I've read all these post about the z51 setup and the standard setup. I have the adj. ride control on mine where does this fit in at? Is it as good as the z51 or the same a the standard setup? Also had the car dynoed sat. at 310rwhp/328rwtq bone stock, with only 1 pull i think i could have gotten more if i let the car cool down. I just wanted to get over 300rwhp, time for the mods now :yesnod:

 

suspension performance is ranked like this:

Base
F45 (stiff setting)
97-99 Z51
00+ Z51 (they have thicker sway bars)
Z06

 

My 1999 Coupe had the F45 suspension.
My 2002 Coupe has the Z51 package (FE3 suspension). I've been braking it in slowly (just hit 500 miles yesterday), so I haven't maxed it out yet (or come nearly close to maxing it out) so at this point, I won't try to do a full comparison. Instead, I'll primarily focus on the F45 suspension, since that's the one I have 2 years experience with as a daily driver. I'll also try to provide an overview of the F45 suspension for those that may be interested.

The F45 suspension implements electronic (or real-time) damping.
First off, I'd like to point out that the Ferrari 360 Modena's suspension system also has electronic damping... and that it's standard equipment. Surely that says the application of electronic damping has a place within a true performance sports car.

I just recently learned the system could do the following: (This was taken from the 1999 Corvette Specialist's Data Book.)

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It improves the use of damping to control vehicle roll in turns and adds additional damping to aid wheel control at higher lateral accelerations as well as to control body lift and dive during acceleration and braking.
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Also, the second generation Active Handling system now makes use of the F45 suspension (if your car is so equipped) for stability control.

Pretty cool stuff!

F45.. there are three settings/modes: Performance, Sport, and Touring.

There is a difference between the settings.
The performance of the suspension systems requires proper tire inflation (believe me... this one makes a HUGE difference in the way the system works) and proper wheel alignment.

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Side note: The F45 control module was updated with newer algorithms in model year 2000. Touring mode was enhanced to offer an even better ride.
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You really notice the difference between Performance and Touring on twisties and bumpy roads. On smooth straight roads, you won't feel that much difference except that it feels a little smoother in Touring. I never used Sport, which is supposed to reproduce the feel of the base suspension. I don't believe in a compromise (medium) setting. For me, it's either performance or comfort with no in-between.

I drove with the system in Performance about 90% of the time.

I normally had it in Performance mode. Especially when I was driving really fast on the highway or on curves, twisties, entrance/exit ramps, etc.. You definitely feel the tight precision on curves. While the stock F45 car might not be as tight as a Z51-equipped car, it comes really close and it's very stable. Plus, you can always replace the factory sway bars with the Z51 bars for a relatively low price if you are so inclined.

Now for the other 10%:

When I went for a long highway cruise, I'd drive in Touring mode. If I was driving on rough streets, I'd put it in Touring mode. Long bridges ride better on Touring mode... especially over those jarring tension joints/spacers. They seemingly disappear on Touring mode.

If I was just trying to unwind and out for a smooth cruise, I'd set it on Touring mode. It does approach the feel of a nice luxury sedan, although it will never equal that feel.

This is an especially nice setting to use when you're driving that special lady out to dinner.

My last car (a sports coupe) had a very tight suspension. After about a year, it started getting really old as far as having to drive it all of the time with that hard suspension for lack of another car. I knew that my first Vette would be a daily driver for most of my ownership, so I really wanted to have the option to choose the way it handled in case I'm just not feeling like a really high performance tight ride all the time.

As far as modifying the F45,
This is from the May 1999 issue of Vette magazine. General Motors' Specialty Vehicles Department modified a '97 F45-equipped Vette. They ran it "against a Porsche 911 Turbo-S and a Dodge Viper GTS. He smoked the Porsche and virtually equaled the Viper, in spite of the Chrysler's racecar-stiff tuning and mega-brakes. The averages were: Corvette Supercar, 90.40 seconds; Porsche, 91.60 seconds; and Viper, 90.36 seconds. Not bad for a hot rod C5 with a little ol' normally-aspirated 350."

You'll soon see that they didn't have to do much with the suspension to drastically improve performance (to 1.00g) over the already great performance (.91g ain't bad, folks for the stock F45 suspension/wheels/tires, considering what it gives you).

Here's a summary with regards to the suspension:

Early-build (Serial No. 00139) '97 Vette with the F45 suspension and 6-speed manual transmission.

The Supercar continued to use the base springs and F45 shocks.

Maximum lateral acceleration went from .91g to 1.00g.

Goodyear Eagle F1 GS-Fiorno tires on four Fikse forged aluminum wheels.

