Eibach springs and sways

[itguy61]

Good explanation here, specifically in the Principles section. With the bar locked to the bushings and unable to rotate it can't function properly.

Anti-roll_bar

 

[MerlintheMad]

The installer I used does quite a bit of stuff like that and commented that it made no sense they that the stock bar was this way. That might explain the flaky handling in the rear end with the stock bar.

Any way to "unstick" the OE sway bar? It seems to me that something tightened down too much can be untightened.

 

[MerlintheMad]

Good explanation here, specifically in the Principles section. With the bar locked to the bushings and unable to rotate it can't function properly.

Anti-roll_bar

"On rough or broken pavement, anti-roll bars can produce jarring, side-to-side body motions (a "waddling" sensation), which increase in severity with the diameter and stiffness of the sway bars."

This seems counterintuitive to our discussion. We get the Eibach (a stiffer sway bar) to reduce this "waddling" sensation; when in fact a stiffer bar should be increasing what we are complaining about!?

 

[YOWStinger]

"On rough or broken pavement, anti-roll bars can produce jarring, side-to-side body motions (a "waddling" sensation), which increase in severity with the diameter and stiffness of the sway bars."

This seems counterintuitive to our discussion. We get the Eibach (a stiffer sway bar) to reduce this "waddling" sensation; when in fact a stiffer bar should be increasing what we are complaining about!?

Yeah, that doesn’t ring right to me, I’ve never experienced that with sways and I’ve had them on every hobby car I’ve ever owned. The Stinger waddles when it’s stock.

 

[Shrikecorp]

Much good discussion here. With just springs I felt that it had improved. Might do sways eventually. But the rear end...I don't know, I've kind of thought it's been a little fun when it's got wiggly. Very easy to correct, typically. Am I the only one?

 

[SteveCo]

Much good discussion here. With just springs I felt that it had improved. Might do sways eventually. But the rear end...I don't know, I've kind of thought it's been a little fun when it's got wiggly. Very easy to correct, typically. Am I the only one?

I've never seen a review state other than that - when the outer rear wheel hits a bump while in a fast curve, there is a brief wiggle in the suspension that while surprising, does not upset the cornering. That is exactly the phenomena I experienced on a fast off-ramp transition, and was able to go back and repeat it to make sure that was the cause.

After contemplating how often I would realistically run across that, combined with my normal driving style and satisfaction with the suspension otherwise, I decided to not go ahead with purchasing the sway bars. I also have no desire to lower the car with springs, and I'm happy with the suspension response as is. I won't be tracking the car, and very rarely pushing it anywhere near it's limits for handling. For other people with different needs, suspension changes are obviously a worthwhile modification.

As for the 'locked bar' idea being floated about the stock sways, I'm not buying in. From pictures I've seen, there is no evidence of welded flanges or pins that positively anchors or 'locks' the bar to the chassis on each side, and would prevent normal torsional twisting of the sway bar inboard of that point. If If someone does have evidence of a mechanical 'lock' that I've somehow missed, I'd love to see it - mechanically pinning a side-to-side sway bar on each side would indeed be a ludicrous 'kludge'.

Forces acting on that bar from suspension movement and weight transfer are very substantial - merely having tight bushings isn't going to prevent the sway from acting as designed.

 

[YOWStinger]

As for the 'locked bar' idea being floated about the stock sways, I'm not buying in. From pictures I've seen, there is no evidence of welded flanges or pins that positively anchors or 'locks' the bar to the chassis on each side, and would prevent normal torsional twisting of the sway bar inboard of that point.

That's why I'm going to take the stock one apart when I get it.

Also, I have the exact bump that unsettles my car right outside my house, down a hill, across the swale of an intersection and around the corner. I don't mind spending the few hundred for the sways, I'm an enthusiast, and I enjoy being picky I also spend hours in Gran Turismo tweaking out suspension settings for laps around Nurburgring

 

[itguy61]

Your are not buying that the sway bar won't rotate in the bushings? I have mine right here and it is so tight it won't rotate. There is not mechanical lock, just very tight bushings. When the end link bolts were removed on both sides you should have been able to turn the bar, it was not rotatable. The Eibach rotes in the bushings. I bet it could be forced but it should rotate pretty easily. The sway bar is a portion device that twists, this behavior inhibits that with the stock bar. Basically ends up being just more springing.

