SMG Gearboxes

[mil]

Steve,

This is very strange indeed and even more strange is that sometimes new gearbox seems to help. What I found interesting is what you say in the very first post that your problems also started after replacing the clutch. It must be is something related to changed clearances and adapting to that somehow. Also this gearbox temperature is an interesting possibility.

After I got new gearbox it was first making the errors on street only after some maybe 10-20km of driving after cold start, so I don't think the oil temperature was too hot. Last summer I was running on Nurburgring for days without any issues on track, but it was happening on streets around the track.

Actually now when I'm more thinking back last summer, the first strange thing with new gearbox after I got SMG software updated was slight delays in 3->4 shifting speed in S4 mode. Started to use to S5 which fixed the delays but eventually that resulted to mechanical noises after couple of days of driving on track... Could it still be somehow related to that damn 5£ spring which fails very quickly in our cars because of some other issue. Maybe this is some sort of chain reaction, which could explain that there are times when this is not happening after make some changes to the system.

[deleted_user_0_csl]

Hi,

Shimmy- my views are always expressed from first hand
experince and things that have happened to my cars.

Just for the record, a Lightweiight flywheel [12lbs] with
a Sachs Uprated Clutch Disc and cover was fitted to my Car, CSL.

It was dreadful, so the Gearbox ECU was reprogramed with the
latest version of the software, no change.

Then the SMG pump fluid was drained the system was flushed and
refilled. No change still would not engage properly, the upshifts and
downshifts were all hit or miss etc.

So the Lighter flywheel was removed, the dual mass refitted, with
the Sachs clutch, and the car has its moments but by and large its
OK. Can still get a small 'slur' now and then without sport or DSC off.
Now done around 1500 hard miles, its only used for Track days and the
odd local blast when trying things out, and its been OK.

I also have a E30 M3 with a CSL S54 engine Motec M800 and Drenth sequential Gearbox running a Dual disc 184MM Clutch with a 10lb
alloy flywheel, and a central clutch cylinder, which on the 'flatshit'
makes the SMG feel very slow.
This car does not run the 'E,Gas' or Fly by wire, but is running a throttle
cable/Linkage, which out of slower bends does allow a quicker pick up.
The S54 without the dual mass flywheel is far more responsive at lower revs
that its a shame that the SMG will not function correctly
with a lighter flywheel.

I did look into lighter dual mass flywheel in steel, but the savings
were not more than around 2-3 Kg which was not worth the costs.

Pectel have now developed a plug and play standalone for the S54 which
has been mapped specifically for the E.Gas, fly by wire, and in therory
will always have the throttle and air optimised as its rev matched and
picking up signals from engine load etc.
Interestingly they do not recommend SMG on a Car running this system.

Regards,

The Gorilla.

I run a sachs sintered paddle clutch on a supercharged m3 e46 smg, had a few problems with adaptation but im told by extending the actuator 5mm should solve the problem so its watch this space, when it was running was fine but shut down a couple of times due to this needed mod...waiting for it to come back in as we speak!:thumbs:

[The Gorilla]

Hi,

Jay959- I hope it works, but I have reservations.

The more I learn and read about SMG II the more
I believe that its problems stem from the fact that
the whole system when designed was based on the
principal that the take up point on the clutch would
always be the same distance.

By reason that the SAC system would compensate
for wear.

Thus when the system goes through its shift pattern
the ECU will not allow the upshift until the system
is within the paramiters.

Hence Slip or 'Slur' as it sorts itself out.

When driving the system hard, those paramiters
move up as throttle load, revs etc are all at the top
end, so the ECU is already primed, and hence the
shifts engage quicker but much harder on the drivetrain.

With the added 'adaptive' element for driving styles is
also factored in then Slur or Slip is the result.

On current F1 Cars if they do not take the box up and
down on the first start up of each session then the
system will revert to base 'mode'.

Manual S54 M3's do not suffer
as badly with clutch slip as SMG cars, although
its almost an identical gearbox, clutch/flywheel
is the same, so the logic clearly points to it
being a electrical/software/hydraulic issue, which
as they wear will bring on more and more issues.

Be interested to hear how your modification works out.

Regards,

The Gorilla.

[mil]

Still not fixed

My car has been investigated further but still no solution has been found. However I have collected some pieces of new information.

The BMW service has taken the transmission into pieces after car was "online" diagnosed by BMW. First instructions were to check the clutch, flywheel etc. and they seemed to be in really good condition and were not replaced again - at least yet. After that my issue was escalated to Germany, who instructed to remove aftermarket software from ECU. So yes, they can see those mods.

