73VetteMan

I was lucky enough to get my hands on a C6 coupe for 5 hours a couple of weeks ago. I was blown away at how well the car rode with the Z51 suspension. I was so impressed that I have changed my order from F55 to Z51. Since I am over 50 and hate the ride of most "sport" suspension vehicles, including my wife's Bonneville SSEI, that is saying a lot! The car handled most bumps and potholes as well as my Yukon. Since I live in the Detroit area where we have some of the worst roads in the country, I gave it some comprehensive testing.

Of some concern to me is the difference in the manual transmission gear ratios with each package. First gear feels fine on the Z51 with it's 2.97 ratio and the 3.42 rear end ratio. The standard suspension (or F55) first gear is 2.66 which might feel too "high" with the stock rear. On the other hand, if I am going to change the rear gears to 3.73, 3.90, or 4.10, the 2.66 trans is more of a close ratio type and would probably be a better choice.

Of course the bigger brakes and the oil coolers included in the Z51 package are a big advantage to consider.

Matt Gruber

as i recall (posted by Duke) the c5 z51 was only 11% stiffer than stock.
i'll get the base sus., then upgrade just the springs to Z07? IF it is too soft. My 72 was too soft and i added F41 springs.
i doubt a car that can go 180+ will be too soft.
i like the base gearing, should match the 364 very well.

Scissors

On bumpy curves, such as those found on real roads, the F55 actually out-handles the Z51 suspension. Since I won't be constantly racing mine, I'm going to opt for the F55.

Some day...

SWCDuke

If C6 follows the C5 example, which is likely, Z-51 has only marginally higher suspension frequencies, but roll stiffness is up significantly - primarily due to larger anti-roll bars, but the higher ride rates also contribute to more roll stiffness.

My experience with a 2000 Z-51 coupe was very satisfactory. The suspension was just about perfect IMO, and I'm also "over 50" and object to some current cars with "sport" suspensions and very short sidewall tires. Wanna buckboard - try a M3.

The C5 Z06 suspension is firmer than Z-51, but still suitable for a daily driver. I've never driven the F-55, but my issue with it is long term maintenance/repair. It will be an expensive system to repair if a shock ever fails or the electronics go south.

Duke

mikeivan

This is a bit of a dilemma for me also, over 50 and a Lexus driver. I decided on F55 after reading that the Z51 includes stiffer springs and shocks. However, your test drive has me thinking, maybe I can get a test drive too.

Corvette Junkie

I'm also over 50. I have Z51 on my 03 and I will have it on my 05. Now if they gave you the same 6-speed with the F55 that you get with the Z51 I would think about getting F55.

73VetteMan

The Z51 car is quicker because of the "lower" first and second gear ratio unless you are changing to a "taller" axle ratio as I plan to. The published reports show it as at least .1 second quicker in the 1/4 mile as well as faster in top end (which is in 5th gear).

What I am trying to point out is that the base trans is actually a close ratio and the performance trans is actually a wide ratio! This is backwards from previous performance packages. Usually, the axle ratio in performance packages is "taller" than base ratios. On the 2005, the axle ratio is the same so they used "lower" gear ratios in the transmission to give better acceleration than the base combination while still accomplishing their fuel economy goal.

73VetteMan

I think I failed to make my primary point when I posted this thread.

BUY THE Z51 PACKAGE. The performance gain, larger brakes, coolers for durability, and better cornering are well worth the cost. The car still rides MUCH better than the base suspension C5 in my opinion. It is definately more of a performance package than a suspension package.

I have changed my order from F55 to Z51 as a result of my test drive.

I was also pointing out that the base transmission may actually be a better choice if you are planning on upgrading the rear axle ratio. For the person not planning on a rear gear change, the Z51 trans is clearly the better choice. Too bad they don't offer us the choice of either the close or wide ratio transmission seperate from any package as they did many years ago.

c2jones

Is this to say then, if one were not getting the manuel transmission, and therefore would not gain the gear ratio differences offered with the manuel, that for city driving in major metropolitians the choice would logically be the F55?

Or, are the better brakes (and oil cooler) still worth consideration upon typically level, mostly uneventful roads (like South Florida) with only minor road bumps, railroad tracks and highway safety deflectors to contend with?

My thinking was that I could get the sportiness of a Corvette with the refinement and feel of its sister platform car, the Cadillac XLR, by getting the F55.

However, if the Z51 is not really that much (noticeably stiffer - given the mostly level roads) than the F55, then perhaps the better brakes and oil cooler (to combat the stop-and-go of my area) would be something to factor in.

Any contributing comments?

I could always just test drive them both when they're both available, but being that this car is currently by-order only, some advanced insight would sure help. Perhaps this is just a matter of personal preference, or, perhaps the difference is far more apparent than anyone's mere personal preference.

