Whats the point of Front Wheel drive?

ok i know that FF drivetrain is cheaper because everything is close together regarding power. but why do people decide to tune FF cars if they dont execute all of it's horsepower. u begin to lose traction as u tap the gas because the car lifts off of its powered wheels. they understeer like hell and because of the axle being in front of the car it wastes room under the hood for tuning.

Not all of us can afford a BMW.


The FWD cars that are popular with the kids and the tuners are cheap to buy and mod, widely available, compact, sporty and lend themselves to modification.

Sure the driveline layout is not optimal, but their appeal and advantages more than outweigh this shortcoming, especially for those thin of wallet.

Historically, this has happened lots int he past. Think of the hot rods of the 1950's (and early '60's)
They were almost all pre-war Fords with flat head V8's. There were plenty of faster cars in the day, but none had the same combination of advantages we see as listed above.

Let me guess, Orido Manabu you would rather still drive a live axle car on leaf springs?


While the ideal is nice, the reality is a F1 car is not really all that practical.

All I can say is go drive a Lotus Elan, or a Type R Civic or Integra, then try and claim FWD is a waste of time.
Small, light, incredibly agile and very responsive with out the huge drive train power losses a RWD suffers from.

I think safety is a large part of it too. Family cars aren't meant to be driven aggressively, and you don't have to worry about them spinning around on you. Slippery conditions in general, are much easier to deal with in a FWD car.

that being said, they can handle pretty decently. Cadillacs keep traction pretty well for 300+ hp, and don't have much torque steer. Same goes for supercharged Grand Prix's. Its kinda nice to be able to stomp on the gas without worrying about the rear end swinging

Not that I'd go out of my way to own one, mind you.

Let me guess, Orido Manabu you would rather still drive a live axle car on leaf springs?


While the ideal is nice, the reality is a F1 car is not really all that practical.

All I can say is go drive a Lotus Elan, or a Type R Civic or Integra, then try and claim FWD is a waste of time.
Small, light, incredibly agile and very responsive with out the huge drive train power losses a RWD suffers from.

:bigthumb:

1. FWD does not understeer because it is FWD. Granted that doesn't help but plenty of mass marketed cars suffer from understeer and that includes AWD and RWD.

2. This is because it is safer than oversteer. The average person will over correct and can't recover from oversteer.

3. Oversteer/understeer are influenced far more by suspension geometry.

4. Like Moppie said, perhaps you should tell Lotus, Acura, and perhaps Alfa which has been killing RWD BMWs in European Touring races.

It isn't worse, it isn't better, it's different.

Positive--
Cheap to make. Leaves lots of room in the cabin for people and cargo. Good traction in very low grip situations.

Negative--
Since a lot of FWD cars are beginners cars, like Civic Type Rs and the like, they get modified by drivers who don't know any better- for more power.
Torque steer problems with high power. Ask the Civic owner with the 600HP drag car.
You are correct that they tend to remove weight off the driving wheels under hard acceleration on grippy surfaces.
They generaly have more understeer problems than RWD.
They are fine for 99% of all driving situations. But when you really have to GO... particularly when your car has lots of power, RWD is the preferred choice--for people who know how to drive.

In addition to what has already been said.

Not having to turn the power 90 deg results in a more efficient drivetrain and higher mpg.

I own a front wheel drive family wagon that drifts evenly when pushed through a corner. Not every fwd vehicle handles like a barge, but some certainly do. There are a lot of crappy handling rwd vehicles too.

Positive--
Cheap to make. Leaves lots of room in the cabin for people and cargo. Good traction in very low grip situations.

Negative--
Since a lot of FWD cars are beginners cars, like Civic Type Rs and the like, they get modified by drivers who don't know any better- for more power.
Torque steer problems with high power. Ask the Civic owner with the 600HP drag car.
You are correct that they tend to remove weight off the driving wheels under hard acceleration on grippy surfaces.
They generaly have more understeer problems than RWD.
They are fine for 99% of all driving situations. But when you really have to GO... particularly when your car has lots of power, RWD is the preferred choice--for people who know how to drive.


