9G Transmission Jerkiness in Stop-n-Go Traffic
 

I'm experiencing some jerkiness in 1st/2nd/3rd in stop and go traffic with the new 9G transmission. Shifts are not very smooth. However, it is fine with normal or spirited acceleration. I've only been driving in Comfort. 700+ miles on the odometer. Has anyone else experienced this?

I literally just took mine to the dealer for this exact issue. They told me they could not detect the issue and therefore made no repairs. I've been driving in Comfort and have about 650 on the odometer. For me, it mainly happens in first gear from a complete stop. I find it very annoying and will continue to argue with MB if it persists after the break-in period.

I don't have my car yet, so I can't specifically give advice on whether something's unusual about the new transmission, but a couple of question and thoughts to level set the concern.

1. What's your car/transmission history? Ever owned a manual transmission or automated manual such as a dual clutch transmission?
2. Do you have the Drivers Assistance package, if so is it jerky if you let the car do the driving?

The power take up in this transmission is a wet-clutch instead of a torque converter found in traditional automatic transmissions. This means a more responsive and more connected drivetrain feel akin to a manual transmission. But it also means it can be less comfortable as drivetrain shocks don't get absorbed by the oil in a torque converter. Having a clutch as the power take up can lead to jerkiness in stop&go traffic or when creeping along as the clutch has to constantly disengage and reengage to keep the engine from stalling. Generally, one has to smooth it out themselves by modulating the throttle and have an ear for the state of the clutch. This should come pretty natural to somebody who has a long history of driving manual transmissions.

Also, stop&go traffic is not exactly a good place to break in the car. The clutch and everything is brand new. This stuff needs to be worn in a bit.

welcome to the 9 gear life. the c43 guys went through this when they added the 9g in 2017. its due to the ratios of the shorter gears. I'm sure Mercedes will get a coding patch that will sort of fix it. but I recommend if you are not in a spirited driving mood to stick with comfort or even economy mode so it never goes into 1st gear. this should eliminate a lot of the jerkiness. search the c43 forum and you can see how this complaint was resolved. essentially Mercedes released better software, and drive in comfort or eco in traffic.

Hey Man! Sorry you're just starting to experience this lol.

I just picked up my 2019 C63S Sedan, and right before that I had a 3 year lease of GLE 43 Coupe AMG, both cars had 9G transmission. When I got my GLE Coupe back in 2016, I had the same exact "Jerkiness" and I went to the dealer as well. This is not an issue with the car, this is the transmission itself, and this is how it is going to work! There is no fix for it. Just as you said it is only in stop and go traffic!

I will tell you that in the 2019 C63S you don't feel it as much as I did in my GLE. The worst is when you're in the first gear driving slowly downwards, while holding foot on the brake, then you let the brake go, and the car shift to the second gear, and it feels like transmission will freaking explode and fly out of the car. I would assume the weight of GLE gave the "Jerkiness" an extra Kick! So long story short the 2019 C63 S is not too bad lol, so just try to ignore it.

To those of you guys who keep going to the dealer, whether this is before your break in or after, I would strongly suggest not to waste your time, as this is just how the 9G transmission is going to work, and there is absolutely nothing wrong with it!

Just to be clear, the C43 has the TCT 9-speed and the C63/S has the MCT 9-speed. They are not the same. The MCT is based on the TCT. Main difference is the MCT uses a wet startup clutch and the TCT uses a torque converter. Gearing is most likely different between to two as well, but I haven't actually compared it yet. Also the MCT has no Eco mode and always starts in 1st gear, even in Comfort mode. The old 7-speed MCT also started in 2nd gear in Comfort, but not the 9-speed MCT. It was a deliberate change by AMG to make it more responsive even in Comfort mode. That's more suitable for the C63, than the C43 which is meant to be a more livable everyday car.

Thanks for clarifying :y Also we actually do have the new Slippery mode that starts in 2nd. Powertrain is on "Reduced" power though so it's really not fun at all.



Interesting, appreciate the info. I'm very familiar with the BMW M manual 6 and M-DCT, as well as the 7G from the pre-FL C63. Yes, the jerkiness really does feel like poor shifts in a manual lol. The 9G is just a bit too eager to upshift to 3rd or 4th when in 20mph traffic. Keeping it in manual mode might solve the problem. Didn't opt for Driving Assist.

