Clutch Slur

[weedavey]

If you time it right a slight lift on upchanges is quicker than a full throttle shift.

Seemed to work for me in the CSL Cup races

Really! I'll be experimenting with this next time im out then..

At what point did you lift? Just before, bang on or just after you clicked to shift?

[The Gorilla]

Hi,

I have always slightly backed off the
Throttle, when changing
gear, and find its much better.

Smoother, quicker, and less
issues.

Plus you do not transmit such aggressive
shock loads through the Transmission
drive train.

I believe all SMG 2 cars suffer some clutch
slur under heavy load, when warmed up,
its just that some drivers are better than others
at actually detecting it at full chat.

If you 'feather' your throttle pedal inputs when
driving the bends on circuit, ala the Senna / Schumacher club,
even on a CSL with SMG updates, you can actually
get ahead of the E.Gas [fly by wire] to the point
where the throttle pedal is being dabbed, but the
engine is no longer actually responding to the inputts.

ie, Throttle pedal is lifted but engine is still increasing revs.

Then go drive a S54 with a throttle cable, not E.Gas
and its a whole new world.

I think that some clutch slur is detected when
under load you have up-shifted quickly but the
stepper motor activated by the throttle pedal petom
are to a point still catching up,
so the ECU/DME 'hangs' for a split second which
gives the impression of clutch slur, or a slight delay
on upshifts, as its not instant.

As the CSL works on a Throttle load input, no MAF,
this combined with E.Gas, is I beleive more to do with
slow shifts or perceived 'clutch slur', than the actual clutch,
until the clutch is actually nearing its life cycle end.

This is borne by the claim, that 'clutch slur' can in
part be rectified by driving hard'

Regards,

The Gorilla.

[Dan_csl]

If you time it right a slight lift on upchanges is quicker than a full throttle shift.

Seemed to work for me in the CSL Cup races

Totally agree there...

Unless ABSOLUTELY FLAT OUT in either 4th gear or upwards I always slightly lift as well, was told to do this when I bought it and it would change better, and IMO it does :thumbs:

[weedavey]

Plus you do not transmit such aggressive
shock loads through the Transmission
drive train.

I Have been concerned with this since buying the car.

[SpineOnABap]

Never experienced clutch slur myself,

Maybe we drive them properly, Rob:whistle:

Sadly it's not caused by driving style, otherwise we could prevent it. It's caused by shit design. It's the only thing I really HATE about CSL, and it's been bugging me since 2003 so it's a good job I really like the rest of the car :hahaha:

[shimmy]

I have a gut feel that the clutch slur issue us an easy fix bit it's just that nobody has worked out what it is yet!

Does the M3 SMG have the same problem?

[danp]

Sadly it's not caused by driving style, otherwise we could prevent it. It's caused by shit design. It's the only thing I really HATE about CSL, and it's been bugging me since 2003 so it's a good job I really like the rest of the car :hahaha:

Is the design different from normal E46 M3 SMG? (apart from software)

They don't slur so much do they?

[SpineOnABap]

Don't know about the design, Dan. Something's different enough to cause this issue though.......


I had an E46 M3 SMG before the CSL and it didn't have this problem during the year I owned it.

[SpineOnABap]

I have a gut feel that the clutch slur issue us an easy fix bit it's just that nobody has worked out what it is yet!

You could well be right Shim! We (the CSL community) have been banging on about this issue since we first encountered it in 2003 - 7 years and still none the wiser. BMW clearly didn't care......

[The Gorilla]

Hi,

E46 M3 SMG 2 has a 'MAF' where the CSL does not.

The infamous CSL clutch slur is as a result
of the way the throttle inputs are received
by the ECU/DME and the commands it makes
based on the data received.

The 'Alpha N' type arrangement on the CSL
works on throttle/load there is no air
reading as such.

Regards,

The Gorilla.

[mattCSLnut]

Sadly it's not caused by driving style, otherwise we could prevent it. It's caused by shit design. It's the only thing I really HATE about CSL, and it's been bugging me since 2003 so it's a good job I really like the rest of the car :hahaha:

I had something resembling what's been described as "Clutch Slur" happen to me @ Bedford TD yesterday. SMG in S5, SPORT on , 2nd into 3rd full throttle and a BIG flat spot, with a delay in execration. Very strange :smt017 Keep in mind my clutch has been changed under warranty along with a new Duel mass flywheel only a year and 8000 miles ago.

[Bounce]

Don't know about the design, Dan. Something's different enough to cause this issue though.......


I had an E46 M3 SMG before the CSL and it didn't have this problem during the year I owned it.

I had an SMG M3 for 4 years before the CSL,and never had one problem with slur.

[shane@mbtech]

I had something resembling what's been described as "Clutch Slur" happen to me @ Bedford TD yesterday. SMG in S5, SPORT on , 2nd into 3rd full throttle and a BIG flat spot, with a delay in execration. Very strange :smt017 Keep in mind my clutch has been changed under warranty along with a new Duel mass flywheel only a year and 8000 miles ago.

What does this mean:smt017

What level was your fuel at? ,I had similar issues always out of a chicane with between 1/4 and empty tank. I try not to run too low on fuel on track now, never had the issue since.

Did you have dsc completely off? or in M track?


Slur as described here is clutch slip so your revs rise then slur back down as clutch bites. Your symptoms sound slighhtly different

[danr55]

so does changing to S1 for a couple of days then changing back seem to fix it?

Any other specific fixes?

Don't fancy driving in S1 just to find out it doesn't improve anything!:hahaha:

[shimmy]

be careful on track as said as it can feel like cluch slur a bit as you can get fuel starvation on long corners then onto the straight (but never had it at Bedford - but coppice at Donny it alwasy happens about 1/6 tank)