You really do miss out in the States.
I know a lot of Lotus Elise, Elan and Esprit owners who drive Jap spec FWD Honda's as their second car.

while its true that fwd cars dont fishtail under power, the do "fish head"
if youve ever driven a fwd car that can spin both the front tires you know that if you punch the gas and the tires light up, you have no steering.

also, generally, fwd balances well while cornering and NOT giving any gas.
its when you give it gas that it understeers.
this could be eliminated if the suspension were designed with a little more lift off oversteer (very easy to do w/ fwd) but then you'd have moms sliding off the road in their corollas...

for 75% of my driving, id be fine w/ fwd, but the 25% of the time when i want to have fun, theres nothing better than my iroc

while its true that fwd cars dont fishtail under power, the do "fish head"
if youve ever driven a fwd car that can spin both the front tires you know that if you punch the gas and the tires light up, you have no steering.

Yes, but lighting up the tyres isn't something that gets you anywhere. It's usally for showing off only.:grinyes:

My fwd car is the econobox version of a 4wd turbo car, they share the same suspension which is why mine handles like most fwd's don't. It takes a fairly slippery road before the 1.8 can break the front end loose.

Generally though, planting the boot hard on the way into a corner is a silly idea no matter which wheels are driving. On the way out planting the boot in a fwd car straightens it out which isn't a problem.

just look up russ swift on youtube.
he can do all kinds of stuff with fwd.
none of it practical.

one of the origional reasons for building a FWD car, apart from space saving, weight saving, ect. was high speed stability. but this isnt an issue because suspension geometry and aerodynamics have advanced and now make any drivetrain stable at speed. even porsches.

oh and nothing personal, but if you think theres nothing better than an iroc for .... well, anything, then you need to get out and drive more cars. camaros are ok for what they are, but theres cars that do everything better.

one of the origional reasons for building a FWD car, apart from space saving, weight saving, ect. was high speed stability.

Wasn't the mini one of the first fwd cars?

oh and nothing personal, but if you think theres nothing better than an iroc for .... well, anything, then you need to get out and drive more cars. camaros are ok for what they are, but theres cars that do everything better.


Says the man who drives a Nissan, the company that were so bad at making cars they went broke, so badly broke that only Renault would buy them...............


If you want to attack someone because of the car they drive, then go find another forum.

huh? moppie, i didnt say one word against him. i said his car isnt the best at a lot of things. its simple fact. the iroc was old technology when it came out. im sorry if it may have come off as offensive, it wasnt meant that way. im a smartass but im not a jerk.

if you have some sort of problem with me, spell it out. all you ever do is jump down my throat at every opportunity whether i deserve it or not. which i mostly do not.

and nissan didnt go broke because it was bad at making cars. very wrong. nissan went broke because its marketing and financial strategy for the u.s. and europe was off the mark.

the mini cooper was not one of the first FWD cars. it was one of the first one that really sold well though. but as early as the 1930s (probably earlier but im talking about popular production cars.) a couple companies were making FWD cars.

huh? moppie, i didnt say one word against him. i said his car isnt the best at a lot of things. its simple fact. the iroc was old technology when it came out. im sorry if it may have come off as offensive, it wasnt meant that way. im a smartass but im not a jerk.

if you have some sort of problem with me, spell it out. all you ever do is jump down my throat at every opportunity whether i deserve it or not. which i mostly do not.


You are as arrogant as you are ignorant, its a dangerous combination.

When you have some real experiance, can provide some useful and real world advice, then you might be in a position to question others on their choice of car.
In the mean time, as far as you are concerned, the Camaro is a very good car.
It sold in very large numbers, and there are thousands of owners who are very passionate about it.
I bet you have never even driven one.

It puts you in about the same class as the 15 year old kids who make assumptions about cars based on the car magazines their daddy brings home.

The point is it's economical, and also, understeer saves lives.

From a performance perspective, it's useless in almost all cases.

The point is it's economical, and also, understeer saves lives.

From a performance perspective, it's useless in almost all cases.

http://www.synapsepc.com/Hosting/Images/Funny/Orly.gif

I suggest you go back and read the entire thread because that's not even close to true.

