SlowCreamPuff
Enthusiast
Now downforce mod. available?
How to get downforce on 2001 GTS?
- Thread starter SlowCreamPuff
- Start date
Ulysses
Enthusiast
Wing and front splitter. None of which are subtle
.
SlowCreamPuff
Enthusiast
So, who makes effective wings and front splitters?
Thanks.
Thanks.
John Moore
Enthusiast
From what I understand Roe's front cooling duct under the chin significantly reduces frontend lift and concomitant drag. It is very difficult to see so I think it along with a slick discreetly done rear diffuser could make a real "downforce-sleeper."
I've found a local carbon fiber molding company and have discussed the diffuser design along with some matching side splitters and have some interest generated. Anyone else have any thoughts on this or know of an already done diffuser?
SlowCreamPuff
Enthusiast
Are there modifications out there that can really give my 2001 GTS down force? Rear is what I am looking for, but I would like the front to be balanced as well. It's probably impossible, but can the modifications be subtle at the same time?
SlowCreamPuff
Enthusiast
Any more ideas?
jrkermode
Enthusiast
I delved rather deeply into this subject, including talking with DC, hiring an aerodynamicist, lots of reading, and, of course, some on track testing.
Big downforce generally comes from big aero devices, so there's not a lot to be gained with subtle aids.
I would advise you steer clear of making a ventrui/tunnel/diffuser car. These things work by manipulating boundary layers that aren't very accomodating of the pitch, roll and yaw characteristics of a real car.
There are a lot of little things you can do that will help. Unfortunately, its something hard to address in messaging since every answer typically has a long winded "it depends" associated with it.
For example, you could get the rear "downforce" by lowering the back of the car, essentially just jacking weight back there. It's not aero downforce, but it would increase rear grip. Front grip could come from reducing front lift. Perhaps with a Roe opening under the nose, the Roe front wheel well spats and a ground rubbing air dam attached to the lip under the nose. Ground rubbing side skirts fitted under the rocker panels could also help. With the exception of the clear plastic wheel well spats none of these things would be visible to the casual observer. But the effectiveness of this package depends on what you'll be doing with it. This particular set-up will not be balanced at all speeds since the front downforce will vary with speed. That means you may end up with a low speed aero push and high speed aero oversteer!
So, you really need to be very specific about your goals and then look at solutions that fit those requirements.
If you're going to VOI, I suggest you track down Herb Helbig, we've discussed this at length. If you're at any of the NorCal events, look up me, Mike Horzewski or Ted May.
Finally, don't buy any aero stuff without data. The vast majority of aero devices are designed with looks as their first priority.
Big downforce generally comes from big aero devices, so there's not a lot to be gained with subtle aids.
I would advise you steer clear of making a ventrui/tunnel/diffuser car. These things work by manipulating boundary layers that aren't very accomodating of the pitch, roll and yaw characteristics of a real car.
There are a lot of little things you can do that will help. Unfortunately, its something hard to address in messaging since every answer typically has a long winded "it depends" associated with it.
For example, you could get the rear "downforce" by lowering the back of the car, essentially just jacking weight back there. It's not aero downforce, but it would increase rear grip. Front grip could come from reducing front lift. Perhaps with a Roe opening under the nose, the Roe front wheel well spats and a ground rubbing air dam attached to the lip under the nose. Ground rubbing side skirts fitted under the rocker panels could also help. With the exception of the clear plastic wheel well spats none of these things would be visible to the casual observer. But the effectiveness of this package depends on what you'll be doing with it. This particular set-up will not be balanced at all speeds since the front downforce will vary with speed. That means you may end up with a low speed aero push and high speed aero oversteer!
So, you really need to be very specific about your goals and then look at solutions that fit those requirements.
If you're going to VOI, I suggest you track down Herb Helbig, we've discussed this at length. If you're at any of the NorCal events, look up me, Mike Horzewski or Ted May.
Finally, don't buy any aero stuff without data. The vast majority of aero devices are designed with looks as their first priority.
Paul Fischer
Enthusiast
A wing will create significant downforce, a double wing even more. Make sure you balance the front with a splitter and reload your shocks/springs and alignment to compensate if you plan on really using the downforce. Remember you are trading energy that would otherwise go into your forward motion, your top speeds will be nothing like they were before without an awful lot of extra horse power (think of aero mods as air brakes and you'll get the idea). With double wing and splitter I couldn't get my car past 175 on a stock motor but it stuck like glue. Little whoop dee doos in the road became negative g drops, a five point isn't a bad idea. My car was lowered a few inches as well and scraped even under 100 mph give the right circumstances.
