No more leaf springs!!!! C5Z06 want coilovers
11-26-2018, 09:55 AM
#21
Racer
Thread Starter
Everything I wrote in the post above still applies to these additional goals. The form of spring you have in your car has absolutely nothing to do with any of these problems. All of this sounds like damper issues to me. I would recommend you forget about spending money on good shocks that are intended for the purpose you describe. And Aldan isn't that, from what I can see. They don't even tell you whose shocks they're actually using, how they're valve, monotube or twin tube, etc. Also, looking at their website it doesn't appear that they make a kit for C4s.
If I can get rid of everything I mentioned with great shocks, I'm all for it.
11-26-2018, 10:12 AM
#22
Le Mans Master
Yes, I think the issues you want to solve are either a result of stiffer factory shocks intended mainly for better handling on a track or autocross course, and/or maybe one or more of them are shot. IME, Koni sport dampers typically provide a really good street ride at their softer settings. The Ridetech HQ shocks can do the same, and they are inexpensive and use really good Fox internal components. If you aren't competing in any events that emphasize handling, you might be better off with the Koni FSD dampers, which are geared toward a better, more compliant street ride. But spending a bunch of money and time to convert to coil springs isn't going to solve the issues.
Last edited by MatthewMiller; 11-26-2018 at 10:13 AM.
11-27-2018, 02:01 PM
#23
The main weakness with the leafs is the cross talk at the rear. Any corner where you need to take some curb upsets the outer wheel and you get oversteer. Or at least have to wait on the throttle a little. Coilovers 'fix' this.
But I would also echo the comments relating to less expensive coilover vs the leafs.
But I would also echo the comments relating to less expensive coilover vs the leafs.
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romandian (11-28-2018)
11-27-2018, 05:37 PM
#24
Racer
Thread Starter
The main weakness with the leafs is the cross talk at the rear. Any corner where you need to take some curb upsets the outer wheel and you get oversteer. Or at least have to wait on the throttle a little. Coilovers 'fix' this.
But I would also echo the comments relating to less expensive coilover vs the leafs.
But I would also echo the comments relating to less expensive coilover vs the leafs.
11-27-2018, 07:43 PM
#25
Le Mans Master
Normal coil springs provide the same wheel rate in both pitch and roll on their own - no anti-roll of their own. The rear leaf on a C4 has both clamps very close together in the middle, and therefore has no anti-roll of its own either. So the "crosstalk" that you refer to doesn't exist with the rear leaf spring at all. Only the front monoleaf in a C4 has any anti-roll component of its own. That's because it has clamps spaced about 2ft apart and is unconstrained in the middle. So as the car rolls, the spring forms an "S" shape between the two clamps, which creates an anti-roll force. It's not fully independent. That sounds bad, but...
You know what else creates an anti-roll wheel rate in any conventional suspension? An anti-roll bar, commonly called a swaybar (it should be "anti-sway"), does. So yeah, literally the entire purpose for any swaybar in any car is to reduce independence of the two corners it connects. It's just a torsion spring that works only in roll. So unless you run without a swaybar of any kind, you have the same "crosstalk" with coil springs as you do with leafs. In fact, Chevy was always able to spec smaller front swaybars because the spring was doing some of that anti-roll work. If they used regular coil spring or clamped the front monoleaf in a way that eliminated the anti-roll, then they would have just had to make up for it with a larger front swaybar. So there's zero difference in "crosstalk" between a coilover setup and a monoleaf setup, as long as you keep the wheel rates in pitch and roll the same.
ETA: To demystify this stuff even further, consider two cars that are identical in every way except that one has 200lb/in of wheel rate in pitch but 400lb in roll (i.e., it has 200lb/in of anti-roll provided by a swaybar or leaf spring), vs a car that has 400lb/in in both pitch and roll (i.e., no swaybar and no leaf spring that provides and anti-roll component). Both cars have a total wheel rate in roll of 400lb/in, so they both resist roll the same amount: if 1G of cornering force creates 3* of roll in one car, it will do the same to other car. They only differ in their resistance to pitch. So, if you hit a curb with the inside wheel while cornering in each car, which one will be upset the most? Answer: they will both be upset by the same amount, because the curb is forcing the suspension into roll, both cars have the same roll rate, and so in both cars the effect of the curb on the outside tire's grip is the same. The tires don't know whether their respective wheel rates come from a coil spring, a leaf spring, or a swaybar - they react the same if the rate is the same.