I suggest you go back and read the entire thread because that's not even close to true.
A quick scan reveals not much to the contrary.

Understeer is probably the biggest problem FWD has. It is not influenced 'far more by suspension geometry', unless the designer was an incompetent fool. The fact remains that the same suspension geometry (well, slightly tweaked) on a RWD would yield better results due to the better weight distribution. It can be fixed to some extent with anti roll bars, but at the expense of ride, comfort and bump handling. Also, with some horrible weight distributions, roll stiffness may not be enough - you may lift the rear inside tyre off the ground, and then you have even more problems.

And I would like to hear the logic behind using lift off oversteer, to solve these problems as well.

And you all know they have horrible drive traction (unless they are on a low friction surface). And while I'm at it, under braking, even more load gets chucked to the front which is already heavier, making the situation worse there aswell.

So in short, the G-G diagram is generally smaller in every direction. I think that is a pretty big problem in performance situations.

And yes, they do handle fine for everyday road use. Obviously we are talking about beyond that.

I don't think anyone can deny that we will never see a FWD F1 car, but FWD has been proven to be very effective in a variety of very high performance applications.
British, European and Australian tour cars have shown that the FWD chassis can compete on equal terms with the RWD ones, and are often faster.
A variety of Japanese racing classes have shown the same things.
Honda and Mazda have successfully campaigned FWD production cars at Le Mans and other events.

In a road car the difference becomes meaningless. You reach the limits of road legal tyres and surface materials long before you reach the limits of a FWD or RWD chassis.

I suggest you go and drive a couple of performance FWD cars before you start making blanket judgements.

A quick scan reveals not much to the contrary.

Understeer is probably the biggest problem FWD has. It is not influenced 'far more by suspension geometry', unless the designer was an incompetent fool. The fact remains that the same suspension geometry (well, slightly tweaked) on a RWD would yield better results due to the better weight distribution. It can be fixed to some extent with anti roll bars, but at the expense of ride, comfort and bump handling. Also, with some horrible weight distributions, roll stiffness may not be enough - you may lift the rear inside tyre off the ground, and then you have even more problems.

And I would like to hear the logic behind using lift off oversteer, to solve these problems as well.

And you all know they have horrible drive traction (unless they are on a low friction surface). And while I'm at it, under braking, even more load gets chucked to the front which is already heavier, making the situation worse there aswell.

So in short, the G-G diagram is generally smaller in every direction. I think that is a pretty big problem in performance situations.

And yes, they do handle fine for everyday road use. Obviously we are talking about beyond that.

1. It is all about suspension geometry. The engineers aren't stupid. Undedsteer is a lot safer than oversteer. You will find AWD and RWD cars that understeer. They do that on purpose because people are stupid, not the engineers.

2. Weight distribution isn't determined by what wheels drive the car. Most cars have a front engine, not just FWD.

3. Under breaking it would be no different between an FF or FR car or even a car with AWD and a front engine.

4. Like Moppie and I have already mentioned Lotus, Honda, Mazda, Alfa Romeo, and others have good FWD performance cars. As a matter of fact Alfa FWD cars have been beating up on a lot of RWD cars in European touring races, this includes the likes of BMW. So that reiterates, it's more about suspension geometry than which wheels drive the car.

I suggest you go and drive a couple of performance FWD cars before you start making blanket judgements.
Sorry if it sounds like I'm making a blanket statement. I know there are FWD cars that handle well. The point I am making is that being FWD isn't helping any.

1. It is all about suspension geometry. The engineers aren't stupid. Undedsteer is a lot safer than oversteer. You will find AWD and RWD cars that understeer. They do that on purpose because people are stupid, not the engineers.
I know. Thats why I said 'understeer saves lives.' in my first post. The problem is when a FWD car understeers more than is nescessary. If the engineers could, then in a lot of cases they would most likely get a lot closer to neutral handling than they do with a FWD car. I am aware that most modern cars understeer. It's a question of magnitude.

