M6 gearbox fault
Discussion
Drove my 2005 M6 on sunday morning , allowing the oil to warm up and then proceded to put the M button on for a grin factor of 10 . When all of a sudden up came the RED COG and drive moderately etc etc . My heart sunk ,I then switched of left it for 2 mins and started the car again and low and behold it disappeared .
this happened again later that day . I Did no more but called my local BMW dealership in Norwich and booked it in . Thankfully I bought a Car with a Full BMW warranty , thank God I did . As low and behold I got the call from the service department saying that a new Gearbox is too be fitted . I am very impressed with the no nonsense approach of this dealership who by the way gave me a loan car as well . The moral of this story is don't buy a M6 without a BMW warranty . Is this a common fault and what causes it so I can prevent it happening again , as other then this they are quiet robust . ARE'NT THEY ???
this happened again later that day . I Did no more but called my local BMW dealership in Norwich and booked it in . Thankfully I bought a Car with a Full BMW warranty , thank God I did . As low and behold I got the call from the service department saying that a new Gearbox is too be fitted . I am very impressed with the no nonsense approach of this dealership who by the way gave me a loan car as well . The moral of this story is don't buy a M6 without a BMW warranty . Is this a common fault and what causes it so I can prevent it happening again , as other then this they are quiet robust . ARE'NT THEY ???
I too had a new gearbox fitted to my 2005 M6 in December last year. However I had no errors flag up but they found metallic deposits in the oil which eventually made them deem a new box was needed. I also got a new clutch and flywheel included due to "consequential" damage. A warranty is definitely needed with these cars, I've also had a new thermostat, sat-nav drive and alternator done. Bit of a pain having to pay the excess but better than the 5 figure costs that would have been incurred. SMG is a fickle thing, how have you found yours to behave at low load gearchanges and stop/start driving up till now?
Do you get clunky/noisy gearchanges, particularly if you let it downshift itself from 3rd to 2nd to 1st at low speeds? Mine did this before the new box and is still the same after the new box so I guess it's an inherant trait of the design, unless mine is a lone case! Also if you are rolling to a stop in either 1st or 2nd gear off the throttle does your clutch release quite aggressively, seemingly lurching the car forward just before you stop? I'm just trying to get some perspective on some of my cars driveability quirks.
m6 Bruce said:
The moral of this story is don't buy a M6 without a BMW warranty .
Cannot echo this statement enough. My 2005 M6 has just been booked in for a new high pressure oil pump or something. £1700 plus over a days labour apparently, a near £3K job cost all under warranty.BMW have always been faultless with getting work done under warranty too.
jon- said:
Yet so many of us run the SMG box in an E46 M3 without warranties
I was thinking the same thing the other day. On the M5 and M6 models it is a case of when and not if the gearbox will need replacing. I've got 2 years AUC warranty on mine. So far I've had to use it 3 times already in just over 8 weeks. If I didn't have one, I'd be a couple of grand short easily.MCambridge said:
Just to add,
I had the 3 stage SMG adaptation performed recently by BMW:
Teach characteristic curve
Adapt complete transmission
Teach clutch slip point
and it really smoothed out the gear box for me (E63 M6).
How much did it cost to get this done? Which dealer did it for you?I had the 3 stage SMG adaptation performed recently by BMW:
Teach characteristic curve
Adapt complete transmission
Teach clutch slip point
and it really smoothed out the gear box for me (E63 M6).
Edited by MCambridge on Friday 7th February 13:03
ChrisMCoupe said:
Cannot echo this statement enough. My 2005 M6 has just been booked in for a new high pressure oil pump or something. £1700 plus over a days labour apparently, a near £3K job cost all under warranty.
BMW have always been faultless with getting work done under warranty too.
Did you have VANOS rattle as a symptom?BMW have always been faultless with getting work done under warranty too.
MCambridge said:
Just to add,
I had the 3 stage SMG adaptation performed recently by BMW:
Teach characteristic curve
Adapt complete transmission
Teach clutch slip point
and it really smoothed out the gear box for me (E63 M6).
