Rear thud sound going over bumps - not the ballbearing in a can sound

[Fboost]

I think people on here are talking about 2 different sounds.
My car does it over bumps when excelerating. Best described as a thud and to me sounds like drive train, possibly diff. I heard this same sound the other day when I was accelerating on an onramp there was a slight bump and traction control kicked in and at the same time heard the thud. There is a corner on my way to work that I can recreate the thud everytime. Medium to hard acceleration will thud, coasting around the bend produces no noise.
Which also leads me to think drive train.

 

[Fl stingergt]

You could be right if you have limited slip diff . I’ve had them make the clunk noise but only when they where on the way to breaking or gear not in gaging properly inside housing.

 

[Ty Davis]

I think people on here are talking about 2 different sounds.
My car does it over bumps when excelerating. Best described as a thud and to me sounds like drive train, possibly diff. I heard this same sound the other day when I was accelerating on an onramp there was a slight bump and traction control kicked in and at the same time heard the thud. There is a corner on my way to work that I can recreate the thud everytime. Medium to hard acceleration will thud, coasting around the bend produces no noise.
Which also leads me to think drive train.

Mine too... The Stinger has a fair amount of front anti-dive and rear anti-squat geometry built in.
These designs use braking force to resist nose dive when braking (anti-dive) and acceleration force to resist squat at the rear (anti-squat).

When we accelerate, the geometry is such that power to the rear wheels effectively stiffens the rear suspension a bit, resisting squat. I’d imagine it takes up a bit of compliance in at least some of the suspension bushings back there too. This all adds up to a stiffer effective wheel rate when you are accelerating. And upping the effective spring/wheel rate is exacerbating whatever is causing that thump.

This is my first car with an LSD, so initially I wondered if the LSD was creating the noise. But notice, 2.0 drivers without LSD have also reported the sound... at this point, I believe poor road isolation is the cause. That big hatch back there isn’t doing us any favors either.

 

[Dan1028]

Is the OP talking about a "boominess," almost like wind buffeting when rear windows are open, or a singular "thud" on a bump?

I've experienced the former "boominess" even on flat, well-paved roads at lower speeds. Almost sounds like a subwoofer just vibrating for the hell of it.

If it's more of a "thud" and not the hatch rattle, in addition to checking the suspension, etc., check that the exhaust is not jostling around.

 

[Ty Davis]

Is the OP talking about a "boominess," almost like wind buffeting when rear windows are open, or a singular "thud" on a bump?

I've experienced the former "boominess" even on flat, well-paved roads at lower speeds. Almost sounds like a subwoofer just vibrating for the hell of it.

If it's more of a "thud" and not the hatch rattle, in addition to checking the suspension, etc., check that the exhaust is not jostling around.

I’ve experienced this as well. I think that sound is road surface induced.
In my opinion the Stinger is very vocal in transmitting road surface via sound and vibration.
On seemingly smooth roads that other cars glide down relatively vibration free, the Stinger transmits road grain and texture info right up through the Steering and Seats. If you listen closely there are all sorts of sounds accompanying this. The alert ear will notice this as a very low rumble, or repetitive thumping.

I think this is a side effect of the Stingers shock and bushing calibration. It simply lets a bit of low frequency chatter, rumble, and vibration in. The Stinger taught me that a lot of roads that I previously considered smooth, weren’t really all that smooth at all. My previous vehicles just did a better job of filtering out that road texture.

I think the Stinger shocks are calibrated to have a very firm initial reaction to small inputs (perhaps too firm). Then that is immediately followed by a soft control of actual bumps. I can’t help but thinking a good bit of Stinger noise complaints come from this tuning.

All of that being said, I think that is just how it is, as the Stinger rides brilliantly on a truly smooth surface.
It rides fairly decent on a bad surface too, but with perhaps too much noise.
But it suffers on average to marginal surfaces that look smooth to the eye.

I drove a couple Stingers before I bought mine. All of them had the same familiar sound and feel as the tires rolled over the pavement. I’m interested to see if the G70 calibration feels or sounds any different.

 

[Fl stingergt]

It should it’s a totally different chassis then the stinger.Kia trimmed a lot of cost by not putting a lot of sound proofing under the stinger compared g70.

 

[Ty Davis]

It should it’s a totally different chassis then the stinger.Kia trimmed a lot of cost by not putting a lot of sound proofing under the stinger compared g70.

I think the chassis is the same. It’s a different configuration though.
Kind of like BMW 3 series convertible, sedan, coupe, wagon, and hatchback.
Same platform. Same chassis. Different bodies. The underpinnings are just scaled to different proportions.

