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What is in a gear box?

Discussion in 'Technical' started by Raj_pol, Sep 4, 2015.

  1. KKAUL

    KKAUL Amatore

    Messages:
    204
    delhi
    Grande Punto 1.3
    The 1 st gear on Punto is 4+ in ratio (exact I think is some where around 4.2) where as for Suzuki it is around 3.75 similar case is with second gear. Now we will wonder why is this done where as we have both the cars having same engine.
    This is due to the extra load we have on this car.
    we all know Japanese car are light weight so they are tolerant to lower gear ratio. The lower the ratio the more you get speed transfer and the lower torque transfer.
    A car with a heavier weight will require more amount of torque to move it from standstill to some reasonable momentum than a lighter one (simple fact). Now comes the point that if we had to increase the 0- 100 timing with gearbox alone to compete with swift then what needs to be done.Though what I am writiing Fiat will never do it but I will Prove they do it in some other case.
    If the ratio have to be maintained same for the car to move then we have to add another gear a sixth gear . Though the final ratio of 0.71 in 5th gear should not change but the timing will definitely increase because then we can have the ratio split up from 4.2 to 3.5 more uniformly and we can have mix of both torque and speed.

    This they have done in case of RENEGADE AMT with addition of 9th gear to improve the shift jerk they say its to increase FE

    Now comes the shifting issue
    Yes the shift quality is not that good
    Again the ratio play havoc . The more closer the ratio are the more buttery you get the shift quality because the increase or decrease in the shaft speed won't be too much and the synchronizing rings don't have to push too hard.The ratio in Punto are too sparsely placed between 1 2 and 3 and that is the reason we get the feeling that after second gear the shift is smooth.

    Engaging the First Gear Problem:
    Again the Ratio : You would agree that a bigger tooth sized Gear will be easy to engage than a smaller tooth size.
    Now if the constraints for the sizes of gear box are there then one has use a lower module gear in same size so as to get higher ratio simple fact thus the no. of tooth coming in contact will also increase there by reducing the quality of shift.
    I hope I have stuck to the topic and these are purely my point of veiw though others may differ on that.

    @prabhjot

    Believe me you have got it wrong a car with low gear ratio will any day yeild more FE than a car with Higher ratio. Because it will require less amount of Fuel to rotate the crank to the revolutions of the tyre required to cover the same distance than a car with higher gear ratio
    --- Double Post Merged, Sep 7, 2015 ---
    @Raj_pol

    You have definitely raised a very sticky topic for FIAT and good that you thought of. But believe me YOu can still run the GP Zippy on a road with not too dense traffic and believe me you won't need to shift to many gears. You need to study the car RPM well and you will enjoy it
    Last edited: Sep 7, 2015
  2. Raj_pol

    Raj_pol Regolare

    Messages:
    495
    Bangalore
    Punto Evo 1.3
    @KKAUL Thanks and you should come to the forum more often - a very clear answer to what I was asking. I personally do not have too much of an issue and I drive the new Punto EVO. However, yes when I was starting off it was difficult in slow moving traffic and it still is not easy in slow moving traffic - the first gear has the tendency to jerk or in rare cases the car would stop. I can of course improve as a driver but then the fact remains that it is not so easy in traffic to drive.
  3. Ganges

    Ganges Esperto

    Messages:
    3,121
    Driver Seat _/
    :
    Grande Punto 1.3
    @KKAUL,
    Even a loaded swift pulls better than punto,if we say initial tourque requirement.
    When i drove colleague's swift(ODO 54000Kms) above 80Kmph the car doesnt have enough power and sounds wierd.
    May be here the gear box design of swift lacks as compared to punto ? In punto,even above 100Kmph a gentle push on accel, will push you behind on your seat.

    @Raj_pol
    When my car was new i too felt a lot of these jerks and have to do a lot of exercise on clutch pedal to negate the jerks.Driven with this problem for 3 years,when i changed the battery i never felt the 1 st gear jerks.Strange, but this is what i have observed.
  4. KKAUL

    KKAUL Amatore

    Messages:
    204
    delhi
    Grande Punto 1.3
    @Ganges

    True that swift will pull better even in loaded condition. I don't deny the fact.
    Weight is just one of the factors for gearbox design. How the torque is transmitted to the wheel is another area and ECU again the torque spreader is a very vast area. I have just covered the gearbox.
    but to show the difference where gearbox plays the role I will give you a example to check .
    Hope your Friend will allow you to do that.
    Load both the cars with 4 people on board and make them move 1 km on a unpaved road with lot of loose gravels.You will understand the weight concept of the gearbox . Here Swift will loose ground and it will not be able to provide good traction.
    It is just a matter of fact what FActor of safety and driving condition you are considering while designing the car.
    It is not the case that FIAT has designed the Gearbox as per India but they have just put the drive train from their stable which will have less wear and tear on both engine and drive train Though it might be quite outdated.