SlowCreamPuff
Enthusiast
You guys are awesome!
![hail[1].gif](/vca/proxy.php?image=http%3A%2F%2Fvca1.viperclub.org%2Fubb%2Fsmilies%2Fhail%5B1%5D.gif&hash=2ae7da1dfdc3fb136480c15ebf3e313e)
So, what tuners know about downforce tuning?
So, what tuners know about downforce tuning?
jrkermode
Enthusiast
Sean Roe
John Moore
Enthusiast
jrkermode
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
I would advise you steer clear of making a ventrui/tunnel/diffuser car. These things work by manipulating boundary layers that aren't very accomodating of the pitch, roll and yaw characteristics of a real car.
<HR></BLOCKQUOTE>
There are a number of Viper Days cars, the Competition Coupe, ALMS Vipers, and Oreca Vipers with rear diffusers. More and more purpose built race cars all over are showing up with them. Of course, nearly all of these cars also have wings too. It seems there is something of a significant advantage in a diffuser, however it may also require a wing to optimize its affect.
I'm not ready to abandon the diffuser idea just yet. Jrkermode, can you elaborate further on why the "real" cars I named above should steer clear of this aid?
Also, does anyone else have any experience on these devices? The specific goals in my search has been: 1) to improve over stock high speed cornering capability by reducing lift, 2) to lower aerodynamic drag, and 3) to minimally or subtly bring about these changes so as to enhance and not intrude on the Viper's already outlandish looks and abilities. By the way I'm not trying to win the Le Mans with this approach but I do love picking off an occasional LTOD in a field of tube frame turbo Porsches, open wheeled formula cars and trailered-in purpose-built racecars with my air conditioned daily driver!
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
I would advise you steer clear of making a ventrui/tunnel/diffuser car. These things work by manipulating boundary layers that aren't very accomodating of the pitch, roll and yaw characteristics of a real car.
<HR></BLOCKQUOTE>
There are a number of Viper Days cars, the Competition Coupe, ALMS Vipers, and Oreca Vipers with rear diffusers. More and more purpose built race cars all over are showing up with them. Of course, nearly all of these cars also have wings too. It seems there is something of a significant advantage in a diffuser, however it may also require a wing to optimize its affect.
I'm not ready to abandon the diffuser idea just yet. Jrkermode, can you elaborate further on why the "real" cars I named above should steer clear of this aid?
Also, does anyone else have any experience on these devices? The specific goals in my search has been: 1) to improve over stock high speed cornering capability by reducing lift, 2) to lower aerodynamic drag, and 3) to minimally or subtly bring about these changes so as to enhance and not intrude on the Viper's already outlandish looks and abilities. By the way I'm not trying to win the Le Mans with this approach but I do love picking off an occasional LTOD in a field of tube frame turbo Porsches, open wheeled formula cars and trailered-in purpose-built racecars with my air conditioned daily driver!
Sonny 00 GTS ACR
Enthusiast
John,
I think Mike's point was that track and race prepared cars tend to have much stiffer suspensions allowing for more consistent results from underbody effects. A car that is driven on the street will have much more body roll which would negatively affect that type of effort. Race cars with high downforce underbody effects can actually get in trouble by hitting a curb on the track and suddenly losing the suction and subsequent grip they were enjoying.
The best advice is to make your car look good on the street but make it go fast on the track - there's a big difference. Check out ViperDays at VOI and see!
I think Mike's point was that track and race prepared cars tend to have much stiffer suspensions allowing for more consistent results from underbody effects. A car that is driven on the street will have much more body roll which would negatively affect that type of effort. Race cars with high downforce underbody effects can actually get in trouble by hitting a curb on the track and suddenly losing the suction and subsequent grip they were enjoying.
The best advice is to make your car look good on the street but make it go fast on the track - there's a big difference. Check out ViperDays at VOI and see!
jrkermode
Enthusiast
Sonny hit it right on, by real cars I mean those without super stiff race suspension.
Like I said, this is kind of a hard question to address via messaging.