G70 and Stinger suspension are directly swappable with one another because they share the same chassis.
This chassis was originally for the Genesis G80. Then it was adapted to the Stinger/G70.
The biggest difference between the Stinger and G70 is the styling and tuning. They are nearly twins otherwise.

You’re right about the sound deadening... I found the Stinger has none that I could see in the trunk. The trunk floor is bare! From the sounds of things, it is scarce on other parts of the car too. Like you, I imagine they did a better job here, on the G70.

 

[MerlintheMad]

Mine does this too, as well as all of the other a Stingers I test drove before purchase. I do think this is “normal” for this platform.
However, the sound should not be there in a well designed and engineered vehicle.

The weird part is a lot of people don’t hear it even though it is there.
Some mistake it for the hatch rattle. This sound is not from the hatch, but rather the rear structure of the car.

For those curious as to what the OP is referring to, there is a distinct bassy/boomy sound that resonates through the rear of the car over pavement irregularities. It is most prevalent at low speeds. The sound is akin to the sound of tight drum being struck. It can vary from just barely audible to very obvious.

Kia definitely needs to fix this in generation 2.0 of the Stinger. It would also be nice if they implement a fix for us current owners.

I think it is just suspension noise resonating through the body of the car back there. High tire pressures increase the sound of it. Accelerating from low speeds while the rear wheels negotiate a bump or crack also will create the sound. Turning and accelerating with moderate briskness from a stop will also induce the sound if the surface under the tires is not smooth.
In fact, there is an ever so slight sound that can be heard whenever a rear wheel looses traction during acceleration from a stop.

I find that the Stinger does an excellent job at transmitting road grain and texture into the cabin. Sometimes this manifests as extra vibration, others it induces hollow bassy thumps and thuds. Sometimes both.

All of this is exacerbated by poorly tuned springs, dampers and bushings.
There is a weirdness to the Stingers suspension that I cannot put my finger on... An unfortunate mix of too hard, too jittery, and too soft.
Then you get to a good road and find that it rides like silk. The Stinger absorbs actual bumps quite well. It just fails at filtering out excess road texture, grain, and small irregularities.

Hopefully aftermarket shocks help. I’d imagine the Stingers poor wheel/body control and cabin isolation contribute to the thumps and thuds being talked about here.

Well, I think that you are @CaliSting's new account. He was always dissing the car for this or that quality issue, then praising it as a great performer (for the money). Heh.

I don't believe that there is anything about the Stinger that is poorly executed, unless it is a bit of chintzy lack of sound deadening in the rear. This has nothing to do with how the suspension performs. If these noises you mention are "ever so slight" then they are ever so tiny as issues, imho.

You can't have a performance suspension that also rides like "silk". There has to be a compromise between comfortable and quiet, and stiff enough to handle at speed.

I’d imagine the Stingers poor wheel/body control and cabin isolation contribute to the thumps and thuds being talked about here.

I have no idea what you are talking about here.

 

[Ty Davis]

Well, I think that you are @CaliSting's new account. He was always dissing the car for this or that quality issue, then praising it as a great performer (for the money). Heh.

I don't believe that there is anything about the Stinger that is poorly executed, unless it is a bit of chintzy lack of sound deadening in the rear. This has nothing to do with how the suspension performs. If these noises you mention are "ever so slight" then they are ever so tiny as issues, imho.

You can't have a performance suspension that also rides like "silk". There has to be a compromise between comfortable and quiet, and stiff enough to handle at speed.

I have no idea what you are talking about here.

Oh no. Don’t get the wrong idea. The Stinger is a great car. A car that I traded my BMW for. I chose the Stinger over multiple other brands and options. However, the Stinger is not perfect. No car is.
I am not bashing Stinger in any way. There are good things about it. There are bad things about it as well.
If you go and look at my posts, you will find that rarely do you find a thread where I speak on the negatives where I don’t also speak on the positives.

I speak honestly about the product and my experience with such, because I love it and have a vested interest in the furthering the platform. I am already eagerly awaiting the 2nd generation Stingers arrival.
But if in your words “there are no poorly executed parts of the Stinger”, what motivation does Kia have to make a an even better product next time around.

More on that...
The suspension calibration is “poorly executed.” But if you find the bouncing, floating, and lack of composure appropriate for the car, I respect that.
Hatch rattle, is another example of “poor execution.”
Paint issues...
NVH (thumps/thuds/etc.)...

I have had my Stinger a relatively short time. Accordingly, I have not wrote my complete review of the Stinger just yet. Be rest assured, plenty of positive praise will be included. But Merlin, buckle up, because there darn sure will be some not so positive things in there as well.

