Clutch / Gearbox

[The Gorilla]

Hi,

I can not help but notice that over the last
few months as many of the CSL's start
to put on the miles, and there appears
quite a few using them repeatedly on the Track as well,
that Clutch and gearbox issues are starting
to become more or less the norm.

Many good points and useful observations
have been made, but it all feels a bit like
putting a 'plaster' over the wider issues and
hoping it will either go away or just sort
of fix itself.

The element of wear on the many components
involved in the SMG 11 process is unhelpful
as the mileage starts to increase, as with all
things of this design.

But the word 'Slur' really meaning slip is now
a common issue with many owners and drivers.

Just wondering if with the information, resources,
and the Technical data available, via this Forum,
that some sort of 'remeadial' or 'to do' type
info sheet could be prepared, or anything else
that that others feel may assist.

Just wondering how others viewed this.

I suppose if I see about 20 CSL cars for sale
shortly then I know what the common consenses
is !!

Regards,

The Gorilla.

[Dan]

I would be a good idea I think, I for one am someone who is suffering from this supposed 'slur' or as you say clutch slip, I tried the car in S6 with the DSC off this morning and it made no difference to how the car changed gear, there is constantly a slip and it's always there now, the only thing that makes it better is me lifting off on upshifts which tends I feel to put less strain on the car in general.

I'm not particularly impressed with this, a 60k car and huge manufacturer it should be spot on IMO, for BMW to have no real solution to this problem is very bad!

I'm a fickle (sp) fucker as it is so it wouldn't take a lot for me to sell the CSL on and try something else, seeing as it's not an everyday car for me anymore I hope BMW/Murkett's can cure it when it's in for it's inspection or I'll be CSL'less very soon... I have a very big itch for a Porka or a Ferrari again at the moment!

[grumps]

Yep with you on that idea! I love my csl but its been nothing but trouble in 6 months of ownership (alternator,rear springs,viscous fan radio,oil leak,battery, v belt tensioner and pulleys and now the clutch) and am also thinking of moving it on! should have got a gt3.
p.S and thats at 48k

[mickaldo]

Originally Posted by grumps

Yep with you on that idea! I love my csl but its been nothing but trouble in 6 months of ownership (alternator,rear springs,viscous fan radio,oil leak,battery, v belt tensioner and pulleys and now the clutch) and am also thinking of moving it on! should have got a gt3.
p.S and thats at 48k

wish id kept my gt3!

[glendog74]

I feel quite lucky in my 2 years ownership to have just had an alternator & throttle potentiometer go tits up! Owning a CSL has been a very positive experience for me

[shane@mbtech]

Mine has been great for the year I have owned it.

Its like any car, just the luck of the drawer.

Some may have a friday car

[Kev.H]

if you dont short shift it doesnt slur thus redline and its fine

[NZ_M3]

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

[Kev.H]

how do you do this one out of interest please ?

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.

[outnumbered]

Originally Posted by NZ_M3

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.

That's a good point. There was a lot of discussion about this 2-3 years ago over on mtorque/bm3w and I think it resulted in pretty much every CSL in the country spending a day at Murketts !