Clunky 7G-Tronic 2nd-3rd

[tbourner]

I'm reliably informed that it's normal, but it feels horrible - the gearbox has a very bad change from 2nd to 3rd (in comfort mode) maybe 50% of the time, depending on throttle. It's actually quite a skill to get it to pull away smoothly! Putting your foot down seems to work.

It also kangaroos sometimes. It used to happen A LOT to the point where it was barely drivable, but then had a new clutch and has been fine, except the last few days it's been kangarooing ever so slightly when I had a lot of mass on board (3 additional people plus luggage).

Soooo... what are your experiences? Is it actually a normal thing that I just have to put up with? It's fine once moving, really good smooth gearbox, changes at the right times etc., it's just 2nd to 3rd.

 

[Zahc]

Mine is a little harsh when cold, but then it's nice and smooth. Around 10 minutes of normal driving. Noticeably the car uses higher revs when cold, which makes sense to me, so that's what I've put it down to. No doubt more experienced folk will set me right.
[emoji16]

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[markjay]

Mine is a little harsh when cold, but then it's nice and smooth...

Same here with my 7g+.

Though the rough change when cold can't really be excused by the higher rev I think... my olg 5g also changed-up at high rev when cold and yet the gear shift did not feel jerky.

The car has latest TCU software, and is due an ATF change later this year... if the latter does not resolve the jerky-shift-when-cold issue, I'll just have to accept that it is a characteristic of the 7g+.

 

[tbourner]

Yeah it's definitely worse when cold. It certainly wasn't cold today though - I'm sure it was affected by weight in the car as well.

 

[Zahc]

By cold I mean first start of the day. I expect it has to do with viscosity of the fluid. I suppose you had the trans oil changed along with the torque convertor. Ha, just realised I've assumed it is a torque convertor and not a automatic clutch set up. I guess I'll have to read up on it now.

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[markjay]

I was referring to the 2 or 3 first up-shifts when driving off in the morning.

 

[slade1]

From my experience all auto boxes jerk when cold. Usually the 7 speed box is very smooth. I would get the codes read using Star.

 

[gianton]

No such issue on my 7g+ transmission (touch wood), all gears change very smooth even after a cold start. My car's mileage is 170k miles and had two oil/filter changes so far always including TC flash.

 

[Stu22]

My 7G+ would give some pretty rough changes but that seems to have been resolved by a software update at the last service.

 

[tbourner]

By cold I mean first start of the day. I expect it has to do with viscosity of the fluid. I suppose you had the trans oil changed along with the torque convertor. Ha, just realised I've assumed it is a torque convertor and not a automatic clutch set up. I guess I'll have to read up on it now.

Yes, worse when cold.
MCT which as I understand it is basically an automatically activated clutch pack, but a wet clutch not like in most manual cars.

I was referring to the 2 or 3 first up-shifts when driving off in the morning.

As above, it's worse when engine oil temp reads below around 50.

From my experience all auto boxes jerk when cold. Usually the 7 speed box is very smooth. I would get the codes read using Star.

Codes have been read at PCS quite recently for something else, and no codes stored.

My 7G+ would give some pretty rough changes but that seems to have been resolved by a software update at the last service.

Maybe that's a thing - does that need to be at Merc? Is it free?

 

[tbourner]

How about these things I'm reading that the 7G likes being driven hard, and driving gently just means it slips the clutch more and causes more wear? I do drive very gently 90% of the time, and when I do pull away aggressively (progressively, I'm not a launcher!) it never has an issue.

 

[markjay]

Maybe that's a thing - does that need to be at Merc? Is it free?

I had the TCU software updated by the Merc dealer (the update is not free as they charge for the STAR labour time), and it made no difference to the rough changes when cold. This is not to say that the software update won't fix the issue on your car, as it might be a different one to mine - it's obviously difficult to compare issues online. I believe that Olly can carry-out TCU software update as well. I think it's a good first step.

 

[zipdip]

That is the problem with the 7G box there is hardly ever any codes stored,even when you have the car not changing up and have to stop switch the car off take the key out and then start up and of course it runs fine after that,my personal feeling is although we get the ATF changed and the filter,you need to have the elctro plate taken out and cleaned,where the valves are you can get fine particles that do not come out with a filter and ATF change,my car had a couple of roads it did not like a fast run towards a roundabout slowing down nothing coming and the the acceleration used to catch it out I have used the same layby about 4 times ,the other was similar fast road to a T junction as you got close and are slowing down you get a clear sight if there is any traffic and so the same thing happens on acceleration,you are pulling 4000 revs doing 30 mph.if I had been in 7th with 4000 revs on the clock I would have been doing around 140 mph.

 

[tbourner]

This was the thread I found before:
MCT gearbox - clutch life?
Suggesting it likes it hard (ooh-err).

 

[tbourner]

Gearbox software needed updating apparently, done today by Olly and the gang at PCS whilst in for an oil change. Will wait and see if that makes any difference. I hope flashing the gearbox doesn't overwrite a remap! Should probably have checked that first.

 

[clk320x]

I hope flashing the gearbox doesn't overwrite a remap!

Well at least your insurance will be cheaper

 

[markjay]

Same here with my 7g+.

Though the rough change when cold can't really be excused by the higher rev I think... my olg 5g also changed-up at high rev when cold and yet the gear shift did not feel jerky.

The car has latest TCU software, and is due an ATF change later this year... if the latter does not resolve the jerky-shift-when-cold issue, I'll just have to accept that it is a characteristic of the 7g+.

My issue is resolved.... though I can't really say why or how.

In short, it no longer shifts-up with a jerk when cold.

The only thing that changed since my last post, is that Richard updated some software on my car, including the ESM (Electronic Selector Module) software.... but I am not sure if this is a coincidence or not.

(Richard - apologies if this post sees our 7g+ members form an orderly queue outside your premises....)

 

[tbourner]

I was told the remap doesn't affect the gearbox changes at all and it is just the engine, so assume it's the same the other way around. I can't tell from driving it if it's still on, I guess that suggests it's not a very good remap! I would think I would know if it wasn't there though.