Once again though, the point is not to bash the product, but to find resolutions to issues that exist on this platform. Maybe there is a bit of a different culture going on here in Stingerland. I grew up on the Honda forums and transitioned to Bimmers over the years. On those forums, we picked the cars apart (often viciously), identifying issues, implementing fixes, and bettering those vehicles for our efforts and enjoyment. That is what I attempt to do here.

I ask that if I, or one of our Stinger brethren, lodge a complaint against the Stinger, don’t view that as an assault on your purchase decision or quality of your vehicle. I am not here to stroke Kias ego. I did that about 46,000 times when I signed on the dotted line. $$$

I am only here to make this car better. For me. For you. For future owners...
It just so happens, there are a few areas that the Stinger could use two good scoops of extra “better”.

Suspension
Rotors
Paint quality
NVH

I do understand that you think the Stinger is perfect, as is.
Again, I respect that. But let’s also respect that others will have differing opinions. Let’s respect that skill levels, knowledge, and experience will vary.
Mind you, I saw you post about some thudding sounds too, even in your magically perfect Stinger.
The forum needs people like you, who will champion for the brand.
The forum also needs people who are more critical. There’s a place for everyone.

One more thing before I digress...
Don’t for a second believe that a high performance suspension has to be unrefined.
A performance suspension can be relatively silky. When I mention the suspension issues of the Stinger, none of them exist because this is a “performance” suspension. These are tuning choices that Kia made, that can easily be improved upon next time around.

 

[Ty Davis]

Oops. Double post.

 

[MerlintheMad]

But if in your words “there are no poorly executed parts of the Stinger”, what motivation does Kia have to make a an even better product next time around.

More on that...
The suspension calibration is “poorly executed.” But if you find the bouncing, floating, and lack of composure appropriate for the car, I respect that.
Hatch rattle, is another example of “poor execution.”
Paint issues...
NVH (Noise, Vibration, and Harshness) (Noise, Vibration, and Harshness) (thumps/thuds/etc.)...

These are production teething problems, not poor design. The balance between cost and quality is constant. As for the rear end handling being "floaty", Albert Biermann said the rear end is "playful". That's putting it kindly to some drivers who expect the stock Stinger to behave like a track car. Before I put the Eibach rear sway bar in, I did not find the Stinger to be "floaty" but it would bounce on an uneven road surface when cornering; at no time did I feel that the handling was compromised by the "bounce". With the Eibach, on "soft", the bounce is reduced a lot, and of course the feeling that the car handles better is pronounced. But I don't think that the handling is actually better, i.e. quicker through turns.

I ask that if I, or one of our Stinger brethren, lodge a complaint against the Stinger, don’t view that as an assault on your purchase decision or quality of your vehicle. I am not here to stroke Kias ego. I did that about 46,000 times when I signed on the dotted line. $$$

I'm not getting ego involved here. My experience is entirely with THIS car. Everything I've driven before is in the realm of practical, cheap family transportation. This is the only brand new car I've ever purchased. I couldn't care less about who created it. Kia? That had me going for months: I could hardly believe that Kia came up with a car like the Stringer. I've had mine just over a year and nothing about it seems poorly executed. Perfect? Not quite. I'll be surprised if Kia's improvements make any dramatic difference, because the concept through testing to production was a home run. It's going to be hard to beat what is already an amazing GT.

It just so happens, there are a few areas that the Stinger could use two good scoops of extra “better”.

Suspension
Rotors
Paint quality
NVH (Noise, Vibration, and Harshness) (Noise, Vibration, and Harshness)

This is where my lack of extensive experience will make anything I say less than credible. But I really don't know what you are on about with any of these. Paint quality is largely good. Very few vehicles have issues. I think that for as thin as it is, the paint is going to look good years down the road. That's my prediction. We'll see. Rotors are also almost entirely without issues. This is not a design flaw, but it might be a less than ideal choice in the product used: Kia may upgrade these later, if they haven't already. The suspension is a balance between cost and performance. If Kia goes with a more "elite" design, it will drive the costs up. This is true in every aspect of the car. I think that they scored big time with where they cut costs.

Don’t for a second believe that a high performance suspension has to be unrefined.
A performance suspension can be relatively silky. When I mention the suspension issues of the Stinger, none of them exist because this is a “performance” suspension. These are tuning choices that Kia made, that can easily be improved upon next time around.

This intrigues me. And I look forward to reading what you have to say about your pursuit of better tuning of the existing suspension. I'm not really interested in aftermarket suspension components. The sway bar upgrade made sense and was simple and inexpensive enough to get maximum improvement for little cost and no risk.