Your post prompted me to look this up and sure enough there's a good DIY on M5board.com. Just did it on my car (2007 M5 w/51K miles and about 12K on a new clutch) and the first gear standing start is much smoother. Before it felt like someone with poor clutch control was not coordinating the throttle input and clutch pedal - much smoother and enjoyable now. Reminds me of when the new clutch was fitted - much nicer to drive. Thanks for the nudge!I had the 3 stage SMG adaptation performed recently by BMW:
Teach characteristic curve
Adapt complete transmission
Teach clutch slip point
and it really smoothed out the gear box for me (E63 M6).
Edited by MCambridge on Friday 7th February 13:03
AW10 said:
MCambridge said:
Just to add,
I had the 3 stage SMG adaptation performed recently by BMW:
Teach characteristic curve
Adapt complete transmission
Teach clutch slip point
and it really smoothed out the gear box for me (E63 M6).
Your post prompted me to look this up and sure enough there's a good DIY on M5board.com. Just did it on my car (2007 M5 w/51K miles and about 12K on a new clutch) and the first gear standing start is much smoother. Before it felt like someone with poor clutch control was not coordinating the throttle input and clutch pedal - much smoother and enjoyable now. Reminds me of when the new clutch was fitted - much nicer to drive. Thanks for the nudge!I had the 3 stage SMG adaptation performed recently by BMW:
Teach characteristic curve
Adapt complete transmission
Teach clutch slip point
and it really smoothed out the gear box for me (E63 M6).
Edited by MCambridge on Friday 7th February 13:03
I did a fair bit of reading (mostly on the M5board) before having it done. Also from what I have gathered the general consensus is to perfrom the adaption periodically. The reason is explained quite well in post 52 http://www.m5board.com/vbulletin/e63-bmw-m6-forum-...
The guy (jcolley) who wrote post 52 seems to know what he is on about, if you read some of his posts on the M5board you should see why.
Edited by MCambridge on Monday 10th February 14:04
Edited by MCambridge on Monday 10th February 14:05
Greetings gents. 
I haven't posted in the M forum here before, but have been lurking in the Ultima GTR section a bit while contemplating jumping ship from BMW.
Glad to see the word is getting around more, it's absolutely a shame what has happened to the value of our cars and I feel the SMG bears a large bit of responsibility for that.
My background is not automotive, so I can't claim direct competency in the field, but I have worked on mechanical and electrical systems for the last 18 years with a large part of that being hydraulic systems. The SMG falls neatly into that category, so it intrigues me and I've studied it quite a bit.
My personal feeling is the majority of complaints owners had about the SMG could have been alleviated by having the sensors recalibrated periodically (adaptation or "teach-in" in BMW parlance). It's a function embedded in the dealer's diagnostic software (ISTA, the older DIS, or more technical INPA) which is run every time a transmission is removed and reinstalled, particularly when a clutch is replaced. I honestly think a large number of cars were prescribed as "needing a clutch and flywheel" when the reality is, a recalibration is all that was needed. Unfortunately, TIS (BMW's electronic service manual) specifies to perform this when replacing the clutch, so the problem was cured when the car left the shop yet could have carried on for quite a while with the old clutch and flywheel.
I have noticed quite a bit of variation in shift "quality" in my car (11/05 build M5) with changes in outside temperature as well. While there is temperature compensation built in to the software, I'm not convinced it works quite as well as it should. Consequently, I have found the smoothest and fastest shifting for my 73k mile SMG came from performing the adaptation routine when the transmission was "properly" warmed up after a grin-inducing drive. Most shops will probably scoff at the idea, but give it a try and see for yourself how it feels.
Any questions, fire away. Like I said, I'm not in the field, but I do have an unhealthy obsession for this car and get a bit OCD about figuring out how things work.
Cheers
I haven't posted in the M forum here before, but have been lurking in the Ultima GTR section a bit while contemplating jumping ship from BMW.Glad to see the word is getting around more, it's absolutely a shame what has happened to the value of our cars and I feel the SMG bears a large bit of responsibility for that.
My background is not automotive, so I can't claim direct competency in the field, but I have worked on mechanical and electrical systems for the last 18 years with a large part of that being hydraulic systems. The SMG falls neatly into that category, so it intrigues me and I've studied it quite a bit.
