[padmrajravi]

Originally Posted by Sutripta

For the purposes of this thread what is 'incomplete' pressing of the brake pedal? How does the system know it.

In automatics, you can modulate the creep speed by keeping your foot on the brake pedal lightly. My Hexa creeps at about 7 kmph if my foot is off the brake pedal completely. I can make it go at any speed upto 7 kmph by modulating the pressure on the brake pedal. It is very convenient in traffic blocks. Apparently torque converters do this very well, but DSGs and AMTs suffer from clutch problems if you do this often. For DSGs and AMTs, it is recommended to have foot completely off while creeping. That is, you should not be trying to modulate the creep speed by adjusting brake pressure.

[Vid6639]

Originally Posted by Sutripta

For the purposes of this thread what is 'incomplete' pressing of the brake pedal? How does the system know it.

Regards
Sutripta

Important for DCT/DSG boxes. Basically the transmission control unit reads the brake pressure applied and based on that disengages the transmission to prevent the car from slipping the clutch.

If you press the brake pedal lightly, the system may not disengage the clutch and keep the car in gear in anticipation to move. This causes damage to the clutch as its akin to half clutching.

Hence DSG/DCT manuals always say if you are waiting at a light and you are in gear, apply the brakes firmly and not gently.

Also, DCT's have very less creep unlike Torque converters so you won't come to know if the clutch is slipping as it doesn't fight the brakes like a torque converter. A gentle touch on brake pedal is enough to prevent the car from creeping but that is what harms the box.

[zhopudey]

If incomplete braking can cause problems, why don't cars using dct/dsg keep very less travel in their brake pedals? Almost like feather touch brakes. I suppose most drivers will get used to it in a short time, and there won't be any problems from the gearbox.

[Vid6639]

Originally Posted by zhopudey

If incomplete braking can cause problems, why don't cars using dct/dsg keep very less travel in their brake pedals? Almost like feather touch brakes. I suppose most drivers will get used to it in a short time, and there won't be any problems from the gearbox.

Will lead to more rear end accidents and no progressive braking. A car is supposed to have progressive brakes, not an on/off switch for braking.

The whole purpose why brake by wire is not as easy as throttle by wire is due to braking feel and progressive braking action which cannot be done by electronics. Braking is all about feel and if you remove that from the equation then you are looking at more accidents.

Thats also the reason EV's have regen braking and lack feel in braking however for hard braking they go back to discs.

[dinu2506]

Originally Posted by manjunathkl

CVT is opted by the manufacturers only for a higher fuel economy. The rubber band effect really kills the fun of driving. Also, CVTs cannot handle high torque as well as TCs/DCTs can. So, it is suited for low powered, light cars. Thats why Kia didn't offer CVT on Diesel variants. So, a car of the power and weight of Seltos, I will think twice to opt for a CVT in it.

I have a slightly different view here. One of the best CVT boxes I have used (and still using) is the one that is there in the previous gen Audi A4. This gearbox has proven to be one of the most reliable CVTs globally and it has dealt with the 380Nm torque of the 2.0 TDI engine consistently. The rubber band effect is not noticeable and if you are in the mood for some fun, the sport mode also performs like a TC with noticeable gear changes. I don't know how they do it but in spirited driving in Sport mode, you can see the RPMs dropping during each upshift. So, I feel, CVTs are probably better suited high powered/torque vehicles. My sister has a CVT Nissan Micra, there you can really feel the rubber band effect.

[manjunathkl]

Originally Posted by dinu2506

I have a slightly different view here. One of the best CVT boxes I have used (and still using) is the one that is there in the previous gen Audi A4. This gearbox has proven to be one of the most reliable CVTs globally and it has dealt with the 380Nm torque of the 2.0 TDI engine consistently. The rubber band effect is not noticeable and if you are in the mood for some fun, the sport mode also performs like a TC with noticeable gear changes. I don't know how they do it but in spirited driving in Sport mode, you can see the RPMs dropping during each upshift. So, I feel, CVTs are probably better suited high powered/torque vehicles. My sister has a CVT Nissan Micra, there you can really feel the rubber band effect.

Thanks for this info, I always thought all Audis and VWs are DSGs. I now know even CVTs can be built for better performance and torque. CVT as tech itself is not the problem, it is the design of the particular CVT box that can determine its performance. Premium segment cars like Audi can plonk this well made CVT. All TC boxes aren't the same, similarly, all CVTs aren't the same.

Mass-market cars will go for the run-of-the-mill CVTs which doesn't have all these goodies.

[Sutripta]

Originally Posted by Vid6639

Important for DCT/DSG boxes. Basically the transmission control unit reads the brake pressure applied and based on that disengages the transmission to prevent the car from slipping the clutch.

The brakeline pressure sensor - where is it placed? User replaceable with an unique part#?

Regards
Sutripta

[Sutripta]

Originally Posted by padmrajravi

For DSGs and AMTs, it is recommended to have foot completely off while creeping.

Progress then will mimic that of a hopping bunny, while what we want is snail like progress.

Ideally machinery should do what we want it to do. And since our first (and actually quite a lot) of auto experience was with TC Autos, any new technology should at least give what the older technology did.

Even in TC autos it is recommended to shift into N for prolonged stops. In stop-go traffic conditions, never did.

Not really paddle shifters, but what is really needed is a steering mounted Neutral <-> First selector.

Regards
Sutripta

[Lobogris]

Originally Posted by padmrajravi

In automatics, you can modulate the creep speed by keeping your foot on the brake pedal lightly. My Hexa creeps at about 7 kmph if my foot is off the brake pedal completely. I can make it go at any speed upto 7 kmph by modulating the pressure on the brake pedal. It is very convenient in traffic blocks. Apparently torque converters do this very well, but DSGs and AMTs suffer from clutch problems if you do this often. For DSGs and AMTs, it is recommended to have foot completely off while creeping. That is, you should not be trying to modulate the creep speed by adjusting brake pressure.