Front tires; 265/40ZR-18s
Rear tires: 295/35ZR-18s

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The Supercar was lowered three-quarters of an inch all the way around.
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Finally, the front stabilizer bar was upgraded from a 23-millimeter base/F45 unit to a special, 25.4 millimeter bar built by Hotchkiss Performance, an aftermarket suspension specialist in California. C5 sharpies realize that the stock Z51 bar is also 25.4 millimeters, and ask, "Why not use that?"
W-W's Jeff Beitzel, who did alot of the chassis tuning himself, told us that with Goodyear Fiornos, traction -- especially the front, with not only a sticker tire but a substantially wider tread, too -- increased so much that the front end rolls a lot more, rather than slipping as it would with the stock tires.

A significant increase in front roll stiffness was required to reduce body roll. It was more than the Z51 bar offered, but W-W did not want a bar larger than 25.4 millimeters because it would require aftermarket polyurethane mounts. For improved noise, harshness, and vibration characteristics, GM uses stabilizer bar mounts having a low-friction lining on all C5s. Urethane mounts increase friction. Wheel-to-Wheel wanted to retain the production parts' advantage, so a larger bar was not acceptable.

Hotchkiss built a prototype hollow stabilizer bar out of tubing having a 6.35 millimeter wall thickness versus the stocker's 4.0mm, so the bar rate rose significantly without a diameter increase. Creating a special bar to fit the stock mounts represents some sharp thinking by Wheel-to-Wheel and Hotchkiss.

The car's alignment is set to the performance end of the factory tolerance range. Considering the input we've received from GM engineers regarding C5 alignment for autocrossing, these specs are really not all that aggressive.

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The rest of the Corvette tuner community should take notice. With the C5, great handling does not always require stiff springs. In fact, it does not seem to even require stock Z51 springs. We were pleased with the Fioranos, the Fikses, and the Hotchkiss front bar.
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Back in April, I took a spur-of-the-moment cruise down to Galveston and back. I have to tell you that there's nothing better than the F45 suspension for a 650 mile cruise!
Very comfortable. I was on the road about 9 1/2 hours total with about a 1 1/2 hour rest in between. (Drove the speed limit down there, but followed some really fast drivers on the way back.)

Now that I've driven some with the Z51, I can say that the Z51 would not have been as comfortable, although, it would still have been a nice ride.

I bought the '99 to drive as a daily driver, so that's why I chose the F45 suspension. I traded it in at 35980 miles about 2 weeks ago after owning the car since it was brand new in April '99.

Some follow up info on the above...
I ran between 30 and 32psi (warm) in my tires (on the F45-equipped Vette). I noticed that if the pressure was 34 and higher or below 28, the system felt way off, almost like it wasn't responding when you switched between ride modes.

GM calibrates the system to the factory specs. Here's an real world example of how sensitive the system is to differences in setup. In the early '97s, the F45 suspension was incorrectly calibrated to the prototype Goodyear EMTs. Since the actual cars were fitted with the production EMTs, this actually caused those cars to behave incorrectly given road conditions. Those cars would "side-step" abruptly when hitting imperfections in the road surface. This is documented. I believe I originally read it in either Vette or CorvetteFever back in late '98 or early '99. After the start of production, the engineers discovered the mistake (based on complaints from owners) and correctly calibrated the system to the production tires. Early '97 car owners can take them back to get their F45 suspension system correctly calibrated. This is the main reason I have opted not to switch tire brands with my '99. But, when all things are setup correctly (as they should be with proper maintenance), the system rides great!

These are my opinions of the F45. As I mentioned in the beginning, I ordered my 2002 with Z51.
I did this, because
a) I won't be driving this Vette the same way as I drove the F45 Vette
b) I wanted to maximize the out-of-the-box performance potential of the Coupe (stiffer springs, bigger sway bars, etc.)
and
c) I intend to eventually lower this C5, and change to different wheels/tires (w/ different tread pattern/handling characteristics compared to the Goodyear EMTs which are what the F45 suspension is calibrated for).

Back to the discussion... it really depends on what you're looking for in your Vette. If you have the opportunity to drive one of each type (FE1, F45, Z51), do it. If you get to drive an F45-equipped car, make sure you drive it not just on the highway, but also on some bridges and rough roads so that you can get a good test of the system's capability. You can trust me that it handles very well on twisties in performance mode. In that setting, the shocks are basically locked down into the highest performance setting possible. So, your selling point on the F45 suspension should be how well you like the dynamic handling characteristics of the other two settings in addition to the performance mode.

The Z51 suspension is going to have better performance handling characteristics from the get-go. That's what it's mission in life is.

