Another M6 clutch/gearbox issue - new owner!

Another M6 clutch/gearbox issue - new owner!

Author
Discussion

flange.

Original Poster:

28 posts

177 months

Monday 2nd March 2015
quotequote all
Hi folks

I know there are roughly a metric ton of these threads on here but I think I must have read every single one and I'm still not 100% sure on a few things.

Picked up the car last friday and LOVE IT. Wanted one for a long time after getting it handed to me in my RS4 by an M5 driving mate. Its so fast its not funny, proper bit of kit. However, all is not wonderful in clutch land. Once up to temperature it starts juddering in a major way, to the point where tonight its shaking like the proverbial bobbing dog. For some unknown reason it also wants to set off in second when in D. Give it the beans down the local dual carriageway, there's a pretty major 'shunt' on the down change, but it seems pretty delayed and somewhat out of sink with the throttle 'blip' if that makes sense.

The judder is most pronounced in first setting off from a standstill, the shunt thing on the down change only started happening tonight. Any ideas? Car has done 61k, no mention of clutch change or the like in the history.

If its the clutch/flywheel/release bearing issue, assuming I can buy the parts and have a local indy fit them? If so, anyone know of a decent Indy in the Kent/East Sussex area?

Schermerhorn

4,342 posts

188 months

Tuesday 3rd March 2015
quotequote all
How miles has it done?

If it is juddering then it is probably a hardware issus so you will have to replace

Clutch
Flywheel
Release bearing
9 x flywheel bolts
Clutch position sensor

And/or

Clutch fork
Brass ball pin

That lot will cost over £1000

Labour £300-500.

Shaoxter

4,048 posts

123 months

Tuesday 3rd March 2015
quotequote all
Just wanna check - are you sure you're driving it properly? It's not like an RS4 where you can just put your foot down from a standstill. The traction control is quite aggressive and blasting it off the line with no throttle control will result in the TC juddering the car. Also on the downshifts is your foot on the throttle?

If it is a clutch issue and you've only just got the car then go back to the dealer? Assuming you bought it from a dealer that is. And did you not notice this on the test drive?

Setting off in second in D is normal. But don't drive in D!! Remember it's a manual box so put it in manual mode and try to drive it like one.

flange.

Original Poster:

28 posts

177 months

Tuesday 3rd March 2015
quotequote all
Hi

You could well be right, although I'm not sure the juddering from stand still is due to the TC as I'm barely feathering the throttle? Seems to pull better if I give it some more beans, however its still juddering quite severely.

Downshifts - foot is off the throttle (from memory), will try it again tonight to make sure. I've got no warning lights on the dash though, if that makes any difference?

Car has done 61k

rassi

2,447 posts

250 months

Tuesday 3rd March 2015
quotequote all
Juddering in stop/start conditions is a classic symptom of a clutch on its way out - luckily it happened to mine while under warranty, but both clutch and flywheel + the throw-out bearing were replaced. It will only get worse, and if you catch it early enough a flywheel is not necessary, but you will only know once they open it and at 61K it is probably due.

Mine was fine afterwards, and the changes in all gears smoother and (perceived) slightly quicker.

If you just picked it up from a dealer, it should be done under warranty.

jcolley

183 posts

125 months

Tuesday 3rd March 2015
quotequote all
Start by having the dealership perform the SMG adaptation procedures (all 3 steps) in DIS, INPA, or ISTA/D. Often, it's no more than a drift of the calibration over the years. This is about an hour of labor and nothing more than computer diagnostics.

If it doesn't improve after that, then look for a component wear/replacement strategy.

Schermerhorn

4,342 posts

188 months

Wednesday 4th March 2015
quotequote all
jcolley said:
Start by having the dealership perform the SMG adaptation procedures (all 3 steps) in DIS, INPA, or ISTA/D. Often, it's no more than a drift of the calibration over the years. This is about an hour of labor and nothing more than computer diagnostics.

If it doesn't improve after that, then look for a component wear/replacement strategy.
My dealership did this. They had my car in for a few days and told me they did the SMG adaptation and cleared some fault codes etc.

6 minutes into my journey (still on the same main road) I got the dreaded BONG again in the iDrive. I was so annoyed because I knew what to expect from these guys by this stage.

jcolley

183 posts

125 months

Wednesday 4th March 2015
quotequote all
Schermerhorn said:
My dealership did this. They had my car in for a few days and told me they did the SMG adaptation and cleared some fault codes etc.

