VW Vortex - Volkswagen Forum banner
1 - 20 of 58 Posts

·
Premium Member
1991 Civic Si
Joined
·
11,638 Posts
Discussion Starter · #1 ·
"Any suspension will work, as long as you don't let it"

This is something I've been thinking about for a little bit as I think about the fact that a car like my modern Fusion should be pretty much impossible to lose control of the thing. That's a great thing! as a commuter. Maybe not wonderful if I end up selling it to the parents of a disappointed 16 year old who wanted a Focus RS, or at least an ST, and ended up with something that just won't rotate (probably)

In the olden days if you had a car that was a great handler a lot of the time you'd describe it as able to rotate, tossable, etc. But you'd also describe it as neutral and controllable, Any car could be a good or a bad handler with any number of characteristics. For the most part now that car is going to be able to brake whichever wheel independently based on speed, yaw, steering/brake/throttle input, and you're not going to get into trouble unless you're just carrying way too much speed into a situation and the computers can't cope. The old joke in race car building is "Any suspension will work, as long as you don't let it". If you had an unruly suspension design in the past on a sports car, tuners, and sometimes factory engineers, would increase spring rates, reduce suspension travel, and throw bigger and bigger tires at it until the problems mostly went away.

Is that where we are with modern cars? Can we now get away with wonky weight distribution and oddball suspension setups, because the computers will save us anyway?



 

·
Registered
1992 Mazda Miata
Joined
·
842 Posts
"Any suspension will work, as long as you don't let it"

Can we now get away with wonky weight distribution and oddball suspension setups, because the computers will save us anyway?
A lot depends on how robust the code is, if you make changes that the code doesn't understand, I suspect things could go badly in extreme conditions. The problem with code is you never know where the boundary conditions are, developers aren't likely to provide any insight.
 

·
Registered
Joined
·
10,431 Posts
Computers aren't magic.

They're just very good at executing instructions on a very precise schedule, or quickly executing in response to an input.

A computer can't make a suspension, or chassis, do anything that it isn't designed to do; it can just do it quicker, and more precisely, than a human driver can in a panic situation.

This means that suspensions that previously would have been unacceptable due to the existence of not-so-edge cases where normal human responses would provoke a dangerous event, may have a chance to get a greenlight now that there is something that can take the *right* action to mitigate those cases.

This may, in fact, open the door to better handling, and even more responsive "driver's cars" by allowing the engineers to focus in on the best performance within the envelop, and then just code around the margins where you'd need gobs of training to safely manipulate the vehicle.
 

·
Registered
A chili pepper and an empty crate.
Joined
·
8,694 Posts
Thing is, oversteer and understeer aren't exactly a yes/no situation. Slip angle is a spectrum, and the dynamics of the car are fluid depending on how it's loaded up. At least for sports cars, a good stability control doesn't intervene unless you're doing something you shouldn't be, and that doesn't prevent a good driver from experiencing the balance and handling characteristics of the car. I know we've had bad stability control systems before, but these days on relevant cars there really isn't an excuse for systems that slams the throttle shut at inconvenient times, or lock the car down if you lift to adjust mid-corner etc.

turbinepowered said:
This may, in fact, open the door to better handling, and even more responsive "driver's cars" by allowing the engineers to focus in on the best performance within the envelop, and then just code around the margins where you'd need gobs of training to safely manipulate the vehicle.
QFT. An F-16 is inherently unstable by design, as that makes it more agile. They can only get away with it because of the sophisticated avionics. No reason we can't apply those principles to sports cars...once the world is OK with drive by wire steering that is. :laugh:
 

·
Registered
Joined
·
29,125 Posts
QFT. An F-16 is inherently unstable by design, as that makes it more agile. They can only get away with it because of the sophisticated avionics. No reason we can't apply those principles to sports cars...once the world is OK with drive by wire steering that is. :laugh:
Seems safe.

 

·
Registered
Joined
·
11,929 Posts
This may, in fact, open the door to better handling, and even more responsive "driver's cars" by allowing the engineers to focus in on the best performance within the envelop, and then just code around the margins where you'd need gobs of training to safely manipulate the vehicle.
In the past, suspension designs had to be calibrated for a certain amount of inherent understeer in order to try to make sure the front stayed out front when the driver was doing something aggressive (or making a mistake), and this wasn't always completely successful despite calibrating "cars for everyone" to have enormous understeer (almost) all the time.

As someone who sees under-car chassis and suspension bits an awful lot ... there is a remarkable convergence of suspension layouts under the skin, across all manufacturers.

