[boomer]

Most likely it is different in a convertible due to the reduced structural rigidity. I was very surprised at just how much difference the strut brace made to the rigidity through corners. I really expected an experience similar to @Michael9.5 describes but from my perspective the car stays far more level and feels significantly more precise in the twisty bits.

 

[dxG6]

Michael is correct. Unless the firewall itself is not very rigid, in which case it might help, especially on the convertible. I'd get one if I can find a factory one or a one-piece aftermarket.

 

[NuptupTDOW]

Seeing as several members with vert's have mentioned an improvement, and the fact you can get the megan ones on ebay for 88 bucks, I think i'll be purchasing one soon.

 

[davez26]

My experience has been 2 thumbs up for the strut brace on the CNV.
The way I see it, full body cars are more or less 'complete' as a structural unit, think of an aluminum can on it side. Realistically stout to torsional loads, (think grab both ends and twist).
Take that same can, shave a 3 inch wide section the length of the can off, now twist. No matter how much bracing to the lower portion of the car, (like the CNV bracing) the further from the base, the more likely to have some movement. Not enough to measure, create gaps and cause notable issues, but enough shift that the convertible feels 'lazy' in a corner. The brace helps tie everything together and makes for a better handling car. My thoughts are that like most manufacturers Pontiac had a chassis and had a great idea, 'lets make a convertible!', problem is, the chassis was not designed that way, and there are a number of changes to the vehicle to make it work, some better than others. Strengthening the firewall and crosscar beam would have reduced front end flex, but the car was already heavy.
I agree with OP, that on a closed body car, it's more eyecandy. On the convertibles, it is an addition that really does have a notable payback.

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[NuptupTDOW]

Thanks for the reply Dave! Just more reason for me to buy one! Anything else you've done it considered doing to improve the driving experience that's worth mentioning?

 

[dxG6]

My thoughts are that like most manufacturers Pontiac had a chassis and had a great idea, 'lets make a convertible!', problem is, the chassis was not designed that way,

Dave, that is not the case. Pontiac didn'y "have a chassis". The GM Epsilon platform was first used on the Vectra and 9-3. And the 9-3 had a convertible from Day 1. So the "chassis" as you call it was most certainly designed as a convertible from the beginning. And a soft top convertible at that.

The 9-3 vert has no cowl shake and no handling issues. My G6 also doesn't have any handling issues but does have a small amount of looseness over rough roads. I can't say that's caused by insufficient torsional rigidity. I'm more inclined to attribute it to 150k+ on the clock, on all original suspension components.

 

[davez26]

Thanks for the reply Dave! Just more reason for me to buy one! Anything else you've done it considered doing to improve the driving experience that's worth mentioning?

In the front, I've switched to poly sway bar bushings and that made a noticeable difference.
Other than that, the front end is pretty much gtg, just stay ahead of the maintenance and don't let things get worn out and crappy feeling. If the basics are in good shape, any upgrade is icing.

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[NuptupTDOW]

If the basics are in good shape, any upgrade is icing.

Cough What if they aren't in good shape because I got the car at 200k miles and the previous owners neglected it? Any suggestions you have in mind? Cough

 

[dxG6]

Nup, that's funny but for real. Refreshing the front end will do considerably more than any aftermarket bar. The lower control arms tend to go bad (bushings), but at that mileage I would definitely consider new everything: tie rods inner and outer, sway bar ends, struts, sway bar bushings.

 

[NuptupTDOW]

Nup, that's funny but for real.

Wasn't exactly trying to be funny, more bashful and sad that my car is falling apart, but, y'know I get how it could be taken in a laughing manner. But, onto the topic at hand, where would I even start with those? Like, which take priority and which are the biggest improvements for price-point value? And just price in general?

 

[dxG6]

Depends on your capabilities and budget. If you can do everything yourself I'd do everything at once, you save a ton of time. I don't have a priority list, at that mileage I'm betting most of the wear items are ...worn I'd stay with brand name parts like Moog and Delco, some of the store brands are not so good. Best prices I found on Rock Auto.

 

[NuptupTDOW]

The lower control arms tend to go bad (bushings), but at that mileage I would definitely consider new everything: tie rods inner and outer, sway bar ends, struts, sway bar bushings.

And for the most part, that's all I really need to worry about suspension wise? Is that only front-end or same goes for rear?

 

[dxG6]

I'm at 150k+ and no issues with engine mounts or anything in the rear, all still original parts. But I don't know if that's common or I'm just lucky.

 

[NuptupTDOW]

Hmmm, I dunno. To be honest, mine feels ok enough when driving it, but I never experienced it when it felt fresh, so I don't know what to compare it to.

 

[dxG6]

Yes, some of the symptoms are hard to notice and not always intuitive. It took me a while to figure out I had a bad lower control arm, the steering pulled very slightly to one side when lifting off the throttle. With a high mileage car I would just replace all wear parts if planning on keeping it for a few years.

 

[NuptupTDOW]

Ok, then beyond what you listed above, what qualifies as a wear part? I apologize for asking questions that should be common knowledge. I am not necessarily a car guy, and this being my second vehicle behind a "run it till it dies" F150, I am not as knowledgeable as I would like to be.

 

[davez26]

dxG6 pretty much covered the wear items above - control arms, tie rod ends, struts, sway bar ends, and sway bar bushings. All of these items work together to keep the car tracking. Definnitely don't shop by price - Delco, Moog, TRW, even Napa Proformer are all good names.
At 200k, things are probably due, and strut bar isn't going to make much difference. It's job is to enhance a suspension that is working well,and it definitely wont make up for a worn front end. The rear isn't as bad for wear and tear and a check over couldn't hurt.
This car is a machine I drive daily, with about 135K. My career is in automotive, and its kind of the culture to keep after the car to keep after it.
I've never had a customer return and tell us that putting money into the suspension was a waste. If you like the car and intend to keep it, you will love the car even more with a freshened suspension.

 

[NuptupTDOW]

Alright, thank you very much! I really do appreciate the help and advice I've gotten from everyone here.