2. Weight distribution isn't determined by what wheels drive the car. Most cars have a front engine, not just FWD.
And most rear wheel drives have a differential in the back and a transmission in the middle. They also are free to put more weight towards the back or move the tyres forward, because they don't lose drive traction by doing so. Ignoring aerodynamic downforce, a 50:50 FWD car would not have nearly enough load on the front wheels for decent acceleration.

3. Under breaking it would be no different between an FF or FR car or even a car with AWD and a front engine.
Look up tyre load sensitivity. With a 60:40 weight distribution to start with, a FWD will wind up braking at something more like 80:20. A RWD which is most likely closer to 50:50, will wind up closer to 70:30 (the numbers are just pulled out my ass to give you an idea).

4. Like Moppie and I have already mentioned Lotus, Honda, Mazda, Alfa Romeo, and others have good FWD performance cars. As a matter of fact Alfa FWD cars have been beating up on a lot of RWD cars in European touring races, this includes the likes of BMW. So that reiterates, it's more about suspension geometry than which wheels drive the car.
If I made an AWD car with solid front and rear axles, 20 degrees of toe in all around and 130 mm wide tyres, and then put it up against, I don't know, a corvette, the corvette would win in pretty much everything. Does that make RWD better than AWD? No. It makes that particular setup of RWD better than that particular setup of AWD. Like I said to Moppie, I am aware that some FWD cars handle better than some RWD cars. But it isn't because they are FWD that that happens.

oh and nothing personal, but if you think theres nothing better than an iroc for .... well, anything, then you need to get out and drive more cars. camaros are ok for what they are, but theres cars that do everything better. ok...
I issue you a challenge.

find me a car for 500 dollars that has a 5 speed manual transmission,
performance suspension,
can run 12 second quarters (ive never tried, but i hear from the previous owner)
has EITHER a targa top or T-tops,
is fuel injected,
has 6month insurance premiums in the $275 range,
can 90% of the replacement parts for it at autozone, that day
and comes WITHOUT all the automated systems that are so "convieneint" to drivers today...
i hate automatic lights, seatbelt dingers, lane change warning systems, ect...


i anxiously await your reply







what it really comes down to is that for what I want, my iroc is perfect.
of course an s2k might be better around an autox track, or an evo xxx or whatever might out corner me
im not even worried that audis or astons will beat me in a straight line.
i like the fact that i have to remember to turn the headlights on, and that if i dont put my seatbelt on right away, it doesnt bing at me, and that there is no traction control to turn off and that it will take a bit of playing with to get it to run perfectly.

if i were you, id start by shutting your mouth

and finish with not ever opening it again...



either that or buy a good shovel, cause you seem to enjoy digging yourself holes.

back on track with the thread...

In a road car the difference becomes meaningless. You reach the limits of road legal tyres and surface materials long before you reach the limits of a FWD or RWD chassis.
this about sums it up

Like I said to Moppie, I am aware that some FWD cars handle better than some RWD cars. But it isn't because they are FWD that that happens.


Which just re-enforced my point, unless your talking about the absolute limit of performance, the drive lay out is not as important as people like to think it is.
Over all chassis design has more impact.


Your point about braking is very relevant, and shows there is more to drive lay out than just the ability to accelerate.
Weight distribution is very important here, and the front heavy tendency of many FWD cars can actually make them quite un-stable under heavy braking.
The result is most FWD cars have large amounts of front brake bias, with the corresponding increase in under steer under brakes.
Personally I like it a bit of oversteer under. Which is one reason I like Honda's. All the performance versions of the Civic and Intega are set up with more than the usual amount of rear brake bias.
The result is a car that turns in very easily and very precisely under brakes, much more so than a RWD car, as the Honda are able to rotate about a CG point that is shift a long way forward, almost over the front wheels.

Which just re-enforced my point, unless your talking about the absolute limit of performance, the drive lay out is not as important as people like to think it is.
Over all chassis design has more impact.
I am talking about the limits - thats where you are supposed to be for high performance driving, and I thought that was what we were talking about (this whole discussion started from me saying 'From a performance perspective, it's useless in almost all cases.').

