Gearbox Tuning Options, Types and Benefits
Gearbox tuning can improve both comfort and performance in different driving conditions and for different kinds of gearboxes
There are many different gearboxes on the market today, so simply referring to them as ‘manual’ or ‘automatic’ when discussing their mechanical operations, intricacies in regards to tuning and modifying the way they work can result in a lot of confusion.
For this reason, we decided to shed some light on this topic and explain the differences between the various types of gearboxes, the ways they work, their benefits and downsides and the ways gearbox tuning can improve their operation in a number of driving conditions.
- Different Types of Gearboxes
- Tuning Options for Different Kinds of Gearboxes
- Why you should tune your gearbox
- Adjusting torque limits
- Adjustment in shift points in Drive and/or ECO modes for both upshifts and downshifts
- Adjustment in shift speed
- Launch Control Activation and/or Adjustment
- Adjustment in Clamping Pressure
- Adjustment in Torque Converter Locking Feature
- Adjustment in RPM Limits
- DCT/S-Tronic/DSG Farts
- Left Foot Braking
- Free Shift in Manual Mode
- Kickdown Off
- Why you should tune your gearbox
Different Types of Gearboxes
While there are numerous differences between the systems of various manufacturers, there are only a handful of the most common underlying systems in most of these gearboxes. Let us see what the different kinds of gearboxes are and how they compare.
First of all, we have manual gearboxes where drivers have to operate a clutch and change gears manually. Due to their inherent mechanical nature of operation where most of the job that a computer would do in an automatic is actually done by the driver, gearbox tuning options for manual gearboxes are limited. However, there are several very interesting tuning services for manual gearboxes that we will present below.
Automatic Gearbox (Tiptronic/Steptronic/7G-Tronic/9G-Tronic/Skyactiv-Drive…)
Secondly, there are conventional automatic gearboxes with torque converters and planetary gears. The torque converter is used to make gear shifts smooth and effortless and, for this application, it is the best option of all the most common types. However, its operation also leads to some losses as it uses liquid in a torque converter to facilitate gear changes.
Most automatics will lock shortly after the change, eliminating the torque converter losses after the lock, but finding the best moment and manner to lock often escapes the manufacturers. It depends on finding the perfect balance between the comfort of liquid transfer of torque and ensuring the best possible efficiency in eliminating the losses through locking. If the gearbox locks too soon and too forcefully, drive quality will be greatly reduced and there may be jerking or even damage to some components. On the other hand, if the lock is too late or even too rare especially while driving in the city, fuel consumption will be greatly increased and performance somewhat reduced.
Similarly, these gearboxes are often slow to react. Leaving them too slow greatly reduces both efficiency and driving pleasure while making them shift too readily makes them too sensitive and results in too frequent gear changes, again reducing the comfort and efficiency. Once again, the solution is not going in either of the extremes but finding the perfect balance.
Due to the fact that computers (TCU) decide on all of these aspects, gearbox tuning services for conventional automatics include a number of options, including alleviating the above-described issues, but also deciding on the best shift points, reducing or increasing shift times, altering the way gearboxes operate in different modes and more. We will discuss these in more detail below.
While some car manufacturers such as Mercedes-Benz or Mazda develop their own gearboxes, many of the most famous brands use gearboxes developed by revered manufacturers such as German ZF or Japanese Aisin. Maybe their names are not familiar to you, but you should know that most car brands that actually use these gearboxes have other, more popular brand names for these gearbox systems.
For example, ZF’s 8HP transmission is known as Tiptronic in a number of vehicles made by VAG and as Steptronic in many BMW vehicles.
Dual-Clutch Gearbox (DCT/PDK/DSG/7G-DTC/S-Tronic/PowerShift…)
Next, there are dual-clutch gearboxes (DCT). The most common setup for those is that they have two clutches, one engaging odd gears and the second one engaging even gears. For example, in the case of the very common 6-speed DSG used in many Volkswagen vehicles, one clutch is in charge of selecting gears 1, 3 and 5, while the other one facilitates selection of gears 2, 4 and 6.
