Bucking while accelerating - DCT?

[chiplee]

So does anyone else hate how reluctant the DCT is to shift from 2nd to 3rd under gentle acceleration in Throttle efficient and DCT in S3/"sport +" auto?

[vstM3]

As long as you have efficient coupled with D1 (for city traffic, stop/go), sport with D2 (for open roads/highway) and sport+ with D3/S3 (for track) you will just have a smile on ur face and not experience any issues

[kinimod]

It's hard to accelerate this car rapidly but smoothly (e.g. half the throttle) from a full stop, like I can on the 535d with ZF8 where torque delivery is aggressive but smooth, perhaps thanks to the torque converter.

The M4 either wants to go gently or full WOT. Attempts to do something in between, fast and smoothly without jerking is usually... slow. And when it feels slow, adding more gas spins the tires or traction control engages. The torque is just too abrupt.

For city driving, I like the 535d diesel torque with a slushbox much better -- it's much more usable, feels faster and doesn't spin tires.

I also agree it takes some time to get used to DCT in Auto mode when accelerating from a stop properly and in sync with the computer's shifting algorithms, as others noted. I drive in manual and let the 1st gear rev up, then shift to 2nd manually.

But overall I should note that I love DCT. For canyon and performance driving, it is pure joy... in contrary, I hated the ZF8 for canyon driving in other petrol BMWs I've driven because it feels so disconnected and has gazillion of gears.

[afadeev]

Originally Posted by chiplee

So does anyone else hate how reluctant the DCT is to shift from 2nd to 3rd under gentle acceleration in Throttle efficient and DCT in S3/"sport +" auto?

I have the opposite (very mild) irritant: how reluctant DCT is to shift down from 3rd to 2nd, resulting in occasional lugging when coasting to a stop light. Seams to be most pronounced in D1, so I'm coasting in D2 for now.

a

[Tomtomdrive]

Sounds like oem summer tires in 30 below temperature to me.

[AYF80]

Originally Posted by bigant66

+1

What I have experienced is that, when slowing down to a gradual stop, it's almost like it won't shift into 2nd in time coming from 3rd and it starts bucking. Sometimes I have to manually shift it into 2nd.

[afadeev]

Originally Posted by AYF80

What I have experienced is that, when slowing down to a gradual stop, it's almost like it won't shift into 2nd in time coming from 3rd and it starts bucking. Sometimes I have to manually shift it into 2nd.

Yep, same here.
DCT allows RPMs to drop to below 1200, and drivetrain starts shuddering.
More pronounced in D1, still present in D2 with both Efficient and Sport throttle modes. May try D3 and Sport+ next, just to exhaust all options. The only solution seams to be to manually downshift as you approach a red light, which I enjoy doing to engine brake and stay in gear ready to accelerate as soon as the light turn green.

a

[AYF80]

Originally Posted by afadeev

Yep, same here.
DCT allows RPMs to drop to below 1200, and drivetrain starts shuddering.
More pronounced in D1, still present in D2 with both Efficient and Sport throttle modes. May try D3 and Sport+ next, just to exhaust all options. The only solution seams to be to manually downshift as you approach a red light, which I enjoy doing to engine brake and stay in gear ready to accelerate as soon as the light turn green.

a

The way i have combated it was... If I'm going to stop or slow down, I make sure to completely let off the gas. You can't feather the throttle as if you were trying to slow more gradually. that for sure endues the bucking behavior.

Same thing for taking off from a stop (In Manual mode). There is a special "sweet spot" in there where the car will buck like crazy. You either need to be easy on the throttle, go commit to it.

[Rick955]

Originally Posted by AYF80

The way i have combated it was... If I'm going to stop or slow down, I make sure to completely let off the gas. You can't feather the throttle as if you were trying to slow more gradually. that for sure endues the bucking behavior.

Same thing for taking off from a stop (In Manual mode). There is a special "sweet spot" in there where the car will buck like crazy. You either need to be easy on the throttle, go commit to it.

You guys got me thinking again! So lets say your in an area where the speed limit is like 15-20, speed bumps, etc... like a nice residential complex. Do you just stay in manual mode, shifting between 1st and 2nd to prevent the bucking vs. using D1 for example?

[Blksnowflake]

Originally Posted by Rick955

You guys got me thinking again! So lets say your in an area where the speed limit is like 15-20, speed bumps, etc... like a nice residential complex. Do you just stay in manual mode, shifting between 1st and 2nd to prevent the bucking vs. using D1 for example?

The sure 100% way to avoid bucking if you're getting it as you learn the DCT would be to leave it in Drive/Auto mode. Most buckers are people in manual mode. I never have bucking in auto, the DCT shifts to second pretty quickly in auto, in my car under moderately heavy throttle mashing in sport+ throttle and DCT on 2, it shifts at around 25/2700 rpms.

