SMG Gearboxes

[shimmy]

Originally Posted by Steve Gill

Shimmy all BMW supplied gearboxes are classed as reconditioned - I'm told that the whole internals are brand new but the case is reconditioned. When I bought a new gearbox from BMW that was all I could order - there wasn't a choice of new or reconditioned.

It did look shiny though if that helps

i like shiney

[mil]

shimmy,

Yes I've read the troubleshooting thread. Good info, but no obvious solution to my issue there.

Spoke yesterday to one expert who was thinking that this could be caused by aftermarket software in my ECU (by Kelleners). He said that SMG and engine ECU will not communicate properly and SMG reset/adaptation is not possibly executed properly. Could be possible, but sounds bit strange, as it worked ok for years. However during that time I did not have to reset SMG ever.

Are you guys with the same issue running stock software or something else?

[TANKSLAPPER]

You may have a point here

I never had to reset my SMG in my current csl which has got a chipped ECU

but my previous CSL had an reset every time it went to the dealers.

[mil]

Small update: it's most likely not ECU software related. Found at least one case in US with all the latest OEM software and still failing occasionally - less frequently though.

Originally Posted by mil

Small update: it's most likely not ECU software related. Found at least one case in US with all the latest OEM software and still failing occasionally - less frequently though.

mil - mine was upgraded to the latest OEM software and the problem still occured. However I replaced everything in the car mechanicals wise (gearbox, SMG pump etc) and it still happened, so I was lost as to what caused it based on my process of elimination.

One thought is that my car had a remap on the main ECU, however I'm pretty sure that was first done at the point of replacing my first gearbox.

Still confused. I hate problems like this that the process of elimination doesn't help.

[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.

Originally Posted by The Gorilla

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!

[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]

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]

Originally Posted by mil

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