I don’t think this is a big issue. I have been driving my DSG Jetta and Passat in Delhi NCR for the past 5 years and have been often stuck in bumper to bumper traffic for extended periods. I have been stuck in traffic jams on highways for even more than a couple of hours in extreme temperatures of 45C and reported at 50C by the car due to the heat from the tarmac and other vehicles. I drive my cars like any other automatic and don’t shift in to neutral at lights or take any other precautions. I use the creep mode all the time just like I would in a torque converter. I have never faced any overheating issues. Of course I try to avoid traffic jams for my sake but not because I fear DSG overheating. I do drive my cars gently and never rev them hard but I don’t think that would lead to any issues unless you redlined it every time you accelerated and did this for a long period of time.

[pgsagar]

Originally Posted by Vid6639

Important for DCT/DSG boxes. Basically the transmission control unit reads the brake pressure applied and based on that disengages the transmission to prevent the car from slipping the clutch.

If you press the brake pedal lightly, the system may not disengage the clutch and keep the car in gear in anticipation to move. This causes damage to the clutch as its akin to half clutching.

Hence DSG/DCT manuals always say if you are waiting at a light and you are in gear, apply the brakes firmly and not gently.

Also, DCT's have very less creep unlike Torque converters so you won't come to know if the clutch is slipping as it doesn't fight the brakes like a torque converter. A gentle touch on brake pedal is enough to prevent the car from creeping but that is what harms the box.

Thanks for insight into it. Now I know why I found DSG cars I drove bit jerky in b-to-b crawl. They seemed to hesitate for a second or two before moving forward. In a TC car, as soon as you start coming off the brake pedal, they start moving absolutely seamlessly. Very crawl-happy system, TC.

So, in DSGs, you have to hit brakes hard and full. But, stomping on brakes comes with the risk of being rear-ended, as our folks tend to drive within inches of guy up front. Also, hard stomping will take toll on right leg calf, same as hard clutch gives you left leg calf pain in an MT car with hard clutch.

My biggest worries in DSG/DCT, more than b-to-b jerkiness and long-term reliability, is the heating issues being reported. If I have to keep watching the temp gauge in addition to looking out for all kinds of hazards on our roads, it would take the fun out of driving. I thought heating in cars was a thing of the past, when rickety Ambassadors and Premier Padminis in 70s/80s were plagued by whistling/boiling radiators, on long highway runs. Who thought it would come back to haunt us in 2020.?

My F-in-L had zeroed in on Baleno CVT to upgrade to from his MT car. But with Brezza petrol AT's launch, his interest shifted to Brezza, as the entry/exit in this car is relatively easy for elderly. Once Brezza came into focus, Venue was also discussed but dropped only because it is a DCT, for the aforesaid reasons. If it were a TC, we would have picked that up in a heartbeat, as he wanted to buy a Hyundai for a change.

[Sasanka_Sanga]

Originally Posted by sandygordon

As expected, got a luke warm response from the service team at Edapally

Can you try Kia Customer Care - 82234648505/1800 108 5000

[audioholic]

Originally Posted by Sutripta

The brakeline pressure sensor - where is it placed? User replaceable with an unique part#?

Regards
Sutripta

Originally Posted by Vid6639

If you press the brake pedal lightly, the system may not disengage the clutch and keep the car in gear in anticipation to move. This causes damage to the clutch as its akin to half clutching.

.

I believe its also a function of time for the creep to disengage upon braking in a DSG. At least the dual clutch transmissions I am familiar with open the clutch after a certain duration of pressing brake irrespective of how much brake is pressed. This is more so in dry clutch boxes. The firm press of brake rule applies for cars with brake hold so that as soon as brake hold is active, the clutch is opened up. In case of a wet clutch, the clutch is held right at biting point so that it does offer some amount of creep due to the turbulence in the fluid. But for a dry clutch, the clutch cant be kept in its mid position for a long time after the brake is pressed.

[Sutripta]

Originally Posted by audioholic

I believe

Actually it would be great if you (or anyone for that matter) could give definitive information on the sequence (algorithms), and more importantly why a particular one was chosen and not (equally reasonable sounding) others. Without this one can bandy about anything which sounds reasonable. eg. why not keep the clutch completely disengaged when at standstill with foot just on brake (enough to operate the brakelight switch)? And start engaging the clutch when accelerator movement is detected.

Regards
Sutripta

[praveen_v]

Originally Posted by Vid6639

If you press the brake pedal lightly, the system may not disengage the clutch and keep the car in gear in anticipation to move. This causes damage to the clutch as its akin to half clutching.

Hence DSG/DCT manuals always say if you are waiting at a light and you are in gear, apply the brakes firmly and not gently.

This kind of half clutching happens in manual gearbox as well right? If I have to creep in a B2B traffic in manual petrol car, I have to tap the accelerator gently and keep the clutch slipping slightly to keep the speed low and smooth? So that should also cause a similar clutch wear? Why is it a bigger problem with DCT/AMT boxes? To me it just looks like mimicking the manual actions.

[sandygordon]

UPDATE
The Car is still at the service center - Day 6

They had contacted me on Friday and said that the issue settled after a software update. Then I asked them to give a summary of my issue and the way by which they solved in writing/email. I asked for an email from Kia regarding this. I also asked for a contact at Kia so that I can correspond and raise my concerns.
I have requested them to resolve the issue once and for all.
I also have said that I would take the car only if they give the summary in writing/ email so that I can submit it in case I have to proceed legally.

They said they would look into the actuator / mechatronic function and revert in a day. As per my understanding, they are still looking for a problem to solve.