Manual to Auto Gearbox change(?)

Discussion in 'Technical Troubles' started by ERIK, Jan 9, 2020.

  1. ERIK
    Offline

    ERIK

    Joined:
    Dec 17, 2019
    Messages:
    1
    Likes Received:
    0
    Ratings:
    +0 / 0 / -0
    The manual gearbox on my 2014 F36 420d x drive needs replacing and before I start searching for a replacement I was wondering if I could replace it with a Steptronic transmission? I've had various BMW models in the past 20 years and I like the Steptronic. Is it possible? Easy? Hard? Costly?

    Any advice would be appreciated

    Thanks

    Paul
     
  2. bishbosh
    Online

    bishbosh WARLORD Site Supporter

    Joined:
    Aug 15, 2015
    Messages:
    1,475
    Likes Received:
    532
    Ratings:
    +838 / 3 / -0
    Costly, you would need:

    The gearbox, gear selector, cooling pipes, probably a new oil filter housing as I think the gearbox oil cooler is located in the vicinity. Different prop shaft most likely, probably new front and rear diffs (ratios are different to manuals), associated wiring and coding. Would it be worth it? Easier and cheaper to trade it in.
     
    • Agree Agree x 1
  3. Wynne71
    Offline

    Wynne71 Site Supporter

    Joined:
    Apr 3, 2019
    Messages:
    918
    Likes Received:
    308
    Location:
    West Midlands
    Ratings:
    +451 / 0 / -1
    New ECU for the gearbox.
     
  4. bishbosh
    Online

    bishbosh WARLORD Site Supporter

    Joined:
    Aug 15, 2015
    Messages:
    1,475
    Likes Received:
    532
    Ratings:
    +838 / 3 / -0
    Isn't the gearbox ecu in the gearbox itself? I always thought so, but never found out for definite.
     
  5. Wynne71
    Offline

    Wynne71 Site Supporter

    Joined:
    Apr 3, 2019
    Messages:
    918
    Likes Received:
    308
    Location:
    West Midlands
    Ratings:
    +451 / 0 / -1
    A good point. It would need cloning to the car ECU though, not sure that could be done? Some rewriting of both ECUs for sure.
     
  6. The_Master
    Offline

    The_Master Site Supporter

    Joined:
    Aug 13, 2015
    Messages:
    168
    Likes Received:
    54
    Location:
    Norfolk
    Ratings:
    +85 / 0 / -0
    Are the diff ratios the same ? - the exhaust may be different, the engine may be mapped different to suit the gearbox, stop start system may not work correctly, pedal set up will be different ....the list goes on...
     
  7. Highsided
    Offline

    Highsided Site Supporter

    Joined:
    Feb 12, 2016
    Messages:
    187
    Likes Received:
    68
    Location:
    SW France
    Ratings:
    +136 / 0 / -1
    And the crankshaft is different, flywheel, ...
     
  8. bishbosh
    Online

    bishbosh WARLORD Site Supporter

    Joined:
    Aug 15, 2015
    Messages:
    1,475
    Likes Received:
    532
    Ratings:
    +838 / 3 / -0
    The crankshaft won't be different, flywheel will be.
     
  9. slim_boy_fat
    Offline

    slim_boy_fat WARLORD Site Supporter

    Joined:
    Jul 31, 2015
    Messages:
    3,586
    Likes Received:
    1,153
    Location:
    Scottish Highlands
    Ratings:
    +2,153 / 1 / -4
    ^^ This
     
    • Agree Agree x 1
  10. a.s.uk
    Offline

    a.s.uk

    Joined:
    Aug 1, 2015
    Messages:
    712
    Likes Received:
    223
    Location:
    Sheffield
    Ratings:
    +393 / 0 / -0
    Dave
    You sound like you’re up for this job..!!



    Sent from my iPhone using Tapatalk
     
    • Funny Funny x 1
  11. Highsided
    Offline

    Highsided Site Supporter

    Joined:
    Feb 12, 2016
    Messages:
    187
    Likes Received:
    68
    Location:
    SW France
    Ratings:
    +136 / 0 / -1
    Try realoem. Different part numbers. I'm guessing attachment of clutch vs tc.
     
  12. bishbosh
    Online

    bishbosh WARLORD Site Supporter

    Joined:
    Aug 15, 2015
    Messages:
    1,475
    Likes Received:
    532
    Ratings:
    +838 / 3 / -0
    The torque converter bolts to the flywheel. Different part numbers are used even if there are only minor updates. Even if a part is then provided by a new supplier. Also, if the crankshafts varied between auto and manual then realoem would list it on the appropriate page. It's the flywheels that are different and they are listed separately :)

    It's all moot anyway unless the op will be going ahead with the conversion :eek:
     
  13. markyboyt
    Offline

    markyboyt

    Joined:
    Aug 16, 2015
    Messages:
    737
    Likes Received:
    143
    Location:
    Shropshire
    Ratings:
    +243 / 0 / -0
    The flywheels are totally different between auto and manual, auto is just like a metal plate whereas manual is dual mass, a couple of inches thick and the clutch plate actually contacts it.

    OP in reality it would probably be cheaper and far easier to buy a 420d auto and keep the manual as well than it would to convert it.
     
    • Like Like x 1
  14. bishbosh
    Online

    bishbosh WARLORD Site Supporter

    Joined:
    Aug 15, 2015
    Messages:
    1,475
    Likes Received:
    532
    Ratings:
    +838 / 3 / -0
    Yes I know the flywheels are different. My point is that the crankshaft will be the same.
     
  15. snrbrtsn
    Online

    snrbrtsn WARLORD Site Supporter

    Joined:
    Jul 30, 2015
    Messages:
    2,146
    Likes Received:
    808
    Location:
    Aberdeen
    Ratings:
    +1,295 / 0 / -2
    Working from the front back, it becomes evident it’s not a financially viable option as mentioned previously
    Oil cooler & thermostat, pipe work, Starter motor, torque converter, gearbox, mounting plate, oil, interior trim, lever, pedal set, wiring harness, ECU coding then the necessary VOSA reclassification and tax liability (often neglected though req’d)
    Whilst a manual box will be Circa £500-£1600 + fitting (clutch if required) it’s the cheaper option to replace, sell and purchase a car with a factory auto box....
    Gone are the Auld days where the Granada’s and Cortina's could be converted on a Sunday afternoon
     

Share This Page