Also during the last 12 months yet another update for SMG software has been released. So I got the latest engine and SMG software. Shifting felt smoother, but I obviously cannot tell if that was because of SMG or engine software. Anyway the problem remains, but software can be ruled out now. The saga continues next week, but at least BMW Germany is involved, hopefully they know their products..

[Mark CSL]

My car has been investigated further but still no solution has been found. However I have collected some pieces of new information.

The BMW service has taken the transmission into pieces after car was "online" diagnosed by BMW. First instructions were to check the clutch, flywheel etc. and they seemed to be in really good condition and were not replaced again - at least yet. After that my issue was escalated to Germany, who instructed to remove aftermarket software from ECU. So yes, they can see those mods.

Also during the last 12 months yet another update for SMG software has been released. So I got the latest engine and SMG software. Shifting felt smoother, but I obviously cannot tell if that was because of SMG or engine software. Anyway the problem remains, but software can be ruled out now. The saga continues next week, but at least BMW Germany is involved, hopefully they know their products..

Is your car under bmw warranty ? i ask as a friend of mine had his warranty removed as the ecu had been chipped so i find this strange but thats bmw for you good luck with a fix soon :whistle:

[Great Pretender]

Folks,

I've been reading this thread with interest. One thought has occurred to me though:

With all the problems some of you have had in respect to the SMG II, why not convert the car to a manual transmission and solve the problem permanently?

[shimmy]

Folks,

I've been reading this thread with interest. One thought has occurred to me though:

With all the problems some of you have had in respect to the SMG II, why not convert the car to a manual transmission and solve the problem permanently?

No point if warranty covers it but you may find a few do this as warranties expire

trouble is the cost for the change over in new clutch and extra possible loss if value as CSL will be harder to sell outweighs the cost of a clutch alone for tge SMG

most will only have this problem once within their ownership

[DuncanR]

With all the problems some of you have had in respect to the SMG II, why not convert the car to a manual transmission and solve the problem permanently?

Cos it would fook peeps like T$ and Lawsy up a bit !:hahaha:

[Bounce]

Cos it would fook peeps like T$ and Lawsy up a bit !:hahaha:

:hahaha::hahaha::whistle:

[flow_csl]

I also have the same problem with the 4th gear , some times it will not shift into 4th and makes a grinding noise .

I had my local shop (BMW specialist) change the clutch en those little cheap springs , but the springs were fine . So the springs can't be the problem with my SMG .

After talking to the mecanic and explaing the problem he said that when installing the clutch he had a problem removing this part nr9




He said that normally with a special tool it is easy to remove , but in my box it was pretty much stuck and according to him that is a part that should be able to move .
Before re installing the part he cleand it and put some grease on it so it can move better .
I did a little test drive and now the SMG shifts are alot smoother .
what are your toughts on that ? could that be the problem or A problem ?
This weekend i'm doing a ring day and monday a ring trackday so i can really test if the SMG is OK now .

[mil]

Hi Flow,

Thanks for the input. Anything is possible in this case I think. Please let us know if that will help with your car.

Since my previous post my car has got:
- gear identification switch (strange call as this should be included in the complete gearbox swap earlier)
- rear differential
- output shafts (left and right)
- rear wheel bearings and hubs (a separate problem there, but changed anyway)
- clutch bleeding several times
- all possible reset/adaptations several times

No solution. Next on the line is clutch output cylinder and then.. you guessed it: the smg hydraulic unit.

[flow_csl]

Hi Flow,

Thanks for the input. Anything is possible in this case I think. Please let us know if that will help with your car.

Since my previous post my car has got:
- gear identification switch (strange call as this should be included in the complete gearbox swap earlier)
- rear differential
- output shafts (left and right)
- rear wheel bearings and hubs (a separate problem there, but changed anyway)
- clutch bleeding several times
- all possible reset/adaptations several times

No solution. Next on the line is clutch output cylinder and then.. you guessed it: the smg hydraulic unit.

I will let you know next week .

[flow_csl]

Car shifts very good and smooth , alot better then before but after a good testdrive the 4th gear problem happend again .

Is it a problem with the syncro's in the gearbox ? because its only one gear ??

[mil]

Flow,

Sorry to hear that the problem still exists. I don't think it's synchros, however it could be, as there are few people who say that new gearbox has helped. New gearbox because you cannot get individual inner gearbox parts from BMW. It's also possible that the same 4th gear grinding symptom is caused by two (or even more) different problems.

In my case new gearbox did not help anything. Only after some hundreds of kilometers it failed again. I suspect it is something outside gearbox and clutch, but so far nobody can confirm this.

[shimmy]

O ad 3-4 grinding and missing gear issue in 2008 at 45k miles.

New gearbox solved it. The gearbox oil showed faint signs of the synchro metal BUT my gut feeling was that this was due to the grinding and bit the cause of it.

Good luck.