Just about anything that's unibody and "car based" has front suspension with MacPherson struts using L-shaped lower control arms - the transverse leg of the L having a stiff "handling" bushing and the offset leg having a soft "NVH" bushing. There are two common rear suspension designs - twist-beam-axle, or a multi-link layout that is based on a flexible trailing arm with two almost-parallel but different-length lateral lower links to "steer" the hub carrier through the suspension movement and one upper lateral link for camber control. Very few exceptions. Some rear-drive vehicles have a different layout of the links.

How come? Well, twist-beam exists because cheap. Outside of that ... The multi-link design just described, and the L-shaped lower arm of a Mac-strut with the bushing arrangement described, gives good separation of "ride" functions from "handling" functions (allowing both good toe control and good NVH control) and allows camber to do the right things with suspension travel.

Mandatory stability control isn't going to allow the return of the swing-axle suspension, or leaf-sprung solid front axles on light duty vehicles where ride quality means anything.

* * *

"Any suspension design will work, as long as you don't let it" -> a classic bad one was the C2 Corvette, whose rear suspension design persisted into the early 1980s. Poor toe control meant the springs and dampers had to be brutally stiff to avoid having the ride height deviate too far from nominal and getting into bump-steer and toe-out.

The gen 1 Honda Civic was another bad one (I had one of those). The rear could get skittish under braking. Didn't understand why until years later when I started understanding suspension designs a bit more. MacPherson rear, with short inverted A-arms guiding the bottom of the struts, and a rubber-bushed trailing link. There's little or no anti-dive (more accurately, anti-lift) geometry in the rear suspension, so the rear would come up quite a bit on the brakes. The short length of the lower arms sent the rear wheels into positive camber when that happened (bad). But ... The braking forces would also pull back on that trailing link, deflecting it in its bushings, and now that inverted A-arm pivoted around the single chassis-end bushing and led to toe-out under braking. No wonder it was skittish on the brakes.

The next generation of Honda cars kept MacPherson rear suspension but with much longer lateral links to cut down on those effects. The current ones are multi-link using the common design that lots of others are using (described above).
 

·
Premium Member
Joined
·
11,687 Posts
"Any suspension will work, as long as you don't let it"

This is something I've been thinking about for a little bit as I think about the fact that a car like my modern Fusion should be pretty much impossible to lose control of the thing. That's a great thing! as a commuter. Maybe not wonderful if I end up selling it to the parents of a disappointed 16 year old who wanted a Focus RS, or at least an ST, and ended up with something that just won't rotate (probably)

In the olden days if you had a car that was a great handler a lot of the time you'd describe it as able to rotate, tossable, etc. But you'd also describe it as neutral and controllable, Any car could be a good or a bad handler with any number of characteristics. For the most part now that car is going to be able to brake whichever wheel independently based on speed, yaw, steering/brake/throttle input, and you're not going to get into trouble unless you're just carrying way too much speed into a situation and the computers can't cope. The old joke in race car building is "Any suspension will work, as long as you don't let it". If you had an unruly suspension design in the past on a sports car, tuners, and sometimes factory engineers, would increase spring rates, reduce suspension travel, and throw bigger and bigger tires at it until the problems mostly went away.

Is that where we are with modern cars? Can we now get away with wonky weight distribution and oddball suspension setups, because the computers will save us anyway?



I don't understand the question. If anything, sports cars are more mechanically optimized than ever. Tires alone make a huge difference.... modern tires enable higher performance on older cars. Modern suspension design is pretty much the best ever thanks to computers. Etc. Stability control and electronics can only do so much... a mechanically optimized design doesn't need it, and there are plenty of mechanically optimized designs on the market.

Plus for a commuter or w/e, at the limit handling/dynamics are irrelevant. If you're exploring the limits of your Fusion on the street, you're a dick. It's designed for the kind of driving 99.9999999% of its buyers will do, which is just tooling around between home/work/school/grocery stores etc.
 

·
Registered
Joined
·
12,317 Posts
If anything, computerized design + stability control is going to mean much better optimized suspension designs. No need to make something inherently understeer for safety If the computers will keep you from spinning. Some of the more advanced stability control systems will let you step the back out and do some drifting, but won’t let you spin.
 

·
Premium Member
1991 Civic Si
Joined
·
11,638 Posts
Discussion Starter · #9 ·
In the past, suspension designs had to be calibrated for a certain amount of inherent understeer in order to try to make sure the front stayed out front when the driver was doing something aggressive (or making a mistake), and this wasn't always completely successful despite calibrating "cars for everyone" to have enormous understeer (almost) all the time.