There's a lot of mysticism about certain aspects of vehicle dynamics, and the monoleaf setup is definitely one of those. Swaybars are another. People tend to think of them as way more complicated or magical than they really are. They are just a spring.
Hey, here's an extra-credit question: how can you design a passive-sprung suspension (active suspensions don't count!) so that it has higher wheel rates in pitch than it does in roll? Here's a hint: no street car I'm aware of has ever been designed like this, but race cars with lots of downforce commonly employ this design strategy.
Last edited by MatthewMiller; 11-27-2018 at 07:54 PM.
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dclafleur (11-28-2018)
11-28-2018, 04:49 AM
#26
This isn't accurate (did we just have this discussion on FB?). Engineers don't commonly use the term "crosstalk" for this, btw. There's only wheel rate in pitch (both wheels at one end move the same direction, either compression or rebound) and wheel rate in roll (one wheel moving in compression while the other moves in rebound). If the wheel rate in roll is higher, then the difference is typically referred to as anti-roll; whereas you're referring to it as "cross talk." Another way to think of this is that a suspension with any anti-roll component is less than 100% independent, because if one wheel at either end is moved into compression or rebound, the anti-roll tries to get the other wheel at that end to do the same thing.
Normal coil springs provide the same wheel rate in both pitch and roll on their own - no anti-roll of their own. The rear leaf on a C4 has both clamps very close together in the middle, and therefore has no anti-roll of its own either. So the "crosstalk" that you refer to doesn't exist with the rear leaf spring at all. Only the front monoleaf in a C4 has any anti-roll component of its own. That's because it has clamps spaced about 2ft apart and is unconstrained in the middle. So as the car rolls, the spring forms an "S" shape between the two clamps, which creates an anti-roll force. It's not fully independent. That sounds bad, but...
You know what else creates an anti-roll wheel rate in any conventional suspension? An anti-roll bar, commonly called a swaybar (it should be "anti-sway"), does. So yeah, literally the entire purpose for any swaybar in any car is to reduce independence of the two corners it connects. It's just a torsion spring that works only in roll. So unless you run without a swaybar of any kind, you have the same "crosstalk" with coil springs as you do with leafs. In fact, Chevy was always able to spec smaller front swaybars because the spring was doing some of that anti-roll work. If they used regular coil spring or clamped the front monoleaf in a way that eliminated the anti-roll, then they would have just had to make up for it with a larger front swaybar. So there's zero difference in "crosstalk" between a coilover setup and a monoleaf setup, as long as you keep the wheel rates in pitch and roll the same.
ETA: To demystify this stuff even further, consider two cars that are identical in every way except that one has 200lb/in of wheel rate in pitch but 400lb in roll (i.e., it has 200lb/in of anti-roll provided by a swaybar or leaf spring), vs a car that has 400lb/in in both pitch and roll (i.e., no swaybar and no leaf spring that provides and anti-roll component). Both cars have a total wheel rate in roll of 400lb/in, so they both resist roll the same amount: if 1G of cornering force creates 3* of roll in one car, it will do the same to other car. They only differ in their resistance to pitch. So, if you hit a curb with the inside wheel while cornering in each car, which one will be upset the most? Answer: they will both be upset by the same amount, because the curb is forcing the suspension into roll, both cars have the same roll rate, and so in both cars the effect of the curb on the outside tire's grip is the same. The tires don't know whether their respective wheel rates come from a coil spring, a leaf spring, or a swaybar - they react the same if the rate is the same.
There's a lot of mysticism about certain aspects of vehicle dynamics, and the monoleaf setup is definitely one of those. Swaybars are another. People tend to think of them as way more complicated or magical than they really are. They are just a spring.
Hey, here's an extra-credit question: how can you design a passive-sprung suspension (active suspensions don't count!) so that it has higher wheel rates in pitch than it does in roll? Here's a hint: no street car I'm aware of has ever been designed like this, but race cars with lots of downforce commonly employ this design strategy.