My personal feeling is the majority of complaints owners had about the SMG could have been alleviated by having the sensors recalibrated periodically (adaptation or "teach-in" in BMW parlance). It's a function embedded in the dealer's diagnostic software (ISTA, the older DIS, or more technical INPA) which is run every time a transmission is removed and reinstalled, particularly when a clutch is replaced. I honestly think a large number of cars were prescribed as "needing a clutch and flywheel" when the reality is, a recalibration is all that was needed. Unfortunately, TIS (BMW's electronic service manual) specifies to perform this when replacing the clutch, so the problem was cured when the car left the shop yet could have carried on for quite a while with the old clutch and flywheel.
I have noticed quite a bit of variation in shift "quality" in my car (11/05 build M5) with changes in outside temperature as well. While there is temperature compensation built in to the software, I'm not convinced it works quite as well as it should. Consequently, I have found the smoothest and fastest shifting for my 73k mile SMG came from performing the adaptation routine when the transmission was "properly" warmed up after a grin-inducing drive. Most shops will probably scoff at the idea, but give it a try and see for yourself how it feels.
Any questions, fire away. Like I said, I'm not in the field, but I do have an unhealthy obsession for this car and get a bit OCD about figuring out how things work.
Cheers
Hi jcolley, thanks for the insight. What kind of variation in shift quality do you tend to see? I'm looking to see if my gearshift quirks/clunks/noises are similar to yours. I had a new gearbox, clutch and flywheel less than 2000 miles ago yet my shifts and clutch "openings" are still not of the quality I'd expect from a new transmission. Cheers
It's pretty dramatic. I bought my car about 12k miles ago coming out of an '06 E46 M3. The transmission in that car was very smooth, even with an ESS S/C and a 4.10 rear. When I traded it for the E60, I really didn't like what I felt and knew it couldn't be right, regardless of what the dealer techs all say ("oh, that's normal for SMG"...BS).
I used ISTA/D to perform the adaptation and there was an immediate improvement, but still not quite right. I keep my laptop in the car usually and one day after driving back from lunch, I was so frustrated with it that I performed the adaptation again while sitting in the parking lot at work. The transmission was nice and warm and the result was an SMG that actually shifted smoothly.
Previously, I always felt like the SMG rev-matched properly, but then blew it trying to guess the correct throttle setting as it let out on the clutch. It felt jerky on the let-out and no matter how I tried to apply the right pedal, I could not get a smooth shift. I never had that problem on the E46 and that SMG was an afterthought design converting a 6MT to automated box. The GS7S47BG SMG III was designed from the ground up to be an automated box and clearly something was amiss. The SMG III can be extremely smooth or a miserable experience.
The more I started reading about the transmission, the more I realized what I feel are shortcomings as a result of trade-offs between manufacturing cost and fail-safe design.
First off, is position sensing:
- The SMG III uses 6 hydraulic control valves to control the motion of 5 actuators. The precise position of those control valves is essential to the smooth and accurate movement of those 5 actuators. However, there is no direct position measurement of the control valves, only of the actuators. The assumption made in the software is that if the actuators aren't moving, the control valves must be in the correct position. The computer stores the value of electrical current necessary to put a control valve in a position and then assumes that current value never changes. Guess what...it does. That's what is being calibrated during "adaptation" / "teach-in", those current values.
Second is temperature:
- The SMG module (computer) receives a temperature input from a single sensor which is mounted to the bottom of the hydraulic block and only measures fluid temperature. It then interpolates gear box temperature since it should follow oil temperature relatively closely. However, there are many different components which are effected by temperature. The net result is that a cold transmission has very different current values for a proper shift routine than a warm transmission.
Well, when is adaptation performed? Usually, right as the car comes off the lift and hasn't been run for days. Only the third of the 3 steps even requires running the engine, so there isn't much heat input into the transmission during the process. So, what happens when we go for a drive? The transmission warms up, the current values drift and things are no longer smooth.
Pay attention to your car...some shift really well when cold and get worse after a few minutes. Some are horrible cold, but fine after a few minutes. Some are really bad unless you flog the snot out of it and then behave properly. While this may seem like she enjoys the abuse, I'm convinced that a poorly shifting SMG will live a shorter life than a smoothly shifting SMG. If you think about that, it's common sense. Syncros get damaged, the clutch wears faster, etc. Everyone acknowledges that P500S, DSC off, S6, WOT shifting will probably reduce clutch life. Well, those low power shifts that are clunky probably do too, right? It's the same mechanism after all, abrupt clutch let out with an RPM differential.
