DCT power shifting: bad?

nugent · 08-01-2013, 05:09 PM

when upshifting I don't take my foot off the gas. with WOT this results in a very abrupt clunk when the gear slams into place, which scares passengers, which i like. does anyone know if this is detrimental to the clutch?

ufgtrs2007 · 08-01-2013, 05:22 PM

I don't think it is although it feels like its harsh for the transmission

alexey21 · 08-01-2013, 05:29 PM

Its not bad.... just think of the lag you would have with you let off the gas every time.
The clunk is how the DCT works. IMO I love it.

M54ccibo · 08-01-2013, 05:47 PM

BMW Performance Center instructors said keep the foot down while shifting. Put me in the "love the clunk" camp.

wrsbmw · 08-01-2013, 05:53 PM

Quote:

Originally Posted by nugent

when upshifting I don't take my foot off the gas. with WOT this results in a very abrupt clunk when the gear slams into place, which scares passengers, which i like. does anyone know if this is detrimental to the clutch?

If you are drag racing how else would you do it? I do this when I get on entrance ramps for the freeway that are decently long. I can get to 100 real quickly on a couple of them and I do just what you describe.

In my experience, the passengers are more scared by the acceleration of the car than the clunk. If you don't have DTC on, the back end can get squirrelly in second and third gears. I was just doing this last night getting on to I -35 from a 50mph running start. I was in 3rd at the end of the entrance ramp and floored it from about 55-60. As I was shifting to fourth as described, the back end broke loose a bit. I cut across two lanes to the far left lane and I was at 100 when I got in. I was by myself though.

Grayblack · 08-01-2013, 07:16 PM

I love the pops when shifting. Definitely leave the foot on the pedal.

04S · 08-01-2013, 07:36 PM

WOT gear changes - that what makes the M DCT great

Longwong · 08-02-2013, 12:39 AM

The ENTIRE point of dct is to provide uninterrupted power through changes which means you need your foot down. it is not harsh at all on the tranny as it is meant for that. In the m3 on S5/6 it is absolutely violent and just insanely makes the car slam into gear. It is absolutely awesome!

wisesoul · 08-02-2013, 12:59 AM

S6 mode on the E60 M5 was far more violent. Felt like the diff was gonna fall off

But don't lift, otherwise you lose the boost you just built up!

Simon H · 08-02-2013, 04:19 AM

What settings do you have on ?. I feel S2 is the sweet spot, if you dont like the thump on the gearchange. Sometimes i feel S3 unsettles the car a little, compared to S2.

PatrickC23 · 08-02-2013, 10:04 AM

Ive never lifted my foot off when shifting, I always assumed with DCT that was the point. The DCT is nothing compared to the violence of SMGII in my e46, totally miss that.

Netwon · 08-02-2013, 11:07 AM

Dual clutch for a reason... Hammer on it!

Northern X5M · 08-02-2013, 12:06 PM

Why on earth would you lift between shifts? That would be defeating the whole concept of the DCT. Hammer down!

nugent · 08-02-2013, 12:45 PM

dudes, I don't lift off. I wasn't asking who lifts off or not, just if anyone had any technical info on clutch/tranny wear. thanks to those who answered my question. m power.

AlphaAlpineM6 · 08-02-2013, 01:18 PM

dont let off. it's an automated transmission. the faster the shift the longer the clutch will laster ironically.
slower shifts = more friction time which as a result causes heat which as a result burns clutches...

RPiM5 · 08-02-2013, 02:08 PM

Do you guys think that downshifting a lot is bad for the clutch/DCT?

I usually like to drive in S2 or S3 a lot and I like to downshift the DCT whenever I'm decelerating to a stop or a red traffic light because I like to hear the exhaust crack on each downshift with the Straightpipes. Does anyone think this is bad? My DCT seems fine and shifts smoother than ever.

M54ccibo · 08-02-2013, 02:27 PM

Quote:

Originally Posted by RPiM5

Do you guys think that downshifting a lot is bad for the clutch/DCT?

I usually like to drive in S2 or S3 a lot and I like to downshift the DCT whenever I'm decelerating to a stop or a red traffic light because I like to hear the exhaust crack on each downshift with the Straightpipes. Does anyone think this is bad? My DCT seems fine and shifts smoother than ever.

I always downshift however usually no lower than 3rd unless I will be #1 at the stop and feel the light will go green.

nugent · 08-02-2013, 02:47 PM

Quote:

Originally Posted by AlphaAlpineM6

dont let off. it's an automated transmission. the faster the shift the longer the clutch will laster ironically.
slower shifts = more friction time which as a result causes heat which as a result burns clutches...

thank you. this is exactly the answer I was looking for.

nugent · 08-02-2013, 03:04 PM

Quote:

Originally Posted by RPiM5

Do you guys think that downshifting a lot is bad for the clutch/DCT?