It would be nice if you could expand on the chassis design comment - I don't really know much about chassis design, all I know is it needs to be stiff, it needs to provide packaging room, and it needs to be at least somewhat aerodynamic (and offcourse it has to be acceptable from a NVH perspective). I am probably oversimplifying things as I have no experience in that area. Anyway, what are you after from the chassis other than this? What impact does it have?

One mans performance is another mans afternoon nap.
Its such a subjective term that you simply can not make blanket statements about it, and the existence of very successful FWD performance cars proves that.
If we simply want to talk about the best, then we would be talking F1 cars with out the restrictions placed on them by the FIA.
But how many people can handle a car with 1000hp, that is able to generate enough G force under brakes to make you pass out.
The technology has already reached a point where engineers can build car that will out perform even the best human body.


With regard to Chassis design?
Well the chassis determines weight distribution, wheel position and suspension geometry.
3 things that have a far bigger impact over performance than which wheels are driven.

One mans performance is another mans afternoon nap.
Its such a subjective term that you simply can not make blanket statements about it, and the existence of very successful FWD performance cars proves that.

By ignoring the way the car interfaces with the driver (because that is too complex and winds up just being subjective) and transient pheomena (again, too complex for most internet based discussions), you are basically left with the G-G diagram, which in my oppinion is a very good indication of how a car handles. What I have been saying is that the G-G diagram of a FWD car is generally going to be smaller in most directions, in most conditions.

With regard to Chassis design?
Well the chassis determines weight distribution, wheel position and suspension geometry.
3 things that have a far bigger impact over performance than which wheels are driven.

Oh right, I have always thought of the chassis as just the cage that holds all those things. Suspension geometry, wheels, etcetera, are seperate items to me.

The problem is, while 'chassis design' (using your definition) can change the amount of under/oversteer, it cannot 'decide' it. For a FWD car, a lot of the weight is going to be towards the front, since all of the drivetrain is towards the front. Furthermore, there isn't much you can, or even should, do about this, because you need it up the front if you want to be able to accelerate at all.

Given that you are stuck with a forwards weight bias to start with, you are left trying to remove understeer with suspension geometry, and unfortunately, there is only so much suspension geometry can do to increase front end grip (if you really want I can try to put some example numbers to this in an hour or two when I get some time). After that, the only way to deal with understeer is to degrade rear end grip, and to me, that is just a waste.

I know. Thats why I said 'understeer saves lives.' in my first post. The problem is when a FWD car understeers more than is nescessary. If the engineers could, then in a lot of cases they would most likely get a lot closer to neutral handling than they do with a FWD car. I am aware that most modern cars understeer. It's a question of magnitude.

Funnily enough I happen to own a bog standard fwd japanese car which drifts evenly when pushed hard through a corner.
There is still plenty of scope in the suspension tuning to give my car oversteer if I wished (it doesn't have a rear sway bar for example).
I have driven other bog standard honda accords which handled in a very similar manner.
A friend who races karts for fun ran a data logger in his fwd toyota windom (sold as a lexus in the US, basically a big fat camry). It pulled 1.1g sideways.
I'm curious as to how many fwd cars you've driven in anger as your blanket statements don't fit with the majority of fwd cars I've driven.

Your comments on braking are way off too. COG height is the biggest factor in weight shift, not COG longitudinal position.

Funnily enough I happen to own a bog standard fwd japanese car which drifts evenly when pushed hard through a corner.

There are ways to get the car to drift or oversteer even if it understeers stock - as you know, rear roll hardness, or more optimal suspension geometry, etc. But these things have compromises involved. For example, a sway bar links the wheels in question and throws off bump handling. Also, it's entirely possible to sacrifice drive traction for lateral traction by moving the COG backwards.

I'm curious as to how many fwd cars you've driven in anger as your blanket statements don't fit with the majority of fwd cars I've driven.

None - this is based purely on engineering theory. That way you can cut the subjective stuff out, and you can cut the outliers out.

Your comments on braking are way off too. COG height is the biggest factor in weight shift, not COG longitudinal position.

