Rough Ride 1999 C4

[gustav356]

Hello All,

After test driving a new M3 with 19" rims, I realized how rough the ride is my C4. The car has the standard suspension with 18" rims. The roads here in Spokane are terrible as everyone drives around on studs for 6 months of the year, but that M3 put the hook in me....why should I be tolerating this bone jarring experience every time I take the C4 out? Before I stray down the path of BMW doom....Does anyone have any solutions or suggestions? I refuse to install the dinky 17" rims as they really look out of proportion with the car. Any tips would be well appreciated.

Many thanks,

Clint

[bnewport]

No question, it's better with 17s. I just switched from my snow wheels, 17s and blizzak LM22s to my summers, 18s pirelli asymms and the ride is noisier and not so smooth on rough roads. But, turning is definitely sharper with the 18s.

My main problem with 18s is you can't bring them to an autowash because the low profile wheels expose the rims to damage from the metal tire runners at the wash. My 17s were protected by the slightly higher tire wall and the excellent LM22s which have a rim saver lip on them.

For just day to day driving, the 18s are a royal pain as a result and I wouldn't mind swapping my 18s for a set of 17s with summer rubber if the summer tires had rim lip protection like the blizzaks.

For now though, it's hand wash only with the 18s on.

[gustav356]

How about the Bilstein PSS9 Suspension? Can this be adjusted to give a softer ride than the stock suspension? Just wondering if anyone has experience with this setup.

Thanks,

Clint

1999 C4

[alter_schwede]

with KW Variante 3 inox-line, you will be able to adjust both heights and pressure of the coilovera

link: KW Suspension

cheers,

Tony

[earlyapex]

Don't make the mistake! I just traded in a 2003 e46 M3 with the standard 18" wheels for a 40th Anniversary 911. My Porsche has 18" wheels as standard equipment and the ride in not much different from the M3. They are both harsh on broken pavement, over expansion joints, road nipples, etc. The M3 with 19" wheels rides more harshly than with 18" wheels. You need to drive the two cars on the same road back to back to make a valid comparison. Everyones' taste is different and we are all looking for a different blend of handling and ride comfort, but you are mistaken to think that a M3 with have a comfortable ride on poor road surfaces. Furthermore, I'm not surprised that your car rides poorly during the winter. The side walls of your tires will be very stiff due to the cooler temperatures and result in a much harsher ride. They may never warm up to the same extent as they do during the summer months.

I wouldn't expect a coil over suspension kit to make much of a difference. Your best bet is to switch to 17" wheels during the winter.

My Porsche has all of the attributes that I wanted in a sports car that was missing my previous M3. I wouldn't make the switch if I were you. You could always get a truly comfortable car (something like a Subaru or even a Lexus RX 330) for the winter and garage your Porsche.

[gry]

So are the 18" wheels a better than the 17" wheels for cornering?

While the 17" wheels are a more quiet ride?

Don't larger wheels enhance the performance of a car since there is more surface area in contact with the ground?

Again, sorry for my ignorance.

[earlyapex]

That is a loaded question! The choice between a 17" and 18" tire depends on personal taste and what you want your tire/wheel package to do. Larger wheels look better up to a point. I think the 996 looks good with 17" wheels, great with 18" wheels, and ungainly with 19" wheels. Your ride will deteriorate as you go up in wheel size because your tire side wall has to correspondingly decrease in order to keep the overall diameter of the tire/wheel the same. Less side wall equals harsher ride. Given the same tire, a 18" wheel will maintain a larger contact patch during hard cornering because there is less tire deflection. This can be offset with stiffer side walls, but this will degrade ride quality. Tire noise has more to do with tire construction, tread design, and rubber compound than wheel size. Every change in the tire/wheel combination has its advantages and trade offs.

I live in the central coast of CA and our weather in never that bad. An 18" wheel/tire package works well over here. I would do it differently if I lived in an area that regularly experienced cold weather, snow, or had very bad roads. Under these conditions, I would run 17" wheels and narrower tires (all season or snows) during the fall/winter months. I would get a better ride and be much safer.

Race conditions require an all together different line of thinking. You are usually limited on your tire/wheel choices by the rules that you run under. Again, bigger wheels are not always better. Autocross competitors regularly run small wheels to minimize weight and thus maximize acceleration out of slow corners. Additionally, larger wheels weigh more unless you shell out the bucks for forged construction. It's also harder to find competition tires to fit 18" wheels. It all depends on the rules and what you want to accomplish.

The 996 has a firm ride and little can be done to the suspension to make it smoother without significantly changing its sporting characteristics. The best way to make a 996 more comfortable is to change to 17" wheels. There are several all season tires in this size that should give you a better ride than the high performance summer tires that are common in the 18" fitment.

[gustav356]

Thanks Eric....I think somebody jumped in on the thread......It hit close to 70 degress yesterday so I took the C4 out for an hour and half drive. There really was a big difference in ride quality over my last 35 degree outing. I installed the Fabspeed Exhaust on Saturday so I can enjoy the exhaust tune over any thumps and creaks. The exhaust and your advise about changing to the M3 has helped me stay on the true path.....although I am not ruling out upgrading to a newer model 996. Thanks again and thanks to all that recommended the FabSpeed Mufflers!

-Clint

[gry]

I appreciate your very insightful and thorough response!

This is a great forum.

[earlyapex]

Glad you stayed on the right path! I am very happy with the switch from the M3 to my current 996. It rides looks and rides better according to my wife. She hated the M3's seats as they gave her a back ache after an hour.

I sometimes wonder if I bought too much car. This lasts only until I fire up the motor and then I realize that I bought the right car. I can't keep the smile from my face.

[gry]

What's weird is that I'm driving the 911 everyday now instead of my Jeep.

My Boxster S, on the otherhand, sat in the garage and after 2.5 years of ownership, only put 4000 miles on highway and Sun-only driving on it (no cloudy weather). ;)

Don't get me wrong, I love my Boxster but something about the 911 makes it seem like an everyday pleasure driving sports car. I'll baby it, like the Boxster, but I find myself always driving it to work.

I'm trying to sell the Boxster S, but the market is full of Boxster S right now.