These clutches are controlled by a computer which determines how often, at what points and how fast gears are changed.
This kind of setup has numerous advantages, but also some disadvantages.
For example, gears are most often changed in sequential order (if you are in gear 3, in the vast majority of cases, you will switch either to gear 2 or gear 4). This means that the next gear can always be prepared by the clutch that is not in use at that point. The result of this is that gear changes are lightning fast, in most extreme cases having next to no drop in power delivery. Due to this, gear changes are seamless and, since there is no torque converter, there are no losses caused by liquid torque transfer, which makes vehicles with dual-clutch gearboxes more fuel efficient.
However, there are also some downsides to the dual-clutch system. For example, many people complain about jerky operation at low speeds for some of the most common DSG gearboxes. There are several reasons for this, but the most important one is that computers of DCT gearboxes try to engage the gears fully as soon as possible in order to both save fuel and reduce clutch wear. While this is a good thing generally, anyone who has driven manual gearboxes at low speeds knows that sometimes some clutch slip is welcome at slow speeds. Those are the moments on a manual when we would not release the clutch pedal fully immediately, but keep it pressed somewhere in the middle to tailor the level of thrust that is sent to the wheels.
When the DCT computer tries to fully engage the clutch too soon in these conditions, the result can be a jerk that is very uncomfortable.
Another downside is that the sequential nature of its operation, while very welcome in most cases, can be a problem. In most cases, when revs rise, the next gear change will be an upshift. For example, if we are driving at 1,800 RPM in gear 4 and we slowly start increasing RPM to 2,200, the computer will think we want to upshift to gear 5 and in most cases, it will be right. This is why the clutch that controls the odd gears will prepare gear 5. However, you may be preparing to overtake someone very soon and you actually want to downshift to gear 3 in a few seconds. When you press the pedal hard, the computer will understand you want to downshift and it will opt for the downshift, but the second clutch has already prepared gear 5 and it will take some time for it to disengage and go to gear 3.
The same thing can be an issue when going uphill on a serpentine road when you may want to downshift to preserve momentum while approaching a sharp serpentine, but the second clutch is prepared to engage the higher gear based on your current speed and RPM.
Aside from easing the jerking at low speeds and tailoring its operation in other conditions, gearbox tuning for a dual-clutch can also adjust shift points, shift times and operation in different modes. You can find more information about those services below.
A subset of dual-clutch gearboxes are multi-clutch gearboxes such as the AMG MCT gearboxes or the stunning 9-speed 7-clutch gearbox in the Koenigsegg Jesko.
Other Gearbox Options
Lastly, there are several other options such as continuously variable (CVT) gearboxes or automated manuals such as the EGC used in PSA Group vehicles or Selespeed used in various Alfa Romeo and Fiat models. However, these gearboxes are not as common as the other ones and they are rarely the subject of tuning efforts.
Tuning Options for Different Kinds of Gearboxes
Before we delve into this, whatever your gearbox tuning needs and preferences, you should make sure that your gearbox is tuned by a tuning company that has full insight into the limits of that engine and its accompanying components. Gearboxes are among the systems that have to endure the hardest torque hits and going too far with TCU tuning can have catastrophic (and very expensive) results for various components.
Why you should tune your gearbox
The issues with different kinds of gearboxes we described above are just some of the aspects that can be improved through gearbox tuning. There are also numerous other benefits you can enjoy with a tailored gearbox tune.
Moreover, if you also tune your engine, an improvement in the way the gearbox works can make a major difference and help enjoy the full ability of the tuned engine, both in terms of performance and fuel efficiency.
Before we move on, you should also know that, while most tuning services are reserved for automatic and dual-clutch gearboxes, there are also several tuning options for manual gearboxes. For example, no-lift shift (NLS) tuning for manual gearboxes can give you massive improvement in acceleration, just like manual gearbox launch control feature can make a world of difference in the way you start off.
