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NZ_M3 · 20-03-2010, 04:41 AM

Aren't you running a full drenth sequential box on your car Gorilla?? This issue shouldn't trouble you at all

Anyway ... back on topic

My take on this is three fold.

Yes there's a genuine software issue with the system that will clear if you catch it early - but it will eventually come back depending on the type of driving and driving style used.

Secondly, the mechanical side and this relates to the SAC clutch pack. The interface between this and the software isn't that great and over time the system either over or under-compensates for wear thus the experienced slip or slur.

Thirdly and this is when the software isn't updated consistently or reset periodically and the eventual clutch plate wears out or the flywheel becomes worn, or another part of the system (such as the release fork, release bearing, plastic sleeve guide) eventually wear out causing the system to 'catch'.

I have personally NEVER experienced the so called 3rd to 4th gear slur.

I have however experienced the take off slur and this was quickly corrected with a reset.

Now to the reset part: I have a suspicion that the dealerships may sometimes not be doing the correct reset on the software. After doing a bit more reading and playing with my Autoenginuity tool, it turns out there's actually 5 different commands that is involved with the SMG clutch.

First is a soft clutch reset (I suspect this is the same as the drive above 30mile/h, in neutral and pull both paddle back reset) - it reinitialises the system vis-a-vis the wheel speed rotation sensors.

Second is a Clutch Slip reset (this is by far the most noticeable and effective reset when you are experiencing s slight slur when taking off) - I do this reset on my car regularly and have not experienced another take off slur ever since.

Third is a clutch curve re-adaptation - this is an interesting one - I tried this on my car the other day and to my surprised it changed the whole dynamic of the way the car shifted and released the clutch. I have to honestly say that this is the MOST NOTICEABLE Reset of them all - whiplash is an understatement with this reset. I was almost a bit concerened that I'd broken my car. But after taking the car for a good moderate drive in different shift speed settings with part and full open throttle shifts I could immediately feel the system "adapting" to the driving style, eventually it became crisp and sharp with no hint of hesitation or clutch slur. I believe this is the full initialisation that the dealership uses when a new clutch pack is installed or a SMG pump is changed.

The fourth is called the clutch take up point reset - I usually do this in conjunction with the clutch slip reset and it works well and take all of 2 seconds to do. With this reset the clutch pack is simply opened and closed once.

The fifth and is one that I have not tried is the longitudinal acceleration sensor reset. This is part of the SMG system and on the system it is a Mandatory Reset whenever the SMG pump has been replaced. I have not tried this, so am not sure what it does exactly yet.

My take on this whole saga.

Yes there's an issue, but being a widely reported item I do think that owners actively 'look' for it, and we hear it on the net as a result.

I do believe that the only way around this is:

1. Buy a tool or buddy up with your indy shop with one and reset your system on a regular basis before anything mechanical is worn;

2. (and somebody really needs to try this out) - use a Non SAC clutch kit with the exact same clamping pressure as the OEM system and if possible run a single mass flywheel rather than a dual mass one (but not a solid centre clutch, a sprung one if you like your drivetrain components).

I thought it might be helpful also if we all record our driving styles and see if there's a common denominator, I've deviced the following template:

When Engine Cold (shift speed): s3
When Engine at operating temp (shift speed): s4
Shift speed used at track : s5 or sometimes s4
Lift on upshift: No
Lift on downshift: sometimes
Full throttle redline upshifts periodically: yes
Part throttle redline upshifts : never
Launch Control use: never
Software reset period: usually every two to three weeks

20-03-2010, 04:41 AM	#8
NZ_M3 S5, Sport On, DSC M-track Join Date: Jun 2008 Location: Auckland, New Zealand Posts: 1,434 Casino cash: $13579	Aren't you running a full drenth sequential box on your car Gorilla?? This issue shouldn't trouble you at all Anyway ... back on topic My take on this is three fold. Yes there's a genuine software issue with the system that will clear if you catch it early - but it will eventually come back depending on the type of driving and driving style used. Secondly, the mechanical side and this relates to the SAC clutch pack. The interface between this and the software isn't that great and over time the system either over or under-compensates for wear thus the experienced slip or slur. Thirdly and this is when the software isn't updated consistently or reset periodically and the eventual clutch plate wears out or the flywheel becomes worn, or another part of the system (such as the release fork, release bearing, plastic sleeve guide) eventually wear out causing the system to 'catch'. I have personally NEVER experienced the so called 3rd to 4th gear slur. I have however experienced the take off slur and this was quickly corrected with a reset. Now to the reset part: I have a suspicion that the dealerships may sometimes not be doing the correct reset on the software. After doing a bit more reading and playing with my Autoenginuity tool, it turns out there's actually 5 different commands that is involved with the SMG clutch. First is a soft clutch reset (I suspect this is the same as the drive above 30mile/h, in neutral and pull both paddle back reset) - it reinitialises the system vis-a-vis the wheel speed rotation sensors. Second is a Clutch Slip reset (this is by far the most noticeable and effective reset when you are experiencing s slight slur when taking off) - I do this reset on my car regularly and have not experienced another take off slur ever since. Third is a clutch curve re-adaptation - this is an interesting one - I tried this on my car the other day and to my surprised it changed the whole dynamic of the way the car shifted and released the clutch. I have to honestly say that this is the MOST NOTICEABLE Reset of them all - whiplash is an understatement with this reset. I was almost a bit concerened that I'd broken my car. But after taking the car for a good moderate drive in different shift speed settings with part and full open throttle shifts I could immediately feel the system "adapting" to the driving style, eventually it became crisp and sharp with no hint of hesitation or clutch slur. I believe this is the full initialisation that the dealership uses when a new clutch pack is installed or a SMG pump is changed. The fourth is called the clutch take up point reset - I usually do this in conjunction with the clutch slip reset and it works well and take all of 2 seconds to do. With this reset the clutch pack is simply opened and closed once. The fifth and is one that I have not tried is the longitudinal acceleration sensor reset. This is part of the SMG system and on the system it is a Mandatory Reset whenever the SMG pump has been replaced. I have not tried this, so am not sure what it does exactly yet. My take on this whole saga. Yes there's an issue, but being a widely reported item I do think that owners actively 'look' for it, and we hear it on the net as a result. I do believe that the only way around this is: 1. Buy a tool or buddy up with your indy shop with one and reset your system on a regular basis before anything mechanical is worn; 2. (and somebody really needs to try this out) - use a Non SAC clutch kit with the exact same clamping pressure as the OEM system and if possible run a single mass flywheel rather than a dual mass one (but not a solid centre clutch, a sprung one if you like your drivetrain components). I thought it might be helpful also if we all record our driving styles and see if there's a common denominator, I've deviced the following template: When Engine Cold (shift speed): s3 When Engine at operating temp (shift speed): s4 Shift speed used at track : s5 or sometimes s4 Lift on upshift: No Lift on downshift: sometimes Full throttle redline upshifts periodically: yes Part throttle redline upshifts : never Launch Control use: never Software reset period: usually every two to three weeks Last edited by NZ_M3; 20-03-2010 at 04:51 AM.