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    Default F series Diff info + Discussion

    Figured we have an S and T thread, the next most common is F series diff. A favourite for when people go turbo, want a bulletproof setup and are sick of smashing T series axles.

    First of all some basic info about the F series Diff.

    Crown Wheel: 7.5"

    Braking: Drum and Disc variations

    RA65 Celica = Drum
    RT142 Corona IRS = Solid Disc
    MA61 Supra = Vented disc
    MX73 Cressida = Vented Disc
    YR22 Tarago = Drum
    MS112 Crown = Drum
    Corona Mk2 = Drum

    RT142 live axle borgwarner discs can be adopted (semi) easily onto some F and T diffs, more info here:

    http://www.toymods.net/forums/showthread.php?t=32132

    F series ratio info here on Toymods too.

    http://forums.toymods.org.au/index.php?t=msg&th=33561

    To see which ratio your F diff is check out this:

    Read the Axle Code from the vehicle indentification plate.

    first digit: ring gear diameter

    A 138mm
    B 145mm
    C 6.25"
    D 6.62"
    E 7.1"
    F 7.5"
    G 8"
    H 9"
    J 9.25"
    K 9.5"
    L 10.5"
    M 12.5"
    N 13.5"
    P 14"
    Q 12"
    R 162mm
    S 6.38"
    T 6.7"
    U 6"
    V 10.6"
    W 15.5"
    X 142mm
    Y 158mm
    Z 202mm
    - no ring gear = FWD

    Second, third digits: gear ratio

    01 3.30
    02 3.36
    03 3.545
    04 3.556
    05 3.70
    06 3.889
    07 3.90
    08 4.111
    09 4.222
    10 4.375
    11 4.444
    12 4.625
    13 4.79
    14 4.875
    15 5.125
    16 5.286
    17 5.60
    18 5.714
    19 5.833
    20 6.167
    21 6.667
    22 6.78
    23 6.833
    24 7.64
    25 4.556
    26 5.571
    27 3.364
    28 4.30
    29 4.10
    30 3.727
    31 3.909
    32 6.591 or 4.807
    33 7.503 or 5.583
    34 6.781 or 4.786
    35 7.636 or 5.60
    36 4.778
    37 3.583
    38 3.417
    39 3.154
    40 5.375
    41 3.308
    42 6.500
    43 3.550
    44 3.214
    45 3.533
    46 2.928
    47 3.944
    48 3.356
    49 3.729
    50 3.400
    51 3.736
    52 3.722
    53 3.250
    54 3.941
    55 3.333
    56 2.821
    57 4.058
    58 3.238
    59 3.234
    60 3.519
    61 2.724
    62 2.892
    63 2.655
    64 4.312
    65 3.837
    66 3.071
    67 3.526
    68 3.095
    69 4.176
    70 5.857
    71 2.962
    72 3.949
    73 4.285

    Fourth digit: no of pinions, ltd slip-yes/no

    Code pinions ls
    2 2 no
    3 2 yes
    4 4 no
    5 4 yes



    Example: F372 = 7.5" 3.58 final ratio 2 pinion diff. Will not be stamped on the diff, you will have to check the build plate on the firewall of the car you pull it from.


    LSD Availability: Altezza LSD's form the likes of Kaaz etc will bolt in but a spacer ring needs to be made up for it to work. Can anyone shed more light on this? Steroidchickens?

    Tomei Altezza centre into an MS112 Crown = Works, no problem!
    Cusco Altezza centre into YR22 Tarago = Success!

    IRS centres will bolt straight into Live axle F diffs so you could use an MA61 LSD but apparently no good for proper driving with small clutch plates and small surface area they aren't very effective and usually well worn out. An aftermarket 1.5 or 2 way or locker is your best bet for grip or drift work. See Kaaz, Tomei, OS Giken, Cusco, (TRD no longer available)

    Side note for celica/cressida/irs corona - Altezza/RS2000 Cusco LSD was a nightmare for my diff guy into RT142/RA65 IRS centre probably due to the car not being LSD to begin with. Machining and lots of hunting for correct bearings needed. Have been told (but can't confirm) that the MA61 diff centre half shafts are needed as they were lsd from factory and are shorter to suit.

    Torsen and Truetracs LSD's are also available. Many hilux 4wd live axle ran 7.5" FRONT diffs too 80 and 90's, possibly 2000's. Lots of options from 4 wheel drive aftermarket companies.



    Cars:

    MX13 Cessida - 3.9 - 1410mm (Same width as T series/S series/KE70 BW)

    Tarago YR22 - 4.1 manual and 4.3 auto - 1435mm
    Uses a G series (Hilux) diff nose flange bolt pattern (60x60mm) All other F series is 55x55mm)


    Crowns:

    MS110 Solid Axle (coils) F362: 7.5", 4.77:1, 2 pinions, Open
    5x114.3 1450mm Solid disc

    MS112 Solid Axle (coils) F292: 7.5", 4.10:1, 2 pinions, Open
    5x114.3 1450mm Solid disc

    MS123 Semi trailing arm IRS F285: 7.5", 4.30:1, 4 pinions,
    Clutch LSD 5x114.3 N/A Ventilated disc, 1 piston calipers

    MS50 Solid Axle (leaf) F292: 7.5", 4.10:1, 2 pinions, Open
    5x114.3 unknown Drum
    Last edited by Konakid; 14th September 2016 at 03:46 PM.
    RT142 Estate.

    AJPS.

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