Some other reasons to tune your gearbox include the following:
Adjusting torque limits
When you tune your engine, measurements of torque at Canbus can be too high for the stock setup. This is why the computer can limit torque and thus reduce or even negate the benefits of tuning.
We can increase the torque limits in the gearbox and thus send more power to the wheels.
Adjustment in shift points in Drive and/or ECO modes for both upshifts and downshifts
In many cars, Drive and/or ECO modes are too limited as manufacturers aimed to snatch any small fuel consumption improvement they could in order to compete with other manufacturers. While most diesels enjoy low down torque so this limitation is not much of an issue, petrol/gasoline cars often suffer from lazy performance in these modes because RPM is kept too low. This can be an issue even in turbocharged petrol engines that have more torque lower in the range, because RPM is kept too low under the point of turbo spool preventing it from providing its benefits.
Adjusting shift points will make your car feel much more powerful as your car will spend more time in RPM ranges where torque is used more efficiently. The fact that this can be done for both upshifts and downshifts means that you can enjoy perfect operating conditions most of the time.
Adjustment in shift speed
We mentioned that shift speed can be a problem if it is both too fast and too slow both for torque converter automatics and dual-clutch gearboxes. We can adjust these to suit your preferences and most common driving conditions.
Moreover, artificial shift delays are written into softwares of many gearboxes. Removing these artificial limitations can make the car feel noticeably faster even without any performance improvements, thanks to the faster reaction time and more immediate acceleration.
Launch Control Activation and/or Adjustment
There are two things we can do regarding launch control in many vehicles – we can activate this feature in many cars that do not have it or we can adjust the RPM at which this feature holds the engine before launching. Let’s examine both.
Launch control is very often an optional feature in many vehicles, reserved for higher trim levels, more powerful versions of the car or those buyers who are willing to pay extra. This means that it is actually present inside the gearbox, yet not activated through software. Some vehicles have it activated, but it is limited in its operation by a number of other features such as engine or outside temperatures, angle of the front wheels or even some other features such as ESP.
All of these features can be adjusted through software modification. However, bear in mind that the gearbox is one of the parts that endures the highest pressures in a car. This is why you should only let a knowledgeable tuner work on your launch control activation or adjustment.
Speaking of adjustment, there are many different aspects that determine what the right RPM for launch control is. Set it too high and the wheels will spin more, losing valuable seconds when rushing off the line; set it too low and you will not use the power efficiently until your engine reaches the optimal RPM. You would be surprised if you knew how often we have customers who feel that the stock setup for their launch control is inadequate and many of those are right.
Similarly, if you tune your engine for more power, the optimal launch control RPM level changes. The higher you go with modifications, the bigger the change. Also, bear in mind that the optimal level can depend on other features as well, such as how grippy your tires are.
Adjustment in Clamping Pressure
As you increase the power of your car, many driveline parts get under more and more stress. This makes them less capable to do their job and the more you increase the power, the bigger the chance something like that will happen. In many cases, the solution is to get a more hardcore aftermarket part. In this case, we are talking about the clutch which can start slipping if it has to deal with more power than the stock car has.
However, before you spend loads of your money on a racing clutch, you can try a much simpler and far more affordable solution – increase the clamping pressure. In many cases the hardware of the clutch, especially if it is in a good condition, is more than able to cope with the increased power. However, its stock clamping pressure, controlled by the TCU software, is intended to support less torque.
Adjustment in Torque Converter Locking Feature
Automatic gearboxes with torque converters have smooth shifts mostly thanks to the liquid coupling inside the torque converter. The force is transferred through the liquid which makes gear changes silky smooth, without any jerks or discomfort. If the input and the output were locked all the time, gear changes would cause aggressive jerks due to the mismatch in RPMs between the two gears.
However, force transfer via liquid cannot be as immediate or as efficient as a proper hardware lock between the input and the output. Simply put, a lot of the push is lost as it is transferred via the torque converter liquid. This means that the shifts are slower, that a certain amount of power is lost in the process and that fuel efficiency is reduced.