Normal coil springs provide the same wheel rate in both pitch and roll on their own - no anti-roll of their own. The rear leaf on a C4 has both clamps very close together in the middle, and therefore has no anti-roll of its own either. So the "crosstalk" that you refer to doesn't exist with the rear leaf spring at all. Only the front monoleaf in a C4 has any anti-roll component of its own. That's because it has clamps spaced about 2ft apart and is unconstrained in the middle. So as the car rolls, the spring forms an "S" shape between the two clamps, which creates an anti-roll force. It's not fully independent. That sounds bad, but...
You know what else creates an anti-roll wheel rate in any conventional suspension? An anti-roll bar, commonly called a swaybar (it should be "anti-sway"), does. So yeah, literally the entire purpose for any swaybar in any car is to reduce independence of the two corners it connects. It's just a torsion spring that works only in roll. So unless you run without a swaybar of any kind, you have the same "crosstalk" with coil springs as you do with leafs. In fact, Chevy was always able to spec smaller front swaybars because the spring was doing some of that anti-roll work. If they used regular coil spring or clamped the front monoleaf in a way that eliminated the anti-roll, then they would have just had to make up for it with a larger front swaybar. So there's zero difference in "crosstalk" between a coilover setup and a monoleaf setup, as long as you keep the wheel rates in pitch and roll the same.
ETA: To demystify this stuff even further, consider two cars that are identical in every way except that one has 200lb/in of wheel rate in pitch but 400lb in roll (i.e., it has 200lb/in of anti-roll provided by a swaybar or leaf spring), vs a car that has 400lb/in in both pitch and roll (i.e., no swaybar and no leaf spring that provides and anti-roll component). Both cars have a total wheel rate in roll of 400lb/in, so they both resist roll the same amount: if 1G of cornering force creates 3* of roll in one car, it will do the same to other car. They only differ in their resistance to pitch. So, if you hit a curb with the inside wheel while cornering in each car, which one will be upset the most? Answer: they will both be upset by the same amount, because the curb is forcing the suspension into roll, both cars have the same roll rate, and so in both cars the effect of the curb on the outside tire's grip is the same. The tires don't know whether their respective wheel rates come from a coil spring, a leaf spring, or a swaybar - they react the same if the rate is the same.
There's a lot of mysticism about certain aspects of vehicle dynamics, and the monoleaf setup is definitely one of those. Swaybars are another. People tend to think of them as way more complicated or magical than they really are. They are just a spring.
Hey, here's an extra-credit question: how can you design a passive-sprung suspension (active suspensions don't count!) so that it has higher wheel rates in pitch than it does in roll? Here's a hint: no street car I'm aware of has ever been designed like this, but race cars with lots of downforce commonly employ this design strategy.
I`m constantly defending the design, I'm in the UK, so you can imagine the stick the car gets in the morning in the pits (where's your horse, you know there are corners here etc etc). I think the overall design is really excellent for its time and intended function. But at the same time there's no point ignoring its drawbacks.
11-28-2018, 09:13 AM
#27
Le Mans Master
- A change in spring rate: There is no solid info on the motion ratio for a stock C4 monoleaf, and I don't know if that value is established and known for a C5 either. And people also forget to account for the fact that front coilovers are inclined about 20 degrees toward the center of the car. This all affects each spring's actual wheel rates, so nobody seems to be really sure if the coil springs they choose are higher, lower, or equal in wheel rate.
- A change in dampers: coilover swaps almost always entail new dampers, and dampers have a lot more influence over how a car reacts to bumps and curbs than spring rates. So I think a lot of the benefits people ascribe to the coil spring is really a result of an upgrade in dampers. The best way to eliminate this variable would be to install the new dampers without the coils first, and test the car. Then swap the springs in a separate procedure. But nobody takes this extra step.
- Changes in suspension limits: Changing the dampers and/or the bump stops that go with them may change the limits of travel for the suspension, especially in compression. If your car was hitting the stops over a curb with the stock setup, and now can compress further without hitting the stops, that would have a massive effect on how well it handles over a curb.
