Yet another Tranny Question

Discussion in 'GT6 Tuning' started by Thumper66, Apr 13, 2016.

  1. Thumper66

    Thumper66

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    Hello all. I know this has been asked a thousand times before, however, I'm still confused on the tranny tuning deal!! Is there an simple, easy "formula" for tuning my tranny? What I have tried is the "flip flop" tuning where you adjust your gears manually and then use final gear for speed. However, I can't figure out the right spacing of the gears to get them right? Now I have moved to a variation of the flip flop that someone told me about where you first move the top speed far left, next move the final gear far right. Then go back to the top speed and move it one click to the right,(it crunches the gears), then back to the left. Then adjust final gear for speed. This seems to be closer to what I want, but just not quite there yet. I've read a lot of different ideas on this, and frankly they don't make a lot of sense to me, especially when it comes to matching gears to rpms, etc., etc. Is there an "easy" over all way to do this that applies to all cars, or am I just left to figure this stuff out on my own? Any help would be appreciated, thanks.
     
  2. demonchilde

    demonchilde

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    As far as the spacing question goes, you want the spaces about as equal to each other as possible. So, eyeball the screen, if it looks like 1/2 inch space between gears, try to make them all that way.
    Now, theres more to it then that, but that is still going to be your goal. The equal spacing helps make the gears not work too hard or not enough, before changing to the next gear. Gets the most out of your torque.

    As far as the set up goes, I will leave that to the rest of the guys here, I am at work on break, and my breaks are never long enough, lol.
     
  3. Lionheart2113

    Lionheart2113

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    As @demonchilde mentioned, it can get complicated real quick. But I would suggest this for a decent start to customizing your transmission.

    Final gear all the way to the right
    Max speed slider all the way to the left
    1st gear- about 15% of the slider
    2nd gear- all the way left, maybe up to 5% of slider
    3rd gear- about 1/3 of the slider
    4th gear- about 2/3 of the slider
    5th gear- about 90% of the slider
    6th gear- all the way to the right
    (This should give you somewhat of equal spacing between the gears) Then the last step....
    Lower the Final to reach maximum speed of the longest straight of the track you are on. The lower the Final, the lower the maximum speed the car can reach.

    This is VERY basic!:nervous:

    I hope this helps.:cheers:
     
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  4. TheInfamousJEW6

    TheInfamousJEW6

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    Check out this tuning guide by @Otaliema! It has the most in depth explination for transmissions in this forum! Good luck! :cheers:
     
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  5. Otaliema

    Otaliema

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    As mentioned above starting out equal spacing is good. A very simple and pretty quick transmission that gives 100% equal spacing is as follows.
    Set final in desired position.
    Full right for a high speed smooth car.
    Middle for a slightly quicker slight ruffer car.
    3/4 left for a quick but harsh car.
    Set top speed accordingly.
    For full right final go to min speed.
    For middle set go three to four clicks from min
    For 3/4 left set it two clicks faster than target speed.
    Now the easy part. Set ALL gears full right.
    Adjust final left to desired top speed.
    Note 3/4 left final is set to full left at the end.
     
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  6. MrGrado

    MrGrado

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    Many people use redundant steps in tuning transmission.

    Step 1
    Final gear to min
    Step 2
    Set top speed slider
    Step 3
    Set gears.

    I have found no loss of performance or loss of tuning advantage from using this simpler method. For example, this is how I tuned my transmission for the zzII time trial and it is every bit as fast as any top 10 time in straight line speed.

    If you find your top speed or RPM at the end of the straight is wrong, then repeat steps 2 and 3.
     
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  7. demonchilde

    demonchilde

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    Theres quite a few methods that work, some on certain types of cars, some on others more, ect.

    Aside from the above, MotorCity's guide in the stickys hits up tranny also. And various garages have tidbits in the first few posts on tuning and trannys also.

    Theres the max method, where you can be done in less then a minute;
    Max final gear
    Minimum speed auto set
    Slide every gear all the way right.
    Adjust final to suit track.

    That sounds nontechnical, but it actually does a good job on a lot of high pp race cars, or maxed out (all power options) cars. And its fast, as it automatically spaces gears to very close spacing, you can buy a car and hit the test track quick.
    I personally use the same type of method as Lionheart and Otaliema, but I usually eyeball spacing starting from highest and going to lowest, never actually using a set 1/2 1/4 or whatever preset. And first gear I adjust while tuning on the track, as some cars need more then others to get going, and some can deal with first gear being all the way left.
     
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  8. eran0004

    eran0004

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    8,779
    If you want to truly master the gearbox, then you need to understand how it works.

    Begin by examining the power curve of your car, is the top more flat and wide or more peaky and thin?

    Flat and wide: Congratulations, the gearbox is probably mostly fine as it is (this is why muscle cars can get away with only having two or three gears). What you may want to adjust is the top speed and get rid of any excessive wheel torque in 1st gear. To adjust top speed, adjust final drive or top gear (smaller number = higher speed). To adjust the amount of wheel torque in first gear, adjust final drive or first gear (smaller number = less torque, adjust this until you can barely spin the wheels in first gear).

    Peaky and thin: This will take some more work to optimise. What you're aiming for is a gearbox that allows the engine to stay as close to peak power as possible for as long as possible.