As someone who sees under-car chassis and suspension bits an awful lot ... there is a remarkable convergence of suspension layouts under the skin, across all manufacturers.
Very insightful post! thank you. That does seem really interesting. I guess after 120 years, manufacturers have finally figured it out and settled on good suspension design for the modern car, with a few variations for cost and quality. That's exactly the type of thing I'm curious about. Do we no longer have to tune for massive understeer since the car can help us out a little if we get it wrong? Will the shape and size of electric drivetrains allow us to get closer to ideal suspension setups that aren't encumbered by the size of an engine and transmission, or fuel tank, or will ease of manufacturing still dictate common shapes and sizes for motors and battery packs?


I always find hearing about design idiosyncrasies interesting, and it's interesting to think of how long it took auto design to gel into a relatively few known standards. they don't always have to be as glaringly strange as Barry2952's '39 Steyr either. I suppose the spooky handling under braking with a raised rear could explain why old GM A-bodies and X-bodies seemed to have extreme anti-dive setups where the rear would physically squat under braking.

QFT. An F-16 is inherently unstable by design, as that makes it more agile. They can only get away with it because of the sophisticated avionics. No reason we can't apply those principles to sports cars...once the world is OK with drive by wire steering that is. :laugh:
exactly! I can't be excited bout DBW but how will the car know the difference between me setting up a perfect Scandinavian Flick for a curve or say, just arcing off the interstate into the ditch in a snowstorm? :laugh:




I don't understand the question.
That's because it wasn't really a question in terms of looking for a specific answer, more of a discussion starter to look at what's possible with modern suspension tech. a Mercedes ML can bounce itself out of being stuck off-road, a Fusion sport can bunny hop a pothole, a Chevy SS can leave C&C sideways and not wreck out, because of stability programming. What else is possible?


Plus for a commuter or w/e, at the limit handling/dynamics are irrelevant. If you're exploring the limits of your Fusion on the street, you're a dick. It's designed for the kind of driving 99.9999999% of its buyers will do, which is just tooling around between home/work/school/grocery stores etc.
Limit handling dynamics are absolutely crucial for all cars, the more common ones I would argue it's even more important. The reason having good handling commuters is vital is weather and skill variances between drivers. Ralph Nader wrote a book on this. If a 348tb is an unruly beast, so what, they only made 6000 of those. If the guy late for work in the lane next to you in his boring commuter can't control it and crashes into you, it wrecks both of your day. But now instead, his dashboard just lights up and you both go to work.

As for exploring the limits in an inappropriate way, whether its a sports car in a canyon, or a tarted up commuter on a back road or racing strangers at an HPDE, that's a discussion for another thread.
 

·
Premium Member
Joined
·
11,687 Posts
Limit handling dynamics are absolutely crucial for all cars, the more common ones I would argue it's even more important. The reason having good handling commuters is vital is weather and skill variances between drivers. Ralph Nader wrote a book on this. If a 348tb is an unruly beast, so what, they only made 6000 of those. If the guy late for work in the lane next to you in his boring commuter can't control it and crashes into you, it wrecks both of your day. But now instead, his dashboard just lights up and you both go to work.

As for exploring the limits in an inappropriate way, whether its a sports car in a canyon, or a tarted up commuter on a back road or racing strangers at an HPDE, that's a discussion for another thread.
Limit handling dynamics are irrelevant in a commuter for a wide array of reasons. Like you said driving skills vary.... so I'd wager the vast majority of drivers on the road wouldn't be able to get out of a sketchy at the limit situation, even with "fine crafted handling dynamics". Plus modern tires are so good most people aren't getting anywhere near the limit in the first place. A new Nissan Altima can twirl a skidpad at 0.93g. Who is driving an Altima that hard?

You mention "the guy next to you being late for work"..... how often have you been in accidents where someone on the road lost control of their car and hit you (where you weren't street racing ;) )? And what makes you think "better at the limit dynamics" would have helped the situation? **** driving overrides any mechanical competence.

I think there's potential for good discussion here but I'm really confused as to what your point is.
 

·
Premium Member
1991 Civic Si
Joined
·
11,638 Posts
Discussion Starter · #11 ·
You mention "the guy next to you being late for work"..... how often have you been in accidents where someone on the road lost control of their car and hit you (where you weren't street racing ;) )? And what makes you think "better at the limit dynamics" would have helped the situation? **** driving overrides any mechanical competence.

I think there's potential for good discussion here but I'm really confused as to what your point is.
Yeah, you're definitely missing the point. It's less about at limit dynamics, and more about balanced sports cars for us and a lot more help for the regular guys.