6 minutes into my journey (still on the same main road) I got the dreaded BONG again in the iDrive. I was so annoyed because I knew what to expect from these guys by this stage.
That's both surprising and not surprising at the same time.

What is surprising is that most dealership techs have such a lack of fundamental understanding of how the SMG hardware and software actually work independently and as a whole that they are reluctant to perform the adaptation routines because nothing in ISTA/D has guided them to it specifically. If the batch of error codes read from the SMG (in some cases there are none, just a complaint) doesn't generate a test routine which includes adaptation, they don't understand why it should be done or how it would help.

What is not surprising is that it didn't solve the error codes. The SMG module (computer) is extremely good at reporting exactly what is wrong, just not in a basic enough syntax for a tech to understand unless they "get" how the whole thing works to start with. I'm not kidding when I say it's very simple to me because it's almost an identical miniaturized version of the submarine hydraulic plants I've been working with for 20 years. There are very few error codes which can be solved with adaptation as it does nothing more than calibrate the sensors to the actuators.

Error codes tell almost everything though. Datalogging the SMG module tells more, but I would guess outside of the Getrag engineers and the BMW engineers who assembled this engine/transmission package, there are less than 20 people in the world who have really looked into it.

There is a great piece of datalogging software called "Testo" written by a guy on one of the other forums and it uses the EDIABAS interface (the underlying component of INPA, DIS, and ISTA-P/D) to query parameters for *every single module on the car*. It has a rough interface because...well...it's free, but the guy has done brilliant work. I have logged a few parameters simultaneously to see what would be useful, but have nowhere near enough free time to play with it as much as I would like.

Think about this for clutch jutter and things to log:
- DME idle actuator positions
- DME throttle actuator positions
- SMG PLCD (clutch position) ordered
- SMG PLCD actual position (there is a lag)
- DME engine RPM-
- DME engine torque (yes, the DME knows what it is making)
- DME load torque (it also knows how much resistance there is to moving the car based on speed and current gear selected)
- DSC wheel rear speeds

If you had all those things graphed together, it would be much easier to tell *why* the thing really feels the way it does. Does the idle actuator position pulsate causing the jerkiness? Does the clutch position cycle? Is it because of a hydraulic leak and the SMG didn't order it?

A bit of rambling there, apologies, but I really do love this transmission. Enough so that I want to see a housing built to convert it to a transaxle similar to what Autobionics has done for an Ultima GTR build.

http://www.autobionics.co.uk/ABV-10%20Part%207.htm...

Schermerhorn

4,342 posts

188 months

Wednesday 4th March 2015
quotequote all
jcolley said:
Schermerhorn said:
My dealership did this. They had my car in for a few days and told me they did the SMG adaptation and cleared some fault codes etc.

6 minutes into my journey (still on the same main road) I got the dreaded BONG again in the iDrive. I was so annoyed because I knew what to expect from these guys by this stage.
That's both surprising and not surprising at the same time.

What is surprising is that most dealership techs have such a lack of fundamental understanding of how the SMG hardware and software actually work independently and as a whole that they are reluctant to perform the adaptation routines because nothing in ISTA/D has guided them to it specifically. If the batch of error codes read from the SMG (in some cases there are none, just a complaint) doesn't generate a test routine which includes adaptation, they don't understand why it should be done or how it would help.

What is not surprising is that it didn't solve the error codes. The SMG module (computer) is extremely good at reporting exactly what is wrong, just not in a basic enough syntax for a tech to understand unless they "get" how the whole thing works to start with. I'm not kidding when I say it's very simple to me because it's almost an identical miniaturized version of the submarine hydraulic plants I've been working with for 20 years. There are very few error codes which can be solved with adaptation as it does nothing more than calibrate the sensors to the actuators.

Error codes tell almost everything though. Datalogging the SMG module tells more, but I would guess outside of the Getrag engineers and the BMW engineers who assembled this engine/transmission package, there are less than 20 people in the world who have really looked into it.

There is a great piece of datalogging software called "Testo" written by a guy on one of the other forums and it uses the EDIABAS interface (the underlying component of INPA, DIS, and ISTA-P/D) to query parameters for *every single module on the car*. It has a rough interface because...well...it's free, but the guy has done brilliant work. I have logged a few parameters simultaneously to see what would be useful, but have nowhere near enough free time to play with it as much as I would like.

