F55 modifications
Drifting
Joined: Jan 2005
Posts: 1,827
Likes: 301
From: Tucson Arizona
St. Jude Donor '08
Z51 bars change ride
Z51 sway bars installed on my F55 have tightened the handling and the ride quality. If you do much bad road driving(uneven pavement or tar strips), you will notice a harsher ride, even in touring mode. So there is a possible down side, depending on your ride quality tolerance, but the handling is tighter and it IS flat in turns!
Burning Brakes
Joined: May 2004
Posts: 996
Likes: 13
From: Dallas TX
Originally Posted by billsee
It'll take someone who was tech or engineer in F55 development to answer this precisely but I'll spit it out anyway and hope.:
1. Will increasing the swaybar diameter (say to Z51 or Z06) seriously reduce the F55 computers ability to maintain a stable platform?
2. How sensitive is F55 to changes in unsprung weight? If I changed to bigger disks and calipers (heavier?), forged wheels (lighter) or aftermarket Z06 wheels (heavier) does this seriously alter the damping?
3. I can't imagine "tuning" F55 like some people can do with engine management, but are unsprung weight and/or swaybar stiffness externally-accessible tuneable constants?
1. Will increasing the swaybar diameter (say to Z51 or Z06) seriously reduce the F55 computers ability to maintain a stable platform?
2. How sensitive is F55 to changes in unsprung weight? If I changed to bigger disks and calipers (heavier?), forged wheels (lighter) or aftermarket Z06 wheels (heavier) does this seriously alter the damping?
3. I can't imagine "tuning" F55 like some people can do with engine management, but are unsprung weight and/or swaybar stiffness externally-accessible tuneable constants?
My reasoning is that control systems can be roughly divided into two groups, closed loop and open loop systems. Open loop systems generate a response based entirely off external inputs. Closed loop systems generate a response from both external inputs and feedback from the control system itself. It would be ridiculous to build a (near) active suspension based off open loop logic. Variability in parts, manufacturing, age of components, vehicle loading etc would cause havoc on this type of system especially considering the number of inputs. More likely, the F55 logic adjusts every subsequent damping response based off the current position of the shocks and their rate of change in addition to the host of other inputs. But then again ... I ain't no GM engie.
Team Owner
Joined: Aug 2003
Posts: 38,314
Likes: 35
Originally Posted by scrannel
Personally I think the Z51 is an over-with technology with a very narrow purpose when compared with the astounding F55.
Burning Brakes
Joined: Sep 2005
Posts: 1,213
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From: Malibu California
Originally Posted by EB20003
Earthshaking. What is your opinion on other time tested and true technologies, such as running water and internal combustion engines?
Last edited by scrannel; Oct 21, 2005 at 10:23 AM.
Safety Car
Joined: Oct 2002
Posts: 4,434
Likes: 1
From: Austin TX
Cruise-In IV Veteran
Cruise-In V Veteran
Cruise-In VI Veteran
St. Jude Donor '03-'04-'05
My '03 coupe has F55 and a fair bit of suspension related mods: Hotchkis swaybars, tunnel reinforcement plate, eradispeed 2 piece rotors with +1 in the rear, oem z06 wheels that went through an aftermarket chroming, and BFG KD tires (non-runflat). It definitely hugs the road better and has a stiffer ride. I think it understeers a bit more than the stock setup. I haven't had anything in the f55 computers tuned, afaik. My custom dynotune was for the supercharger/cam and everything else.
You can still do a lot of suspension mods with f55 to change its handling, and it won't thoroughly confuse the programming for f55.