Ground effects is a pretty efficient (lots of downforce for minimal drag) way to get downforce, which is why it is used at the top levels of motorsport. However, to get the kinds of numbers you see on an ORECA car, "stability of the aerodymaic platform" becomes paramount. That means those big downforce numbers are only achieved when the car is precisely oriented to the air. A real car , which dives under braking, squats under acceleration, and rolls during cornering isn't stable enough to maintain those big downforce numbers. You can still get some downforce, but it comes at a price.
How about a real world example? It is likely that a GTS could generate similar downforce to a Ferrari 355, a real car with underbody ground effects, making about 400 lbs of downforce at 160 MPH. However, to do this would require a full undertray and a carefully designed diffuser, one which could tolerate the roll, yaw and pitch angles of the GTS. Seems easy enough, except once you've enclosed the underbody, you'll need to find a way to cool the trans and diff (right now they're cooled by the air flowing under the car). Where will you mount those coolers? You'll also have to find another place to exhaust the underhood air (right now most of it goes under the car). The GTSR vented hood works well for that, but I'm not sure it satisfies the "subtle" requirement of the original post. In short, you'll need to expend a great deal of effort and dollars to get a rather minimal amount of downforce.
Ground effects is certainly a worthwhile venture for professional race teams, even possibly for a serious VRL racer. For the rest of us, I think its a poor application of resources.
You're requirements are identical to those I investigated. However, when we did the numbers on the package I mentioned in my previous post (skirts and spats), the car's owners said "not enough" and opted instead for wings and splitters. Not subtle, but very effective.
Regarding the interaction of wings and ground effects, they can, and often do, help one another's performance. However, each can be effective when used alone.
Again, the most important thing is to have the appropriate parts for your specific application and budget.
P.S. A diffuser works by helping a low pressure area "communicate" with the car's underbody. Most people think of only rear diffusers, however they can be located just about anywhere. Basically you're trying to create a situation where the underbody air can quickly escape from beneath the car. The better you're able to do this, the more "suction" you create.
Like I said, this is kind of a hard question to address via messaging.
Ground effects is a pretty efficient (lots of downforce for minimal drag) way to get downforce, which is why it is used at the top levels of motorsport. However, to get the kinds of numbers you see on an ORECA car, "stability of the aerodymaic platform" becomes paramount. That means those big downforce numbers are only achieved when the car is precisely oriented to the air. A real car , which dives under braking, squats under acceleration, and rolls during cornering isn't stable enough to maintain those big downforce numbers. You can still get some downforce, but it comes at a price.
How about a real world example? It is likely that a GTS could generate similar downforce to a Ferrari 355, a real car with underbody ground effects, making about 400 lbs of downforce at 160 MPH. However, to do this would require a full undertray and a carefully designed diffuser, one which could tolerate the roll, yaw and pitch angles of the GTS. Seems easy enough, except once you've enclosed the underbody, you'll need to find a way to cool the trans and diff (right now they're cooled by the air flowing under the car). Where will you mount those coolers? You'll also have to find another place to exhaust the underhood air (right now most of it goes under the car). The GTSR vented hood works well for that, but I'm not sure it satisfies the "subtle" requirement of the original post. In short, you'll need to expend a great deal of effort and dollars to get a rather minimal amount of downforce.
Ground effects is certainly a worthwhile venture for professional race teams, even possibly for a serious VRL racer. For the rest of us, I think its a poor application of resources.
You're requirements are identical to those I investigated. However, when we did the numbers on the package I mentioned in my previous post (skirts and spats), the car's owners said "not enough" and opted instead for wings and splitters. Not subtle, but very effective.
Regarding the interaction of wings and ground effects, they can, and often do, help one another's performance. However, each can be effective when used alone.
Again, the most important thing is to have the appropriate parts for your specific application and budget.
P.S. A diffuser works by helping a low pressure area "communicate" with the car's underbody. Most people think of only rear diffusers, however they can be located just about anywhere. Basically you're trying to create a situation where the underbody air can quickly escape from beneath the car. The better you're able to do this, the more "suction" you create.
Jim Hodel
Enthusiast
Here is a basic question - why do you want more downforce? Does your car feel unstable at speed? It seems like more downforce will create more drag and result in less acceleration and top speed, so unless there is a stability problem I don't understand the benefit.
Also, I am guessing that tuning aerodynamic devices will complicate the all ready difficult process of setting up shocks, springs, alignment etc. In other words, they are just more things to get wrong.