.93gs happens on on a skidpad, not on say, a dual left turn in the rain in an intersection where 18-wheelers, city busses, and every other vehicle is depositing oil and debris, and it's raining, etc. If you want specific examples just google the name of "your nearest big city" + "bad drivers of" + "dashcam", and you'll find examples of people suddenly being in at-limit situations that wouldn't be, for a competent driver, and where stability control would definitely have helped. I've seen people spin on on-ramps in the rain, I'd assume you have too, I'm not talking about street racing here. At-limit can mean the limit of the driver's skill (where the car can then step in) and not the limit of the car in the hands of someone like Randy Pobst.
 

·
Premium Member
Joined
·
11,687 Posts
Yeah, you're definitely missing the point. It's less about at limit dynamics, and more about balanced sports cars for us and a lot more help for the regular guys.

.93gs happens on on a skidpad, not on say, a dual left turn in the rain in an intersection where 18-wheelers, city busses, and every other vehicle is depositing oil and debris, and it's raining, etc. If you want specific examples just google the name of "your nearest big city" + "bad drivers of" + "dashcam", and you'll find examples of people suddenly being in at-limit situations that wouldn't be, for a competent driver, and where stability control would definitely have helped. I've seen people spin on on-ramps in the rain, I'd assume you have too, I'm not talking about street racing here. At-limit can mean the limit of the driver's skill (where the car can then step in) and not the limit of the car in the hands of someone like Randy Pobst.
I'm still kind of confused as it seems like you're talking about 2 completely separate things. I'd argue that sports cars have probably never been more balanced. Even 10 years ago you had to spend big money to get the feel and balance of something like a BRZ. The 911 has never been more mechanically optimized. They finally made the mid engine Vette! So there is definitely still pride and market value in a mechanically optimized chassis. We have seen all the tricks, and they help, but they're not gonna make my TLX ever handle or feel like a Cayman. If it were that easy they'd just go all in on software and tricks. But physics are physics.

As for the rain scenario, electronics can't outdo bad decisions. If someone makes smart decisions behind the wheel and maintains their car, driving dynamics will never matter on the road in the context of safety. There are tons of other way more likely factors that will cause an accident than inadequate situational at the limit dynamics.
 

·
Registered
2018 Trek Domane
Joined
·
3,845 Posts
I'm still kind of confused as it seems like you're talking about 2 completely separate things. I'd argue that sports cars have probably never been more balanced. Even 10 years ago you had to spend big money to get the feel and balance of something like a BRZ. The 911 has never been more mechanically optimized. They finally made the mid engine Vette! So there is definitely still pride and market value in a mechanically optimized chassis. We have seen all the tricks, and they help, but they're not gonna make my TLX ever handle or feel like a Cayman. If it were that easy they'd just go all in on software and tricks. But physics are physics.

As for the rain scenario, electronics can't outdo bad decisions. If someone makes smart decisions behind the wheel and maintains their car, driving dynamics will never matter on the road in the context of safety. There are tons of other way more likely factors that will cause an accident than inadequate situational at the limit dynamics.
Aaaaaaaaaactually...

An MR car and an FF car will handle remarkably similar to each other when set up well, up until the MR car has tons of power.

FR cars are the weird exception that handle like nothing else.
 

·
Premium Member
Joined
·
11,687 Posts
Aaaaaaaaaactually...

An MR car and an FF car will handle remarkably similar to each other when set up well, up until the MR car has tons of power.

FR cars are the weird exception that handle like nothing else.
I'm not following.... FF cars have the engines outside the center of the two axles, MR doesn't. FF unloads the driven wheels under power, MR loads them. FF overloads one axle under braking, MR balances weight load. FR and MR are more similar, especially if the FR engine is behind the front axle.
 

·
Registered
2018 Trek Domane
Joined
·
3,845 Posts
I'm not following.... FF cars have the engines outside the center of the two axles, MR doesn't. FF unloads the driven wheels under power, MR loads them. FF overloads one axle under braking, MR balances weight load. FR and MR are more similar, especially if the FR engine is behind the front axle.
Put your protractor down and drive more cars. Good FWD and MR both respond to inputs about the same. FR is weird.
 

