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E46 325ci 5 to 6 speed upgrade possible?

  • 23-04-2012 3:16pm
    #1
    Idbatterim
    Registered Users, Registered Users 2 Posts: 18,533 ✭✭✭✭


    Hi, would i be able to swap the standard 5 speed gear box on a 03 facelift msport, for the 6 speed one used in the E46 m3?


Comments

  • #2
    Onwardandupwar
    Closed Accounts Posts: 130 ✭✭Onwardandupwar


    I feel I'm in a good place to answer this as this is our area of expertise eg. Bmws it will work yes of course but bear in mind the car will have a different rev out speed and shorter or faster acceleration. There is only one thing I'm not sure of and that is that u need to make sure that the bell housing bolts will match the engine block.do u have a reason for doing this as its not just as easy as put that gearbox in there there are a hole host of things to take into consideration seriously


  • #3
    Owen
    Registered Users, Registered Users 2 Posts: 12,683 ✭✭✭✭Owen


    You'll also lose cruise control. It takes it's calculations from the flywheel speed vs road speed.


  • #4
    Matt Simis
    Registered Users, Registered Users 2 Posts: 8,718 ✭✭✭Matt Simis


    Onwardandupwar wrote: »
    I feel I'm in a good place to answer this as this is our area of expertise eg. Bmws it will work yes of course but bear in mind the car will have a different rev out speed and shorter or faster acceleration.

    For $hits and giggles, Ill dispute your answer. The ratios are so close the acceleration will be exactly the same. Im not totally sure what you mean by Rev out speed, but since the ratios are effectively the same there would be no difference there either.

    What is different is the car would gain an overdrive type gear for motorway crusing, which effectively drops RPM and torque by 20%.
    M3 Coupe E46 Coupe 6sp manual
    1st: 4.23
    2nd: 2.53
    3rd: 1.67
    4th: 1.23
    5th: 1.00
    6th: 0.83
    vs
    325ci E46 Coupe 5sp manual
    1st: 4.23
    2nd: 2.52
    3rd: 1.66
    4th: 1.22
    5th: 1.00
    From: http://www.bokchoys.com/differential/GearRatios.htm


    To the OP: If you are looking at this to reduce fuel cost, its not worth it, the cost of the box and installing it would take massive motorway (6th gear zone) mileage to gain back. If you really want to pursue this, a cheaper and easier option would be to change the final drive (ie Rear diff) in your car from the 3.15 (I guess) to something like 2.91. This would reduce RPM and acceleration in all gears and give you a higher top speed but lower RPM and increased time to reach top speed.


  • #5
    Idbatterim
    Registered Users, Registered Users 2 Posts: 18,533 ✭✭✭✭Idbatterim


    Thanks for all the replies, yeah was just wondering if it would indeed be possible, doubted the figures would stack up though and this has been confirmed, as I do less than 1k miles per year where I would actually benefit from the 6th gear, just saw the below and know a mechanic who charges me virtually nothing for labour... pity the 6 cylinders didn't come with 6 speed gearbox!

    http://www.ebay.co.uk/itm/E46-M3-6-Speed-Manual-Gearbox-Transmission-Z3m-Z4-Off-S54-Engine-/320890063694?pt=UK_CarsParts_Vehicles_CarParts_SM&hash=item4ab689cb4e#ht_500wt_949


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