You're going to be limited to an extent by what you can easily do with regards to modifying your F45 suspension (depending on how much you want to keep your F45 suspension working at optimum level in all 3 modes of operation), but the example of what GM's performance group did should give you an idea of what can be done at least on the performance side. I didn't mention it in my previous post, but they basically killed the touring/sport side of the F45 suspension by doing those mods, but they were after extreme performance and wanted to see how far you could go with the initial F45 setup without replacing the shocks. Yes, they could've done the same thing with a Z51-equipped suspension.

I mentioned that the F45 system (at least mine) felt like it wasn't even working when the pressure wasn't set correctly. Well, what happened was that I had the car in for oil service at the dealership. I noticed the difference in F45 operation (basically, non-existent) when I got the car back. It turned out that the sloppy service department guys put about 36 psi in each tire. Once I reduced that to within the 30-32 psi range, everything felt right again.

Once again, if you drive alot, want the option to dynamically alter the ride depending on your mood/circumstances, want the most technologically advanced Corvette suspension choice, and are willing to pay the price... go with the F45 suspension. F45 will give you everything the FE1 (base) does, plus higher performance out of the box and the ability to actually get a smoother ride (by using the Touring mode) than the base suspension. If you want to do alot of modification to the suspension in the future such as major ride height changes, wheel camber changes, etc., you'll probably want to stay away from the F45 suspension unless you're okay with possibly causing the system to not respond at its optimum level in one or more of the three modes. As far as sway bar changes, you can do that without negatively affecting the system. If you decide to replace the shocks, you're basically turning off the F45 suspension, since (at a high level) the shocks and computer are what basically make the system so this would be reason not to go with the F45 option.

One last thing, I just recently noticed in my Corvette Illustrated Buyer's Guide (written by Michael Antonick - author of the Corvette Black Book) that the FX3 (forerunner to the F45) was the STANDARD suspension on the ZR1 in 1989.

Okay, now for a few observations of Z51. Remember, I only have about 500 easy miles at this point, this will be short.

First off, I do really like it.

Overall body feel: The Z51 Coupe feels much tighter. The F45 Coupe feels a little loose by comparison. I'm talking about body feel. (Keep in mind I'm comparing an F45 Coupe with 35980 miles to a Z51 Coupe with less than 1000 miles.)

Straight-line Highway driving: The Z51 Coupe feels almost the same as the F45 Coupe in Performance mode. It's probably a little bit rougher, but not by much. Feels like a sports car!

Mix-master curves: I will make this brief, since I have not yet taken curves at high speed in the Z51 Coupe. At moderate speeds, the Z51 Coupe feels a little bit tighter than the F45 Coupe (in Performance Mode). They both feel like you're on rails. :D I expect the Z51 Coupe to have superior handling at higher speeds than the F45 suspension.

In conclusion, I like both suspensions, but the Z51 is the right suspension for my 2002.

My two pennies (and more)

Hopefully, this gave you some idea of at least of how I feel the F45 suspension compares to the Z51.


Good luck with your decision.




[Modified by targac5, 7:26 PM 8/30/2001]

 

Wow thanks targac5, that was alot of info. that helped alot :D

 

Very good info. thanks for sharing your thoughts and Oponions. I'm seriously considering the Z06 stab bar package. And seriously considering using the goodrich SSS tires. but now I'll have to rethink that. Thanks again. :chevy

 

Wow... great post! Lots of valuable info for me (F45 equipped ragtop) since I have been considering making some handling upgrades. The tip on tire inflation really hits home... when I got my car 3 months ago the tires were over inflated and the handling was NOT so inspiring.. I experimented and found a sweet spot 29psi cold / 32psi warmed up that made all of the difference in the world. I really would like to upgrade the bars and loose the run-flats. I'll probably do the bars first then buy some Z06 size wheels/tires.. if I find the tire change throws the F45 calibration too far out of wack I'll always be able to go back to the stock tire/wheel combo and sell the Z06 tire/wheel combo to someone with Z51 suspension!!!

 

Thanks for all the great info Keith; I upgrade my F45 sway bars to the Hotchiss system and found noticable improvement in handling. The car is being lowered 1/2" in the front and 1" in the rear (might go 3/4 in the front now) this week with CCW's and Michelin coming also. I can not wait to feel how this set-up works. I have considered changing the F45 suspension to coil overs or some of the other adjustable shocks. However, I like the easy of flipping a switch in the car and improving performance or going on a 4 hour drive.

 

Any time! :cheers:
I'm curious to know how your Vette handles after making the changes. It should smoke in Performance mode!