·
Premium Member
1991 Civic Si
Joined
·
11,638 Posts
Discussion Starter · #16 ·
I'm still kind of confused as it seems like you're talking about 2 completely separate things. I'd argue that sports cars have probably never been more balanced. Even 10 years ago you had to spend big money to get the feel and balance of something like a BRZ. The 911 has never been more mechanically optimized. They finally made the mid engine Vette! So there is definitely still pride and market value in a mechanically optimized chassis. We have seen all the tricks, and they help, but they're not gonna make my TLX ever handle or feel like a Cayman. If it were that easy they'd just go all in on software and tricks. But physics are physics.
It's not just software and tricks. I think the point made above is worth noting that 'software and tricks' are what allow us to have the best of both worlds. There are a few hard set points about a family sedan like your TLX that can't be changed, like weight distribution, wheelbase, etc. But a lot of the difference of feeling between a sedan or CUV and a sports car can be wiped away if we give the suspension tuning of the sports car to the sedan, and let stability stand in for the engineered-in huge inherent understeer, and thus, imbalance, that we've come to associate with non-sporty cars.
 

·
Premium Member
Joined
·
11,687 Posts
It's not just software and tricks. I think the point made above is worth noting that 'software and tricks' are what allow us to have the best of both worlds. There are a few hard set points about a family sedan like your TLX that can't be changed, like weight distribution, wheelbase, etc. But a lot of the difference of feeling between a sedan or CUV and a sports car can be wiped away if we give the suspension tuning of the sports car to the sedan, and let stability stand in for the engineered-in huge inherent understeer, and thus, imbalance, that we've come to associate with non-sporty cars.
I kind of saw what that was like in my G37 which I put on coilovers and wider tires. It depends on how hard you drive, I suppose. On the street it pretty much felt like my old 350Z. Maybe even more nimble and planted. But at the track it understeered like hell through the tight stuff (until it didn't lol)

Automakers are using more and more chassis tricks like super fast steering ratios and rear wheel steering to make bigger + heavier cars feel smaller. The magazines seem pleased, but they also still wax poetically about mechanically optimized chassis'. The fakery is getting a lot better but there's still a sizable gap. Plus for people who want the genuine article nothing else will do.
 

·
Registered
Joined
·
1,900 Posts
Aaaaaaaaaactually...

An MR car and an FF car will handle remarkably similar to each other when set up well, up until the MR car has tons of power.

FR cars are the weird exception that handle like nothing else.
This is true. Although the only common FR car (911) has been becoming more and more benign over the years. The G body was already pretty benign unless you really pushed it hard, and the water cooled cars are far more benign.
 

·
Registered
Joined
·
1,900 Posts
I kind of saw what that was like in my G37 which I put on coilovers and wider tires. It depends on how hard you drive, I suppose. On the street it pretty much felt like my old 350Z. Maybe even more nimble and planted. But at the track it understeered like hell through the tight stuff (until it didn't lol)

Automakers are using more and more chassis tricks like super fast steering ratios and rear wheel steering to make bigger + heavier cars feel smaller. The magazines seem pleased, but they also still wax poetically about mechanically optimized chassis'. The fakery is getting a lot better but there's still a sizable gap. Plus for people who want the genuine article nothing else will do.
That's your own lack of skill or bad driving. Quit blaming the car- every car has a limit and nearly all street cars give you a ton of warning before you approach that limit. If you can't discern that limit, then you need more instruction. If you're unwilling to learn that, then you shouldn't push your car hard, as that's a recipe for disaster.

I don't know what cars you're referring to in the second part, but stuff like the 991.2 GT3RS have rear wheel steering and a fast steering ratio but are far more capable than anything that came before it. They're also pretty accessible in terms of how approachable the limits are. Go drive a 2nd or 3rd gen Viper if you want to see what a snappy chassis can do with a ton of power and no driver's aids- if you can't drive well, you'll crash one of those.
 

·
Premium Member
Joined
·
11,687 Posts
That's your own lack of skill or bad driving. Quit blaming the car- every car has a limit and nearly all street cars give you a ton of warning before you approach that limit. If you can't discern that limit, then you need more instruction. If you're unwilling to learn that, then you shouldn't push your car hard, as that's a recipe for disaster.

I don't know what cars you're referring to in the second part, but stuff like the 991.2 GT3RS have rear wheel steering and a fast steering ratio but are far more capable than anything that came before it. They're also pretty accessible in terms of how approachable the limits are. Go drive a 2nd or 3rd gen Viper if you want to see what a snappy chassis can do with a ton of power and no driver's aids- if you can't drive well, you'll crash one of those.


The more I read your post the more confused I get....

Where did I blame the car?
Where did I put down driver's aids?
Where did I say that tricks make cars less capable, or are only used on less capable cars? (Bonus question, who was the first person in this thread to use the word "capable"?)

Literally every point in this post is a response to something I didn't say :confused: Why would you do that?
 
1 - 20 of 58 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top