    Why is that? Well, we need to understand what makes the car accelerate. There are two properties of the engine: torque and power. The torque is the force that the engine is producing, more precisely the force that rotates the crankshaft, thus:

    "The greater the torque, the better the acceleration."
    Except that is only half the truth, because we've got a magical box that can multiply the torque for us: the gearbox. What the gearbox does is that it trades speed for torque. A ratio of 2.000 halves the speed, but doubles the torque. What this means is that torque alone doesn't tell the full story; because we can trade speed for torque, the true potential of the engine becomes the product of torque and speed, and that is what we call power.

    Peak power is the point that would achieve maximum acceleration at any given speed (as long as there is traction, that is). So in terms of performance it's always beneficial to run as close to peak power as possible, even if it means that you'll never run the engine at its peak torque. In terms of fuel consumption it's better to stay at peak torque, but that's a different story...

    Now take a look at the power curve again, and try to identify some key points in it. Here is an example, where torque is the Nm curve and power is the kW curve:

    torque.png
    This entirely fictional power curve is fairly peaky, but there is a nice flat region at the top, between 5000 and 7000 rpm. When tuning the gearbox for this engine, the goal would be to try and stay between 5000 and 7000 rpm between all the shifts, and the closer to the peak at 6000 rpm the better. Before 5000 rpm there is a sharp drop in power, so avoid dropping below 5000 rpm. You can do this mathematically by calculating each ratio and what they would need to be in order to stay within the rpm range, but it also works fine to make a rough estimate and then test it to see how far the RPM drop when you shift up. As a visual guide you have the gear ratio graph, where the vertical axis is the engine speed and the horizontal axis is the wheel speed. In this case 5000 rpm would be just above 2/3rds towards the top of the graph.

    If you've managed to set the gears so that the car stays near peak power but you don't get enough top speed, first see if there is any excessive wheel spin in first gear. If there is you can just reduce the final drive ratio to make the entire transmission taller. If there is no excessive wheel spin in first gear you have a difficult decision to make: at what speed does it hurt the least to reduce the performance of your car? In general, it's best to reduce the performance at the speeds where you'll spend the least amount of time during the race. At a fast track with long straights that would be 1st or 2nd gear, while on a track with only brief moments at top speed you could reduce the performance at the top gear. So what you'd be doing then is to shift the power to the speeds where you need it the most. Keep in mind that as the gears get taller, you'll spend a longer period of time in each gear, why I would advice you to try to minimize the time spent far off peak power in the top gears. Most stock gearboxes are set in this way, so the gap (in terms of RPM) between the gears get smaller and smaller the higher up you go.

    Finally: Another effect of the gap between the gears is the amount of time it will take to shift gears. The bigger the gap, the longer it will take to complete the shift, as the engine will require more slowing down to match the revs of the next gear. At most this will account for a tenth or two of a second, but if you're really chasing the top times then it might be worth exploring.
     
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  9. Lionheart2113

    Lionheart2113

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    So does that mean your final gear is always set at minimum (Step 1) no matter if you want the cars max speed for the end of straight at 150mph or 200mph?
     
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  10. MrGrado

    MrGrado

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    Yes
     
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  11. Lionheart2113

    Lionheart2113

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    I can see a couple of issues setting it up that way...
    I'm currently tuning a DB9 at 500pp at GVS. The fastest I want this car to go is 182 mph, but when at GVS I only need 154mph. Using the basic flip method I only have to adjust the End Final to change the max speed. The gear values themselves stay the same. Using the Minimum Initial Final technique that you are describing forces you to have to change the gear values themselves every time you want to change the max speed, which can get very time consuming.

    And because you are changing gear values based on speed desired, but keeping the End Final constantly at Minimum, that changes what the RPMs drop down to @ shift. That may lead to different handling characteristics.

    The gear values themselves are a higher value in general which leads to the lunge effect when entering corners. For trail brakers I can see that being beneficial, but for me being a straight line braker it causes headaches getting the car slowed down enough going into the turn. I'm not saying it's a bad thing, it just hurts my driving style.

    Below is a picture of what I'm describing about the RPMs @ shift.
    Blue = My current setup which is a 48% flip (Initial Final 3.450) and max speed set for 154mph.
    Red = Initial Final set @ Minimum (2.000) and a max speed set for 156mph.
    Green = Initial Final set @ Minimum, but I want the max speed to hit 182mph.

    Let's just concentrate on the Red & Green for a moment...
    You can see that I had to refigure and change all of the gear values just to keep the same slider percentage if I wanted to change from 154mph to 182mph. And it also shows the difference in the RPM @ shift values as well. Granted it isn't much in this scenario.
    image.png
    I will add that I believe you are correct in saying that it doesn't cost you any speed (Tested 5,000M & 10,000M) although it did cost me about .2xx at GVS, but that is down to the larger gears/lunge effect.
     
    Last edited: Apr 15, 2016
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  12. MrGrado

    MrGrado

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    It's 50 seconds to completely tune a transmission. It's 25 seconds to reset speed slider and redo gears.

    If your fairly close with the top speed in top gear and your not too OCD about your setup, you can adjust sixth to be taller, or final to be shorter.
     
    Last edited: Apr 15, 2016