[AYF80]

Originally Posted by Blksnowflake

The sure 100% way to avoid bucking if you're getting it as you learn the DCT would be to leave it in Drive/Auto mode. Most buckers are people in manual mode. I never have bucking in auto, the DCT shifts to second pretty quickly in auto, in my car under moderately heavy throttle mashing in sport+ throttle and DCT on 2, it shifts at around 25/2700 rpms.

We're talking about the car down shifting into 2nd. The RPMs drop way low in some conditions when slowing down, but the car does not down shift in time and the car bucks.

For this situation in particular, there is nothing to learn. This is in regular drive mode under normal driving conditions. Very annoying.

[AYF80]

Originally Posted by Rick955

You guys got me thinking again! So lets say your in an area where the speed limit is like 15-20, speed bumps, etc... like a nice residential complex. Do you just stay in manual mode, shifting between 1st and 2nd to prevent the bucking vs. using D1 for example?

For that situation, if you're in Manual, just shift into and and stay in 2nd. You don't need 1st at all unless stopped. Even then I don't always use 1st

If your in D mode, once the dam thing decides to actually shift into 2nd from 3rd.... Lol (it does not do this EVERY time I know) then you are good to go.

But M mode, lock her in 2nd or even 3rd if you speed up a bit.

[er130]

Finally, today is the first day in the car by myself. I want to try some thing fun. So, I put the M4 in Sport Plus mode. Fully stop, and here is my setting:
- Throttle: Sport Plus
- Suspension: Sport Plus
- Steering: Sport Plus
- Transmission: S3
- DSC: ON
- HUD: M View

Once I take off, push the gas.WOW, The car jump like a horse. . it move but not fast at all. after 3 gear, everything is fine. Am I do something wrong. First time having a M car. My 650iGC didnt do that. Please help! Thanks!

[nene]

I think you may have purchased the GhostMustang option...
All kidding aside, I have not had that experience, mainly because I'm still below the 1200 mile list and have not pushed "her" that hard. This is one powerful car.

[er130]

Originally Posted by nene

I think you may have purchased the GhostMustang option...
All kidding aside, I have not had that experience, mainly because I'm still below the 1200 mile list and have not pushed "her" that hard. This is one powerful car.

Thanks for you reply! But my cousin M3 happen the same too. He had drove more than 1200 mils. and also i did push hard on the gas too. I am not sure what went wrong.

[CanAutM3]

DSC cuts the balls off the F8X. As a minimum, go into MDM, but even then it will reign it back significantly.

The only way to truly appreciate the F8X power is with DSC off. Be warned though, you need to have quick hands if you elect to do so

[er130]

Originally Posted by CanAutM3

DSC cuts the balls off the F8X. As a minimum, go into MDM, but even then it will reign it back significantly.

The only way to truly appreciate the F8X power is with DSC off. Be warned though, you need to have quick hands if you elect to do so

DSC off sound too crazy for me. Just want to a bit fast and loud( so i can enjoy the engine noise). If i set the Throttle to Efficient. I dont think the car is quick enough. Please suggest a M setting. Thanks!

[solstice]

Is this your first DCT?

[er130]

Originally Posted by solstice

Is this your first DCT?

Yep

[solstice]

Originally Posted by er130

Yep

Ok, then I think your car is fine. My E90 with DCT did the same if you punched the throttle from standstill. Huge jump even with DSC off. There's a bit of a learning curve to take off fast and smooth with the DCT vs the ZF in your 650.

Give gas smoothly until you feel the clutch fully engaging, then punch it. If punching it is what you want. It's more rewarding to modulate in 1st and 2nd unless you want wheel spin.

[er130]

Originally Posted by solstice

Ok, then I think your car is fine. My E90 with DCT did the same if you punched the throttle from standstill. Huge jump even with DSC off. There's a bit of a learning curve to take off fast and smooth with the DCT vs the ZF in your 650.

What should I do to make take off fast and smooth happen? my 650 is easy. push the gas hard and It go quick!

[CanAutM3]

Originally Posted by er130

DSC off sound too crazy for me. Just want to a bit fast and loud( so i can enjoy the engine noise). If i set the Throttle to Efficient. I dont think the car is quick enough. Please suggest a M setting. Thanks!

Try at least DSC in MDM. Also, the DCT in S3 will slam very aggressive shifts accentuating DSC/MDM intervention and slowing the car down; it is better suited for DSC off. Try bringing it down to S2. Further, dampers in Sport+ will be very stiff and will not favour traction on bumpy surface, try EDC in Sport instead. Steering is up to you, but I find Sport+ too stiff for my liking.

My recommendations:
DSC: MDM
Throttle: Sport+ (or Sport)
Steering: Sport
EDC: Sport
DCT: S2