- Changes in ride height: Unless the car is sitting at exactly the same ride height as it did prior to the swap, you've added an important variable. People tend to run their cars lower after such a change, and a lower rear ride height (with its lower roll center) should help the rear stay more settled during upsetting inputs.
- A change in anti-roll component: in the front, if you change from the monoleaf to coilovers of the same wheel rate and you don't change the swaybar stiffness, then you've reduced the roll resistance in front because the monoleaf has an anti-roll component that you just removed. This could significantly affect the handling of the car.
I`m constantly defending the design, I'm in the UK, so you can imagine the stick the car gets in the morning in the pits (where's your horse, you know there are corners here etc etc). I think the overall design is really excellent for its time and intended function. But at the same time there's no point ignoring its drawbacks.
Coil springs were invented over 350 years ago (in England, btw), and the first steel coil springs were used in mattresses. Does that mean that all cars with coils should be likened to mattresses and tall ships? Many modern sports prototype and open-wheel race cars use a form of leaf spring called a Belleville washer in their suspension linkages either for anti-roll or as a heave spring. Does that mean they are antiquated buggies too?
Tell your buddies that they are betraying their lack of understanding of how suspensions work. Let them know that a leaf-sprung 2019 ZR1 is going around setting all kinds of new track records in the US right now. Tell them that a fiberglass monoleaf is typically lighter than the coils and extra swaybar size it replaces, and that it often allows better spring geometer with better tire/wheel clearance than a coilover spring arrangement.
11-28-2018, 09:24 AM
#28
Whenever someone around here trips over a reference to the transverse leaf springs in the Corvette's suspension, they recoil in horror. You can see that it makes them think of some kind of bad pickup truck, not a sports car.
Of course, the Corvette's use of the leaf spring isn't what you think. For one, these are not springs located longitudinally on an axle, locating the axle and providing suspension action. Instead the springs are mounted transversely, one between each of the front wheels and the other between each of the rear wheels.
So fine, you say. Instead of a pickup truck, what we have here is some kind of cross-springer racing car from the 1940s. But it turns out that the Corvette guys were up to something when they first adapted this design to the platform of the Corvette C4, introduced as a 1984 model.
When we were all standing around the bare chassis of the Corvette C4 at Riverside International Raceway in 1982, just as horrified at the presence of a leaf spring as you are now, Corvette chief engineer Dave McLellen explained his choice. It had a lot to do with packaging, he said. It was about an effort to keep the first all-new Corvette in 20 years as low and narrow as possible. And with a sports car that carries a lot of V8 engine under the hood, a transverse leaf spring solved a lot of problems.
In the process of making the design work, McLellen said, the Corvette engineers learned a few things. First of all, a transverse leaf spring weighs less than two coil springs, a factor of even more importance when you consider that coil springs represent unsprung weight, which affects the compliance and precision of suspension action. And as McLellen later pointed out in his book about his time as the Corvette's chief engineer, Corvette From the Inside (2002), the change in spring material from steel to fiberglass reduced weight by more than 30 pounds.
There is also some cleverness in the impact of the transverse leaf spring on handling. The engineers discovered that when the leaf spring was located by twin mounts in the center of the car, it gave them some effect on body roll, a crucial attribute when it came to getting the most from the then-new, super-wide Goodyear tires. As a result, a smaller anti-roll bar can be used for fine tuning, which reduces overall weight and also fosters more ride compliance, plus the suspension geometry isn't compromised.
Of course, when you see that the Corvette C5R and C6R racing cars have been converted to coil-over suspension, it's easy to start thinking once again that coil springs are the answer. But while such a setup makes it possible to optimize corner weights and tune a chassis for racing, it doesn't deliver anything you'd want to drive on the street, since wheel travel is so restricted.
As you can tell from this cutaway drawing of the C5 that legendary artist David Kimble created for GM, there's a lot of stuff inside the Corvette. And as Kimble could tell you, it takes a lot of effort to get it all in there. A transverse leaf spring might seem crude, but instead it's an example of the unique style of integrated engineering that's so typical of the Corvette.
If you'd like to see more of Kimble's work, a will soon be available. There's also plenty of more information about the use of https://en.wikipedia.org/wiki/Corvette_leaf_spring in suspension design.