Fortunately the majority of my mileage so far has been spirited driving. Sometimes the random traffic jam is just inevitable though. Probably why it's taken me so long to notice this.




Ok awesome, thanks so much for this info! That's funny hearing your experience with the GLE, glad it's not nearly as bad with our C63S :)

You are welcome. I would say take it through the break-in period and give it some time. There's a lot of calibration going on in these cars during the first 1000-1500 miles and these kinds of transmissions adapt to your driving style over time. At the beginning they may not feel right until they learn how you drive. A bit of chunkiness and raw feel with th occasional jolt and jerk from the drivetrain is somewhat desired in a car like this. It's after all not a plush S-Class that tries to isolate its occupants from what's going on. I prefer that. Makes me feel connected to the car. My current '13 RS5's dual-clutch transmission also occasionally jerks or jolts. That's part of the experience, but I've learned over time how to drive it, when to override using the manual mode and how to modulate the throttle, and it also learned my driving style. I will definitely report back once I have my car and spent some time with it. I opted for the driver assistance package, so in the occasional traffic jam I will let it drive itself as I do with my current car.

Agreed!

Looking forward to your review ;) I used to not want any "driving nannies" but as I get older I really do appreciate the thought of having additional safety... also the convenience too during things like traffic.

Wish they didn't require Multimedia Package bundled (Carplay hello?).

Quick follow up. Found a local dealer that had a couple of coupes in stock and went to drive one for my first experience with the 2019 model. It had only 40 miles on it. The car I drove was Obsidian Black with the Red Pepper/Black performance seats and nicely equipped with the 19/20" wheels. Boy does this car look good in black! Very mean with the new grill and night package. I'm happy with my color choice. It didn't have the Areo package, unfortunately, so looking forward to seeing it on mine. The new steering wheel with the AMG Drive Unit is great. Drove it in Comfort for a bit, but mostly in Sport+ and manual mode.

Regarding the transmission, I see what you are saying. I made sure I brought everything up to operating temperature but didn't drive in stop&go traffic. However, the new transmission seems indeed on the snappy/aggressive side when shifting, but I have a feeling that the car just needs to loosen up. Coming from my well worn in RS5, this car felt like new leather shoes that haven't molded around my feet yet. From past experience, these kinds of cars need a few 1000 miles to loosen up before feeling proper. It didn't seem very driveable in Sport+ w/o being jerky, which reminded me of my car. I can't really drive my RS5 with transmission in Dynamic mode around town, either. It gets very jerky as well. So overall I would say I like what I saw, but it definitely needs some time to loosen up and me getting used to the new car. I would say I didn't quite feel at home yet.

On a side note, I do like the new suspension tuning as well. It's actually driveable in Sport+ at normal speeds w/o being jarring over manholes and other bumps. The lower spring rates and software tuning at least at normal speeds seems to be what I hoped. Looking forward to seeing how it performs in Sport+ at fast pace on some technical roads.

Nice write-up! Agreed on the black, I think it's the perfect color for these cars. So mean!

I've had a very similar experience so far at almost 900 miles. The car is much smoother overall than it had been with 8 delivery miles. Took it this weekend to Lime Creek Road in Austin, TX (pretty much the only technical road in Texas). I was impressed with the performance despite only putting it into Sport and trying my best to keep rev's not too high.

Only complaint I have is handling/turn-in while in Comfort. Right at the beginning of an aggressive corner, the car suddenly becomes more eager on turn-in. This is actually a bit off-putting as it's unexpected and comes on late when I'm already 1/4 of the way into the corner. Putting the car into Sport generally fixes this issue although occasionally I still slightly feel the steering adjusting at times. Will report back once I've tried Sport+.

I know "AMG Dynamics" is a new thing this year and I suspect this is what's happening as I definitely did not experience this phenomenon with the 2017 model.