    There are hundreds of factor which are taken into consideration while designing anything of which economics is the biggest in current scenario.
  5. asimpleson

    asimpleson Esperto

    Messages:
    2,999
    Heptanesia
    Linea 1.3
    @Raj_pol, I would recommend a remap by tune-o-tronics. Actually just one map, which can make the traffic drive very easy. I have recently experienced one such car and it is more than atleast I could ask of a car like Punto. A remap with very less side effect on emissions, and the right NVH as well.

    Also recommended further read of this >link< in case.
    Raj_pol and prabhjot like this.
  6. KKAUL

    KKAUL Amatore

    Messages:
    204
    delhi
    Grande Punto 1.3
    @Raj_pol

    The gearing is perfect if you are using the car for mixed use i.e city as well as highway . If only city then definitely you will need to think to make any amends for the ECU programme. The best is always to stay with the default program provided with the company. Any tuning guys will just remove the limits set by the company there by increasing the wear and tear overall.
    If you are really a enthusiast then definitely you need a mod and if you are one of the guys who just need to move on the road without any hassle then stay within the limits.
    About starting in first gear though you will take some time to gain confidence but you will do that in few months.
    The tuning is definately going to take toll on all the drive parts and that I can guarantee.
    So in my opinion try to love what was original rather than modifying it as suggested.
    Raj_pol and prabhjot like this.
  7. asimpleson

    asimpleson Esperto

    Messages:
    2,999
    Heptanesia
    Linea 1.3
    @KKAUL with EVO there is some definite improvement for traffic driving. Although like I said, for making it much more effortless a tune that sorts this issue without pushing too much on rail parameters and stuff is still worth the risk, I now feel after driving this specific one I talked about. Besides I like their tuning philosophy.
    EDIT: The changes are subtle and so very relaxing in the way the car handles. Not too many unnecessary gear shifts. This is ofcourse based on South bound Mumbai based traffic, other places may have varying pattern of traffic.
    prabhjot likes this.
  8. KKAUL

    KKAUL Amatore

    Messages:
    204
    delhi
    Grande Punto 1.3
    @asimpleson

    I don't know if these guys you are talking are different from the rest. Just 1 question from my side
    as Per me Drivebility definition is that you have much more linear acceleration than what we have currently
    Now if you could ask a question from my side to those guys

    Do they guarantee that can they increase the drivebility i.e Kinear acceleration through 1st and 2nd gear without increasing the default torque and power?
    Possibly the answer will be no

    Now Do you know why we have a timing chain issue in GP than rest of the other cars. If you do come to know that then you will also rule out any mods
  9. asimpleson

    asimpleson Esperto

    Messages:
    2,999
    Heptanesia
    Linea 1.3
    I have been enough vocal about (against) mods and remaps in the past. Perhaps more than anyone else. With regards minor changes in parameters that could not translate in too much of a noticable damage or excessive maintenance costs of clutch or timing chain etc. I suppose the risk will be a calculated one.

    By the way FYI I do know the side effects. :rolleyes: But I will not care explain the minor nuances because everyone has their own risk appetite. Having said that the particular car has not faced any issues since a long time. But of course why should one guarantee the safety of any remap. What's in it for me ?
    --- Double Post Merged, Sep 8, 2015 ---
    Remap is not something everyone will weigh pros and cons. Obviously some prefer better driveability more than anything else. Besides the name of tuner and his website shows up on google. Please definitely forward your questions there. Also the remap scene is increasing in popularity. So I am willing to bet some remaps atleast could be "not too bad" for engine health. Although there will always be ifs and buts.
    Last edited: Sep 8, 2015
    prabhjot likes this.
  10. KKAUL

    KKAUL Amatore

    Messages:
    204
    delhi
    Grande Punto 1.3
    @asimpleson

    Good to hear that you also not totally convinced by remap.
    Though if we discuss a remap here we would defeat the purpose of the thread may be we can discuss it on some other.
    But still to summarize
    As far as engine health is concerned nothing is going to happen to it till you make the peak output till 90 hp i.e 75% of the design power. I am never concerned about the engine health till 90 hp. There are so many other things which will not tolerate it and thus reducing there life. Again there is a niche the word LIFE
    For me Life is defined as 2L km and not more than 5 years.
    this word will have different meaning for everybody. My running is high that is the reason I play safe and want to spend minimum on wear and tear.For you It might have a different meaning I don't deny the fact.
    People on this forum get a mileage of 20 to 24 but I always get a FE of 15 to 16 in summers and 17 to 18 in winters consistently(AC on always).That does not rule out the fact that I cannot extract that much FE on my car I can but it would cost me more than to stay on the road then to be at my works.
    Similar is with Remap what are your Priorities.
    Though we got OT but hope the thread and it replies served the purpose for what it was started

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