Diff Ratio change for ZF4HP14 auto?
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  1. #1
    Fellow Frogger! Aprilia's Avatar
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    Default Diff Ratio change for ZF4HP14 auto?

    Hello all, my DKZ engined S1 205 GTi 4 speed auto is running like a dream, the gearing though is a little tall, 100kph at 2600 rpm. Is it possible to install a CWP from a BE-3 box, which would give me around 100kph at 3000 rpm shortening my gears and adding a tad more pep. Or do I need to find a diff from another model ZF trans for compatable components.
    Thanks Doug

    I found an AA car review with some 205 auto box ratios.
    1st 2.51
    2nd 1.43
    3rd 1.04
    4th 0.77
    FD 3.82:1
    36 kph @ 1000 rpm in 4th top gear
    100 kph = 2800 rpm

    ZF Auto diff 3.820 is 36.0 km/h/1000rpm = 108 kph @ 3000 rpm : from AA review a 205 w/13" wheels

    S1 GTi diff 3.940 is 30.9 km/h/1000rpm = 92.7 kph @ 3000 rpm

    S3 GTi diff 3.620 is 33.7 km/h/1000rpm = 101.1 kph @ 3000 rpm : this would be my ideal ratio.

    Mi16 diff 4.430 is 31.4 km/h/1000rpm = 94.2 kph @ 3000 rpm

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    My current speed and rpm readings = 115 kph @ 3000 rpm : 14" pepper pots w/ 185/60/14

    The S1, S3 and Mi16 diff & ratio information I copied from an earlier post from Peter T. thank you Peter for the valuable info you post on this site. And I apologize if my dislexia has misread any of your calcs.
    Doug
    Last edited by Aprilia; 22nd April 2013 at 11:15 AM. Reason: found more info

  2. #2
    1000+ Posts BIGRR's Avatar
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    13" wheels may be easier?
    Present fleet:-
    Peugeot 93' 205 Gti 16v
    Peugeot 73' 504 Ti from new
    Peugeot 08' 407 Hdi Coupe from new

    Previous fleet:-
    Peugeot 95' 605 Sv
    Peugeot 92' 205 Gti
    Renault 72' 16TS from new
    Renault 69' 10
    Renault 71' 10s
    Renault 68' 10 from new

    "Be reasonable do it my way!"


  3. #3
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    Hi,
    I am not so familar with the exact boxes, but generally the auto boxes use a different diff arrangement to the manual boxes. If you wish to change the diff ratio you would have to look at different models which use that auto.
    Not recommended unless you like a lot of work or have deep pockets.
    Jaahn

  4. #4
    Fellow Frogger! Aprilia's Avatar
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    Hello Jaahn
    I don't mind the work, but my pockets have big holes in them, I have also been looking at ZF boxes in volvo,bmw etc. If its too much trouble I'll just live with the tall gearing and the 37mpg.
    Doug

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