cars. Maybe the roadtest performed after service was of a slightly harder nature than you would normally drive causing the gearbox to relearn a different adaption for a small period of time whilst it relearns your style??

    One thing you can be assured of is changing oil and checking over your vehicle will not change its performance for the worst.
     
  3. television

    television Always remembered RIP

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    Could it be that the switch for the W -S has been moved.

    When my V70R was new it always came out of the workshop with the switch in the N setting where as I always kept it on S
     
  4. moosehead

    moosehead Senior Member

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    Every time they upgraded the s/w on my 7G it came back with a different set of characteristics. I'm sure the 5 speed is completely different though.
     
  5. television

    television Always remembered RIP

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    Indeed it is, whe 722.6 was a fine box, but saying that so the the 7G possibly rushed through because of the competition from ZF. The 7G is very good when set correctly and the later version are much better
     
  6. Alex M Grieve

    Alex M Grieve Senior Member

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    agreed Malcolm. I have a 7G on the R Class and the old cliché applies that "you have to watch the rev counter to know when it changes gear".

    It can be that good. It is disappointing to hear the experiences of others, but hopefully they can be encouraged by the knowledge that it can be seamless, with no hesitation on takeoff.
     
  7. markg14

    markg14 Senior Member

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    I have experienced the same thing on my 2007 C Class C220 CDI.

    The original software on the gearbox was rubbish, and caused 3 torque converter failures in my car.

    They were constantly trying new gearbox software in an effort to get it right, and eventually (after 2 years and 90,000 miles) they sorted it.

    But a word of warning - I was staggered to hear from an MB technician that he thought I had the 7-speed gearbox, when in fact the 7-speed gearbox is only an option on the C320 CDI.

    So maybe that have downloaded the wrong software.

    But I am sure if you take it back they will sort it out (eventually)

    They really should warn us that we are guinea pigs in the Mercedes Development program.......
     
  8. jackwall5

    jackwall5 Senior Member

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    I can imagine.... I'd be pretty annoyed in that case!!!! I'm not meaning all up in arms but certainly talking to someone who should be wearing a tie!!!!
     

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