I usually like to drive in S2 or S3 a lot and I like to downshift the DCT whenever I'm decelerating to a stop or a red traffic light because I like to hear the exhaust crack on each downshift with the Straightpipes. Does anyone think this is bad? My DCT seems fine and shifts smoother than ever.

I love downshifting. I often do it into 1st as well just to hear the exhaust blip with the e-race.

M54ccibo · 08-02-2013, 03:19 PM

Quote:

Originally Posted by nugent

thank you. this is exactly the answer I was looking for.

Absolutely correct about wear based on shift speed. I got to thinking about this. Isn't shift speed dependent on the drivelogic setting, not torque being passed through the transmission? I.e., 1 being the smoothest shift (the longest engagement) vs. 3 being the quickest (shortest engagement). So less wear on the clutches when using 3, but more work for the DCT pump. Vice-versa for 1.

When you lift, it doesn't change the shift speed, right? It just changes the torque on the input shaft. While there may be a minute difference in engagement speed (due to the potential increase clutch slippage) I'd think it'd be too short to be relevant, and, the torque would be passed to the inner input shaft immediately.

Either way...better to not lift. Another benefit is near constant power to the wheels which is what also a big plus for the DCT!

nugent · 08-02-2013, 04:56 PM

Quote:

Originally Posted by M54ccibo

Quote:

Originally Posted by nugent

thank you. this is exactly the answer I was looking for.

Absolutely correct about wear based on shift speed. I got to thinking about this. Isn't shift speed dependent on the drivelogic setting, not torque being passed through the transmission? I.e., 1 being the smoothest shift (the longest engagement) vs. 3 being the quickest (shortest engagement). So less wear on the clutches when using 3, but more work for the DCT pump. Vice-versa for 1.

When you lift, it doesn't change the shift speed, right? It just changes the torque on the input shaft. While there may be a minute difference in engagement speed (due to the potential increase clutch slippage) I'd think it'd be too short to be relevant, and, the torque would be passed to the inner input shaft immediately.

Either way...better to not lift. Another benefit is near constant power to the wheels which is what also a big plus for the DCT!

this. Thanks.

greentrbo95gst · 08-02-2013, 06:53 PM

Are you guys still holding the brake pedal down when stopped?
I remember in the e60 if you didnt press the brake pedal down when stopped the clutch disk would wear out.

