FrostyZoob

Recreating this thread from the GLC Class (X253) forum.

To recap: This thread is intended for GLC43 / GLC63 owners whose vehicles exhibit a jerking / bucking behavior when applying partial throttle from a low speed. From the owners that have commented so far, it seems this behavior occurs most while the car is in Sport+ mode.

One owner (ajgraham) reported a successful fix via his dealers service department:

UPDATE 8/13/2018: An update from ajgraham. The previously mentioned fix doesn't fully address the issue:

FrostyZoob

I've got this issue as well. I'm on my 2nd visit to the dealer trying to get this addressed. I sent them copies of of ajgrahams invoice (see images above), pointed out the bulletin number (LI27.00-P060741) and asked them to install the associated update.

Result so far? They didn't install the update. (They said it was for GLCs with 4-cylinder engines.) They've asked me to describe when the problem occurs which I've done but they refuse to let me ride with a tech to show them. They've asked me to keep the car overnight. ("So the car can cool down." or somesuch.)

I'm not really thrilled with the service I'm getting but I'm not sure what else I can do. (Any advice here would be appreciated.) Until then...I guess I'll hope for the best and enjoy the loaner they gave me. (E300)

Spencer1990

Yep same thing with my 17 GLC43, told dealer about it when making service appointment. When I went to pick it up they said they installed the latest tranmission software, but same issue still exists.

jinrsvl

psychlox

Chrisk03

The throttle response in Sport+ is very "touchy" and probably not the best setting for the street. I've experienced the "jerking" a few times and certainly wakes you up. You either need to mash the throttle or use the paddles to overcome...kinda how these vehicles are meant to be driven.

I agree it's annoying and can be frightening when it happens, but will live with it, as I'm not sure MB's "fix" will do anything other than neuter the car. These vehicles can take the abuse, so mash away. Just my .02.

psychlox

Understood about Sport+, however, all the other times I've been in Sport+ it has not exhibited this behavior. This was noticeably different, and not just a jerky start. I kept the pedal down to a constant degree and the car jerked on and off until I switched back to Sport.

Not sure I'm going to bother taking it in for this, but I'm pretty sure something's not right. I didn't notice if the GLC was actually changing gears last night while jerking.

FrostyZoob

During one of the times it happened to me I was fortunate enough to have the AMG screen displaying in my gauge cluster. It said the car was in 1st gear and wasn't changing.

Chrisk03

Dont get me wrong, there is probably some trans software changes they could make. Oh, and the first time it happened to me, it was like a bucking bronco...crazy. I was slowing down to take a right hand bend/turn at say 30ish/3rd gear, let off gas, it down shifted to 2nd and then I got back on the gas slightly after the turn and jerked back/forth like mad. I couldn't mash the gas as there was a car in front of me and didn't think to use paddles at the time...it was my first incident, but had read about it. It's happened a couple other times but much more subtle plus I deal with it immediately via throttle or paddles. Oh well, still enjoy the vehicle and maybe they will come up with a fix.

OMSE

bluejae

any updates? did this resolve your issue?

OMSE

Not really. I still have the same issue.
According to the dealer they just received new update which will solve the issue. My appointment on May 7th.
will keep you posted.

GLC43NV

Anyone get this jerking behavior when slowly braking to a stop? It happens when releasing the brake, too, but it's intermittent and hard to reproduce when I want to make it happen to show my dealer.

I've had this since day 1 on my GLC43. I did get the dealer to update the transmission software, but that largely did nothing. I feel like it's a real problem, but have largely adapted my driving around it.

scotchy

Myself more or less the same as you since new as well. (2017 with almost 50,000 kms now) Typically the worst when engine/tranny is cold or when in Sport+ at low speeds when shifting in and out of 1st and 2nd at low speeds. I've adapted how I drive to avoid it too, can't be bothered to push the issue with the dealer and possibly be stuck with a loaner for weeks when it seems there isn't a solution.

johnz1954

Have had the"jerky when braking to stop issue" since day one. Transmission tear down twice, car out of service for two weeks, no results. Really feels like torque converters aren't
unlocking when coasting. Of course the service guys don't listen when I suggest that. Wouldn't have bought the car if the demo had driven like that. Does it in all modes. Learned to adapt too but not for much longer.

MBenz111

Same issue here. This is by far the worst transmission I've used. Even American cars have smoother transmissions.

But then again, going from a Porsche with pretty much flawless transmission to a GLC43 was a downgrade.

