Silverton

Can anyone comment on how the C6 Z51 handles compared with the C5 Z06 and the M3? I’m not talking about skid pad, slalom or lap times, which the C6 excells at. I’m using the word handling to mean the “tight” feel of the controls, or the sports car “feel.” I’ve driven a C6 Z51 and an M3, but I haven’t driven a C5 Z06. After driving the C6 Z51, I was amazed that it didn’t feel “tight” like an M3 and didn’t have that sports car feeling. I’ve read that the Z06 is much more “buttoned down” than other C5’s.

Is there anyway to improve the handling of the C6 Z51? I’m familiar with Doug Rippie’s performance handling kits: bushings and coil-overs. (I’m sure that there are other suppliers that produce handling kits.) Does anyone know how well these work? Thanks!

jschindler

I have driven all three cars (and own a C6), and I agree with your comments. Here is my thought on the C6. First, for 99.9% of drivers it is probably fine. For those that want to get it a little more "buttoned down", I'd add a set of Bilstein Sport shocks.

Here is why I say that. I had a 2001 C5 with the base suspension. Then I added Bilstein sports. They made a huge difference in suspension composure. Then I bought a 2003 Convertible with Z51. It had much crisper turn-in, but did not actually feel as good in the shock damping as my 2001 with the Bilsteins.

The one thing that has surprised me about my C6 (which does have Z51) is that the shock valving is a little "looser" than I expected. Other than that, the supsension feels very good to me.

GM really worked on the shock valving on the Z06 - to the point that they improved the shocks quite a bit - I think for '04. I believe that car was very well sorted out.

I hope this helps.

ivan111

Well C&D magazine main criticism to the C6 Z51 has been the lack of body control (too much up and down motion) i never heard those kind of complaints from the C5 Z06, they will like to see stiffer shocks in the C6 Z51....

In the March C&D comparion despite that the C6 Z51 beat the SLK 350 in both the skidpad and in the lane change manuever they still gave the SLK a score of 10 in handling versus a 9 for the C6 the reason was that the SLK had better body control that the C6....

Is hard to believe that a MB that leans more toward luxury has better body control than a C6 which is a more sporty car....

Corvette team still has some tunning to do to the C6 Z51 suspension calibration.....

elh0102

I bought my Z51 C6 in October,and sold my E46 M3 a month later. Your observations are consistent with mine. Compared to the M3, the Z51 C6 feels a bit sloppy. Its handling limits are quite high, but the suspension movement, particularly in front, is a bit disconcerting at initital turn in. After the suspension compresses, and if you stay smooth in your input, the car will proceed marvelously through the turn. But, it does lack the confidence-inspiring feel of the M3. I am talking with a couple of folks now who are developing suspension packages for the C6. Even with the additional cost of that investment, the Corvette package is a performance bargain. Good luck,
Ed

ivan111

Can you put the C5 Z06 shocks in the C6 Z51?

Will they fit?

jschindler

Good question. The C6 rear suspension has more suspension travel. I don't remember reading that the front does - I'm not sure. As I posted earlier, I'd check with Bilstein. They sure made a big difference on my 01 (I also did some autocrossing in that car, and can attest that even with the base suspension it's handling was amazingly good with just the additon of the Bilsteins).

RichieRich

I've never driven a late model M3, but I have driven other late model sports cars (Esprit, 350Z Track, NSX) and know what you mean. I can only think that this feature must have something to do with making the car more driveable on a day to day basis. I noticed it when I first drove my car on a track (01 coupe) and later that day in an 01 Z06 (to a lesser extent) - sort of a float over the wheels and then bite and hold. The mags have mentioned it, too, accurately. It's fairly subtle though, and something I've gotten used to with the car and will with the C6 when I get one later this year.

I'd be curious as to whether you notice this much in aggressive driving on the road or just on the track. It seems to me it's only evident in the C5 when really pushing the outer handling limits of the car, so I don't experience it much on the street, even though I drive fairly aggressively at times. I've heard from others that Bilsteins virtually eliminate this tendency in the C5, but have never driven one to experience whatever difference there is for myself.

elh0102

I have not had my C6 on the track yet, so yes, the difference is noticeable on the road. I have my first track event next weekend. Now that I am used to the car, it will be interesting to see how the car feels on the track.

A shock absorber change might help but, from my perception, jounce control is not lacking as much as spring strength.

Silverton

Thanks for your response! After reading an article comparing the C5 Z06 and the C6 Z51 in the current edition of Corvette Quarterly, I need to re-phrase my question. How can you make a C6 Z51 handle like a C5 Z06? The answer seems to be stiffer (urethane)bushings and the Bilstein shocks (dougrippie.com). What I don't know is how the sway bars compare. Does anyone know the thickness of the C5 Z06 sway bars? Thanks, again!

TTRotary

The problem is, and has always been, the Sachs shocks. All of them (including even the '04 ones) have poor rebound control and poor damping of high velocity movements. This is at the root of the floaty feeling. Part of this stems from the challenge of engineering a shock that works well with the extremely stiff sidewalls of the run-flat tires, yet provides a compliant ride. Chevrolet never adequately adressed this in the non-Z06 C5, hence the skipping over bumps and sometimes scary suspension movements at higher speeds.

But they had none of these constaints on the Z and still the shocks are not good. Inferior product, that's all.

The C6 has more advanced (compliant) EMTs and more suspension travel, so the engineers had more liberty to firm valving rates while maintaining a plush ride. Unfortunately, they went too plush on the Z51 and are still stuck with a crappy shock.

