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Rough auto downshift even in comfort?

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Old 08-01-2018, 01:32 AM
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Rough auto downshift even in comfort?

Hi All,

I have recently taken delivery of my 2018 c43 sedan! Everything is great except the rocking back and forth issue in S+ if I'm not mashing the throttle, and thanks to the insight on this forum, I have gotten the latest software update from the dealer.

However, this other issue that I have experience which was expected to be fixed by the update still exists, where even when I'm driving in comfort mode and auto shifting, when the car brakes to low speed u can certainly feel the rough downshifts from 3rd to 2nd and 2nd to 1st. It's like the car jumps a bit and the car suddenly brakes harder during those two shifts despite ur foot being steady and not applying anymore brakes.

I'm wondering if anyone else is currently experiencing it and if anyone has any knowledge on this?

Thanks in advance!

Old 08-01-2018, 01:53 AM
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How rough are the downshifts? Because what you're describing there is engine braking. Do the rough downshifts occur when braking gradually in C?

As far as the S+ issue is concerned, this is a common trait in modern performance cars with aggressive automatic and DCT transmissions. The M-DCT is especially brutal if you're unfamiliar with the transmission.

You have to either commit to the throttle fully in low speed situations in S+ (particularly through the first 2 gears) or make sure that you are gently "rolling" on the throttle with your foot vs. stabbing or bouncing it.
Old 08-01-2018, 02:40 AM
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First comment nailed it; rough downshifts are an artifact of these systems especially in S+, and even somewhat in comfort. Such is life with a sports car
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Old 08-01-2018, 08:47 AM
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I experience what equates to some additional torque braking when coming to full stops in C as the engine downshifts based on RPM minimums. Just one of the small quirks of the tranny, especially the S+. The one thing that comes to mind from your post though is if your car is actually dropping all the way in 1 when driving in comfort. It's my understanding that, unless manually shifted to 1, the lowest gear you should see in C is 2.
Old 08-01-2018, 12:00 PM
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Exact same thing happens to me as well. I don't think you should be alarmed. Aggressive gearing makes for unpleasant braking. This car ALWAYS engine brakes regardless of whether or not the actual brakes can handle it.

Sucks coming from a 10 year old Lexus with zero brake boost and weak brakes (makes for the smoothest stops, ever).
Old 08-01-2018, 01:02 PM
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Thanks for the input everyone! That make sense, I figured it's the engine braking that's creating the slight jerky feeling but didn't think it would be so noticeable in Comfort, I guess that's what AMGs are all about haha.
Cheers
Old 08-01-2018, 08:47 PM
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Originally Posted by hornyhelmets
Hi All,

I have recently taken delivery of my 2018 c43 sedan! Everything is great except the rocking back and forth issue in S+ if I'm not mashing the throttle, and thanks to the insight on this forum, I have gotten the latest software update from the dealer.

However, this other issue that I have experience which was expected to be fixed by the update still exists, where even when I'm driving in comfort mode and auto shifting, when the car brakes to low speed u can certainly feel the rough downshifts from 3rd to 2nd and 2nd to 1st. It's like the car jumps a bit and the car suddenly brakes harder during those two shifts despite ur foot being steady and not applying anymore brakes.

I'm wondering if anyone else is currently experiencing it and if anyone has any knowledge on this?

Thanks in advance!
Shouldnt you be driving in comfort mode for the first 1000 miles/1500kms ???? Breaking in period?
Old 08-03-2018, 02:06 PM
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Happens to me all the time. 2 down to 1 is jerky.

How does the car drive after the software update? Did it change the feel of the car?
Old 08-03-2018, 05:47 PM
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I took my 2018 in for first prepaid maintenance package and of course complained about jerky and indecisive shifting.Was told that there is no tranny update but there is a fuel update. The car is shifting way smoother and the engine just feels snappier.
Old 08-15-2019, 11:21 AM
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I have started to have this rough downshift problems after nearly 60k kilometers. Seems like almost normal then as all of you guys are experiencing this?
Old 08-15-2019, 11:27 AM
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Originally Posted by munis
I have started to have this rough downshift problems after nearly 60k kilometers. Seems like almost normal then as all of you guys are experiencing this?
This started happening to me too recently, never happened before. Every once in a while it feels like it's downshifting in S+ when I'm really in C or E mode. I'm only at 16k miles so if this indicative of a possible future problem I definitely want to get it looked at.
Old 08-15-2019, 12:55 PM
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Originally Posted by munis
I have started to have this rough downshift problems after nearly 60k kilometers. Seems like almost normal then as all of you guys are experiencing this?
I’m only at 4k miles and I’ve had it.

Has only happened maybe 2x while the car was still “cold.”
Old 08-15-2019, 01:35 PM
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Originally Posted by C43Flyby
This started happening to me too recently, never happened before. Every once in a while it feels like it's downshifting in S+ when I'm really in C or E mode. I'm only at 16k miles so if this indicative of a possible future problem I definitely want to get it looked at.
If a lot of us are having this issue, which we are, having confirmed this in our whatsapp group, then I think it is kind of normal. Does not happen all the time, but shows up sometimes. My car is tuned, so I cannot be as aggressive with the service dept. as some of you guys might manage to with stock cars. How about one of guys give it a chase and see where it goes? It might be normal but certainly is not pleasant.

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