Honestly can't wait to get rid of this car.

viper3ez

so which is it? the thread seems to have started on this issue

"This thread is intended for GLC43 / GLC63 owners whose vehicles exhibit a jerking / bucking behavior when applying partial throttle from a low speed"

but some of you are describing an issue while braking. different problems I assume.

On the original issue, I experience it in my 19 GLC63 but only after first cold start of the day and immediately starting to drive in Sport+ or Individual mde which is mostly Sport+ for my setting.

Did that specific issue get any resolution whatsoever?

4npower

This happens from time to time for me, but for the most part, I know exactly how to stop it quick so I don't look like an idiot now. My wife is still hesitant to go into sport + because of this.
Honestly, I think it's mostly self induced. And the super sensitive transmission in sport + makes it worse. When it does it initially, the back and forth motion forces your foot to sort of punch the pedal over and over until you either completely let off or basically floor it. You think your foot is staying still, because you are "holding" it motionless, but the jerking motion of the vehicle makes it worse. That exact type of motion is what makes a "bump-stock" function. Definitely irritating, but if you know what to do, it's less embarrassing

viper3ez

I am definitely not jerking my foot when it happens. It wuld take a phenomenally quick and direct electronic throttle to jerk like that in relation to foot action.

scotchy

Same. Typically for me, probably said it before, it's at really slow speed usually after braking, then coasting for a second and then getting back on the throttle when in sport plus. IDK if it has something to do with it going from 2nd into 1st at this time or something else but it'll spill your coffee and snap yo neck.

4npower

I know your not, and I even said so. The vehicle is moving around your foot as you hold it motionless if that makes sense. I'm not sure how else to explain what I'm saying. The only example I can think of this motion, is how a bump stock operates. Maybe this link will help understand better, but notice your trigger finger(foot) stays motionless as the gun(pedal) operates around you. Pure garbage, but they work.

"Essentially, bump stocks assist rapid fire by "throwing" the trigger against one's finger (as opposed to one's finger pulling on the trigger) thus allowing the firearm's recoil, plus constant forward pressure by the non-shooting arm, to actuate the trigger."



Is that not exactly what we have in Sport + mode?


I'm not here trying to say that there isn't a problem with your GLC. Maybe there is, maybe there's not, but that's between you and your dealership/mechanic to decide. They will "look" at every issue you drag your ride back in for, even if they know there is no "real fix" just to make you think they are doing something about it. They will tear your gearbox apart and spread it all over the shop as many times as you ask them to, possibly creating other future issues in the process. I became very familiar with my ride, very quick, and for these reasons. I have not been back to the dealership one time since I signed the paperwork, and I plan to keep it that way. I won't even take the free car washes and yearly inspections option lol. I can repeat the bucking motion at will now, and I can also stop it at will, now that I understand what is going on. Maybe this info will help, maybe it won't. All I can do is type my opinion on what causes MY GLC to do this. My transmission is perfectly fine, and will remain unopened until I decide so

viper3ez

looks like you are trying to apply laws of physics but you forget inertia. you are traveling at the same speed as the car you are inside of as is your foot so how can the pedal work like a bumpstop that travels at a different speed from your motionless body while shooting?

If this was the case, wouldn't it happen all the time?

the car is jerking at constant pedal pressure. there is not fluctuating pedal position.

if you are replicating this at will then there is nothing wrong with your car, you are just doing weird **** with your gas pedal.

as far as quick transmission goes, flooring and releasing in rapid successions would confuse any modern auto transmission as it tries to figure out whether to downshift and go or stay at current speed and rpm. torque management system would also not like it.

viper3ez

exactly mine. first or second stop signs as i leave my subdivision depending on when i switch to sport plus on. only on first drive of the day as i roll away from the stop sign. so far only happened on left turn from the stop sign also... because my first 2 stop signs are left turns for me. proably not a factor

4npower

Definitely keep us posted as to what you find. Good luck!

Chrisk03

It's a throttle issue and you are crazy if you take it to a dealer and have them tear down the trans to find the "cause"...IMO. This isn't a Lexus LS. I believe in the manual it even states that you shouldn't be in Sport+ or driving like a bat out of hell until your trans warms up. The software is VERY aggressive in S+ and shifts aren't real smooth, even when warm, but they are quick and responsive. I agree the first time you experience it, you are like WTF, but it's all in probably millimeters of movement of the gas pedal on whether it happens or not and some can make it happen (or not) at will. If it's not to your liking, its probably not the vehicle for you...and that's ok. Some have been able to get a software update that helps fix it, but also neuters the vehicle from my understanding. Good luck.