Maximum traction is achieved (assuming similar tyres/pressure/geometry all around) when front and rear loading is the same. During braking, the front loads up and the rear unloads. lets say at 1 G 20% of the load moves forward. If you start with 60:40, in a FF car, you will wind up with 80:20. If you have an RR car, starting at 40:60, you wind up with 60:40. The loadings are more even the more weight is towards the back.

None - this is based purely on engineering theory. That way you can cut the subjective stuff out, and you can cut the outliers out.



And that maybe your problem.
Is it the engineering that is letting the idea of FWD performance down, or our failure to reconcile your understanding of the engineering with our real world experiance?


As has been said several times, there are a variety of very quick, very fun to drive, FWD performance cars. Made by companies with an understanding of automotive engineering that far away exceeds the knowledge of anyone on this forum.



Try and look at it a different way.
Motor bikes go very quickly on two wheels.
If you watch a fully race prepped FWD, driven properly on a circuit, they tend to do the same thing. It's just the wheels are laid out differently, and there are an extra set hanging out the back that stop it tipping over backwards under acceleration.

And that maybe your problem.
Is it the engineering that is letting the idea of FWD performance down, or our failure to reconcile your understanding of the engineering with our real world experiance?
I don't know what you are saying, but keep in mind you generally can't trust real world experience for such a broad thing - there are too many variables. The reason you like a FWD car more than a RWD car may not be because it is FWD, but because, for example, it is more responsive or has a firm-feeling ride. To compare such a basic part of a car, you have to break the car down to very basic principles, and in real life, comparing say a camaro to a corolla, absolutely everything has changed. It's impossible.


As has been said several times, there are a variety of very quick, very fun to drive, FWD performance cars. Made by companies with an understanding of automotive engineering that far away exceeds the knowledge of anyone on this forum.
And there are a variety of very fun RWD cars. They are not fun because they are FWD, they are fun for a whole multitude of reasons. You have to seperate 'FWD' out from all the other parameters involved.



Try and look at it a different way.
Motor bikes go very quickly on two wheels.
If you watch a fully race prepped FWD, driven properly on a circuit, they tend to do the same thing. It's just the wheels are laid out differently, and there are an extra set hanging out the back that stop it tipping over backwards under acceleration.
...that is a really poor analogy and I doubt you need me to explain why.


I have had a similar discussion on another board. Fortunately, I had the good sense to just quote out of a reliable book rather than try to explain the things myself. I'm going to quote myself from that forum right now:

Heres a lot of points from Race Car Vehicle Dynamics, by Milliken and Milliken. Mostly quoted, somewhat edited (square brackets) if its long and winding/unclear:


plagiarizing

[FWD:]

1) FWD has been most successful [compared to FWD performance in other areas] in the lower power/weight range and in situations where superior directional stability on low [coefficient of friction tracks] is important. There has never been a successful front-drive Grand Prix car nor a competitive Indianapolis car of more than 300hp.

2) In straight-line acceleration, the load on the front wheels is reduced by the longitudinal load transfer. This leads to the use of forward static weight bias to control higher powered, lighter vehicles and may require 60-70% (or more) of the static weight on the front wheels. A limited slip differential may be desirable to control the lightly loaded wheel under combined cornering/acceleration (turn exit) but this may induce undesirable steering forces and generally interfere with control feedback to the driver. Some success is now found with the viscous type limited slip

3) Forward weight bias with tractive effort on the front tends to induce excessive understeer in the linear range, plow at the limit (in steady-state), and reduce max lateral. This is due to tire load sensitivity [coefficient of friction on pneumatic tires reduces with load] and friction circle effects and is most noticeable on acceleration out of turns. The understeer/plow may be reduced by stickier tires on the front and by taking some of the lateral load transfer on the rear [stiffen roll hardness on rear]. The amount of [lateral load transfer taken by] the rear is limited by lift of the inside rear wheel.