 

[Manaz]

The AWD GT2 looks like a Group B rally car in stock form...probably would make a good one too!

God no, *way* too heavy.

 

[Ruturaj]

Your are not buying that the sway bar won't rotate in the bushings? I have mine right here and it is so tight it won't rotate. There is not mechanical lock, just very tight bushings. When the end link bolts were removed on both sides you should have been able to turn the bar, it was not rotatable. The Eibach rotes in the bushings. I bet it could be forced but it should rotate pretty easily. The sway bar is a portion device that twists, this behavior inhibits that with the stock bar. Basically ends up being just more springing.

Were you able to twist one side? I guess it would take some force (more than 114 lb/in torque), but cars weight should put more than that but oppose from bushing is more than bending force (approx 114 lb/in) then it would always bend than move. I have been trying to get garage in my apartment community, I can try it as well then.

 

[Manaz]

Hahaha, gotta love the “Financial Controller” , another tack you could take is that Christmas is around the corner.

"The Minister for War & Finance"...

 

[MerlintheMad]

Much good discussion here. With just springs I felt that it had improved. Might do sways eventually. But the rear end...I don't know, I've kind of thought it's been a little fun when it's got wiggly. Very easy to correct, typically. Am I the only one?

Not at all. Albert Biermann thinks his Stinger's rear end is "playful".

I didn't have an issue with how my stock Stinger behaved. But then, I am not a performance driver. I like to push corners and accelerate and drive fast. That's not the same thing.

 

[MerlintheMad]

Were you able to twist one side? I guess it would take some force (more than 114 lb/in torque), but cars weight should put more than that but oppose from bushing is more than bending force (approx 114 lb/in) then it would always bend than move. I have been trying to get garage in my apartment community, I can try it as well then.

Are we debating a deliberate design decision? Could Kia have cut costs with the smaller diameter sway bar, yet tightened it up somehow so that a thinner, less expensive bar does what a thicker, more expensive bar could do? Or close enough, anyway?

 

[Manaz]

Not at all. Albert Biermann thinks his Stinger's rear end is "playful".

Playful means that it is lively, but controllable and reliable in its response. I don't consider a rear-end that removes driver confidence by responding in unexpected ways to be "playful".

 

[Manaz]

Are we debating a deliberate design decision? Could Kia have cut costs with the smaller diameter sway bar, yet tightened it up somehow so that a thinner, less expensive bar does what a thicker, more expensive bar could do? Or close enough, anyway?

I don't think so.

By locking the swaybar, they've cut off interaction between sides of the car (which is what a swaybar is meant to do). What they've effectively done is added an additional spring to each side - possibly resulting in the car being "over-sprung" (or more correctly sprung for its weight/characteristics - it may be under-sprung without a swaybar).

A swaybar when properly implemented, allows interplay across the chassis - it does help effective spring-rate to a degree, but it also makes the two sides of the car behave in a more similar fashion - meaning that as the spring on one side unloads, the spring on the other side resists loading up (because the swaybar absorbs some of the load itself). This is why a car with a swaybar (or heavier duty swaybar) sits flatter - it's also why serious 4WD cars that are doing "rock-hopping" etc on very uneven terrain often decouple the swaybars entirely - so that you get fully independent suspension movement on each side of the vehicle.

 

[Manaz]

For those who are concerned with different sway-bar settings at front/rear having an impact on chassis stiffness - if the chassis is relying on the swaybars for stiffness (as may well be the case given they're locked into the mounts on this car), then IMHO, the chassis needs (better/different) bracing.

