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Thread: 915 trans

  1. #1

    915 trans

    Does anyone know the cutoff year for the 7:31 R&P on the 915 trans?
    Has anyone run a later 915 w/8:31 R&P on an early 911S? Any acceleration changes, any problems with running your engine hard, or daily driving?

  2. #2
    Moderator Chuck Miller's Avatar
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    Oct 2002
    Reseda, CA.

    915 trans

    The 8:31 R&P change came in 1976...

    FYI ... They changed the 4th and 5th gear ratios for the later boxes.

    Early 915:
    1st - 3.181
    2nd - 1.833
    3rd - 1.261
    4th - 0.9615
    5th - 0.7586
    Final ratio 4.4285

    Late 915:
    1st - 3.181
    2nd - 1.81
    3rd - 1.261
    4th - 1.000
    5th - 0.821
    Final ratio 3.875

    It also seems they kept changing the 5th gear ratio in the later boxes, maybe because of the increases in the cars weight.

    Sorry, I have no experence with the later diff. in the earlier box
    Chuck Miller
    Creative Advisor/Message Board Moderator - Early 911S Registry #109
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