This is why engineers came up with the perfect solution to keep the gear changes smooth, but also reduce losses. As the gears change, the force is transferred through the liquid. However, when operating conditions allow it, the torque converter is locked. The problem with this setup is that finding the perfect spot to lock is not always easy, so many automatics have poor performance because locking happens too late. Maybe you have heard of the term ‘slushbox’. This is what it refers to.
This is why we wanted to change the way the torque converter locks. This way we can improve the way a car speeds up from low speeds or off the line. This feature is still in development for many cars, so contact us to see if we have developed it for your vehicle.
Adjustment in RPM Limits
Every mode of operation on automatic gearboxes has a different rev limit. Some drivers feel that the current limit is too high, so the car is often in high RPM, while others feel it is too low and the gearbox shifts up too soon. We can adjust RPM limits in each mode independently to suit your preferences.
This admittedly poorly chosen name represents a very cool feature on dual-clutch gearboxes. It is most commonly found on Volkswagen’s DSG models, but it is also present on Audi’s S-Tronic and various other DCT gearboxes.
When this kind of a gearbox shifts, it makes a very distinctive sound. It is similar to our stunning pop&bang tune, but it is used for a different reason. Before we move on to DSG farts, enjoy some pop & bang sounds in the video below.
Dual-clutch gearboxes, as we explained in the first part of this article, use two clutches to facilitate faster, more immediate shifts. One clutch engages the current gear and the other clutch prepares the second. However, at the moment of the shift, for a portion of the second, no gear is engaged.
Due to the fact that we do not lift our foot off the throttle pedal while driving cars with automatic shifting, when this shift happens, revs would shoot up and once the next gear is engaged, the car would lurch forward due to the high revs. This is especially important when upshifting, because revs need to be lower for the higher gear at the same speed.
For this reason, engineers came up with an idea to prevent spark ignition in the cylinder whose ignition stroke happens at the same time as the gear shift. This way there is no push for that portion of the second and the revs will not rise. Perfect.
However, this feature has that lovely sound byproduct. Since the air and fuel mixture did not burn during the ignition stroke because ignition was prevented, during the exhaust stroke the unburnt fuel and air are pushed out of the cylinder into the exhaust. There they are met with the hot pipes which causes self-ignition to occur which results in what we now know as DSG farts. It is actually the sound of the air and fuel spontaneously combusting in the exhaust.
You will notice that this feature is less present on cars with GPF/OPF/PPF because they can get damaged if this combustion is hard. Similarly, on many DSG and S-Tronic gearboxes it is completely excluded when in launch mode. The reason for this is that launch mode on those vehicles engages both clutches at the same time so the drag from the clutch keeps the revs in control and there is no need to cut spark ignition during the shift. This is, of course, only limited to launch control because engaging both clutches at the same time all the time is not the best thing for reliability.
Anyway, back to the DSG farts. We can increase this sound through software modification and make your shifts much more hardcore.
Left Foot Braking
If you keep your foot on the throttle and you apply the brakes at the same time in most cars the throttle will go off. This is made so in order to improve reliability in everyday cars. However, in high-performance conditions, experienced drivers will know how to safely use the brake and throttle at the same time for improved performance. Our software tune enables left foot braking and gives you the feature that only racecar drivers currently enjoy.
Free Shift in Manual Mode
Manual mode on automatic and DCT gearboxes is not all manual on most cars. While we are allowed to change gears when we want to, the TCU software can override our command if it determines we should have shifted by havent. This can be very frustrating, especially so in specific conditions such as low speed towing, or racing conditions when approaching a curve.
While kickdown is a beloved feature among many car drivers, some of them find it annoying. If you are one of them, we can deactivate it.
Now that you have a better understanding of the different types of gearboxes, their tuning options and the benefits of adjusting their operation to your needs, you know if and how we can help you. Tuning possibilities and benefits differ between various gearbox and TCU types, so contact us if you need more information.
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