 

[Ty Davis]

These are production teething problems, not poor design. The balance between cost and quality is constant. As for the rear end handling being "floaty", Albert Biermann said the rear end is "playful". That's putting it kindly to some drivers who expect the stock Stinger to behave like a track car. Before I put the Eibach rear sway bar in, I did not find the Stinger to be "floaty" but it would bounce on an uneven road surface when cornering; at no time did I feel that the handling was compromised by the "bounce". With the Eibach, on "soft", the bounce is reduced a lot, and of course the feeling that the car handles better is pronounced. But I don't think that the handling is actually better, i.e. quicker through turns.


I'm not getting ego involved here. My experience is entirely with THIS car. Everything I've driven before is in the realm of practical, cheap family transportation. This is the only brand new car I've ever purchased. I couldn't care less about who created it. Kia? That had me going for months: I could hardly believe that Kia came up with a car like the Stringer. I've had mine just over a year and nothing about it seems poorly executed. Perfect? Not quite. I'll be surprised if Kia's improvements make any dramatic difference, because the concept through testing to production was a home run. It's going to be hard to beat what is already an amazing GT.


This is where my lack of extensive experience will make anything I say less than credible. But I really don't know what you are on about with any of these. Paint quality is largely good. Very few vehicles have issues. I think that for as thin as it is, the paint is going to look good years down the road. That's my prediction. We'll see. Rotors are also almost entirely without issues. This is not a design flaw, but it might be a less than ideal choice in the product used: Kia may upgrade these later, if they haven't already. The suspension is a balance between cost and performance. If Kia goes with a more "elite" design, it will drive the costs up. This is true in every aspect of the car. I think that they scored big time with where they cut costs.


This intrigues me. And I look forward to reading what you have to say about your pursuit of better tuning of the existing suspension. I'm not really interested in aftermarket suspension components. The sway bar upgrade made sense and was simple and inexpensive enough to get maximum improvement for little cost and no risk.

I understand that you can only judge a product by your own expectations and experiences...
But, my question to you is what advice do you offer to those whose who are seeing things differently than you do?
We’ve crossed paths in several threads regarding rotors, suspension tuning, and NVH.

In the majority of those threads I was not even the original poster. I often was just responding with the benefit of my own personal experience and knowledge of why the OP was experiencing what he posted about. I’m fairly savvy when it comes to vehicles but don’t purport to know everything.

Multiple people have rotor issues. Multiple people have the same rattles. Multiple people have paint issues. Multiple people know that the bouncy suspension could use some tweaking. Multiple people....

This car (and most cars) has a distinct pattern of “issues”. Some are calibration issues. Some are quality issues. Some are design issues. But that is not the point. When people post here, I would like to offer them some resolution to their issue. Maybe a bit of info on why they are experiencing it... Or even just letting them know that they are not alone and I see their issue too (if I’ve seen it).

But I think we are losing focus here and also derailing the original posters thread.
Once again, I pose this question to you. What useful advice do you have for the original poster who was inquiring about his noisy Stinger? What useful advice do you have for the numerous other people in this very thread that are recounting similar and related sounds?

My posts were not meant to be malicious in any way. Please don’t perceive them that way.
I was just giving support, info, and care/concern to my fellow Stinger brethren.

 

[Revvdmedia]

I also have a low frequency "deep" thud (how best to really explain it?). It's surprisingly one of the few things that don't really bother me about the car (I'm rather picky), I think it could be better but I don't consider it a defect. I have seen some suggestions here on possible causes and do also believe it could be due the weight in the rear, lack of sound deadening, contributing factors of the hatch (bumpers, threaded rubber stops, etc). I think one major contributor to the thud compared the the front suspension is the fact the rear suspension is more EXPOSED than the front to the interior of the car due to the hatch design. Normally you would have some isolation between the shocks and the interior of the car due to the design of a coupe or sedan - rear window, seats, parcel shelf, etc. While the cargo cover will offer some isolation, I think a big part of why the rear makes thuds compared to the front (which is isolated from the interior due to the firewall) is the exposure of the steel the rear suspension is connected to the interior with minimal isolation combined with not a lot of additional sound deadening. I'd be curious to see if a similar car (Audi sportback, BMW Gran Coupe) has a similar rear end thud, and if not, how the interior and underbody insulation compares to the Stinger.