Think about this for clutch jutter and things to log:
- DME idle actuator positions
- DME throttle actuator positions
- SMG PLCD (clutch position) ordered
- SMG PLCD actual position (there is a lag)
- DME engine RPM-
- DME engine torque (yes, the DME knows what it is making)
- DME load torque (it also knows how much resistance there is to moving the car based on speed and current gear selected)
- DSC wheel rear speeds

If you had all those things graphed together, it would be much easier to tell *why* the thing really feels the way it does. Does the idle actuator position pulsate causing the jerkiness? Does the clutch position cycle? Is it because of a hydraulic leak and the SMG didn't order it?

A bit of rambling there, apologies, but I really do love this transmission. Enough so that I want to see a housing built to convert it to a transaxle similar to what Autobionics has done for an Ultima GTR build.

http://www.autobionics.co.uk/ABV-10%20Part%207.htm...
I love this gearbox too. I managed to 'work out' how to drive it smoothly within the first 1000m on my first test drive.

Your expertise on this transmission is second to none and you are probably among those special 20 people on earth who know it inside out.

My dream combo would like an Ultima/Radical car with this S85 engine and the 7 speed DCT gearbox coupled with an exhaust blown diffuser with a special engine map that still blows maximum exhaust gasses into the diffuser even off throttle to pin the rear end down in medium/fast sweeping corners.

This engine is pure art it really is. It would not be out of place in a racing/ GT3 car if the rev limit could be raised to 10-12000rpm.

Christy O'Rourke

30 posts

123 months

Wednesday 4th March 2015
quotequote all
+1 on the sentiment to Jim's extensive knowledge of how these machines work, you sir are a truly gifted Engineer!

Christy O'Rourke

30 posts

123 months

Wednesday 4th March 2015
quotequote all
+1 on the sentiment to Jim's extensive knowledge of how these machines work, you sir are a truly gifted Engineer!

Helicopter123

8,831 posts

155 months

Wednesday 4th March 2015
quotequote all
flange. said:
Hi folks

I know there are roughly a metric ton of these threads on here but I think I must have read every single one and I'm still not 100% sure on a few things.

Picked up the car last friday and LOVE IT. Wanted one for a long time after getting it handed to me in my RS4 by an M5 driving mate. Its so fast its not funny, proper bit of kit. However, all is not wonderful in clutch land. Once up to temperature it starts juddering in a major way, to the point where tonight its shaking like the proverbial bobbing dog. For some unknown reason it also wants to set off in second when in D. Give it the beans down the local dual carriageway, there's a pretty major 'shunt' on the down change, but it seems pretty delayed and somewhat out of sink with the throttle 'blip' if that makes sense.

The judder is most pronounced in first setting off from a standstill, the shunt thing on the down change only started happening tonight. Any ideas? Car has done 61k, no mention of clutch change or the like in the history.

If its the clutch/flywheel/release bearing issue, assuming I can buy the parts and have a local indy fit them? If so, anyone know of a decent Indy in the Kent/East Sussex area?
OP has had car for less than a week do surely just take back to dealer and get fixed under warranty?

thegreatdogwood

299 posts

196 months

Wednesday 4th March 2015
quotequote all
Helicopter123 said:
OP has had car for less than a week do surely just take back to dealer and get fixed under warranty?
No mention of a dealer in his post - could have been private from someone who knew clutch was on way out....

Shaoxter

4,048 posts

123 months

Thursday 5th March 2015
quotequote all
thegreatdogwood said:
Helicopter123 said:
OP has had car for less than a week do surely just take back to dealer and get fixed under warranty?
No mention of a dealer in his post - could have been private from someone who knew clutch was on way out....
If it was a private sale surely he would have test driven it extensively? scratchchin

longintheleg

551 posts

142 months

Thursday 5th March 2015
quotequote all
Shaoxter said:
thegreatdogwood said:
Helicopter123 said:
OP has had car for less than a week do surely just take back to dealer and get fixed under warranty?
No mention of a dealer in his post - could have been private from someone who knew clutch was on way out....
If it was a private sale surely he would have test driven it extensively? scratchchin
Sometimes these things can hide themselves.

If it was a private sale then the chap probably doesn't need his nose rubbing in the fact that he perhaps overlooked the issue. smile

Have you run any diagnostics yet?