DCT Basics / Questions

[M5_Raz]

Hey guys,

I wanted to ask some questions to get to know the transmission better.

1. How do you start from a stop? I used to just press the gas and go. However, that sometimes caused the car/transmission to shake a bit while the clutch caught (especially on light acceleration). So nowadays I tap the gas to activate Creep mode, then press the gas and go.

2. Which mode is going to ensure the clutch lasts the longest? Is it D1/S1, where the gear changes are super smooth? D2/S2, where they're a bit faster? Or D3/S3 where they're the fastest?

3. When coming towards a stop, is it better to avoid stopping completely and braking early/coasting till it turns green? Or it doesn't matter?

4. When downshifting, do you downshift in to 1st as well? I heard it's not good to do so, so I stopped.

5. When waiting at a red light, is there any wear to any components if your foot is off the brake pedal?

6. How often do you recommend fluid and filter changes? I know it's not lifetime.

Thanks!

[SpeedProtocol]

Creep mode is best to get used to and learn. When I first got the car I thought something was broken how it jerks and lurches if you dont know how to drive it, especially cold. I still cant reverse on inclines smoothly.

[Noggie]

I'll try to answer from a general mechanical point of view.

1. I do both, but sometimes I get the jerky motion at intersections etc, it's better in efficient than in sport or sport+ as the throttle is really sensitive. I find myself mostly in efficient around town and I press the throttle quite gently. High powered cars typically drive very slow in the city or in queues, simply because if you don't feather the throttle, you will leap forward and crash, spinn the tires or have jerky drive.

2. mode should not have much impact during normal driving, its the load change that will wear the clutch, so during normal driving it will have very little effect, for sporty driving (at high revs) it should be more aggressive/faster.

3. should not really matter, the gearbox will coast and activate the clutch when needed. All controlled by software.

4. not sure why that should be a problem, unless you downshift very early and engine brake. i.e In D1 it will usually downshift to 2nd, but that is for a smooth comfort start. in D3 it will downshift too 1st.

5. No. this is completely controlled by the electronics, you dont have a thrust bearing or anything on these gearboxes that is affected by driver input. Unless you are on a hill.

6. I do my engine oil every 10-15.000km/6200-9300miles. My car had transmission and diff oil replaced as a service item around 80.000km/50.000miles.
If you want to be extra cautious 50.000km/37.000 miles, but it should normally last 100.000km/62.000miles.

[M5_Raz]

Originally Posted by Droner

Creep mode is best to get used to and learn. When I first got the car I thought something was broken how it jerks and lurches if you dont know how to drive it, especially cold. I still cant reverse on inclines smoothly.

I'm the same! Every time I reverse on a hill the tires lose a bit of traction hahaha

[M5_Raz]

Originally Posted by Noggie

I'll try to answer from a general mechanical point of view.

1. I do both, but sometimes I get the jerky motion at intersections etc, it's better in efficient than in sport or sport+ as the throttle is really sensitive. I find myself mostly in efficient around town and I press the throttle quite gently. High powered cars typically drive very slow in the city or in queues, simply because if you don't feather the throttle, you will leap forward and crash, spinn the tires or have jerky drive.

2. mode should not have much impact during normal driving, its the load change that will wear the clutch, so during normal driving it will have very little effect, for sporty driving (at high revs) it should be more aggressive/faster.

3. should not really matter, the gearbox will coast and activate the clutch when needed. All controlled by software.

4. not sure why that should be a problem, unless you downshift very early and engine brake. i.e In D1 it will usually downshift to 2nd, but that is for a smooth comfort start. in D3 it will downshift too 1st.

5. No. this is completely controlled by the electronics, you dont have a thrust bearing or anything on these gearboxes that is affected by driver input. Unless you are on a hill.

6. I do my engine oil every 10-15.000km/6200-9300miles. My car had transmission and diff oil replaced as a service item around 80.000km/50.000miles.
If you want to be extra cautious 50.000km/37.000 miles, but it should normally last 100.000km/62.000miles.

Awesome, thank you very much for the detailed response! That's exactly what I was looking for

[M5Yams]

Originally Posted by M5_Raz

Hey guys,

I wanted to ask some questions to get to know the transmission better.

1. How do you start from a stop? I used to just press the gas and go. However, that sometimes caused the car/transmission to shake a bit while the clutch caught (especially on light acceleration). So nowadays I tap the gas to activate Creep mode, then press the gas and go.

2. Which mode is going to ensure the clutch lasts the longest? Is it D1/S1, where the gear changes are super smooth? D2/S2, where they're a bit faster? Or D3/S3 where they're the fastest?

3. When coming towards a stop, is it better to avoid stopping completely and braking early/coasting till it turns green? Or it doesn't matter?