73VetteMan

After driving the Z51 equipped manual C6, I think I would still get the Z51 with an automatic. The ride truly impressed me.

You get the optional 3.15 axle ratio instead of the 2.73 at no additional cost with the package. You also get stickier tires with the option. The Z51 option might actually be a better value when combined with the automatic trans since the optional axle which normally costs $395 is mandatory in my opinion.

I seriously doubt the F55 ride is anywhere near that of the XLR. Considering the shock absorber rate is the only thing that electronically changes with the F55, I imagine the springs with the F55 are very close to the rate of the stock suspension. I have not seen any specifications on the springs, nor have I driven an F55 equiped C6 so I am only expressing my opinion.

Corvette Junkie

The XLR and C6 both have their own programming for the magnetic suspensions.

jazzlove

Has anyone seen, or know of any comparison road tests on the C6 between the Z51 and the F55 set on sport? I would love to see those performance numbers....

jazzlove

OWENMUSTANG

VetteMan, this is somewhat off topic..
did you ahem, sample full throttle in 1st or 2nd?
curious as to traction and throttle response with the Z51 option.
my current SS M6 makes 4.10's almost manditory for um, brisk
acceleration.

73VetteMan

You must be kidding! Now let me think, the car was loaned to me for over 5 hours with no one watching or supervising how I "tested" it.

I forgot how many times I "tested" first and second gear. Redline in second gear is almost 80 mph, but it got there so fast, I can't be positive! If the car did not have the deeper gearing of the Z51 option, the speed would have been much higher but acceleration would have be compromised. Throttle response at all speeds is unbelievable. It even has power when lugged down to 500 rpm in 6th gear! That indicates to me that this engine can definately handle a wilder camshaft which will gain even more horsepower.

A slightly wilder cam and slightly taller axle ratio could make this amazing car into a street terror.

73VetteMan

Now that a few cars have been delivered, are there any C6 Z51 owners that want to give some feedback to my advice?

mikeyc6

Can't comment on the C6 Z51 but I can comment on the C5 Z51 versus C6 base. I drove a C5 Z51 for 3 years and I can tell you that the base C6 suspension has a bit too much body roll for me compared to even the C5 Z51. With my 99 Z51, I could take corners so hard that the tires would be starting to give and there was no detectable body roll at all! With the C6, the same corners at the same speed make the car feel like it's starting to tip a little! In addition, driving the base C6 is a bit like driving a Lexus and a bit less like driving a sports car... so more stiffness would be welcome here.

Based on my above observations, I'd recommend the Z51... and wish I had it. Now I'm faced with upgrading a few suspension parts down the road because I didn't get the Z51.

Mike

73VetteMan

I brought my new baby home yesterday. DSOM, Z51, MN6, roof, XM, polished wheels. I still maintain that it rides better than a base suspension C5.

Even my wife agrees with me that the ride is fine. We live in the Detroit area - AKA POTHOLE CITY. Of course the big potholes are rough just like with any other car, but the average crappy road is very tolerable.

Erik_In_Carlsbad

The Z51 tire/suspension combination on my C6 is softer than my modded C5 suspension, and gives a nice non-jarring ride on our fairly good So. Calif. roads.

My C5 has the base suspension, which I upgraded with Bilstein shocks and Hotchkis sway bars. The C5 is absolutely flat in turns. My Z51'd C6 has a slight roll to it.

My C5 has such little body roll that it was difficult to feel where traction was starting to give during spirited cornering. I think I'll be more comfortable in pushing the C6 harder in turns, as I get a better seat-of-the-pants feeling because of the slight lean.

There's also the factor of the very solid-walled C5 EMTs vs. the C6's slightly more flexible models.

Now that the 5-day-old C6 is at the Chevy dealer -- where, over the past 24 hours, they haven't been able to diagnose an indicator light problem but they have manged to drain the battery -- I've been driving the C5 some more.

-Erik

LS WON

it is 500 to 750 to replace each shock on the F-55 plus labor. The base warranty of 3 years or 36,000 will cover it but the GMPP extended warranty will not cover it.

StanNH

My car was ordered with the Z51 package. For me, it was a very easy decision. I am NOT buying this car as a daily driver or a commuter vehicle. I have a 2003 Audi A6 Quattro twin turbo that does just fine for that. I bought a sports car and I want it to feel like a sports car when I drive it. Every road test of this car that I've read noted that the Z51 was more compliant than last years's C5 base suspension package. Every user review states the same. Coming off a sport package equipped Z4, anything has to feel better on rough roads.

I want the best handling I can get, the quickest performance, the best brakes, the best tires. Isn't that the point of owning a sports car?

The endless arguments over NAV, XM radio, and OnStar leave me laughing. Everyone has different tastes and needs...just order what you want and enjoy your car. I want the Z51 because that's what I want...you may not want the same things in your car at all because you won't be driving it where or how I'll be driving it.

Stan