There has been a consensus for years that if your clutch is worn, performing the adaptation will make it fail sooner. BS. All the SMG really want to know about the clutch is how to operate it's control valve smoothly (it's the most complex of the 6 control valves), the position of the slave cylinder (directly read by the PLCD), and the PLCD value where the clutch "kiss" point is. If it knows those things and the shift rods are calibrated properly, you get a smooth shift.
There have been some mechanical fault as well over the years, the most common/talked about being pump motor failure. BMW issued an SIB in the first year of production noting a manufacturing defect in the brushes used in the DC motor which drives the pump. The brushes would fail prematurely and cause pump failure. Now, given the fact that the motor uses brushes at all says it's a potential wear item as all commutating brushes in DC motors will eventually wear and fail. Bushless DC motors are a better choice, but much more expensive and require more complex control circuity and weren't used.
The biggest notable wear item has been the clutch release bearing (throwout bearing). There were apparently some vehicles from the factory where this was not even greased properly causing premature failure. BMW released a revised part a year or so ago that uses a delrin sleeve on this as opposed to the previous metal design. This is a carryover from many other manual transmissions as the E39 guys got this a while ago. This delrin sleeved variant requires no lubrication (it would attract clutch wear dust) and should last longer in theory.
Finally, the hydraulic block. There are numerous ways in which this can fail and without a fairly thorough understanding of hydraulic systems, this can be hard to troubleshoot. BMW issued an SIB on this pretty much stating if you receive 3 specific error codes, try replacing the accumulator and if that doesn't work, replace the whole block. In my opinion, this was done to lower cost of warranty claims as 10-12 hours of labor guessing...I mean troubleshooting can quickly cost BWM more than a new hydraulic block. I see both sides of the argument, but for an out of warranty owner, new hydraulic blocks aren't cheap when a little bit of understanding of the system goes a long way.
Adaptation can fail sometimes though. Several members on M5board have reported that step 1 (teach in clutch valve) fails and the SMG is stuck in the adaptation routine and will not complete. While it still drives, the red cog is always present until the problem is fixed. I have looked at a few of these now and even monitored one SMG in Canada remotely using INPA. Without going into great detail, this is usually solved by replacing the slave cylinder, release fork, and pivot ball pin.
Another one I'm working on right now will not shift into 6th gear during adaptation, yet shifts fine while driving, so he has a permanent "not adapted" error code.
Keep in mind though, adaptation failure does not mean the process broke something, it means a fault was identified. It's akin to blaming your doctor for telling you that you have cancer.
I truly believe adaptation should be done periodically, perhaps yearly or every 10k miles. Note that after clutch replacement or any work on the SMG, you may want to do it again after 1000 miles or so, it has been noted to improve smoothness. I have run the program on my car no less than 50 times in 15 months, so I'm fairly confident when I say it doesn't harm anything that isn't already harmed.
I hope this is useful to some, they really are great car/engines/transmissions with a really bad rap.
I used ISTA/D to perform the adaptation and there was an immediate improvement, but still not quite right. I keep my laptop in the car usually and one day after driving back from lunch, I was so frustrated with it that I performed the adaptation again while sitting in the parking lot at work. The transmission was nice and warm and the result was an SMG that actually shifted smoothly.
Previously, I always felt like the SMG rev-matched properly, but then blew it trying to guess the correct throttle setting as it let out on the clutch. It felt jerky on the let-out and no matter how I tried to apply the right pedal, I could not get a smooth shift. I never had that problem on the E46 and that SMG was an afterthought design converting a 6MT to automated box. The GS7S47BG SMG III was designed from the ground up to be an automated box and clearly something was amiss. The SMG III can be extremely smooth or a miserable experience.
The more I started reading about the transmission, the more I realized what I feel are shortcomings as a result of trade-offs between manufacturing cost and fail-safe design.
First off, is position sensing:
- The SMG III uses 6 hydraulic control valves to control the motion of 5 actuators. The precise position of those control valves is essential to the smooth and accurate movement of those 5 actuators. However, there is no direct position measurement of the control valves, only of the actuators. The assumption made in the software is that if the actuators aren't moving, the control valves must be in the correct position. The computer stores the value of electrical current necessary to put a control valve in a position and then assumes that current value never changes. Guess what...it does. That's what is being calibrated during "adaptation" / "teach-in", those current values.
