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Changing final gear/drive ratio

Discussion in 'Engine Compartment' started by Sat-Chit-ananda, Oct 25, 2012.

  1. puntosat

    puntosat Superiore

    Messages:
    588
    Bangalore
    @Italia linea meant almost..

    I'm sure 90 hp would do somewhere 180+
  2. Ganges

    Ganges Esperto

    Messages:
    3,123
    Driver Seat _/
    :
    Grande Punto 1.3
    rishi,
    yesterday i been on Mumbai-Pune-Mumbai Express way,i was very much excited to test once again my punto nerves.i have habbit of taking off slowly...
    first 60-70-80-90Kmph.for few mins i keep constant on 90Kmph... then frequently above 100Kmph,but when i went to 130 Kmph ,maximum 140Kmph.i felt odd about the engine sound then immidiately i slowed down to 120Kmph,, at this point i felt punto is good car at this speed 120Kmph :( with not much engine noise.otherwise i feel like i'm sitting in diesel generator,The polo's was moving easily above 140Kmph on express way..
  3. Akshay4384

    Akshay4384 Superiore

    Obviously engine wont be silent.
    Its normal,as engine drone will be present in every car at high revs.
    and you do not need to downshift in a diesel,upshift to 5th at 90 and then press the throttle.
    @Ganges,you need to push,a Polo is noisier than a Punto owing to 3 cylinder motor.
    Last edited: Oct 29, 2012
    1 person likes this.
  4. Tron

    Tron Superiore

    Messages:
    667
    Mumbai
    Hey ganges, seriously?? You haven't touched speed more that 120kmph?? OMG! How could you?? Im always tempted to touch my linea atleast till 150kmph!

    About post 120 lazy bull feeling, thats strange! I never felt that. Yeh at 60/70kmph in 5 th gear, yeh my Linea is a helluva lazy bull but at 120 she is pretty much responsive!

    Sorry for being off-topic!

    @sat-chit, how could you make your 5th gear more taller can you elabourate?? I mean, i think we have work on whole gear-box + clutch, flyWheel i guess? Correct me if im wrong though.
    1 person likes this.
  5. rishike007

    rishike007 Esperto

    Messages:
    1,416
    Mumbai-Pune
    Pune- Mumbai
    Grande Punto 1.2
    Ganges, have you did your servicing or same is due?
    Try to do that once the servicing has done. As I drove both punto diesel & polo diesel till 140kmph. Both are hassle free. In fact Polo has 3 cylinders & punto has 4. So the acceleration for punto should be more than polo as well as the noise is also lesser that polo.
    1 person likes this.
  6. I am thinking if we can change the final drive alone?
    if that is possible then need to hunt for smaller cog for 5th gear , i am not sure whether it needs flywheel and clutch change,swapping 0.744 to 0.614 may not warrant big change?
    I have seen people doing this in baleno and touch speeds of a TSI!!
    Last edited: Oct 29, 2012
  7. Quote from Wiki
    A close-ratio transmission is a transmission in which there is a relatively little difference between the gear ratios of the gears. For example, a transmission with an engine shaft to drive shaft ratio of 4:1 in first gear and 2:1 in second gear would be considered wide-ratio when compared to another transmission with a ratio of 4:1 in first and 3:1 in second. This is because the close-ratio transmission has less of a progression between gears. For the wide-ratio transmission, the first gear ratio is 4:1 or 4, and in second gear it is 2:1 or 2, so the progression is equal to 4/2 = 2 (or 200%). For the close-ratio transmission, first gear has a 4:1 ratio or 4, and second gear has a ratio of 3:1 or 3, so the progression between gears is 4/3, or 133%. Since 133% is less than 200%, the transmission with the smaller progression between gears is considered close-ratio. However, the difference between a close-ratio and wide-ratio transmission is subjective and relative.[3]

    Close-ratio transmissions are generally offered in sports cars, sport bikes, and especially in race vehicles, where the engine is tuned for maximum power in a narrow range of operating speeds, and the driver or rider can be expected to shift often to keep the engine in its power band.

    Factory 4-speed or 5-speed transmission ratios generally have a greater difference between gear ratios and tend to be effective for ordinary driving and moderate performance use. Wider gaps between ratios allow a higher 1st gear ratio for better manners in traffic, but cause engine speed to decrease more when shifting. Narrowing the gaps will increase acceleration at speed, and potentially improve top speed under certain conditions, but acceleration from a stopped position and operation in daily driving will suffer.

    Range is the torque multiplication difference between 1st and 4th gears; wider-ratio gear-sets have more, typically between 2.8 and 3.2. This is the single most important determinant of low-speed acceleration from stopped.

    Progression is the reduction or decay in the percentage drop in engine speed in the next gear, for example after shifting from 1st to 2nd gear. Most transmissions have some degree of progression in that the RPM drop on the 1-2 shift is larger than the RPM drop on the 2-3 shift, which is in turn larger than the RPM drop on the 3-4 shift. The progression may not be linear (continuously reduced) or done in proportionate stages for various reasons, including a special need for a gear to reach a specific speed or RPM for passing, racing and so on, or simply economic necessity that the parts were available.

    Range and progression are not mutually exclusive, but each limits the number of options for the other. A wide range, which gives a strong torque multiplication in 1st gear for excellent manners in low-speed traffic, especially with a smaller motor, heavy vehicle, or numerically low axle ratio such as 2.50, means that the progression percentages must be high. The amount of engine speed, and therefore power, lost on each up-shift is geater than would be the case in a transmission with less range, but less power in 1st gear. A numerically low 1st gear, such as 2:1, reduces available torque in 1st gear, but allows more choices of progression.

    There is no optimal choice of transmission gear ratios or a final drive ratio for best performance at all speeds, as gear ratios are compromises, and not necessarily better than the original ratios for certain purposes.
  8. Ganges

    Ganges Esperto

    Messages:
    3,123
    Driver Seat _/
    :
    Grande Punto 1.3
    Akshay,
    the push is comfortable till 120Kmph only for me...

    Tron,
    the top speed achieved on my punto is 160Kmph,but somehow i didnt like that much speed drive due to more engine sound.
    As the engine goes old,the engine sounds more ?

    rishi,still 6K Kms due for my 4th service :)


    Sat,
    sorry for being offtopic
  9. Italia-Linea

    Italia-Linea Staff Member Janitor

    Messages:
    2,123
    Pune
    Yes it can be done. You can even ask some reputed company to manufacture a gear with one/two teeth more as per the ratio desired. There wont be any need to change the flywheel or clutch or anything else.
    1 person likes this.
  10. Thanks Italia-Linea, It's encouraging, I am thinking whether is it possible to source them from eby or some thing like that, or else hunt for them in JC road Bangalore.Do you know any company doing that?

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