Of course, the Corvette's use of the leaf spring isn't what you think. For one, these are not springs located longitudinally on an axle, locating the axle and providing suspension action. Instead the springs are mounted transversely, one between each of the front wheels and the other between each of the rear wheels.
So fine, you say. Instead of a pickup truck, what we have here is some kind of cross-springer racing car from the 1940s. But it turns out that the Corvette guys were up to something when they first adapted this design to the platform of the Corvette C4, introduced as a 1984 model.
When we were all standing around the bare chassis of the Corvette C4 at Riverside International Raceway in 1982, just as horrified at the presence of a leaf spring as you are now, Corvette chief engineer Dave McLellen explained his choice. It had a lot to do with packaging, he said. It was about an effort to keep the first all-new Corvette in 20 years as low and narrow as possible. And with a sports car that carries a lot of V8 engine under the hood, a transverse leaf spring solved a lot of problems.
In the process of making the design work, McLellen said, the Corvette engineers learned a few things. First of all, a transverse leaf spring weighs less than two coil springs, a factor of even more importance when you consider that coil springs represent unsprung weight, which affects the compliance and precision of suspension action. And as McLellen later pointed out in his book about his time as the Corvette's chief engineer, Corvette From the Inside (2002), the change in spring material from steel to fiberglass reduced weight by more than 30 pounds.
There is also some cleverness in the impact of the transverse leaf spring on handling. The engineers discovered that when the leaf spring was located by twin mounts in the center of the car, it gave them some effect on body roll, a crucial attribute when it came to getting the most from the then-new, super-wide Goodyear tires. As a result, a smaller anti-roll bar can be used for fine tuning, which reduces overall weight and also fosters more ride compliance, plus the suspension geometry isn't compromised.
Of course, when you see that the Corvette C5R and C6R racing cars have been converted to coil-over suspension, it's easy to start thinking once again that coil springs are the answer. But while such a setup makes it possible to optimize corner weights and tune a chassis for racing, it doesn't deliver anything you'd want to drive on the street, since wheel travel is so restricted.
As you can tell from this cutaway drawing of the C5 that legendary artist David Kimble created for GM, there's a lot of stuff inside the Corvette. And as Kimble could tell you, it takes a lot of effort to get it all in there. A transverse leaf spring might seem crude, but instead it's an example of the unique style of integrated engineering that's so typical of the Corvette.
If you'd like to see more of Kimble's work, a will soon be available. There's also plenty of more information about the use of https://en.wikipedia.org/wiki/Corvette_leaf_spring in suspension design.
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MatthewMiller (11-28-2018)
11-28-2018, 09:34 AM
#29
Le Mans Master
^^ great thread!
I recently bought suspension components myself, stuck with leaf springs. A lot of folks say 'leaf spring bad!' but cannot explain why. they just repeat 'leaf spring bad!'
Above info from MatthewMiller and Sub8 is great fun reading
I recently bought suspension components myself, stuck with leaf springs. A lot of folks say 'leaf spring bad!' but cannot explain why. they just repeat 'leaf spring bad!'
Above info from MatthewMiller and Sub8 is great fun reading
Last edited by acroy; 11-28-2018 at 09:34 AM.
11-28-2018, 01:44 PM
#30
It's also worth noting that if you look at the c5 development back story - it was done under a super tight budget as the development team had to sell the product to management.
I believe I've read here guys running T1 setup, fair to say a purpose developed track optimisation of the available hardware, going quicker with decent coilovers.
There was also a recent thread about the infamous vette mid-corner wiggle. Only resolved with coilovers.
I believe I've read here guys running T1 setup, fair to say a purpose developed track optimisation of the available hardware, going quicker with decent coilovers.
There was also a recent thread about the infamous vette mid-corner wiggle. Only resolved with coilovers.
Last edited by Sub8; 11-28-2018 at 02:14 PM.
11-28-2018, 03:16 PM
#31
Melting Slicks
Originally Posted by Sub8
It's also worth noting that if you look at the c5 development back story - it was done under a super tight budget as the development team had to sell the product to management.
I believe I've read here guys running T1 setup, fair to say a purpose developed track optimisation of the available hardware, going quicker with decent coilovers.
