Page 1 of 3 123 LastLast
Results 1 to 10 of 26

Thread: 901 SWB trans gearing

  1. #1

    901 SWB trans gearing

    I am running a smidge over 3200 rpm at 60mph and a smidge over 3600 rpm at 70mph in my '68 911.

    Anyone care to guess what gearing I have? Do I have "airport gears"?

    The gearing seems a bit short, can't really cruise above 75 mph, rpm's get over 4K.

    Even with my '70 T motor, my car moves out pretty well. Very torquey. It may have to do with my gearing?

    What are other's experiences?

  2. #2
    Senior Member CamBiscuit's Avatar
    Join Date
    May 2006
    Location
    Adelaide, Australia
    Posts
    1,447
    I've just changed my gearing to AFMSX and am running 205/60 R 15 tyres.

    At 70mph its pulling about 3400rpm.

    What are your tyre specs?
    Looking for engine # 6208151
    '74 RS 3.0 Replica
    '70 911E Bahia Red (SOLD)
    '71 911 S/T Replica 2.3 Twin plug BEAST (SOLD)
    Australian TYP 901 Register #78
    Early S Registry # 1076

  3. #3
    I suspect your gearing is stock. If you had airport ratios you would be turning about 5k at 70mph.
    Tom F.

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

    #736

  4. #4
    Senior Member gtgroupe3's Avatar
    Join Date
    Sep 2006
    Location
    MD
    Posts
    233

    MPH estimates.

    These are estimates of MPH for the S-Z gears at 3750-4500 RPM based on tire size with a 901 transmission.

    Calculations do not reflect drive losses and issues with speedometer calibration which can greatly effect actual speed.

    It would be better to have more information of speeds in certain gears in a wider range of RPM. Hope this is helpful.

    3750 4000 4250 4500
    S 61.5 65.6 69.8 73.9
    T 64.0 68.3 72.5 76.8
    U 66.6 71.0 75.4 79.9
    V 69.1 73.7 78.3 83.0
    W 72.0 76.8 81.6 86.4
    X 74.7 79.7 84.6 89.6
    Y 77.9 83.1 88.3 93.5
    Z 80.7 86.1 91.5 96.8

    901 Section Series Diameter
    25.20 185 70 15

    3750 4000 4250 4500
    S 60.3 64.3 68.3 72.4
    T 62.7 66.9 71.1 75.2
    U 65.2 69.6 73.9 78.3
    V 67.7 72.2 76.8 81.3
    W 70.5 75.2 80.0 84.7
    X 73.2 78.0 82.9 87.8
    Y 76.3 81.4 86.5 91.6
    Z 79.1 84.3 89.6 94.9

    901 Section Series Diameter
    24.69 205 60 15

    3750 4000 4250 4500
    S 58.3 62.2 66.1 70.0
    T 60.7 64.7 68.7 72.8
    U 63.1 67.3 71.5 75.7
    V 65.5 69.9 74.2 78.6
    W 68.2 72.8 77.3 81.9
    X 70.8 75.5 80.2 84.9
    Y 73.8 78.8 83.7 88.6
    Z 76.5 81.6 86.7 91.8

    901 Section Series Diameter
    23.88 205 55 15

    Please pardon the formatting, it didn't carry over.
    Sumner
    Registry Member #970



    1970 914-6
    Adriatic Blue

    1972 911T (vice)
    Gemini Metallic

    1967 911S (vice)
    Slate Grey

  5. #5
    Quote Originally Posted by Cam Arnott
    I've just changed my gearing to AFMSX and am running 205/60 R 15 tyres.

    At 70mph its pulling about 3400rpm.

    What are your tyre specs?
    I have 195/65's on my car.

  6. #6
    Quote Originally Posted by tfiv
    I suspect your gearing is stock. If you had airport ratios you would be turning about 5k at 70mph.
    Oh, wow, so the airport gears were very short then!!

    Maybe I have "Nurburgring" gears?

    Actually I have no reason to believe the gearing in my '68 is anything other than stock. The RPM's just seem a tad high is all, but that usually happens when comparing older cars to newer cars.

    I think the gearing in the newer 911's was/is geared to high speed cruising on the highway. Maybe the gearing in the older 911's was not focused on this?

  7. #7
    Senior Member gtgroupe3's Avatar
    Join Date
    Sep 2006
    Location
    MD
    Posts
    233

    195/65/15

    3750 4000 4250 4500
    S 61.0 65.1 69.2 73.2
    T 63.5 67.7 71.9 76.1
    U 66.0 70.4 74.8 79.2
    V 68.5 73.1 77.7 82.2
    W 71.4 76.1 80.9 85.7
    X 74.0 79.0 83.9 88.8
    Y 77.3 82.4 87.6 92.7
    Z 80.0 85.3 90.7 96.0

    901 Section Series Diameter
    24.98 195 65 15
    Sumner
    Registry Member #970



    1970 914-6
    Adriatic Blue

    1972 911T (vice)
    Gemini Metallic

    1967 911S (vice)
    Slate Grey

  8. #8
    You might find this little utility useful.
    Attached Files Attached Files

  9. #9

    Red face I'm still confused; please advise

    I downloaded the utility which was generously posted. I appreciate the work but am having a hard tme understanding the information.

    I have 225/50-16 rear tires on 16x8 inch Fuchs. I am turning 4000 revs at 80 mph.
    I have the following transaxle numbers:
    typ 911/01
    serial 7112077
    case 911.301.101.0R
    differential housing driver side 901.301.311.2R

    Can someone please tell me what gears I likely have?

    Danke!
    1971 911S, 2.7RS spec MFI engine, suspension mods, lightened
    Early 911S Registry Member #425

  10. #10
    Senior Member 911quest's Avatar
    Join Date
    Mar 2006
    Location
    Louisville KY
    Posts
    1,530
    From the info I have........

    A,GA,O,V.ZA

    But if it has been apart gears could have been changed etc.
    Tony Proasi

    52 split window coupe

Similar Threads

  1. Gearing Question
    By Sisuman in forum Technical Info
    Replies: 0
    Last Post: 06-23-2012, 05:07 AM
  2. US vs RoW gearing
    By Jules Dielen in forum Technical Info
    Replies: 4
    Last Post: 11-07-2011, 08:54 AM
  3. 901 gearing for a 2.5l engine
    By Anatol in forum Technical Info
    Replies: 6
    Last Post: 07-05-2010, 03:58 PM
  4. 915 Gearing References
    By gtgroupe3 in forum Technical Info
    Replies: 3
    Last Post: 02-11-2009, 01:13 PM
  5. Help with Gearing..
    By Mudi in forum Technical Info
    Replies: 4
    Last Post: 04-18-2008, 07:50 AM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  

Message Board Disclaimer and Terms of Use
This is a public forum. Messages posted here can be viewed by the public. The Early 911S Registry is not responsible for messages posted in its online forums, and any message will express the views of the author and not the Early 911S Registry. Use of online forums shall constitute the agreement of the user not to post anything of religious or political content, false and defamatory, inaccurate, abusive, vulgar, hateful, harassing, obscene, profane, sexually oriented, threatening, invasive of a person's privacy, or otherwise to violate the law and the further agreement of the user to be solely responsible for and hold the Early 911S Registry harmless in the event of any claim based on their message. Any viewer who finds a message objectionable should contact us immediately by email. The Early 911S Registry has the ability to remove objectionable messages and we will make every effort to do so, within a reasonable time frame, if we determine that removal is necessary.