You can still do a lot of suspension mods with f55 to change its handling, and it won't thoroughly confuse the programming for f55.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 142
Likes: 0
From: Twin Falls Idaho
F55 IS a feedback system. A nonlinear feedback system, which is not traditional and much more difficult to analyze and design. When you change anything in a feedback system you could degrade its response. Actually, if well designed, you WILL degreade the response from the design goal. That doesn't stop me: MY desired response is probably a little more "sporty" than the designer was told to provide
If F55 seperates roll inputs from other inputs I'm convinced stiffer swaybars won't hurt its response to other inputs terribly. Comments from those who did it kinda confirm that. A modest increase in harshness for better turnin sounds a reasonable tradeoff to me. I'll go with Z51 bars, leave Z06 bars to someone with more guts than me. Im off and running. Thanks for all the input on that guys.
Still hanging is the question of "how much additional unsprung weight (different tires/rims, different brakes) can F55 handle without acting upset?". I'll try asking GM if there's a way to ask.
If F55 seperates roll inputs from other inputs I'm convinced stiffer swaybars won't hurt its response to other inputs terribly. Comments from those who did it kinda confirm that. A modest increase in harshness for better turnin sounds a reasonable tradeoff to me. I'll go with Z51 bars, leave Z06 bars to someone with more guts than me. Im off and running. Thanks for all the input on that guys.
Still hanging is the question of "how much additional unsprung weight (different tires/rims, different brakes) can F55 handle without acting upset?". I'll try asking GM if there's a way to ask.
Thread Starter
Instructor
Joined: Dec 2004
Posts: 142
Likes: 0
From: Twin Falls Idaho
Thanks
Thanks for all the great input, GTC the latest feedback but lots of good information from others. I'm really excited to get on with this.
Scrannel, I'm with you. Too bad GM can't handle a little more individuality in the Vette.
I would happily pay $1000 more for a slicker manual transmission. But the base car price would have to increase to pay for the additional choices: more engineering, toughter logistics in production, very expensive safety and pollution tests for all the combinations.
Some would have to take a Mustang and we wouldn't want that, would we?
Scrannel, I'm with you. Too bad GM can't handle a little more individuality in the Vette.
I would happily pay $1000 more for a slicker manual transmission. But the base car price would have to increase to pay for the additional choices: more engineering, toughter logistics in production, very expensive safety and pollution tests for all the combinations.
Some would have to take a Mustang and we wouldn't want that, would we?
Safety Car
Joined: Dec 2004
Posts: 3,565
Likes: 5
From: stafford country, va. Avatar: Me on turn 3 @ Bristol (The World's Fastest Half-Mile)
just curious, would replacing the stock sway bars with either the z51 or z06 ones permit the dealer to deny warantee work if a shock or something else went wrong with the f55 system ?
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Le Mans Master
Joined: Feb 2005
Posts: 6,886
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From: Any City USA
Originally Posted by Zig
just curious, would replacing the stock sway bars with either the z51 or z06 ones permit the dealer to deny warantee work if a shock or something else went wrong with the f55 system ?
Thread Starter
Instructor
Joined: Dec 2004
Posts: 142
Likes: 0
From: Twin Falls Idaho
How To Change
Outright failure of F55 couldn't be attributed to changing the bars. More subtle changes might raise the issue that your mods are involved. Since bone-stock sway bars have essentially zero value, it would be prudent to keep the olds one around in case you ever wanted to change back, either to prove something to a dealer, or to prove it to yourself.
Four bolts hold the rear swaybar. On a flat, level surface, is the bar under tension? How easy is it to roll the car up on ramps and change? Or jackstands? I've never done it.
Four bolts hold the rear swaybar. On a flat, level surface, is the bar under tension? How easy is it to roll the car up on ramps and change? Or jackstands? I've never done it.
Burning Brakes
Joined: Sep 2005
Posts: 1,213
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From: Malibu California
billsee, here's a couple of install links in case you have not seen them.
http://forums.corvetteforum.com/show....php?t=1045925
http://forums.corvetteforum.com/showthread.php?t=990020
http://forums.corvetteforum.com/show....php?t=1045925
http://forums.corvetteforum.com/showthread.php?t=990020
Melting Slicks
Joined: Nov 2004
Posts: 2,407
Likes: 145
From: Northcentral, Pennsylvania
St. Jude Donor '09-'11
Originally Posted by Zig
just curious, would replacing the stock sway bars with either the z51 or z06 ones permit the dealer to deny warantee work if a shock or something else went wrong with the f55 system ?