4. When downshifting, do you downshift in to 1st as well? I heard it's not good to do so, so I stopped.

5. When waiting at a red light, is there any wear to any components if your foot is off the brake pedal?

6. How often do you recommend fluid and filter changes? I know it's not lifetime.

Thanks!

To start of with the first question, press the pedal down to enable creep mode and then just after it starts to creep i press slightly more until you feel the clutch engage. This generally gives me the smoothest set off from a red light. Technically creep mode allows the clutch to slip slightly, which is why rpms don't change and it feels so smooth to engage, so its not great on the transmission. that being said its not hard on it at all and shouldn't be something to avoid at all costs or anything like that.

Second question, the computer optimizes everything for performance and longevity. which basically means that the car is very good at taking car of itself and you don't need to worry that much about the slight differences between s1/2/3. The clutches in these cars have proven themselves to be quite resilient and reliable, really depends much more on how you drive than what settings you're in.

third question, the only thing you're really saving when coasting to a stop more is brakes. the only reason you stay in gear while coming to a stop is because that's when your alternator kicks in and charges the battery. In fact BMW had to push out a program update for the standard 5ers because in America its was much less common for people to coast to a stop and people batteries were going dead. (they didn't charge while braking, just light throttle and coasting.)

fourth question, have no clue.... back on alternator rant, the car in auto mode usually stays 2nd until stopped so I'd imagine you don't need to downshift to 1st. I could only think it being a bad thing if you shift down too early, seeing how short the gear is, and there being excess heat build up.

fifth question... Doesn't matter at all for the trans, you are essentially in neutral while stopped(clutch disengage) so the transmission isn't bothered. the only time that you aren't in neutral and won't roll freely is while on a hill and hill start mode kicks in which it then actually just holds your brakes on until you hit the throttle.

sixth, I don't know this one. engine oil is 5k miles no more.(many threads as to why) but tranny i don't know. I figure bmw will tell me to spend oreillys money one day.

honestly man it's great that you want to treat your car as perfect as possible but the great news is that bmw did an incredible job programing this one and isn't like the ferrari f430's which was nictorious for eating dcts like French fries.

[M5_Raz]

Originally Posted by M5Yams

To start of with the first question, press the pedal down to enable creep mode and then just after it starts to creep i press slightly more until you feel the clutch engage. This generally gives me the smoothest set off from a red light. Technically creep mode allows the clutch to slip slightly, which is why rpms don't change and it feels so smooth to engage, so its not great on the transmission. that being said its not hard on it at all and shouldn't be something to avoid at all costs or anything like that.

Second question, the computer optimizes everything for performance and longevity. which basically means that the car is very good at taking car of itself and you don't need to worry that much about the slight differences between s1/2/3. The clutches in these cars have proven themselves to be quite resilient and reliable, really depends much more on how you drive than what settings you're in.

third question, the only thing you're really saving when coasting to a stop more is brakes. the only reason you stay in gear while coming to a stop is because that's when your alternator kicks in and charges the battery. In fact BMW had to push out a program update for the standard 5ers because in America its was much less common for people to coast to a stop and people batteries were going dead. (they didn't charge while braking, just light throttle and coasting.)

fourth question, have no clue.... back on alternator rant, the car in auto mode usually stays 2nd until stopped so I'd imagine you don't need to downshift to 1st. I could only think it being a bad thing if you shift down too early, seeing how short the gear is, and there being excess heat build up.

fifth question... Doesn't matter at all for the trans, you are essentially in neutral while stopped(clutch disengage) so the transmission isn't bothered. the only time that you aren't in neutral and won't roll freely is while on a hill and hill start mode kicks in which it then actually just holds your brakes on until you hit the throttle.

sixth, I don't know this one. engine oil is 5k miles no more.(many threads as to why) but tranny i don't know. I figure bmw will tell me to spend oreillys money one day.

honestly man it's great that you want to treat your car as perfect as possible but the great news is that bmw did an incredible job programing this one and isn't like the ferrari f430's which was nictorious for eating dcts like French fries.

Oh wow, I was under the impression that a slow, smooth start was the best. So you're saying that it's better to just accelerate and get going right away?

Thanks a lot on the other information, I really appreciate it! Yeah, I'd like to keep it running perfectly. I've only had it for about 4-5 months, but I want to keep it for a while longer.

It's my first DCT car and I'm loving it so far! I would've went with an F90 M5, but the race car feel wasn't there as much as this one. Plus I saved $15-20k!

[bmwdinan5]

It’s best to run the trans in the most aggressive setting (3) if you want to improve longevity. The smoother the transition the more clutches are allowed to slip