560SEC gearbox - is it actually specific to the 560?

Discussion in 'Engine' started by mattsimis, Jan 11, 2013.

  1. mattsimis

    mattsimis New Member

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    Im reading conflicting stuff online, some people claim to have fitted 500SEC boxes and others claim they arent interchangeable. My 560SEC engine is super, pulls strongly etc. Transmission has rough/slammy Reverse and Flaring from 2nd to 3rd, has 170k miles on it, so not surprised.

    500SEC gearboxes seem cheap and plentiful:
    Mercedes * 4-speed Auto gearbox * w126 420 420se 420sel 500 V8 | eBay

    Can I just have one dropped into my 87 560SEC?
     
  2. mct_cars

    mct_cars Active Member

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  3. OP
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    mattsimis

    mattsimis New Member

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    I wouldnt be worried about a (within reason) gearing change, its something I and others have done on other cars for performance reasons anyhow. Surely wouldnt affect the speedo though? Never has before on other stuff.

    As long as it physically fits that would be fine.
     
    Last edited: Jan 12, 2013
  4. jaymanek

    jaymanek Authorised Forum Sponsor Authorised Forum Sponsor

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    They had various different models of gearbox... If you can supply me with your reg or chassis number ill tell you the type of box you need.
     
  5. OP
    OP
    mattsimis

    mattsimis New Member

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    Well I can find out the correct original one that was in it easy enough, thats not the question though!
    Availability is mostly 500SEC gearboxes, I want to confirm one of them fits ok.
     
  6. jaymanek

    jaymanek Authorised Forum Sponsor Authorised Forum Sponsor

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    What im saying is the gearboxes arent engine specific but there were various changes over the years. So you need the gearbox code. My 560 is a 722.350
    So any 722.3 box will fit and work on my car.

    So a 500 box may well fit the 560 but not all 500 boxes are the same...
     
  7. OP
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    mattsimis

    mattsimis New Member

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    Right then the chassis is WDB1260452A331024.
    I can edit this post later if posting VINs isn't kosher here.
     
  8. jaymanek

    jaymanek Authorised Forum Sponsor Authorised Forum Sponsor

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    Yours is a 722.323 box, so again any 722.3 box should be fine... You must check the bell housing has the cut out for the crank sensor.
     
  9. mct_cars

    mct_cars Active Member

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    Don't think it would affect the speedo as long as the final drive isn't changed?

    The difference seems to be a 560 box has a Shorter (3.87 v 3.68) first and a longer (2.25 v 2.41) second. Third and Fourth identical, with a Shorter Reverse (with a shorter final drive to?).

    Be interesting to see how much it changed the drive - I've considered replaceing the Diff in my SL as I find it too long. If I could replace with a shorter gearbox instead, that might be easier!
     
    Last edited: Jan 12, 2013
  10. mct_cars

    mct_cars Active Member

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    mattsimis

    mattsimis New Member

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    Ah right thanks. If it doesn't have the cut out, any options?
     
  12. khimani_mohiki

    khimani_mohiki Active Member

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    The basic gearbox is the same between all W126 V8's, they are all type W4A040, the 722.3 part number indicates the assembly of the W4A040 gearbox and vehicle specific parts such as vacuum modulator, cooler pipes, filler tube, bowden cable.

    If you were to find a gearbox without the bellhousing cut-out for the crank sensor you could just cut it out with and angle grinder. You may also need to swap over the bowden cable and vacuum unit in order for your E/S switch to work correctly as this wasnt present on the earlier cars, yours will have a red vacuum pipe on it. The vacuum modulators may also need to be swapped over, they are colour coded.
     
  13. jaymanek

    jaymanek Authorised Forum Sponsor Authorised Forum Sponsor

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    Im fairly sure there are differences in gear ratio's too. There was a table I came across comparing all the W126 boxes with codes and ratios...but havent got time to look for it now.
     
  14. khimani_mohiki

    khimani_mohiki Active Member

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  15. mct_cars

    mct_cars Active Member

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    Yep, but not sure if that was W124 only or all cars fitted with that gearbox.
     
  16. 201035

    201035 Member

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    I think it is...
     

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