There was also a recent thread about the infamous vette mid-corner wiggle. Only resolved with coilovers.
I believe I've read here guys running T1 setup, fair to say a purpose developed track optimisation of the available hardware, going quicker with decent coilovers.
There was also a recent thread about the infamous vette mid-corner wiggle. Only resolved with coilovers.
11-28-2018, 03:25 PM
#32
Drifting
This isn't accurate (did we just have this discussion on FB?). Engineers don't commonly use the term "crosstalk" for this, btw. There's only wheel rate in pitch (both wheels at one end move the same direction, either compression or rebound) and wheel rate in roll (one wheel moving in compression while the other moves in rebound). If the wheel rate in roll is higher, then the difference is typically referred to as anti-roll; whereas you're referring to it as "cross talk." Another way to think of this is that a suspension with any anti-roll component is less than 100% independent, because if one wheel at either end is moved into compression or rebound, the anti-roll tries to get the other wheel at that end to do the same thing.
Normal coil springs provide the same wheel rate in both pitch and roll on their own - no anti-roll of their own. The rear leaf on a C4 has both clamps very close together in the middle, and therefore has no anti-roll of its own either. So the "crosstalk" that you refer to doesn't exist with the rear leaf spring at all. Only the front monoleaf in a C4 has any anti-roll component of its own. That's because it has clamps spaced about 2ft apart and is unconstrained in the middle. So as the car rolls, the spring forms an "S" shape between the two clamps, which creates an anti-roll force. It's not fully independent. That sounds bad, but...
You know what else creates an anti-roll wheel rate in any conventional suspension? An anti-roll bar, commonly called a swaybar (it should be "anti-sway"), does. So yeah, literally the entire purpose for any swaybar in any car is to reduce independence of the two corners it connects. It's just a torsion spring that works only in roll. So unless you run without a swaybar of any kind, you have the same "crosstalk" with coil springs as you do with leafs. In fact, Chevy was always able to spec smaller front swaybars because the spring was doing some of that anti-roll work. If they used regular coil spring or clamped the front monoleaf in a way that eliminated the anti-roll, then they would have just had to make up for it with a larger front swaybar. So there's zero difference in "crosstalk" between a coilover setup and a monoleaf setup, as long as you keep the wheel rates in pitch and roll the same.
ETA: To demystify this stuff even further, consider two cars that are identical in every way except that one has 200lb/in of wheel rate in pitch but 400lb in roll (i.e., it has 200lb/in of anti-roll provided by a swaybar or leaf spring), vs a car that has 400lb/in in both pitch and roll (i.e., no swaybar and no leaf spring that provides and anti-roll component). Both cars have a total wheel rate in roll of 400lb/in, so they both resist roll the same amount: if 1G of cornering force creates 3* of roll in one car, it will do the same to other car. They only differ in their resistance to pitch. So, if you hit a curb with the inside wheel while cornering in each car, which one will be upset the most? Answer: they will both be upset by the same amount, because the curb is forcing the suspension into roll, both cars have the same roll rate, and so in both cars the effect of the curb on the outside tire's grip is the same. The tires don't know whether their respective wheel rates come from a coil spring, a leaf spring, or a swaybar - they react the same if the rate is the same.
There's a lot of mysticism about certain aspects of vehicle dynamics, and the monoleaf setup is definitely one of those. Swaybars are another. People tend to think of them as way more complicated or magical than they really are. They are just a spring.
Hey, here's an extra-credit question: how can you design a passive-sprung suspension (active suspensions don't count!) so that it has higher wheel rates in pitch than it does in roll? Here's a hint: no street car I'm aware of has ever been designed like this, but race cars with lots of downforce commonly employ this design strategy.
Normal coil springs provide the same wheel rate in both pitch and roll on their own - no anti-roll of their own. The rear leaf on a C4 has both clamps very close together in the middle, and therefore has no anti-roll of its own either. So the "crosstalk" that you refer to doesn't exist with the rear leaf spring at all. Only the front monoleaf in a C4 has any anti-roll component of its own. That's because it has clamps spaced about 2ft apart and is unconstrained in the middle. So as the car rolls, the spring forms an "S" shape between the two clamps, which creates an anti-roll force. It's not fully independent. That sounds bad, but...
