I have w212 with om651 and 722.6 transmission (5G gearbox). In the past couple of years I noticed it developed a slight jerk when shifting 1-2 when cold, basically during autumn and winter. Also sometimes, many times, irrelevant of temperature or season, when I come to a stop in stop and go traffic I can feel it a bit harsh releasing the gear and going into neutral (I guess?).

this summer I changed the oil from both gearbox and torque converter (I had the tc screw). Changed oil and filter, and the electric plug with oem plug, filled back up to spec. Checked oil level with engine running and the specified dipstick. Also reset the transmission to relearn the shift points. I have a Delphi ds150e clone. All great! In the summer it shifts flawlessly - except when coming to a stop sometimes like I mentioned before. It’s like holding the gear, and then releasing it abruptly. I’m not sure how to describe it.

anyway, now that winter is coming and it’s colder outside, the 1-2 shift jerk is back, not as noticeable but still here. When outside temp is between 1-10 degrees Celsius, the harsh up shift only exists in the morning when it’s coldest, and literally just the first time it shifts. I leave car running for 1-2 minutes before taking off. First 1-2 shift is jerky, then everything is fine. If I leave the car running for 5-10 minutes before taking off, the fluid is warmer so there is not jerkyness.

but now with 0 degrees Celsius or colder, the upshift jerks are present more.. and I can hear some noise, like click clack noises, probably engaging and disengaging gears. Which I don’t recall ever hearing before.

No errors on the gearbox with my Delphi clone.

so my questions would be, why am I still getting these harsh up shifts when cold? I thought with new fluid there should not be any harsh shifts , regardless of temperature.

Should I worry about the engage/disengage gear noises? When gearbox is hot, I can’t really hear them. Either it’s very quiet, or there is no sound.

I don’t know if all these are gearbox problems, or maybe these could be related to engine and tranny mounts, starting to go out. All mounts have been change 5-7 years ago.

 

Could it be that it is slightly underfilled and it’s requiring the heat in the fluid to be at the proper height? I will add, however, that most cars I’ve had act this way when it is extremely cold with the first shifts of the day. Always drive the car slowly up to temperature because everything has a lot of stress on it when it’s cold.

 

Oil level is correct, i checked multiple times at low temp and at operating temperature.
maybe I do have too high expectation for the transmission to shift flawlessly even cold, but that’s why I’m also asking here to see if it’s normal or not

 

Changing the transmission oil is preventive maintenance item. It prevents excessive wear and corrosion on the transmission, it does not repair it. If the issue existed before the oil replacement it's expected for it to continue afterwards. If you already tried running performing the shift times calibration, it's likely the issue is internal. I don't have much information on the common issues with the 722.6, but I think the conductor plate and solenoids are a common failure point that could be investigated.

In any case, a good inspection on the engine and transmission mounts is always a good (and cheap) way to start.

Best

 

COLD is bad for tranny elegant operation, even with my 30C ambient temperature I can detect it for the first 1 kilometer of drive.
If you want super smooth, tranny oil to be at 50C or higher.

My 7G plus does not jerk at all, but it can be super super elegantly smooth at proper oil temperature ( just like engine ),
thus I can sense easy when it does not.

 

W212 transmissions, with proper maintenance, OEM or higher grade aftermarket fluid (much preferred option), proper reset and re calibration of everything through xentry (some people here may see here it is not important, but from my experience it played huge role),and certainly ensuring transmission is properly cooled - if your cooling system and radiator are old and not efficient, expect failures slowly and eventually developing in the transmission.

my gearbox shifts smooth like butter, but slightest jerk during cold drive in the first minute or two is absolutely normal. New cars have this as well.

 

You've performed a gearbox service with a reset. What you describe is fairly mild!
Don't spend too much ressources as lots of new MB don't shift any better.

The valve body keeps track of three temp range for each clutch and a long history of past up/down shifts. This should lead to perfectly adapted shifts... sometimes it does not due to EXTERNAL reasons affecting shift timings.

You may want to experiment with simple effective steps:
Fault clearing to begin with
chassis reboot
battery voltage float