Jim
Also, I am guessing that tuning aerodynamic devices will complicate the all ready difficult process of setting up shocks, springs, alignment etc. In other words, they are just more things to get wrong.
Jim
jrkermode
Enthusiast
The downforce improves your grip so you can break harder, corner faster and accelerate harder. So, for high HP cars, it usually results in lower lap-times/ETs.
Aero devices do indeed make set-up more complicated.
Aero devices do indeed make set-up more complicated.
John Moore
Enthusiast
Mike and Sonny,
Thanks for the info!
Mike,
How much downforce were you able to achieve without a wing? Do you know what can be achieved without a full undertray? Correct me if I'm wrong but I don't recall much if any undertrays on some of these cars( haven't seen under many of them though.) Also, can "some" amount of side splitters, Roe opening, and rear diffuser help or make any noticeable stick in the corners? I know it can look slick
I just don't want to go to a lot of trouble to disappoint myself!.
If it's enough to matter, I'm running 900# rear and 600# front springs. With no aero the car is currently a consistant front runner and I'd just like to make it a little more secure but not to the extent that I'd upset the handling or make it too reliant on the aero to be safe. Oh yeah, it really is my daily driver too, so the skirts and dams to the deck aren't gonna work. The "game" is to beat the racecars with a daily driver.
Thanks for the info!
Mike,
How much downforce were you able to achieve without a wing? Do you know what can be achieved without a full undertray? Correct me if I'm wrong but I don't recall much if any undertrays on some of these cars( haven't seen under many of them though.) Also, can "some" amount of side splitters, Roe opening, and rear diffuser help or make any noticeable stick in the corners? I know it can look slick
If it's enough to matter, I'm running 900# rear and 600# front springs. With no aero the car is currently a consistant front runner and I'd just like to make it a little more secure but not to the extent that I'd upset the handling or make it too reliant on the aero to be safe. Oh yeah, it really is my daily driver too, so the skirts and dams to the deck aren't gonna work. The "game" is to beat the racecars with a daily driver.
John H
Enthusiast
This might not be directly related to the topic, but is there any way to reduce the drag on the GTS? Unfortunately, it's not the cleanest car through the air at higher speeds.
John Hein
John Hein
Sonny 00 GTS ACR
Enthusiast
John,
You might check out Autoform Development. http://www.autoformgroup.com They produce a Daytona edition of the GTS which not only looks good but works pretty well too. Bernie Katz drove one last year in the ViperDays Michelin Challenge Series and was very competitive. You would have to be careful of the splitter under the nose, but it's relatively easy to change the ride height so you can have less on the track and more on the street. Lowering the car to the proper height front to rear also makes a big difference on the track. Bernie used his car as a daily driver as well as giving me all I could handle on the track!
You should talk to people at ViperDays however, because as you move towards stiffer suspensions, more downforce, and better tires you need to consider the risk to other components such as the steering rack, wheel bearings and oil distribution for example. Safety should be a primary concern for both yourself and the car.
As you know, right out of the box, the Viper is a formidable car, but the real fun is doing what you are doing - learning how to make it better. Have fun.
You might check out Autoform Development. http://www.autoformgroup.com They produce a Daytona edition of the GTS which not only looks good but works pretty well too. Bernie Katz drove one last year in the ViperDays Michelin Challenge Series and was very competitive. You would have to be careful of the splitter under the nose, but it's relatively easy to change the ride height so you can have less on the track and more on the street. Lowering the car to the proper height front to rear also makes a big difference on the track. Bernie used his car as a daily driver as well as giving me all I could handle on the track!
You should talk to people at ViperDays however, because as you move towards stiffer suspensions, more downforce, and better tires you need to consider the risk to other components such as the steering rack, wheel bearings and oil distribution for example. Safety should be a primary concern for both yourself and the car.
As you know, right out of the box, the Viper is a formidable car, but the real fun is doing what you are doing - learning how to make it better. Have fun.
jrkermode
Enthusiast
John M,
We never track tested the skirts and spats package so I don't have any real numbers for that. I did some calculations and came up with approximately 500#, however this number varies greatly depending on how well the skirts seal. The Gen II GTSR rear wing can generate that much on its own. The front splitter a little less. So that's why the guys I worked with opted to start with wings and splitters. I say "start with" because in the next few months we will likely do a test where we add the skirts to see how much additional downforce we get. If some's good more is better, right?