 

[Ty Davis]

I also have a low frequency "deep" thud (how best to really explain it?). It's surprisingly one of the few things that don't really bother me about the car (I'm rather picky), I think it could be better but I don't consider it a defect. I have seen some suggestions here on possible causes and do also believe it could be due the weight in the rear, lack of sound deadening, contributing factors of the hatch (bumpers, threaded rubber stops, etc). I think one major contributor to the thud compared the the front suspension is the fact the rear suspension is more EXPOSED than the front to the interior of the car due to the hatch design. Normally you would have some isolation between the shocks and the interior of the car due to the design of a coupe or sedan - rear window, seats, parcel shelf, etc. While the cargo cover will offer some isolation, I think a big part of why the rear makes thuds compared to the front (which is isolated from the interior due to the firewall) is the exposure of the steel the rear suspension is connected to the interior with minimal isolation combined with not a lot of additional sound deadening. I'd be curious to see if a similar car (Audi sportback, BMW Gran Coupe) has a similar rear end thud, and if not, how the interior and underbody insulation compares to the Stinger.

The 3 series Grand Coupe does not have this problem. No other hatchback, I have driven has either. Station wagons and SUVs have been free of this sound too. I do regularly hear it on U-Haul Chevy vans. Stiff suspension on those. Minimal sound deadening too.
Incidentally, my BMW F10 535i sedan had a similar sound, though less frequent and a bit quieter. On that car, I swapped the upper strut mounts for units that were softer.
The Adaptive suspension on that car came with stiffer strutmounts front and rear to help accommodate the Electronic dampers.

I knew from driving other 535i, that only the ones with the adaptive struts made that sound.
I went through the parts list and found the only difference was the spring/shocks/mounts.

I put the regular suspension mounts in and the problem went away.

On the Stinger, it seems that all models use the same rear strut mounts.
Our mount is shared with the first generation Kia K900.
I still need to get my hands on a G70 to see how/if it is different in this regard.
There may be an opportunity for improvement with G70 mounts, if so.

 

[Ty Davis]

Sorry, double posted again...

 

[AV8R]

It’s not the exhaust hitting the car is it?

 

[Fboost]

I don't know about other people but on my car it's doesn't sound like something loose, I have had loose exhausts hatch rattle etc
This is more of a drive train thud, sound is deep and only happens when accelerating over uneven surface, I don't think it's faulty just think the rear end/cradle needed more engineering not sure how they didn't sort this when the rest of the car is so good, the car feels very unsettled when driving around a corner with uneven service, for reference I had a 460hp 1100kg Silvia and could accelerate hard around a corner without the rear suspension misbehaving or making strange sounds, I'm obviously referring to staying within the limit of the tyres for these examples. On a side note are people with non lsd's also having this deep thud? As generally mechanical lsd's are very clunky (I have had 2 before) I was quite Suprised when I read the stinger would have mechanical diff.

 

[Ozstung]

Im late in on this thread so i haven't read all the pages. I can say i have this thud noise since day one when going over speed humps this is when i only hear it.

To me its defintely not hatch related it sounds suspension related? I thought it might have been the exhaust. But the car has been on a hoist and the exhaust was completely changed. Whilst annoying i only ever hear it on speed bumps which i take gently.

 

[GenesisG70]

Have a 2019 the car absorbs bumps and holes solidly. Cannot hear the bump you mention...

 

[MerlintheMad]

But I think we are losing focus here and also derailing the original posters thread.
Once again, I pose this question to you. What useful advice do you have for the original poster who was inquiring about his noisy Stinger? What useful advice do you have for the numerous other people in this very thread that are recounting similar and related sounds?

My posts were not meant to be malicious in any way. Please don’t perceive them that way.
I was just giving support, info, and care/concern to my fellow Stinger brethren.

All my earlier comments on this forum are directed at reality. When "multiple" people complain about an issue, someone always chimes in eventually and makes the problem bigger; sometimes even asserting that "all" Stingers are affected. That's when I chime in and say "no, not all: mine doesn't." And off we go.

On this thread, I mentioned what I heard in my car, then presented a few possible causes to look into.

In this specific case: It seems likely that something in the way the rear end works causes a "thump" sound when calling on the car to perform (as opposed to just driving the car normally). When I am accelerating and cornering in a "spirited" manner, I don't expect the car to remain quiescent and noise free. So any additional noises that manifest under more demanding conditions are considered "normal operation." That is a Kia manual phrase I've run into many times. Notably under Brembo "high performance" brakes. "Scratching" or "rrrrr sound" is explained as "normal operation" and not a defect, etc. This "thump/thud" sound when going over bumps, especially at speed, shouldn't be bothering anybody. It's in a completely separate class of car noises from a continuous and irritating "rattle".

So my advice is: "If it ain't broke, don't bother with it." Don't expect perfection. Don't set your expectations of a complex machine so high.