That does sound like the effect of torque vectoring. I'm very used to that. My RS5 also has a torque vectoring rear differential combined with a passive system that applies a slight braking torque to the inner front wheel around corners for an additional yaw moment. I'm surprised, though, that you find this in comfort mode. Like my RS5, I would expect that comfort mode keeps the car neutral in corners. It could be the soft suspension setting, too. Have you tried leaving the car in Comfort mode, but set the suspension to Sport or Sport+? Not using Sport/Sport+ during the break-in only applies to the engine/transmission really. You could set up Individual mode so that engine/transmission stays in comfort mode, but you can play with the AMG Dynamics setting, suspension and steering to start getting a feel for the handling characteristics in each mode.

I think it's more noticeable in Comfort mode because the car doesn't expect dynamic driving. So when it detects unexpected aggressiveness, it activates the torque vectoring.

I'm at 900+ and I'll finish break-in this weekend. Going to test all of this out! I suspect it's tied to Suspension or AMG Dynamics like you suggested.

Lol, welcome to AMG MCTs.

Its funny, stick a conventional auto in there and the 'internet' complains that its old, slow changing and not a 'drivers transmission'. Swap to to the MCT and the 'internet' still complains that its not a dual clutch and hence inferior. Go to a 7 speed box and the 'internet' complains that its not enough gears as all of the best have 8 or 9 gears and it still wont respond like a race tuned DCT,. Supposedly that 10-20ms difference in changes IS a big thing when you are driving on the street!

So they swap to the latest gen 9 speed and sharpen up everything to make it even faster than before now we start suffering for the 95% of driving that we all do, just for that 5%.

The “internet” is a difficult crowd to please lol

LOL so true

Almost as if the "internet" is not just one person but many people with different preferences. Amazing

yes I am aware the transmissions are different even though they both have 9 speed. but the principle is the same. its 9 gears. its a lot of gears. I figured Mercedes would have you guys start in 2nd for comfort or eco, I guess not. seems like something they should implement. nothing wrong with making the c63 more livable daily :)


thanks for clarifying though for those that may not know the difference another main difference is the rated torque capacity :) the MCT has a much higher rating obviously due to it being paired with higher power engines. I wonder if any parts from the MCT can be retrofitted to the TCT to beef it up. these turbo upgrades are really pushing the limits.

I actually found the 2nd gear start of the 7-MCT quite odd and didn't like it. It basically slipped the hell out of the clutch. In terms of the number of gears, yes 9 seems a lot of gears at first, but if you look at the gear ratios, it makes a lot of sense. They basically just spread out the first 7 gears. 1 through 6 are now your normal driving gears with 6 being 1:1, and 7,8,9 are overdrive gears for cruising or efficient driving. 8th in the new transmission has about the same ratio as 7th in the old, and 9th is a new taller gear for improved highway long distance fuel economy. The first 7 gears are now shorter for better acceleration. The 2019 is across the board 1/10th faster 0 to 60 than the 2018 for example with the same amount of power. City fuel economy stayed the same despite the shorter gears and higher resulting revs, but the highway fuel economy improved.

agreed with you on 2nd gear starts. Very annoying.

Disagree on 19s being faster than 18s. Data to prove? Mercedes claims same 0-60 IIRC?

Nope, MB claims faster 0-60. The 2018 C63CS has a claimed 3.8s and the 2019 is 3.7s. Here are the official specs for both the 2018 and 2019 coupes from the horse's mouth. The performance numbers are towards the bottom.

https://www.media.mbusa.com/releases...specifications

https://www.media.mbusa.com/releases...specifications

Well I’ll be. I stand corrected. :)

:) 1/4 mile is faster, too according to C&D. 2018 is 12.0 @ 121 mph, and 2019 11.9 @ 122 mph.

https://www.caranddriver.com/reviews...e-test-review/

https://www.caranddriver.com/reviews...-drive-review/

Actually, the 12.0s is the coupe, and the 11.9 the sedan. The sedan was actually quite a bit slower before the 2019. 12.2s @ 116 mph. Can't find 2019 Coupe 1/4 mile times at the moment. Based on the sedan's 0.3s improvement, I'm guessing the 2019 Coupe must come in at 11.7s. The improved times are not just the transmission, but the revised suspension and the new traction control. Everybody has been saying that one of the big improvements in the 2019 is that it does a better job at putting the power down.

https://www.caranddriver.com/reviews...tested-review/