The rear diffuser and side splitters really need the full undertray to work effectively, so I don't think you'd notice their effect when used on a stock underbody. Although, the splitters do a really good job of terrorizing your ankles.
If you get much stick, you're springs will need to change significantly, not quite double you're current rates. As Sonny mentioned, aero devices are very sensitive to rake so, you'll need to go with really stiff suspension to keep the rake where you want it. I believe this alone makes an aero car unstreetable, but there are some who believe anything with lights and turn signals is a street car.
For whatever its worth, the skirts are streetable and relatively insensitive to changes in rake, roll, etc... Recall we developed that solution because we started with exactly your requirements.
John H,
I don't know of anything which can make a significant reduction in drag short of cutting up the car.
There isn't any drag at the front, other than frontal area. So, the only place to look for help would be to reduce base pressure, that pocket of air being sucked along behind the car. That's why all the super-economy cars have narrow little tapered tails, to reduce base pressure.
P.S. Who's Mike?
We never track tested the skirts and spats package so I don't have any real numbers for that. I did some calculations and came up with approximately 500#, however this number varies greatly depending on how well the skirts seal. The Gen II GTSR rear wing can generate that much on its own. The front splitter a little less. So that's why the guys I worked with opted to start with wings and splitters. I say "start with" because in the next few months we will likely do a test where we add the skirts to see how much additional downforce we get. If some's good more is better, right?
The rear diffuser and side splitters really need the full undertray to work effectively, so I don't think you'd notice their effect when used on a stock underbody. Although, the splitters do a really good job of terrorizing your ankles.
If you get much stick, you're springs will need to change significantly, not quite double you're current rates. As Sonny mentioned, aero devices are very sensitive to rake so, you'll need to go with really stiff suspension to keep the rake where you want it. I believe this alone makes an aero car unstreetable, but there are some who believe anything with lights and turn signals is a street car.
For whatever its worth, the skirts are streetable and relatively insensitive to changes in rake, roll, etc... Recall we developed that solution because we started with exactly your requirements.
John H,
I don't know of anything which can make a significant reduction in drag short of cutting up the car.
There isn't any drag at the front, other than frontal area. So, the only place to look for help would be to reduce base pressure, that pocket of air being sucked along behind the car. That's why all the super-economy cars have narrow little tapered tails, to reduce base pressure.
P.S. Who's Mike?
Frank Parise
VCA Venom Member
Take a close look at all 4 sides of one of the Oreca GTS-R Vipers. This is the state of the art in Viper aerodynamics. Effective aero parts don't make any sense on a street car unless you are doing it for looks only. They will slow your car down everywhere except high speed turns and, even then, you have to be a highly skilled driver to take advantage of the downforce.
Autoform sells multiple aero packages for street/track application and they have been doing it successfully for over 5 years.
Meaningful downforce will only come from a badass rear wing that slows your top speed by 10 or more MPH. To eliminate the natural front lift condition of the car (which is exacerbated by an effective rear wing) you will also need a front splitter that extends anywhere from 6 to 8 inches in front of the bottom leading edge of your front fascia. This is very impractical for street use and makes it nearly impossible to get in and out of your driveway.
The angle of the bottom of your stock rear body panel already acts as a diffuser to clear up the air stream interacting with the stock rear spoiler (the lip on the rear deck of a GTS acts as a spoiler).
The diffusers you see on race cars are an enhancement and are meaningfully effective only if you cover up the entire underbelly of your car. This will require you to install transmission and differential coolers. The diffuser cleans up the air stream coming out the rear of the car so that it doesn't interfere with and separate the air flow coming off the rear wing.
Side splitters are intended to interfere with air attempting to migrate underneath the car from its sides. Side skirts are more effective but not practical at all for the street.
Dive planes on the corners of the front fascia are tuning devices that only work to enhance all the other pieces. They are marginally effective in most circumstances.
If you could figure out how to install a powerful suction fan underneath the engine compartment, you might have an effective device that was invisible on the street. This has been done on the infamous F1 Maclaren that holds the world record for top speed in a production street car of 244 MPH. This is not a joke.
Autoform sells multiple aero packages for street/track application and they have been doing it successfully for over 5 years.
