[dbphelps]

Hey guys, so I have a 2015 ATS Luxury 2.0t AWD. I am going with new wheels/tires, basically 19" x 8" up front (+42 offset) and 19" x 9" rear (+52 offset) along with Continental Extremecontact DWS06 Plus tires in 235/35ZR19 up front and 265/30ZR19 out back.

The car is a FE2 optioned suspension and I am looking to "finish off" the suspension for a variety of purposes.

First off I want to drop the car only about .5"/.75" MAX. It sits "almost" perfect stock, but I feel it could be dropped ever so slightly. This means that ANY of the lowering springs are out of the question as they drop the suspension just too far in my opinion.

So, to accomplish this I am considering BC Coilovers (NOT the "Extreme Low" version). My concern is being able to have a comfortable ride for regular driving and being able to "tweak it" for cruises in not only dampening, but also ride height if I feel it needs it. But I do NOT want to ruin the balance the ATS has naturally and to that effect I also don't want it to be too bouncy and harsh. I know the BC coilovers have 30 levels of adjustment. I also know there is a "Swift Spring" upgrade option available for these coilovers, but I really cannot find any solid references as to what "effective changes" it does to go with that option. I can only "assume" it means a better overall spring rate, but what does that actually MEAN in real-world driving terms???

Next it would seem that sway bars would be the next valid option. I know what sway bars do and how they help the car stay planted, but again, there has been no definitive references on how effective the stock sway bars are.

I know the AWD ATS comes with a 19mm solid rear bar and I know that some people prefer to swap that out to a ATS-V 26mm hollow bar or a ZZP 26mm solid bar for a little more control in the twisties. The majority of the people talking about swapping the sway bars are RWD cars that originally ran the 14mm solid bar. For them going to a AWD bar or even the Eibach 19mm hollow bar is an improvement.

In regards to the front sway bar, there is really only one option for the AWD platform and that is the ZZP 27mm solid bar. The stock bar is already 23mm solid on the AWD platform and usually large enough most don't consider swapping it out.

But, in going "all out" in the suspension department, especially considering going "slightly" lower with BC coilovers, I would imagine swapping to 27mm front bar and a 26mm rear bar would "round out" the suspension and afford for the most flexibility overall in all cases, would it not?

Especially considering I am going with wider tires both in front as well as back (235/265 setup)?

I am looking for any and all feedback on this. I would REALLY like to hear about the differences between the BC Coilover "standard" springs vs the "Swift" spring upgrade.

Also, the car has an upgraded turbo, forged internals and every other mod conceivable, so the power output is in the upper 400hp range, for reference, so it is no-where near stock power levels. And, if I do upgrade the sway bars I will also be putting in adjustable end-links to make sure the geometry is proper for the ride height chosen.

I have adjustable shocks on other vehicles and the ability to "tweak" the suspension is just too much of a draw to leave the stock suspension "as is", regardless of how good it is. I mean I have the MRC suspension on my CTS and LOVE it, but there is no way I would sell the ATS to go the MRC route with a different car. I just wish the MRC suspension was able to be added to the Luxury trim with an AWD in some way or form, but considering the amount of integration it has I do not expect that to be possible short of selling the car and buying one that has it already.

I am just concerned about ride quality and overall "manners" before jumping into going with coilovers and sway bars. I mean I have read of horror stories of people that have done it on other platforms have have hated the car afterwards because it comes harsh, bouncy and it overall kills the platform. I just have not heard from enough people that have done it to the Alpha family of vehicles to know how it turns out. Most people are already from the former "bouncy and harsh" background with other platforms so when they converted their 6th gen Camaro it is not really a valid point of feedback.

 

[dbphelps]

Oh, also, I am not even considering changing out control arms or anything like that. I don't feel those kind of changes are necessary unless you start getting into competitive setups.

I do question the validity of strut tower braces on the Alpha platform (and just WHY can't you run a strut tower brace with a set of coilovers???), as well as teh various under-body braces that are available for the platform as well. I would love to hear some feedback from those that have used such braces and if there is any sort of noticeable change by adding them. I am just afraid a LOT of that kind of stuff is hard to justify and the feedback is more placebo-effect than any sort of measurable positive change.

