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Thread: Mainshaft (GA) from 65 box - OK with 2.0s?

  1. #1
    Member #1525 gilbert911's Avatar
    Join Date
    Oct 2006

    Mainshaft (GA) from 65 box - OK with 2.0s?

    As the title says.
    Have a GA mainshaft sourced from an early 65 911 box.
    Should it be robust enough to be mated with a 901/02 2.0s stock engine?
    Tyres are skinny at 5.5"
    No LSD

    I have read that the imput shaft is not as strong (1st gear) as the later boxes. Would I be correct in this and should I be concerned?
    Suppose the alt would be seperate mainshaft and GA gear, but expensive.

    Thanks for advice

  2. #2
    Vintageracer John Straub's Avatar
    Join Date
    Sep 2006
    La Quinta
    I have one and have never had a problem.

    1959 356 Coupe, 1600 Super, sold
    1960 356 Roaster, race car, SCCA, sold
    1960 356 Roadster, show car, sold.
    1962 356 Cab, show car, sold.
    1965 911 #301111, Red Book Vol 1 "Cover Car," owned 54 years.
    1967 911 #307347, bare-bones, some road wear, a little surface rust, and a few dents..., owned 14 years.
    1970 914/6GT, (Sold - ran the last three Rennsports)owned 30 years.

    Photography Site:

    Registry #983
    R Gruppe #741

  3. #3
    GA second is not a 2,0 liter gear, it's a 2,2. AGAOVZA 70-71 only.

    It's fine with a 2,0 S

    The problem is that first isn't as strong because it's cantilevered off the end of the mainshaft inside the end cover. If you have a 3,0 motor and hammer first it will pull the gear off the end of the shaft.

    No concern about doing that with a 2,0 S
    1966 911 #304065 Irischgruen

  4. #4
    Member #1525 gilbert911's Avatar
    Join Date
    Oct 2006
    Getting alot of help from you John!
    Thanks again

    Chris N

  5. #5
    Senior Member
    Join Date
    Oct 2008
    Burford, ON, Canada
    The GA mainshaft came in the first 911 transmissions in 1965 models (type 901/0), and also appeared in several other types later on such as the 914/01. It had a 12mm nut securing first gear in the 1965 version. Later mainshafts had a 14mm nut instead. As long as the transmission is lightly loaded it should be fine. If you have questions, then I suggest contacting Grady Clay for definitive information on these early mainshafts.
    Porsche Historian, contact for Kardex & CoA-type Reports
    Addicted since 1975, ESR mbr# 2200 to 2024 03
    Researching Paint codes and Engine Build numbers

  6. #6
    I think you would like the performance of your car with the lower F shaft a 2.0 came with
    Tom F.

    '67 911S Slate Gray
    '70 911T 2.8 hotrod (in progress)
    '92 964


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