Quite a bit has been said about the "large hatch" and its impact on chassis stiffness - many years ago, I drove a VW Bora (Jetta in the US) V6 4Motion, it had the same basic layout as the Mk4 Golf R32, but was in a sedan shape rather than hatch. The Mk4 (and Mk5, and I suspect Mk6) hatch (and its Audi stablemates) was considered quite "loose" in the back due to the hatch configuration, and the following was created as an after-market accessory:

UNIbrace

They also do an under-body brace, and a rear-brace.

I know the MX-5 (Miata) owners do a fair bit of bracing too - of course, they're in a convertible chassis, and every bit of bracing they can get will be helpful).

I think putting something like those onto the Stinger could be very interesting..

 

[MerlintheMad]

Playful means that it is lively, but controllable and reliable in its response. I don't consider a rear-end that removes driver confidence by responding in unexpected ways to be "playful".

But others have described their driving experience by the former and not the latter. Other than understeer, which I found out about as "unexpected" (before the Eibach rear sway bar), my experience with the movements in the rear end always felt controllable; the gription felt reliable.

By locking the swaybar, they've cut off interaction between sides of the car (which is what a swaybar is meant to do).

The jury seems to be out on whether the OE sway bar is locked; really firmly gripped by the bushings, but not locked per se.

What they've effectively done is added an additional spring to each side - possibly resulting in the car being "over-sprung" (or more correctly sprung for its weight/characteristics - it may be under-sprung without a swaybar).

Now it sounds like you're entertaining deliberate design. "Gimmicky", perhaps, but effective? (At least to most drivers; since most do not push the car anywhere near its performance potential; and those that do are divided in their opinion as to whether or not the Stinger handles reliably or does "unexpected" things.)

For those who are concerned with different sway-bar settings at front/rear having an impact on chassis stiffness - if the chassis is relying on the swaybars for stiffness (as may well be the case given they're locked into the mounts on this car), then IMHO, the chassis needs (better/different) bracing.

Quite a bit has been said about the "large hatch" and its impact on chassis stiffness - many years ago, I drove a VW Bora (Jetta in the US) V6 4Motion, it had the same basic layout as the Mk4 Golf R32, but was in a sedan shape rather than hatch. The Mk4 (and Mk5, and I suspect Mk6) hatch (and its Audi stablemates) was considered quite "loose" in the back due to the hatch configuration, and the following was created as an after-market accessory:

UNIbrace

They also do an under-body brace, and a rear-brace.

I know the MX-5 (Miata) owners do a fair bit of bracing too - of course, they're in a convertible chassis, and every bit of bracing they can get will be helpful).

I think putting something like those onto the Stinger could be very interesting..

I think the usual concern isn't about chassis stiffness with different settings on front and rear sway bars; it is about how those settings affect steering.
​

There was a discussion last year about chassis bracing on the Stinger. Some forum members have added bracing. There was no consensus, that I recall, as to efficacy or its opposite.

Stinger chassis is stiff for a hatch. The chassis is designed to be quiet, comfortable, safe and a performer.

 

[Manaz]

But others have described their driving experience by the former and not the latter. Other than understeer, which I found out about as "unexpected" (before the Eibach rear sway bar), my experience with the movements in the rear end always felt controllable; the gription felt reliable.

Different drivers will interpret it in different ways. To me though, a car that reduces the driver's confidence in it isn't "playful". Of course, this is a subjective matter.

The jury seems to be out on whether the OE sway bar is locked; really firmly gripped by the bushings, but not locked per se.

A fair call. I guess what I'm saying here is that even if it's just really firmly held, it's not being used in the same was swaybars are traditionally used in other deployments, and quite differently to the way the Eibachs work.

Now it sounds like you're entertaining deliberate design. "Gimmicky", perhaps, but effective? (At least to most drivers; since most do not push the car anywhere near its performance potential; and those that do are divided in their opinion as to whether or not the Stinger handles reliably or does "unexpected" things.)

I think so, yes. If (as several have noted, I'll take a good look myself soon) the rear swaybar is locked and is effectively acting as an additional spring rather than to control load across the chassis, that would potentially explain the behaviour that many are experiencing.