Melting Slicks
Joined: Feb 2005
Posts: 2,179
Likes: 96
From: Palm Coast, FL
Originally Posted by Zig
just curious, would replacing the stock sway bars with either the z51 or z06 ones permit the dealer to deny warantee work if a shock or something else went wrong with the f55 system ?
Burning Brakes
Joined: May 2004
Posts: 996
Likes: 13
From: Dallas TX
Originally Posted by purple heart
Just out of couriosity, what could go wrong with changing theZ51 sway bars with a stock suspension? Are there computers afftecting the ride similiar to the F55 computer or do computers not enter into the equation?
Burning Brakes
Joined: Sep 2005
Posts: 1,213
Likes: 0
From: Malibu California
Originally Posted by billsee
Outright failure of F55 couldn't be attributed to changing the bars. More subtle changes might raise the issue that your mods are involved. Since bone-stock sway bars have essentially zero value, it would be prudent to keep the olds one around in case you ever wanted to change back, either to prove something to a dealer, or to prove it to yourself.
Four bolts hold the rear swaybar. On a flat, level surface, is the bar under tension? How easy is it to roll the car up on ramps and change? Or jackstands? I've never done it.
Four bolts hold the rear swaybar. On a flat, level surface, is the bar under tension? How easy is it to roll the car up on ramps and change? Or jackstands? I've never done it.
Team Owner
Joined: Feb 2001
Posts: 27,217
Likes: 108
From: Short Hills, NJ
Originally Posted by Daylon
Put Z51 bars on my F55, best money I ever spent! Much better handling, no down side that I know of.... 
Team Owner
Joined: Dec 2002
Posts: 32,073
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From: San Francisco CA
Originally Posted by LS1LT1
Well there is one small downside, those thicker sway bars DO weigh a tiny bit more.
Plus if you don't drive like that you won't notice the difference anyway would rather have the more comfortable ride which is more useful especially on these torn up roads.
Burning Brakes
Joined: Jun 2005
Posts: 984
Likes: 1
From: Austin Texas
Originally Posted by scrannel
Although, I found this interesting: "On Germany's bumpy, challenging Nuerburgring circuit--an increasingly popular suspension-development venue--they report that the F55-equipped Corvette is actually quicker in the Tour mode."
Link for that is: http://motortrend.com/roadtests/coup...0208_corvette/
Nevertheless, I am going with the Z-bars.
Link for that is: http://motortrend.com/roadtests/coup...0208_corvette/
Nevertheless, I am going with the Z-bars.
And as far as your comment that "the Z51 is an over-with technology with a very narrow purpose when compared with the astounding F55" its funny that an "over-with technology is still in 99.9% of all cars made today.
And of course it has a narrow purpose, so does the Corvette: to be a sports car. This would be in contrast to MSRC cars. As the article points out, the only other cars with MSRC are both Cadillacs and I think anybody who buys a Vette with MSRC should have just bought a Cadillac anyways since that is clearly the ride they were looking for.
Team Owner
Joined: Jun 2001
Posts: 26,714
Likes: 344
From: Houston, TX
Originally Posted by jeffgdula
.....points out, the only other cars with MSRC are both Cadillacs and I think anybody who buys a Vette with MSRC should have just bought a Cadillac anyways since that is clearly the ride they were looking for.
I've had both Z51 and F55 C6's. You people who think the Z51 is the end all, and that all Corvettes should have it sure are narrow minded. I don't criticize anyone for their choices. But I see an awful lot of Z51 fans acting like if you don't by Z51 you are some kind of second class citizen. The really annoying part of it is that most of the Z51 zealots have never spent any time driving the other variations.
If you have Z51, and it's the only way you would by a Corvette, that's fine. But please quit talking down to those who don't have it as if they are idiots.