08-01-2013, 05:09 PM	#1
nugent Captain 65 Rep 602 Posts Drives: f10 m5 Join Date: Apr 2011 Location: san francisco iTrader: (0)	DCT power shifting: bad? when upshifting I don't take my foot off the gas. with WOT this results in a very abrupt clunk when the gear slams into place, which scares passengers, which i like. does anyone know if this is detrimental to the clutch? __________________ e92 m3 6MT, RS4 6MT, S4 Avant 6MT, WRX 5MT, Corsica
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08-01-2013, 05:22 PM	#2
ufgtrs2007 dentite 339 Rep 758 Posts Drives: 718 GT4, M2C, JLU392, e92 M3 Join Date: Feb 2008 Location: NC iTrader: (9) Garage List 2013 BMW M3 [0.00] 2013 BMW M5 [0.00]	I don't think it is although it feels like its harsh for the transmission
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08-01-2013, 05:29 PM	#3
alexey21 Lieutenant 60 Rep 422 Posts Drives: Turbo Join Date: Apr 2012 Location: Philly iTrader: (0)	Its not bad.... just think of the lag you would have with you let off the gas every time. The clunk is how the DCT works. IMO I love it.
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08-01-2013, 05:47 PM	#4
M54ccibo Major 85 Rep 1,489 Posts Drives: '16 GT4 Join Date: Apr 2012 Location: Orange County, CA iTrader: (0)	BMW Performance Center instructors said keep the foot down while shifting. Put me in the "love the clunk" camp. __________________ Current: '16 GT4 Past ///Ms: '13 F10 M5, Alpine Weiss III/Sakhir Orange Full '10 E60 M5, Space Gray/Black
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08-01-2013, 07:16 PM	#6
Grayblack Captain 182 Rep 995 Posts Drives: E92 M3 and G07 X7 Join Date: Nov 2012 Location: OC, CA iTrader: (8)	I love the pops when shifting. Definitely leave the foot on the pedal.
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08-01-2013, 07:36 PM	#7
04S Captain 174 Rep 839 Posts Drives: M4 xDrive, X5 40i and U11 X1 Join Date: Sep 2008 Location: Sydney, Australia iTrader: (0)	WOT gear changes - that what makes the M DCT great
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08-02-2013, 12:39 AM	#8
Longwong Banned 38 Rep 370 Posts Drives: e92 m3 catless Join Date: Jun 2013 Location: USA iTrader: (0)	The ENTIRE point of dct is to provide uninterrupted power through changes which means you need your foot down. it is not harsh at all on the tranny as it is meant for that. In the m3 on S5/6 it is absolutely violent and just insanely makes the car slam into gear. It is absolutely awesome!
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08-02-2013, 12:59 AM	#9
wisesoul Savoir Faire 74 Rep 1,772 Posts Drives: 2013 BMW M5 Join Date: Aug 2010 Location: Los Angeles, Ca iTrader: (0)	S6 mode on the E60 M5 was far more violent. Felt like the diff was gonna fall off But don't lift, otherwise you lose the boost you just built up! __________________ Current: Alpine White F10 M5\|H&R springs\|12mm/10mm spacers\|Eisenmann Race Sold:Imola Yellow RS4-KW V3\|MTM 10mm spacers\|Hotchkis rear sway bar\|APR Stage 1\|Milltek Catless\|RNS-E\|Euro RS4 Flat bottom Steering Wheel Sold:E46 323i
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08-02-2013, 04:19 AM	#10
Simon H Major 876 Rep 1,319 Posts Drives: M5 Competition Join Date: Mar 2010 Location: UK iTrader: (0)	What settings do you have on ?. I feel S2 is the sweet spot, if you dont like the thump on the gearchange. Sometimes i feel S3 unsettles the car a little, compared to S2.
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08-02-2013, 10:04 AM	#11
PatrickC23 Colonel 184 Rep 2,245 Posts Drives: '16 991.1 911 GTS, '16 F85 X5M Join Date: Apr 2012 Location: NNJ iTrader: (0) Garage List 2013 BMW ///M5 [0.00]	Ive never lifted my foot off when shifting, I always assumed with DCT that was the point. The DCT is nothing compared to the violence of SMGII in my e46, totally miss that. __________________ 2016 991.1 911 Carrera GTS 2016 F85 X5M - Carbon Black/Mugello Red
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08-02-2013, 11:07 AM	#12
Netwon Second Lieutenant 8 Rep 222 Posts Drives: '12 BMW M5 Alpine White Join Date: Nov 2012 Location: Northern Alberta iTrader: (0) Garage List 2012 BMW M5 [0.00]	Dual clutch for a reason... Hammer on it!
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08-02-2013, 12:06 PM	#13
Northern X5M Captain 104 Rep 806 Posts Drives: 2014 Tanzanite Blue M5 Join Date: Oct 2010 Location: Edmonton, Alberta, Canada iTrader: (0)	Why on earth would you lift between shifts? That would be defeating the whole concept of the DCT. Hammer down! __________________ 2014 ///M5 CP Tanzanite Blue/Cohiba - 11.15 @ 128.8 & 1.84 60' (2150' DA) - BPM Tune - MSR Intake - SSP DCT - SS DPs & HFC Mid Pipes/X-Over - E Race Muffs - 19" MT DRs... On to a new home.
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08-02-2013, 12:45 PM	#14
nugent Captain 65 Rep 602 Posts Drives: f10 m5 Join Date: Apr 2011 Location: san francisco iTrader: (0)	dudes, I don't lift off. I wasn't asking who lifts off or not, just if anyone had any technical info on clutch/tranny wear. thanks to those who answered my question. m power. __________________ e92 m3 6MT, RS4 6MT, S4 Avant 6MT, WRX 5MT, Corsica
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08-02-2013, 01:18 PM	#15
AlphaAlpineM6 First Lieutenant 36 Rep 380 Posts Drives: 2014 BMW M6 & 2012 AMG CLS63 Join Date: May 2013 Location: Planet Earth iTrader: (0) Garage List 2014 BMW M6 Coupé [10.00] 2012 CLS63 AMG [0.00]	dont let off. it's an automated transmission. the faster the shift the longer the clutch will laster ironically. slower shifts = more friction time which as a result causes heat which as a result burns clutches... __________________ 2008 M3 Sedan + catless + Tune 2012 CLS63 AMG 2014 M6 Coupe + catless + KW V3 2015 Porsche GT3 , 2015 M3, all stock, 1/1 Space Grey
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08-02-2013, 02:08 PM	#16
RPiM5 Major General 2872 Rep 7,885 Posts Drives: Black M5 Join Date: Apr 2012 Location: Earth 616 iTrader: (0)	Do you guys think that downshifting a lot is bad for the clutch/DCT? I usually like to drive in S2 or S3 a lot and I like to downshift the DCT whenever I'm decelerating to a stop or a red traffic light because I like to hear the exhaust crack on each downshift with the Straightpipes. Does anyone think this is bad? My DCT seems fine and shifts smoother than ever. __________________
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08-02-2013, 06:53 PM	#22
greentrbo95gst Brigadier General 1231 Rep 4,106 Posts Drives: 21 M5 Comp Join Date: Jan 2011 Location: Orange County iTrader: (6)	Are you guys still holding the brake pedal down when stopped? I remember in the e60 if you didnt press the brake pedal down when stopped the clutch disk would wear out. __________________ Current: 21 M5 Comp, 17 X5M, 06 M3, 14 Ferrari FF, Tesla Model S Performance.
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