You know what else creates an anti-roll wheel rate in any conventional suspension? An anti-roll bar, commonly called a swaybar (it should be "anti-sway"), does. So yeah, literally the entire purpose for any swaybar in any car is to reduce independence of the two corners it connects. It's just a torsion spring that works only in roll. So unless you run without a swaybar of any kind, you have the same "crosstalk" with coil springs as you do with leafs. In fact, Chevy was always able to spec smaller front swaybars because the spring was doing some of that anti-roll work. If they used regular coil spring or clamped the front monoleaf in a way that eliminated the anti-roll, then they would have just had to make up for it with a larger front swaybar. So there's zero difference in "crosstalk" between a coilover setup and a monoleaf setup, as long as you keep the wheel rates in pitch and roll the same.
ETA: To demystify this stuff even further, consider two cars that are identical in every way except that one has 200lb/in of wheel rate in pitch but 400lb in roll (i.e., it has 200lb/in of anti-roll provided by a swaybar or leaf spring), vs a car that has 400lb/in in both pitch and roll (i.e., no swaybar and no leaf spring that provides and anti-roll component). Both cars have a total wheel rate in roll of 400lb/in, so they both resist roll the same amount: if 1G of cornering force creates 3* of roll in one car, it will do the same to other car. They only differ in their resistance to pitch. So, if you hit a curb with the inside wheel while cornering in each car, which one will be upset the most? Answer: they will both be upset by the same amount, because the curb is forcing the suspension into roll, both cars have the same roll rate, and so in both cars the effect of the curb on the outside tire's grip is the same. The tires don't know whether their respective wheel rates come from a coil spring, a leaf spring, or a swaybar - they react the same if the rate is the same.
There's a lot of mysticism about certain aspects of vehicle dynamics, and the monoleaf setup is definitely one of those. Swaybars are another. People tend to think of them as way more complicated or magical than they really are. They are just a spring.
Hey, here's an extra-credit question: how can you design a passive-sprung suspension (active suspensions don't count!) so that it has higher wheel rates in pitch than it does in roll? Here's a hint: no street car I'm aware of has ever been designed like this, but race cars with lots of downforce commonly employ this design strategy.
11-28-2018, 03:55 PM
#33
The transverse leaf spring system is definitely good enough for a very fast car. But, it really sucks if you want to change the spring rates in 50 lbs increments which is very easy to do with a coilover system. Assuming somebody would step up to the plate and make multiple leaf springs with different spring rates, the cost is very expensive versus buying a additional set of coil springs. The Corvette management group is also very much stuck in their ways.....call it tradition, call it a power trip or lack of budget, the transverse leaf spring is a tried and true system that has worked for the Corvette. Yet amazingly, cars built with near unlimited budgets use coil overs or hydraulic suspensions.....I can't think of one other high performance car that uses a transverse leaf suspension.
I believe that a spring (coil, leaf, torsion, etc) should only be weight carrying and not have any anti-roll properties caused by them. It is too hard to be quantify or even be able to measure the anti-roll effect produced by a Vette transverse leaf suspension. Does anybody know how the anti-roll effect can be adjusted?
Coils are great for getting to the spring rate you want inexpensively and then you add an anti-roll bar for final tuning to meet changing track conditions, tire issues, weight balance, aero, etc.
I believe that a spring (coil, leaf, torsion, etc) should only be weight carrying and not have any anti-roll properties caused by them. It is too hard to be quantify or even be able to measure the anti-roll effect produced by a Vette transverse leaf suspension. Does anybody know how the anti-roll effect can be adjusted?
Coils are great for getting to the spring rate you want inexpensively and then you add an anti-roll bar for final tuning to meet changing track conditions, tire issues, weight balance, aero, etc.
11-28-2018, 03:59 PM
#34
Le Mans Master
That is definitely one of (at least) two ways to accomplish this. Nice work! For those not familiar with it, a Z-bar looks and mounts just like a swaybar, except that instead of both arms pointing the same way away from the bar, they point in opposite directions (it literally looks like a Z when viewed from above or below). When the car rolls, it moves right along with the suspension and provides no resistance (no wheel rate). But when both wheels move into compression or rebound together, the Z-bar acts as a torsion spring to resist that pitch/heave motion. It's a familiar mod for swing-axle cars like old Beetles, which had a nasty habit of jacking up the rear under cornering loads and then rolling over. In fact, I think SCCA requires a Z-bar for any swing-axle car before it can be allowed to autocross or road race.