 

[13blackruby]

I have the renick lower chassis brace and ZZP strut tower brace didn't notice any difference in handling. But the bmr rear cradle brace was a great mod to have done. Bmr doesn't list it to work for the ATS but it does.

I also have both ZZP sway bars and they made the most impact on my suspension. I have stock fe2 suspension with struts and shocks that probably have 100k miles on them and it was night and day difference in handling.

 

[dbphelps]

I also have both ZZP sway bars and they made the most impact on my suspension. I have stock fe2 suspension with struts and shocks that probably have 100k miles on them and it was night and day difference in handling.

Yeah, I have aftermarket sway bars on most of my sports cars and I know they work well if they are balanced. Thanks for confirming that they are, in fact, balanced.

I will add, that is one of my concerns with adding in stiffer bars, is that if I DON'T go with the BC Coilovers that the bars themselves will make the suspension lose some of its "suppleness" that makes the car drive so nice.

That is why all of the cars that have aftermarket sway bars have adjustable shocks/struts... I would go that route if any were available for the ATS, but as it stands the closest I can get is coilovers.

 

[hoser450]

Sway bars won’t affect the ride quality. If you have so much into the car why run a cheap set of BC coilovers?

 

[dbphelps]

Well I wouldn't consider the BC Coilovers "cheap". And they are one of the few spec'd specifically for AWD variants. Almost all of the higher end options I would consider full-on "race" and spec'd for RWD.

Sway bars won’t affect the ride quality. If you have so much into the car why run a cheap set of BC coilovers?

Also I do know that certain "stiffer" sway bars CAN affect ride quality. Call it more of a "jarring" of the passengers over uneven pavement transitions that can happen when the shocks are not designed to dampen such pull.

Again that is the desire for adjustable shock/struts in unison with the bigger sway bars.

 

[AAIIIC]

I am looking for any and all feedback on this. I would REALLY like to hear about the differences between the BC Coilover "standard" springs vs the "Swift" spring upgrade.

I've never particularly understood the Swift spring upgrade. My impression is that the Swift springs are supposed to be better quality (as discussed here), but I don't know how much of that is advertising BS and how much is truth. My CTS-V has Swift springs on it with the KW V3 coilovers because I bumped the spring rates from the "stock" KW rates and Swift had the rates and sizes I needed. (The KWs use two different spring diameters front and rear, so not everyone makes the rates I wanted in both diameters.) I couldn't tell you whether they were any "better" than any other brand of springs. What I do know is that I wasn't terribly impressed by the production quality, despite all the Swift fan-bois on the internets. It's been years since I installed them, so I can't remember the exact details, but as I recall one set of springs was somewhat undersized (so they barely fit onto the KW perches) and the other set was oversized (so they're loose on the spring perches). Really, this company that makes the bestest springs in the world can't even make a 60mm spring actually measure 60mm? So with all that said, based on your described usage case, I'm not sure I see the point in spending 25% extra to get the Swift springs.

I am just concerned about ride quality and overall "manners" before jumping into going with coilovers and sway bars. I mean I have read of horror stories of people that have done it on other platforms have have hated the car afterwards because it comes harsh, bouncy and it overall kills the platform. I just have not heard from enough people that have done it to the Alpha family of vehicles to know how it turns out. Most people are already from the former "bouncy and harsh" background with other platforms so when they converted their 6th gen Camaro it is not really a valid point of feedback.

I haven't got any experience with BC coilovers. Some people seem to love them, others say they're cheap garbage (and I feel like many of the internet experts who say that have zero experience with them). In light of your concerns about ride quality I'd say it would be worth your while to try to find a car you can get a ride in to be sure you'll not be disappointed. It may be hard to find another ATS around you with coilovers installed for you to do a test ride, but maybe you can find a Camaro owner? Larger pool of vehicles and larger pool of people who modify them.

Sway bars won’t affect the ride quality.

Sway bars change the wheel rate and suspension frequency, so they absolutely do affect ride quality.

If you have so much into the car why run a cheap set of BC coilovers?

So your suggestion would be....??