Meaningful downforce will only come from a badass rear wing that slows your top speed by 10 or more MPH. To eliminate the natural front lift condition of the car (which is exacerbated by an effective rear wing) you will also need a front splitter that extends anywhere from 6 to 8 inches in front of the bottom leading edge of your front fascia. This is very impractical for street use and makes it nearly impossible to get in and out of your driveway.
The angle of the bottom of your stock rear body panel already acts as a diffuser to clear up the air stream interacting with the stock rear spoiler (the lip on the rear deck of a GTS acts as a spoiler).
The diffusers you see on race cars are an enhancement and are meaningfully effective only if you cover up the entire underbelly of your car. This will require you to install transmission and differential coolers. The diffuser cleans up the air stream coming out the rear of the car so that it doesn't interfere with and separate the air flow coming off the rear wing.
Side splitters are intended to interfere with air attempting to migrate underneath the car from its sides. Side skirts are more effective but not practical at all for the street.
Dive planes on the corners of the front fascia are tuning devices that only work to enhance all the other pieces. They are marginally effective in most circumstances.
If you could figure out how to install a powerful suction fan underneath the engine compartment, you might have an effective device that was invisible on the street. This has been done on the infamous F1 Maclaren that holds the world record for top speed in a production street car of 244 MPH. This is not a joke.
SlowCreamPuff
Enthusiast
Wow! You guys are truly amazing. I enjoy reading all the information posted here and is exactly what I am looking for.
Sadly, unless I have a few hundred thousands or more to spend, my conclusion is no real downforce for a street car.
I have accepted the fact that I am crazy.
I wanted the downforce for gaining traction at high speed for insane acceleration. 4 digits power level (what I want) is just not usable.
Thank you, aero-experts.
Keep the awesome information flowing.
Sadly, unless I have a few hundred thousands or more to spend, my conclusion is no real downforce for a street car.
I have accepted the fact that I am crazy.
I wanted the downforce for gaining traction at high speed for insane acceleration. 4 digits power level (what I want) is just not usable.
Thank you, aero-experts.
Keep the awesome information flowing.
Tom and Vipers
Enthusiast
A lot of people think the Viper needs more front tire.
If such is the case, wouldn't a splitter be the first order of business - and not a rear wing?
If such is the case, wouldn't a splitter be the first order of business - and not a rear wing?
jrkermode
Enthusiast
SlowCreamPuff,
Are you sure you want balanced downforce? If you're problem is hooking up 1,000 HP, the car's natural front lift may actually be working in your favor as the rearward rake will help load the rear tires.
In any case, don't give up, just set realistic goals.
Tom,
I believe a stock bodied car can be made very neutral with appropriate shocks, springs and alignment. So, I'm not sure why you say more front grip is needed. However, a front splitter, a front difuser, the Roe opening under the nose, and a vented hood will all improve front grip.
Are you sure you want balanced downforce? If you're problem is hooking up 1,000 HP, the car's natural front lift may actually be working in your favor as the rearward rake will help load the rear tires.
In any case, don't give up, just set realistic goals.
Tom,
I believe a stock bodied car can be made very neutral with appropriate shocks, springs and alignment. So, I'm not sure why you say more front grip is needed. However, a front splitter, a front difuser, the Roe opening under the nose, and a vented hood will all improve front grip.
Tom and Vipers
Enthusiast
I was under the impression that alignment for good turnin will wear tires excessively on street since a fair amount of negative camber is required.
I'm looking for a setup that will be more balanced when I drive my street car onto the track. As it stands, stock Viper setup is somewhat frustrating on track due to turnin. (Of course, I can only imagine what a loose Viper would be like!)
I'm looking for a setup that will be more balanced when I drive my street car onto the track. As it stands, stock Viper setup is somewhat frustrating on track due to turnin. (Of course, I can only imagine what a loose Viper would be like!)
Tom and Vipers
Enthusiast
...I also have essentially the same problem with Hennesey facia and louvered hood.
Shocks: while they may help turnin, won't they still not help once the car is established within a corner?
Springs: I'm not sure about this one. For one, I'm not getting any bottoming problems and I do like the ability to absorb rough track and road surfaces which may imply a soft setting like stock. If a change in springs affected over/understeer, wouldn't that be because a different spring rate changed the roll stiffness which can also be done with a sway bar? I'd really like to find a cockpit adjustable rear sway bar so I can balance out the car while I drive it.