The other pitch-only spring requires a spring linkage like you see on prototype and formula cars. You can arrange it so that the car has separate springs (or just a swaybar) for roll resistance, and then the whole linkage assembly is tied to a third spring (called a heave spring) that only resists when both wheels move the same direction.
The other pitch-only spring requires a spring linkage like you see on prototype and formula cars. You can arrange it so that the car has separate springs (or just a swaybar) for roll resistance, and then the whole linkage assembly is tied to a third spring (called a heave spring) that only resists when both wheels move the same direction.
11-28-2018, 03:59 PM
#35
11-28-2018, 04:56 PM
#36
Le Mans Master
The transverse leaf spring system is definitely good enough for a very fast car. But, it really sucks if you want to change the spring rates in 50 lbs increments which is very easy to do with a coilover system. Assuming somebody would step up to the plate and make multiple leaf springs with different spring rates, the cost is very expensive versus buying a additional set of coil springs.
The Corvette management group is also very much stuck in their ways.....call it tradition, call it a power trip or lack of budget, the transverse leaf spring is a tried and true system that has worked for the Corvette. Yet amazingly, cars built with near unlimited budgets use coil overs or hydraulic suspensions.....I can't think of one other high performance car that uses a transverse leaf suspension.
I believe that a spring (coil, leaf, torsion, etc) should only be weight carrying and not have any anti-roll properties caused by them. It is too hard to be quantify or even be able to measure the anti-roll effect produced by a Vette transverse leaf suspension. Does anybody know how the anti-roll effect can be adjusted?
Originally Posted by TrackAire
I've never even heard of a Z-bar......I thought the answer was the mounting points and angles of the a-arms to limit or stop dive.
11-28-2018, 07:34 PM
#37
Drifting
i have been told on here that coilovers will eliminate "corvette hop" (rear end skip at the apex of a tight corner). how about putting them just in the rear?
Last edited by romandian; 11-28-2018 at 07:35 PM.
11-30-2018, 10:01 AM
#38
Racer
Thread Starter
All that contributed to my thread.....
THANK YOU! You've all have been so incredibly informative.
I have made my decision. I'm going with nitrous! Hahaha!
I'm most definitely going with coilovers.
THANK YOU! You've all have been so incredibly informative.
I have made my decision. I'm going with nitrous! Hahaha!
I'm most definitely going with coilovers.
12-02-2018, 11:52 PM
#39
Le Mans Master
I just installed a set of LG GT2 coilovers on my C7 Z06, combined with a proper alignment and corner balance they are amazing. I plan to run different compound tires as well as do road course and auto-x so the adjustability is a definite added bonus. Install was easy and the quality is great.
12-06-2018, 02:37 AM
#40
Melting Slicks
Matthew Miller - surely you must be on the payroll of the Leaf Spring Manufacturers Association !
We didnt have a debate on the c4 forum - you berated anyone who dared to disagree with you as you wrote volumes of technical opinion.
we get it - you love leaf springs and think they are wonderful - but for the life of me I cant understand why you keep coming onto coil over threads and dominating the conversation with your own pro leaf spring/anti coil over opinions. You are entitled to your opinion, but just have your say and move on, dont come in at post #18 and still be rattling on at post #36 and stifling any real conversation amongst the people who want to discuss (or just read the thread) on fitting coil overs.
We didnt have a debate on the c4 forum - you berated anyone who dared to disagree with you as you wrote volumes of technical opinion.
we get it - you love leaf springs and think they are wonderful - but for the life of me I cant understand why you keep coming onto coil over threads and dominating the conversation with your own pro leaf spring/anti coil over opinions. You are entitled to your opinion, but just have your say and move on, dont come in at post #18 and still be rattling on at post #36 and stifling any real conversation amongst the people who want to discuss (or just read the thread) on fitting coil overs.
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