clutch slurrrr

[shane@mbtech]

I'll be phoning Andy tomorrow, the software updates have really upset the car :banghead: put your foot down and the dsc kicks in big time ! just no pull and feels like you've knocked the gear stick into neutral :banghead:

try turning traction off

[glendog74]

try turning traction off

:hahaha: :hahaha:

[shimmy]

Unless you pay a contribution, which I doubt they will let you, your new clutch will only have warranty until your warranty expires on the clutch they are replacing now. So you wont get 2 years on it I'm afraid shimmy.

i can see ill have to try something crafty:thumbs:

[Mark CSL]

i can see ill have to try something crafty:thumbs:

There is the cheeze thing again dont get Daz and Alex started Shimmy :hahaha::hahaha:

[NZ_M3]

Shimmy is in part right, there is certainly an issue in the interface between the clutch and the software, the problem is that the software is unable to adjust fast enough to allow for mechanical wear that the clutch naturally suffers, this wear also manifests itself in dirt build up etc, basically anything that causes the mechanical interface to differ (wear or lots of time in traffic - essentially the same thing to some extent).

I am more on the camp that it has more to do with the SAC (self adjusting clutch pressure plate) rather than the software not accounting for wear to be honest. The normal 6 speed get this on some occassions also - I certainly had it in my 3 pedal 6 speed M3 that was bad enough to warrant the dealer to swap out the clutch - when it came out, it was like new, but the self adjusting clutch mechanism had somehow locked itself and stopped moving.

Here's a possible experiment for somebody - get a pressure plate the same clamping rate as the OEM LuK unit but without the self adjusting mechanism - I wonder if it'll stop all that slurring that's going on!!.

To be honest though, I've only ever experienced the slurring on take off and never on shifting up or down - but then again I never use my car in traffic :supz:

The solution is regular re-calibration, think of it like rebooting your PC, every now and then you do that to clear out memory, IE cache etc etc, the PC doesn't 'need' it per se but it works better after its done. Sadly this re-calibration can only be done with a handful of diagnostic tools, we sue the Autologic (which is by far the most expensive but also the most sophisticated, with upgrades its nearly £15k) or even an older GT1 but these are rapidly getting out of date. BMW continually update the software (I'm not sure if they're trying to fix it or whatever) so you do need things updating.

Couldn't agree more. I am making it a habit of this now with my Autoenginuity tool. It takes no more than 10 minutes or so to reset everything and once it's done, it feels great!!

[s.mac]

try turning traction off

Quote:
Originally Posted by lawsy
try turning traction off

:hahaha: :hahaha: Yesterday 08:37 PM

:wanker:



:smt044

thats how I get round it :birdman:

[The Gorilla]

Hi,

The ''SAC'' system is as NZ_M3 says at the heart
of a lot of the Clutch issues.

Talk to any spirted E39 M5 Owner and they
will tell you all about clutch slip [Slur].

Put a 850i CSi V12 Clutch pressure plate on a
E39 M5 and you will not have a clutch slur
problem, but you will start ripping out std
rear ARB brackets and Propshaft bearings
for a past time.

The SAC in trying to adjust itself so that the
distance travelled everytime is always the same,
does not function 100 % correctly, never has,
never will, its an inherent design flaw.

It works slighty better on a real Manual Car to a point
but does not like large sharp input loads.

The only two issues with using a uprated Pressure
plate from Sachs etc, is that you have to get into
the habit of keeping it re-calibrated as stated,
and you will start pushing much greater stresses
through the drivetrain.

The 'slur' does in part assist with reducing
drive train load.

Why do you think the E60 M5 came with
the magic 100 BHP sport button.

Most dealers were instructed via BMW to upload
Software changes to the really early SMG Cars as they
were chewing up the Drive train quicker than
BMW could make the replacement parts.

From there on in the cars were supplied from
the factory with the amended and albeit
slower/softer Gearbox software.

SMG is on the whole quite good when its
all working properly, problem is there is
just to much to it, and wear does bring
on functionality issues and problems.

I do not think its possible for a 100% fix for what
was in part flawed from the outset.

Regards,

The Gorilla.

[_Nathan_]

My car had the early software put back on it as it was supposed to be faster.

I've read that you shouldn't use the uprated sachs clutch with a drexler plated diff as the driveline becomes too harsh and starts breaking things - I've got a standard clutch and a plated diff - what setup do you run with your drexler?

[The Gorilla]

Hi,

Nathan- I am currenly running a S50 B32 Dual Mass
Flywheel, with a S50 B32 Pressures plate, and the
S54 Standard Disc.

The S50 B32 Gearbox input shaft is a smaller
diameter, so you use the S54 Disc and
have 2mm skimmed out the flywheel so
the disc is correct distance.

It all seems to work quite well.

I was going to swap out the Dual Mass
Flywheel for a Single Steel one which is about
5kg lighter, so that it does not start
playing around with the SMG, but
allows a little better throttle response,
without getting into 'stall' issues.

The S54 Clutch although the same 240mm
diameter is a different bolt pattern onto the
flywheel.

The S50 B32 std Pressure plate is not
'SAC' and takes around 380/400 bhp comfortably.

Its about 15% less clamping force than the
SACHS uprated one, and about 10 % more
than the S54 'SAC' one.

I did try a 2.5 TD Clutch pressure plate, and
interestingly the Disc in that kit was exactly the same as
the E46 M3 but with a smaller gearbox shaft spline and
thrust bearing.

The 2.5 TD Pressure plate worked fine, but I just
think the S50 B32 is proven.

In the picture, top is S54 Alloy Flywheel,
centre is S54 Dual Mass Flywheel, and
lower one is S50 B32 Dual Mass Flywheel.

Regards,

The Gorilla.

[grumps]

Thank guys for all your help and advise,spoke to dick lovitt (supplying dealer)for warranty or goodwill contribution as very small mileage since purchase five months ago and they basically said sod off ! Bless them.

[glendog74]

spoke to dick lovitt (supplying dealer)for warranty or goodwill contribution as very small mileage since purchase five months ago and they basically said sod off ! Bless them.

How nice - good to see customer support exists there! :banghead:

[NZ_M3]

I was going to swap out the Dual Mass
Flywheel for a Single Steel one which is about
5kg lighter, so that it does not start
playing around with the SMG, but
allows a little better throttle response,
without getting into 'stall' issues.

That'd be mighty harsh on your drivetrain and gearbox components with that setup - you'd basically be running a full solid clutch setup with zero dampening or vibration absorption characteristics.

Interesting what you've managed to mix and match to get working though - worth investigating for sure.

Also what pressure plate's the one on the top right corner of your picture?

[The Gorilla]

Hi,

NZ_M3 - The pressure plate is from a
E39 525 Diesel 1998.

They make about 390/410 Nm of Torque
so it has enough clamping pressure
and fits straight onto a E46 M3 Flywheel
and you can retain the standard clutch
disc.

If and when I change to single mass
steel flywheel, I would use a sprung Hub
clutch disc, but it would not do
much for the loads through the
drivetrain but would assist with
absorbtion/vibration and maybe gearbox
chatter in 1st.

Regards,

The Gorilla.

[SpineOnABap]

The Gorilla - I have a question for you and it's rather technical....


Why are all you posts so 'narrow'? :hahaha: These days most of us use a monitor that can support a full 80 characters across the screen

[NZ_M3]

The Gorilla - I have a question for you and it's rather technical....


Why are all you posts so 'narrow'? :hahaha: These days most of us use a monitor that can support a full 80 characters across the screen

LOL ... at a guess, he's typing his replies out on an iPhone perhaps or similar?