PS. A friend of mine replaced his stock fronts with 315's and he is AMAZED at the improvement in handling.
Shocks: while they may help turnin, won't they still not help once the car is established within a corner?
Springs: I'm not sure about this one. For one, I'm not getting any bottoming problems and I do like the ability to absorb rough track and road surfaces which may imply a soft setting like stock. If a change in springs affected over/understeer, wouldn't that be because a different spring rate changed the roll stiffness which can also be done with a sway bar? I'd really like to find a cockpit adjustable rear sway bar so I can balance out the car while I drive it.
PS. A friend of mine replaced his stock fronts with 315's and he is AMAZED at the improvement in handling.
GTS Dean
Enthusiast
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Tom and Vipers:
(Of course, I can only imagine what a loose Viper would be like!)
<HR></BLOCKQUOTE>
You don't want to know. I was forced into a situation of 315 Hoosiers up front and 335 MXX3s in the back one time. NOT FUN.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
Shocks: while they may help turnin, won't they still not help once the car is established within a corner?
<HR></BLOCKQUOTE>
Nope.
<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>
PS. A friend of mine replaced his stock fronts with 315's and he is AMAZED at the improvement in handling.
<HR></BLOCKQUOTE>
The Viper needs more tire than the factory is willing to put on - hydroplaning fears, steering kickback, average owner complaints.
(Of course, I can only imagine what a loose Viper would be like!)
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You don't want to know. I was forced into a situation of 315 Hoosiers up front and 335 MXX3s in the back one time. NOT FUN.
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Shocks: while they may help turnin, won't they still not help once the car is established within a corner?
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Nope.
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PS. A friend of mine replaced his stock fronts with 315's and he is AMAZED at the improvement in handling.
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The Viper needs more tire than the factory is willing to put on - hydroplaning fears, steering kickback, average owner complaints.
jrkermode
Enthusiast
Tom I suggest you contact Bill Pemberton, he's done a lot of work with street/race set-ups.
In general, the 2 set-ups are at odds with one another. For the track you usually want high frequency (stiff) springs so that the suspension recovers quickly from inputs. On the street you usually want low frequency (soft) springs to better isolate you from road irregularities.
You have a similar situation with alignment. On the track you want a car that responds quickly to small inputs, something twitchy. On the street a twitchy car gets tiring real quick. Bill can help you choose a good compromise.
I would especially ask him about toe settings. They typically have the greatest influence on turn-in.
As for shocks not helping in a corner...
While it is true a shock is a dynamic device, working only when the suspension is moving, many adjustable shocks can be set-up to deal with some pretty divergent frequencies. The low speed setting can be so low that in fact you do feel some effect mid corner. Imagine setting your front shock rebound circuit such that the suspension takes forever to recover from a bump (wheel goes up but won't come down). Under braking the suspension compresses but doesn't return. This leaves you going through the corner with compressed, hence stiffer suspension. I'm not suggesting you do this, it's just to illustrate that modern shocks can have a great influence on all aspects of handling.
If you choose externally adjustable shocks, it makes it a lot easier to back off to an acceptable street setting after a track day. Again, Bill can help you sort through all this stuff.
In general, the 2 set-ups are at odds with one another. For the track you usually want high frequency (stiff) springs so that the suspension recovers quickly from inputs. On the street you usually want low frequency (soft) springs to better isolate you from road irregularities.
You have a similar situation with alignment. On the track you want a car that responds quickly to small inputs, something twitchy. On the street a twitchy car gets tiring real quick. Bill can help you choose a good compromise.
I would especially ask him about toe settings. They typically have the greatest influence on turn-in.
As for shocks not helping in a corner...
While it is true a shock is a dynamic device, working only when the suspension is moving, many adjustable shocks can be set-up to deal with some pretty divergent frequencies. The low speed setting can be so low that in fact you do feel some effect mid corner. Imagine setting your front shock rebound circuit such that the suspension takes forever to recover from a bump (wheel goes up but won't come down). Under braking the suspension compresses but doesn't return. This leaves you going through the corner with compressed, hence stiffer suspension. I'm not suggesting you do this, it's just to illustrate that modern shocks can have a great influence on all aspects of handling.
If you choose externally adjustable shocks, it makes it a lot easier to back off to an acceptable street setting after a track day. Again, Bill can help you sort through all this stuff.
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