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      08-02-2011, 06:09 AM   #1
persian54
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DCT Clutch smell

On my 2011, I notice the clutch smell quite a lot

I shift gears, upshift/downshift, like i do with my 09, but the 11 smalls bad, it's as if I was driving a manual and mis-shifted, was riding the clutch, stalled the car, etc.

When I leave it in D, it's fine

Is this how the Z4 DCT is during break in? Does this mean I shouldn't be changing the gears...

my 09 DCT never smelled like this, not even after the track.

Nor did the DCT in my M3.
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      08-02-2011, 07:08 AM   #2
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The DCT is a wet clutch system so I would be surprised if you're smelling the clutch like you would on a manual transmission. Are you sure it's not the brakes? I haven't noticed any unusual smells on mine and I just passed 1200 miles. Maybe a visit to the dealer is in order.
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      08-02-2011, 11:35 AM   #3
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It's a pretty distinct clutch smell. Plus, when I put it in D and drive 'normal' (meaning no revs past 3k or so, little throttle) I don't smell it at all
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      08-02-2011, 05:47 PM   #4
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Never had a bad smell from my DCT or brakes.
Take it in.
Go for a drive with them if it is easily repeatable.
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      08-02-2011, 09:09 PM   #5
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Quote:
Originally Posted by Dr Stig 2 View Post
Never had a bad smell from my DCT or brakes.
Take it in.
Go for a drive with them if it is easily repeatable.
Well the car still only has 300 miles on it

if it continues after 'break-in' I'll take it in

My tech is my friend, so maybe when we go out one night I can show it to him (err 'smell it' to him lol)
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      08-02-2011, 09:26 PM   #6
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I'm at 415 miles, and I haven't smelled anything. I'm in SPORT mode and manually shifting most of the time.
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      08-02-2011, 11:48 PM   #7
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Quote:
Originally Posted by mike0804 View Post
I'm at 415 miles, and I haven't smelled anything. I'm in SPORT mode and manually shifting most of the time.
I think I am being too aggressive on it

It's cause I still drive the 09 Z4 and when I switch to the new one I kind of forget it's 'new' cause it's well..the same car lol
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      08-03-2011, 08:12 PM   #8
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I have never smelled the clutch with my DCT but it feels like it is splipping every once in a while in 1st or 2nd.
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      08-03-2011, 08:23 PM   #9
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Quote:
Originally Posted by richard in NC View Post
I have never smelled the clutch with my DCT but it feels like it is splipping every once in a while in 1st or 2nd.
Certainly when you are just moving off after a start - slowly - say in a car park - it rides the clutch like a bejesus. You have to give it a fair bit of welly to get it to take you seriously and engage the clutch fully.
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      08-04-2011, 09:28 AM   #10
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Quote:
Originally Posted by Dr Stig 2 View Post
Certainly when you are just moving off after a start - slowly - say in a car park - it rides the clutch like a bejesus. You have to give it a fair bit of welly to get it to take you seriously and engage the clutch fully.
Agreed. Had my Z4 for a week now and this is one of the first things I noticed about the DCT.
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      08-08-2011, 03:58 PM   #11
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I've been driving the 09 for the past week

going to drive the 11 tomorrow and day after

I'll see if it still smells

it should have around 500 miles on it now
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      08-12-2011, 12:01 AM   #12
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Quote:
Originally Posted by persian54 View Post
On my 2011, I notice the clutch smell quite a lot

I shift gears, upshift/downshift, like i do with my 09, but the 11 smalls bad, it's as if I was driving a manual and mis-shifted, was riding the clutch, stalled the car, etc.

When I leave it in D, it's fine

Is this how the Z4 DCT is during break in? Does this mean I shouldn't be changing the gears...

my 09 DCT never smelled like this, not even after the track.

Nor did the DCT in my M3.
You're not smelling your DCT clutch. The "clutch" in a DCT transmission is a misnomer in the traditional sense.

A traditional clutch is a simple, spining disk sandwiched between a flywheel and pressure plate, that uses dry friction to engage and disengage. It's also separated from the transmission and somewhat exposed to the atmosphere so when it slips excessively it makes a burning smell that can be normally detected.

