The Best Suspension Mod for your Stinger: Another Eibach springs/swaybar review

[Mr Skillet]

Eibach Pro-kit Springs and Swaybar Impressions

Special thanks to David from K8stinger.com – I was told by Eibach that the rear sway bar was out of stock until the end of September! David was able to source a full set and get it shipped out from their east coast warehouse the very next day!

The numbers: GT2

OE Spec Spring Rate

Front: 172 lb/in

Rear: 489 lb/in

Eibach Rates (increase vs stock rate)

Front: 195 lb/in (+13%)

Rear: 331-565* lb/in (Progressive*) (+15%)

*According to the Eibach tech I spoke with the lower rate only applies to the first inch of compression, and really would only apply in full droop scenarios, similar to a helper spring on a coilover when the car sitting on the ground or in motion the main spring rate of 565 lb/in applies.

Sway Bars - Keep in mind sway bars act as springs connecting the left and right side of the car reducing the “independence” of the suspension and this causes reduced body roll. They are only functional when there is a twisting force caused by a difference of compression between the left and right suspension due to cornering forces or uneven pavement. While driving on even flat surfaces, the sway bars do not affect handling or ride.

OE Size and bar rate (increase vs stock rate)

Front: 23mm 263 lb/in

Rear: 16mm 114 lb/in

Eibach Size and Bar Rate

Front 25mm adjustable: Soft 366 lb/in (+39%), stiff 398 lb/in (+51%)

Rear 19mm adjustable: Soft 201 lb/in (+76%), stiff 244 lb/in (+114%)

Subjective review:

I have driven the car for about 2000 miles of mixed highway and local driving as a daily commuter as well as a few quick trips to the local canyons. I really appreciate the handling balance Kia chose with one exception, the rear rebound dampening is inadequate, this is one of the key reason the rear of the car gets unsettled in mid corner bumps and many have reported a “floating” sensation over rough pavement or speed bumps. After some research and even reaching out to reputable aftermarket damper companies like KW, Koni, Bilstein, I was told that there were no plans for any adjustable dampers in the near future. Eibach springs and sway bars were the only offering for our cars from a reputable brand I could find.

Ride quality:

I experienced approximately 1” drop front and rear similar to what several others have reported here on the forum. I can certainly see now, why KIA NVH and handling dynamic guys settled on these particular spring/damper rates. The only car that rides better in this class would be an E-class or CTS-V. If you live somewhere with pristine pavement (everyone in south OC) just ignore this section.

The 13-15% increase in spring rate have reduced suspension compression over the same bumps and pavement noticeably, but the ride is now also noticeably busier but by no means harsh or jarring. There is still some slight “float” in the rear, although I would say 70-80% of what is felt is gone and for the vast majority this is an adequate solution to the issue. When I first had the sway bars installed, they were set on stiff for both front and rear. While response to steering inputs and body roll were greatly improved, the suspension also forced the body of the car to follow uneven pavement more. I later moved the end links to the soft position front and rear and the ride over rough pavement improved noticeably with a slight increase in body roll and ever so slightly less response to steering input. I consider this tradeoff perfect for me. Keep in mind, I live and work in LA, where we have the 2nd poorest quality of roads in the nation. Where the factory suspension absorbed all but the largest of impacts and felt like it glided over most of the road imperfections, the increased spring/bar rates allowed more of the “road texture” into the cabin. The car still rides with poise and comfort particularly at cruising speed on the highway.

Handling:


I feel like this car handled amazingly well right off the showroom floor particularly for a daily driven GT car. If Kia actually allowed us to dial up the rear rebound rate a bit to address the mid corner bump issue, I would have been perfectly content. The stock car turns in sharply, actually allowing you to trail brake coming into a corner. It reminds of 3 series of the e30-e46 era! Mid corner, there is a moderate amount of body roll, as the suspension loads up, the car feels pretty neutral right up to the limit, and when you exceed it, reacts with a bit a gentle understeer that’s easily balanced with your right foot. If you keep your foot in it, the rear steps out progressively. I really love this playful aspect of the handling balance and didn’t want to ruin it.

I’ve heard a few people complain about rear traction on RWD models on corner exit where people complain about the car stepping out suddenly. The only time I feel like the car is not progressive is if you are accelerating out of a corner, but revs are too low <2,500 rpm. As the boost kicks in and the available torque triples between 1500-2500rpm, it can break rear traction a bit suddenly. Reminds me a bit of older turbo RWD Japanese cars from the 90’s or even AP1 S2k (Vtech kicked in YO!!!!) but if your love to hoon around this is perfect!

With the springs installed and the sway bars on stiff front and rear, the car really drives like a true sports sedan, taut, responsive, flat cornering and confident. I chose to set the bars on soft because it gives me a little bit more compliance over rough and uneven pavement around LA. The additional body roll and reduced twitchiness makes for a more relaxed and comfortable drive. There is also a noticeable reduction in squat and dive, but I didn’t think it was excessive before. I prefer a car that is under-sprung and over-dampened (think 2000’s 3 series or Porsche 911/cayman). The body roll allows weight shifts to happen more slowly and makes the car more forgiving and easier to drive close to the limit. The handling balance is still close to neutral, and very throttle steerable. I still wish someone can crack the EDC software and allow us to dial up the rebound/compression values on the rear shock, that said, for daily use and the occasional spirited run through the canyons, the car is 80% where I’d want the suspension to be.

I hope that answers for people still on the fence and gives another subjective perspective on ride and handling changes.