Bilstein has always been the best street shock out there (Boge - used by BMW - is not quite as good but better than Sachs) and offers tremendous control due to the presence of a high pressure reservoir which exerts significant force on the oil chamber, and allows the shock to literally push the wheel back down to the road in the rebound phase. This means the tire is exerting force on the road quicker and grip is regained faster. The Bilstein also benefits from larger piston size, which has an effect on sensitivity to high speed movements (spring vibration). This has been the case since the 70s. They are a superior shock to the Sachs and they will work better on the C6, just like they did on the C5.

As far as what shocks to use...on the C5, the Z51 and FE4 (Z06) suspension specs on the front axle are the same. The rear springs and shocks were 11% stiffer on the 2001 FE4 to help the Z06 rotate quicker. That was softened a bit in 2002 and later, to about 9% stiffer than Z51.

However, you cannot merely transfer Z06 shocks to the C Z51 because much has changed. Yes, the C6 shares similar weight distribution and roll couple to the C5 Coupe, but C6 has more unsprung weight than the Z06 (bigger heavier wheels and runflats) and the Z51 option adds even more unsprung weight due to bigger brake rotors. That means more spring and more control is needed. So I wouldn't bother transferring a Z06 shock to the C6 Z51. You're just transferring the problem and you don't have enough shock anyway.

I would just let Bilstein sort out the suspension on the C6Z51 and produce a shock that works well for it, just like they did on the C5.

No I don't work for Bilstein.

PeterK

I do get this "floating" feeling even in 2003 Z06. My 99 coupe with stock suspension was floating all over the place - like a Cadillac.

While some might say it is shocks - I think it might be something to do with the springs - after all M3 has a truly independent suspension, while corvette's lateral springs still have some cross-talk. So it is more of a bump-steer.

catbert

There is a misconception that a suspension has to be very "taut," to get big numbers in the handling department, and that isn't really the case. Great handling requires a combination of control and compliance to handle a variety of surfaces and on-gas situations. Cars can easily be too stiffly sprung for ultimate all around handling. I remember when the Alfa Romeo was still imported, and they were arguably the best handling street sports car around. The suspensions were set up with lots of controled travel, and they absolutely looked top-heavy in competition, but they outhandled almost anything in street or semi- race conditions. Many racers learned to resist the temptation to tighten up the suspension with Konis set on full stiff and race springs - because to do so was sure to slow up the car.

BMW has chosen the go cart ride, but that doesn't mean that stiff is the way for all cars.

The Z51 handles well enough for any street application, and its' absolute limits are well above 95% of the drivers who drive on the street, autoXs and track days. I know this from experience.

Get the Z51, and if you feel you are more driver than it can handle, upgrade it. I don't think it will be a problem however.

jschindler

I understand you point, and as I stated in my first post, I agree that most owners will be more than happy. But IMHO, the Z51 has too stiff springs, and too soft shocks - exactly the opposite of what I would want.

And believe me, I agree with your point. I roadraced motorcycles about 20 years ago. Because the track I raced at most of the time was in pretty rough shape, I ran relatively soft "spring" rates, but tried to keep the shocks set up to control the motions as best as possible without being to stiff. I wanted the suspension to be able to move over the bumps in order to keep the tires in contact with the pavement.

Good post

ivan111

Great info thanks.....

So why the Vette Team don't use Bilstein instead?

Are they under contract with Sachs to produce the Vette shocks?

Does this means that the new Z06 will have the same floating feeling?

mikeyc6

It's unfortunate that a more compliant suspension often transfers a feeling of less control while in reality, you may be operating at higher limits. I was used to my 99 Z51 and now have a base C6. The C6 feels more "floaty" and initially gives a feeling of less control, but what I've noticed is that I end up operating at higher limits, taking the same corners faster and with more control in the base C6 than I did the 99 Z51. Still, the 99 Z51 still felt more "connected" with the ground and with me. I've driven a C6 Z51 and it had less body roll but otherwise felt the same as the base C6: less "connected" than the C5 Z51.

The way I look at this is that it's a double edged sword. If you give that solid feel like it is running on rails like the C5 Z06 or even C5 Z51, people will complain that it rattles their teeth out and takes more effort to drive on long trips and will also complain that it gets "skippy" around bumpy corners. If you make it compliant so that the ride is more comfortable and you have a little more control on uneven pavement, people will then complain that they feel more disconnected.

I don't care what shocks you put on a car, you'll always have this dilemma. The sharper you make one edge of the sword, the duller the other side gets.

Mike

shopdog

How do you figure that? The transverse spring is solidly bolted to the frame in the center. It can't move at all relative to the frame at its center, so it can't translate any movement between its two ends. In other words, it is no different than if two separate springs were being used. (You could actually cut the spring in two at its center, and nothing would change.)

Realize also that the spring isn't hard connected to the independent suspensions at either end. It merely presses against thrust pads with the ride height adjusting bolts. This is *totally* different than the old Ford transverse spring arrangement where the spring was shackled to each end of a *solid axle*. That certainly communicated from side to side, but the Corvette's system doesn't.

mikeyc6

In addition, if you don't want crosstalk, you'd better remove your [anti] sway bars.

Mike

PeterK

What I was thinking is that the spring can transmit some oscillations from one end to another and sometimes go into a resonance and make some sort of standing wave.

krwman007

wouldn't that would be something

of course you could just speed up... or slow down to stop the standing wave

jschindler

If I see a Corvette coming the other way, and some guy is standing up "waving", at least I'll know who it is