A Z4 DCT clutch is wet and integrated into the transmission, using the same fluid as the transmission itself. It's really no different than an automatic transmission clutch pack. You're not going to smell the clutch per se, but if you did smell something like burning transmission fluid than have the transmission checked for leaks or damage.

It could be a leaking coolant line dripping on the exhaust system.
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Last edited by teagueAMX; 08-12-2011 at 12:07 AM..
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      08-12-2011, 01:15 AM   #13
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Quote:
Originally Posted by teagueAMX View Post
You're not smelling your DCT clutch. The "clutch" in a DCT transmission is a misnomer in the traditional sense.

A traditional clutch is a simple, spining disk sandwiched between a flywheel and pressure plate, that uses dry friction to engage and disengage. It's also separated from the transmission and somewhat exposed to the atmosphere so when it slips excessively it makes a burning smell that can be normally detected.

A Z4 DCT clutch is wet and integrated into the transmission, using the same fluid as the transmission itself. It's really no different than an automatic transmission clutch pack. You're not going to smell the clutch per se, but if you did smell something like burning transmission fluid than have the transmission checked for leaks or damage.

It could be a leaking coolant line dripping on the exhaust system.

Thanks for the info

I need to drive the car more to see as I just returned the 09 today I haven't driven the 11 much at all.

I guess I shouldn't have said 'clutch smell' and instead "smells like when you miss a shift in a manual, or stall it, or ride the clutch, or shift hard" etc

The smell only came on when I would shift aggressively and/or quickly (meaning I'd go 1 2 3 4 before I hit 40 mph)
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      08-12-2011, 07:11 PM   #14
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No worries.

It's a common mistake, easily made due to the fact that auto manufactures insist on using the term dual clutch. For all practical purposes the DCT is an another type of automatic transmission. But that doesn't sound too sexy, does it?

Did you use Launch Control? I highly recommend not using it. It's true they provide the feature, but. . .

If the smell persists, even under hard driving I would be a little bit concerned.
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      08-12-2011, 11:14 PM   #15
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Quote:
Originally Posted by teagueAMX View Post
No worries.

It's a common mistake, easily made due to the fact that auto manufactures insist on using the term dual clutch. For all practical purposes the DCT is an another type of automatic transmission. But that doesn't sound too sexy, does it?

Did you use Launch Control? I highly recommend not using it. It's true they provide the feature, but. . .

If the smell persists, even under hard driving I would be a little bit concerned.
Well really. No. Seriously.

There is no hydaulic torque converter - just a pair of wet clutches.
It's not an auto, but a dual clutch.
As one wet clutch disengages, the other wet clutch engages...

It can slip either clutch, as a clutch would under manual control, but the computer determines how much.

Not an auto. Banish the thought. Never let it be said again. please.
You will give the DCT a bad name.

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      08-13-2011, 01:58 AM   #16
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Quote:
Originally Posted by Dr Stig 2 View Post
Well really. No. Seriously. Not an auto. Banish the thought. Never let it be said again. please.
You will give the DCT a bad name.
Really - There are manual transmissions, automatic, & automated transmissions. Automated clutch SMG being merely a subset of the prefix "auto"transmission, however you cut the cheese.

1. automatic transmission - a transmission that automatically changes the gears according to the speed of the car.
2. automated transmission - a manual-style transmission operated by computer.
3. manual transmission - requires human interface to make the vehicle move and uses a driver-operated clutch.
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      08-13-2011, 02:12 AM   #17
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Quote:
Originally Posted by teagueAMX View Post
No worries.

It's a common mistake, easily made due to the fact that auto manufactures insist on using the term dual clutch. For all practical purposes the DCT is an another type of automatic transmission. But that doesn't sound too sexy, does it?

Did you use Launch Control? I highly recommend not using it. It's true they provide the feature, but. . .

If the smell persists, even under hard driving I would be a little bit concerned.
No I haven't done LC on this car, it's too new
I did LC multiple times on the 09 (at least a dozen times, probably more) and never ever had the smell

I never did multiple launches at a time.

I have done LC on my M3 maybe 5 times?
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      08-13-2011, 08:54 AM   #18
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Quote:
Originally Posted by HerrK View Post
Really - There are manual transmissions, automatic, & automated transmissions. Automated clutch SMG being merely a subset of the prefix "auto"transmission, however you cut the cheese.