 

[Never thought]

Great detailed write up. Any guess on how just doing springs would impact the harshness of the ride? I’d like a little less body roll and unsettleness hitting bumps on turns but I don’t want to lose significant comfort.

 

[Mr Skillet]

Great detailed write up. Any guess on how just doing springs would impact the harshness of the ride? I’d like a little less body roll and unsettleness hitting bumps on turns but I don’t want to lose significant comfort.

You won't with just springs, the ride is busier but still very much a comfortable car. It'll never be an s class, but the stinger still rides better than my wife's 2017 mdx.

 

[DaJackson]

Great detailed write up. Any guess on how just doing springs would impact the harshness of the ride? I’d like a little less body roll and unsettleness hitting bumps on turns but I don’t want to lose significant comfort.

The ride with just springs will be almost identical to the ride with springs and sways. The sway bars only impact the lateral movement of the car not the vertical movement.

 

[Ozstung]

Excellent write up Mr Skillett and lots of info for people deciding. I have the Eibach springs only and agree 100% in what you have added.

 

[KLR STINGER]

Great review and thoughts exactly. Car needs more rear dampening. I've got sways on soft front and hard rear. Makes for a good balance and easy rotation

 

[Never thought]

The ride with just springs will be almost identical to the ride with springs and sways. The sway bars only impact the lateral movement of the car not the vertical movement.

I’ve read the opposite. That the sways reduce the amount the wheels independently react from one another which causes a stiffer/bumpier ride.

 

[CaliSting]

Do you notice any rattle from eibach bars on rough surfaces?

 

[DaJackson]

I’ve read the opposite. That the sways reduce the amount the wheels independently react from one another which causes a stiffer/bumpier ride.

I’d be interested to hear a detailed explanation on that. Over something like a speed bump maybe but on normal rough roads the springs and shocks do more for ride comfort than sways.

Now if you are talking super thick sways on a very stiff setting (race set up) that don’t allow the springs/shocks to do their job I could see it being rougher but the Eibach aren’t anywhere close to that.

 

[Mr Skillet]

Great review and thoughts exactly. Car needs more rear dampening. I've got sways on soft front and hard rear. Makes for a good balance and easy rotation

I was going to try this setting eventually, car as it, is pretty neutral at steady state cornering. With so much torque going to the rear wheels, I typically like to have a softer rear end. How much oversteer are you getting with the bar set at F:soft R:stiff?

 

[Mr Skillet]

I’ve read the opposite. That the sways reduce the amount the wheels independently react from one another which causes a stiffer/bumpier ride.

You're both right, actually. There's some subtlety here, I'll try to explain it. The vast majority of the time while driving straight on a smooth road only spings and shocks will affect ride quality as there are only vertical movements. However, if you are driving over uneven pavement such as a rut in the road caused by heavy trucks or pothole repairs on one side of the car, this will cause the swaybars to act as only one side of the suspension experiences the road imperfections. This is particularly noticeable on cars with fairly stiff bars and to me, the bars on stiff is starting to get into that territory. Still nothing harsh, but similar to the difference between an m3 suspension vs 335 m-sport, or civic si vs s2000.

Do you notice any rattle from eibach bars on rough surfaces?

Not at all, eibach includes their own bushing and mounting bracket, it even comes with its own grease fitting on the bracket to add lubrication down the road without disassembly, very well made!
However with the added spring rates, body flex is more noticeable on steer driveways where I do the 45 degree thing, I hear the weather seals rubbing. I'll need to get some silicon lube on it this weeknd.
Added bonus, with the higher spring and bar rates I no longer hit thr bump stop while cornering over a large bump. There is a highway transition that has a really terrible expansion join, at the posted 35mph speed its no problem, but at 65-70, the bump is enough to cause enough compression on both front and rear bumpstops, it really reminds you how heavy the stinger actually is, and full compression mid corner is followed by some white knuckles...

 

[KLR STINGER]

I was going to try this setting eventually, car as it, is pretty neutral at steady state cornering. With so much torque going to the rear wheels, I typically like to have a softer rear end. How much oversteer are you getting with the bar set at F:soft R:stiff?

Mine's an AWD so doesn't quite have that rwd oversteer baked in. I'd say it feels like a rwd car now on turn initiation with the AWD benefit of putting the power down after the apex and just pulling you through to the next one. I live the way this car handles with this setup, I would just love to rid that last bit of mid corner upset by bumps

 

[Mr Skillet]

Mine's an AWD so doesn't quite have that rwd oversteer baked in. I'd say it feels like a rwd car now on turn initiation with the AWD benefit of putting the power down after the apex and just pulling you through to the next one. I live the way this car handles with this setup, I would just love to rid that last bit of mid corner upset by bumps

I have a feeling that's going to be an expensive project, unless someone figures out that there is extra room in the edc and allows us to make some changes.

 

[Ruturaj]

Great review and thoughts exactly. Car needs more rear dampening. I've got sways on soft front and hard rear. Makes for a good balance and easy rotation

I am planning to get AWD as well. Might end up doing just soft on rear and keeping factory on front.

 

[Mr Skillet]

I am planning to get AWD as well. Might end up doing just soft on rear and keeping factory on front.

If the awd bars are the same, it'll still be a 70% increase in bar rate

 

[Ruturaj]

If the awd bars are the same, it'll still be a 70% increase in bar rate

Yes, they are the same. I think the feel will be very similar to front soft and stiff rear.

 

[Ruturaj]

Great review and thoughts exactly. Car needs more rear dampening. I've got sways on soft front and hard rear. Makes for a good balance and easy rotation

Just curious, why you went for this setup (soft front and hard rear)? How both on soft felt?