Second is temperature:
- The SMG module (computer) receives a temperature input from a single sensor which is mounted to the bottom of the hydraulic block and only measures fluid temperature. It then interpolates gear box temperature since it should follow oil temperature relatively closely. However, there are many different components which are effected by temperature. The net result is that a cold transmission has very different current values for a proper shift routine than a warm transmission.
Well, when is adaptation performed? Usually, right as the car comes off the lift and hasn't been run for days. Only the third of the 3 steps even requires running the engine, so there isn't much heat input into the transmission during the process. So, what happens when we go for a drive? The transmission warms up, the current values drift and things are no longer smooth.
Pay attention to your car...some shift really well when cold and get worse after a few minutes. Some are horrible cold, but fine after a few minutes. Some are really bad unless you flog the snot out of it and then behave properly. While this may seem like she enjoys the abuse, I'm convinced that a poorly shifting SMG will live a shorter life than a smoothly shifting SMG. If you think about that, it's common sense. Syncros get damaged, the clutch wears faster, etc. Everyone acknowledges that P500S, DSC off, S6, WOT shifting will probably reduce clutch life. Well, those low power shifts that are clunky probably do too, right? It's the same mechanism after all, abrupt clutch let out with an RPM differential.
There has been a consensus for years that if your clutch is worn, performing the adaptation will make it fail sooner. BS. All the SMG really want to know about the clutch is how to operate it's control valve smoothly (it's the most complex of the 6 control valves), the position of the slave cylinder (directly read by the PLCD), and the PLCD value where the clutch "kiss" point is. If it knows those things and the shift rods are calibrated properly, you get a smooth shift.
There have been some mechanical fault as well over the years, the most common/talked about being pump motor failure. BMW issued an SIB in the first year of production noting a manufacturing defect in the brushes used in the DC motor which drives the pump. The brushes would fail prematurely and cause pump failure. Now, given the fact that the motor uses brushes at all says it's a potential wear item as all commutating brushes in DC motors will eventually wear and fail. Bushless DC motors are a better choice, but much more expensive and require more complex control circuity and weren't used.
The biggest notable wear item has been the clutch release bearing (throwout bearing). There were apparently some vehicles from the factory where this was not even greased properly causing premature failure. BMW released a revised part a year or so ago that uses a delrin sleeve on this as opposed to the previous metal design. This is a carryover from many other manual transmissions as the E39 guys got this a while ago. This delrin sleeved variant requires no lubrication (it would attract clutch wear dust) and should last longer in theory.
Finally, the hydraulic block. There are numerous ways in which this can fail and without a fairly thorough understanding of hydraulic systems, this can be hard to troubleshoot. BMW issued an SIB on this pretty much stating if you receive 3 specific error codes, try replacing the accumulator and if that doesn't work, replace the whole block. In my opinion, this was done to lower cost of warranty claims as 10-12 hours of labor guessing...I mean troubleshooting can quickly cost BWM more than a new hydraulic block. I see both sides of the argument, but for an out of warranty owner, new hydraulic blocks aren't cheap when a little bit of understanding of the system goes a long way.
Adaptation can fail sometimes though. Several members on M5board have reported that step 1 (teach in clutch valve) fails and the SMG is stuck in the adaptation routine and will not complete. While it still drives, the red cog is always present until the problem is fixed. I have looked at a few of these now and even monitored one SMG in Canada remotely using INPA. Without going into great detail, this is usually solved by replacing the slave cylinder, release fork, and pivot ball pin.
Another one I'm working on right now will not shift into 6th gear during adaptation, yet shifts fine while driving, so he has a permanent "not adapted" error code.
Keep in mind though, adaptation failure does not mean the process broke something, it means a fault was identified. It's akin to blaming your doctor for telling you that you have cancer.
I truly believe adaptation should be done periodically, perhaps yearly or every 10k miles. Note that after clutch replacement or any work on the SMG, you may want to do it again after 1000 miles or so, it has been noted to improve smoothness. I have run the program on my car no less than 50 times in 15 months, so I'm fairly confident when I say it doesn't harm anything that isn't already harmed.
I hope this is useful to some, they really are great car/engines/transmissions with a really bad rap.
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