1. automatic transmission - a transmission that automatically changes the gears according to the speed of the car.
2. automated transmission - a manual-style transmission operated by computer.
3. manual transmission - requires human interface to make the vehicle move and uses a driver-operated clutch.
I would further define the DCT as an Automated Clutch Transmission. The key difference being a traditional Automatic has a torque converter that never fully disengages. It merely slips when in drive at 0 MPH. Whereas the DCT disengages the clutches and is technically in neutral when at a stop light.
Ditto when shifting. The DCT disengages one clutch and engages the opposite one. An Automatic merely allows slippage when shifting.
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      08-14-2011, 12:43 AM   #19
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Quote:
Originally Posted by HerrK View Post
Really - There are manual transmissions, automatic, & automated transmissions. Automated clutch SMG being merely a subset of the prefix "auto"transmission, however you cut the cheese.

1. automatic transmission - a transmission that automatically changes the gears according to the speed of the car.
2. automated transmission - a manual-style transmission operated by computer.
3. manual transmission - requires human interface to make the vehicle move and uses a driver-operated clutch.
Sorry HerrK.
Thats OTT.

You may be yelling in font, but you just shot yourself down.

The DCT is an automated transmission. We agree on that.

My comment was about it baing called an AUTOMATIC transmission.
The Automated transmission is a new term, and when people say "auto", I dont think they are really saying automated by default, especially when they have used the exact term "automatic transmission" in the previous sentence.
Please read the thread before you flame.
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Last edited by Dr Stig 2; 08-14-2011 at 01:03 AM..
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      08-14-2011, 01:23 AM   #20
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Quote:
Originally Posted by persian54 View Post
Well the car still only has 300 miles on it

if it continues after 'break-in' I'll take it in

My tech is my friend, so maybe when we go out one night I can show it to him (err 'smell it' to him lol)
That's quite normal. I work at a BMW Dealership and the mechanics there have told me it'll take a few thousand miles for that smell to go away. Don't take it in for something trivial.
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      08-18-2011, 07:43 PM   #21
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Quote:
Originally Posted by Dr Stig 2 View Post
Well really. No. Seriously.

There is no hydaulic torque converter - just a pair of wet clutches.
It's not an auto, but a dual clutch.
As one wet clutch disengages, the other wet clutch engages...

It can slip either clutch, as a clutch would under manual control, but the computer determines how much.

Not an auto. Banish the thought. Never let it be said again. please.
You will give the DCT a bad name.


teagueAMX's definition of an "automatic" transmission:

Quote:
A mechanical device, otherwise described as a "black box", that transmits power at various ratios with respect to the input shaft speed vs output shaft speed, and, the device is capable of changing ratios automatically or manually as selected by the driver.
So, based on the definition above, are we taking about a MB 8 speed "automatic" transmission or a 7 speed DCT?

Not wanting to hurt anybody's feelings, but I'm simply saying the automotive industry has refined the concept. To you Stig, all those things you mentioned are what defines an "automatic". I'm suggesting an "automatic" is simply a box of parts.

The interesting thing is once you eliminate the torque converter, the clutch packs, the fluid modulation, and put regular gears back in there along with a 1:1 linking dual clutch, the "automatic" transmission becomes extremely efficient. My feelings there will always be a place for what some think of as an "automatic", but dct's will make them obsolete within a few years.

And lastly, I would disagree about the term "automated" when applied to the DCT. By comparison, M5/M6 had the SMG Sequential Manual Transmission which had a thin guise of automation (i.e., external servo actuation). It was a terrible interim step (between a full manual and "automatic") to satisfy those clambering for a Ferrari F1 transmission. I would apply the word "automated" when talking about something design for one purpose but automated to be used a different way.

In the case of the DCT, it was designed and built to work a certain way from inception. Furthermore, the DCT can't work without a computer to convert the driver's impulses to mechanical activity - automatically or manually. The DCT has virtually no resemblance to it's Neanderthal ancestor, the manual gearbox with a gear selection lever and foot peddle clutch.
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Last edited by teagueAMX; 08-19-2011 at 12:23 AM..
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