I've felt the movement in the rear of the Stinger myself during test drives - I can reproduce it easily at a variety of speeds from sub-40km/h by turning over a road surface change to well over 100km/h through a crest with a following dip, and it's disconcerting (especially at higher speeds, the car dealership salesman swore and had firmly white knuckles when I induced it over corner I know very well) unless you're really expecting it (and to be honest, it shouldn't be expected). Evidence (albeit anecdotal) is that new swaybars help to eliminate this (likewise springs, to a lesser effect).

I don't for a second believe I know better than Biermann or the other suspension tuners at Kia, I'm sure in the situations they experienced it in, they did the job they were financially allowed to do. But for me especially in Australia, where cars often receive market-specific suspension tuning due to our road surfaces and road maintenance (or lack thereof?) regimes, it doesn't work the way I want it to - and if I'm putting down AUD$60k for a car, I'm not in the slighest bit concerned if I have to spend another $1k to make the suspension behave the way I want it to.

I think the usual concern isn't about chassis stiffness with different settings on front and rear sway bars; it is about how those settings affect steering.

There was a discussion last year about chassis bracing on the Stinger. Some forum members have added bracing. There was no consensus, that I recall, as to efficacy or its opposite.

Unmatched swaybars will absolutely impact on steering (and can be used to tune turn-in and power-on behaviour in corners). But I've seen quite a few comments about uneven swaybar installation settings and the potential for additional chassis flex, with addiitional hatch and sunroof creaking being potential results. *If* those things are true, then the chassis could potentially do with more stiffening.

Stinger chassis is stiff for a hatch. The chassis is designed to be quiet, comfortable, safe and a performer.

Undoubtably so for a hatch - but the fact that we're saying "for a hatch" is telling, because it means we understand that hatches are naturally not as stiff as over body styles. Stiffening the chassis more may well introduce unacceptable NVH - hopefully a balance can be found between stiffness and NVH - the brace I mentioned earlier certainly helped me to achieve it in my Bora (and the Bora wasn't natively as flexible as the Golf/A3/etc hatch, where it had an even bigger impact on structural rigidity) without any substantial NVH increase.

 

[MerlintheMad]

I don't for a second believe I know better than Biermann or the other suspension tuners at Kia, I'm sure in the situations they experienced it in, they did the job they were financially allowed to do. But for me especially in Australia, where cars often receive market-specific suspension tuning due to our road surfaces and road maintenance (or lack thereof?) regimes, it doesn't work the way I want it to - and if I'm putting down AUD$60k for a car, I'm not in the slighest bit concerned if I have to spend another $1k to make the suspension behave the way I want it to.

Then we are talking about US suspension tuning compared to AUS: our suspensions are reputed to be the stiffest, and yours are the softest, from the factory. So we may be talking apples and oranges here, since the starting point is likely quite different. Then AWD, RWD differences, electronically monitored/controlled suspension, and now we have a bunch of different factors before we even start to swap OE sway bars.

… the fact that we're saying "for a hatch" is telling, because it means we understand that hatches are naturally not as stiff as over body styles.

Well, this is a practical performance car, a Gran Turismo, not a track car. Nobody in their right mind would expect to take a Stinger to a track and compete with sports cars intended to be driven from track to street and back again. The Stinger is that compromise. And a compromise is not going to be a top performer: impressively good, "for a hatch", but no Porsche.

Stiffening the chassis more may well introduce unacceptable NVH

That was happening, iirc, as reported on the earlier discussion about stiffening the chassis. But also some reduced noise? I think so. Different vehicles and drivers noticing different stuff.

 

[Ruturaj]

Are we debating a deliberate design decision? Could Kia have cut costs with the smaller diameter sway bar, yet tightened it up somehow so that a thinner, less expensive bar does what a thicker, more expensive bar could do? Or close enough, anyway?

Man, we are going in circles and circles. Tight (not freely moveable) sway is not a sway. I don't think thicker bar would have been much expensive than current. Please learn how sways work and then try to understand how locked bar wouldn't.