4) The forward weight bias is basically unfavorable to maximum braking because of tire load sensitivity losses due to unequal front and rear loading. The situation is improved if larger tires are used on front. Proportionally more rear brake (or even lockup of the rear tires) is one technique which has been used to get the tail out for promoting "turn-in" and rear slip angle for cornering. It has been used in various forms such as the so-called "hand-brake turn" (popular in rallying) and "trail braking" where the left foot is used for braking and the right foot remains on the throttle to keep the front wheels from locking up.

5) Trim [ ie. heading] changes occur frequently in circuit racing, for example, if balked by another competitor in a turn. Dropped throttle transfers load forward, increases the inward lateral force on the front wheels, and increases the [grip available] on front. [The car turns into the corner to an extent] dependent on the amount of engine motoring torque (note that with an automatic transmission, motoring torque at the wheels may be very small). If the vehicle is stable it will retrim without control action at a higher lateral acceleration. If near the limit it may spin out if not caught by control action. As Reid Railton pointed out, when a front drive is loose and near incipient spin the best treatment may be to ease on the throttle and transfer load aft, but "the relief is only temporary." Driving a high powered front drive at the limit requires more judgment and experience, as the Novi history demonstrates.

In summary, it is more difficult to achieve a neutral vehicle over the operating range with front-wheel drive than with rear- or four-wheel drive. The compromises required to achieve a balance of handling and performance over a circuit are critical. The situation becomes progressively more difficult as power is increased.

/plagiarizing

I feel kind of guilty to have copied all that, but its less than 10% (By a lot) so I think it's legal. Anyway, as thanks to the Millikens, I hereby recommend you all go out and buy yourself a copy, as there is much more to read than that.
The text in question is very well known amongst automotive engineers, something of an industry standard. And if you are interested in the subject, I do think it's worth buying, but it's not particularly cheap.

ok...
I issue you a challenge.

find me a car for 500 dollars that has a 5 speed manual transmission,
performance suspension,
can run 12 second quarters (ive never tried, but i hear from the previous owner)
has EITHER a targa top or T-tops,
is fuel injected,
has 6month insurance premiums in the $275 range,
can 90% of the replacement parts for it at autozone, that day
and comes WITHOUT all the automated systems that are so "convieneint" to drivers today...
i hate automatic lights, seatbelt dingers, lane change warning systems, ect...

I know this isn't directed at me, but here's your answer. 1989 Dodge Daytona Turbo II.

Can be found for around $500, has a five speed Getrag, and has a very good suspension for the time.
Can run 12s reliably for very cheap.
Can be found with t-tops.
Port fuel injection.
I'm not sure of insurance, but it should be in the same range.
You can find replacement parts anywhere.
No automated crap

I know this isn't directed at me, but here's your answer. 1989 Dodge Daytona Turbo II.

Can be found for around $500, has a five speed Getrag, and has a very good suspension for the time.
Can run 12s reliably for very cheap.
Can be found with t-tops.
Port fuel injection.
I'm not sure of insurance, but it should be in the same range.
You can find replacement parts anywhere.
No automated crap
ding ding ding
we have a winner.

and guess what?
i actually really wanted one of those before i got my camaro
it was as simple as, i couldnt find one.

also, body build-quality is an issue too.
my camaro is rust free


whats funny is that from the right angles, they even look pretty similar
the daytona even has the "camaro" rear taillight triangles...
(if you havent noticed, when viewed from the side, the rear tailights form a triangle-esque shape
http://www.moparautos.com/images/84day2.jpg

There are ways to get the car to drift or oversteer even if it understeers stock - as you know, rear roll hardness, or more optimal suspension geometry, etc. But these things have compromises involved. For example, a sway bar links the wheels in question and throws off bump handling. Also, it's entirely possible to sacrifice drive traction for lateral traction by moving the COG backwards.

If you're claiming that sway bars are a bad thing, then you'd have some serious arguments with anyone who designs or tunes suspension.

The drive traction you are soo concerned about is only an issue in two situations. One is traffic light racing, the other is the 1/4 mile drags. In all forms of racing other than stupid straight lines it is not an issue.


None - this is based purely on engineering theory. That way you can cut the subjective stuff out, and you can cut the outliers out.
You should have mentioned that earlier.
See the problem with your theory is that it hasn't been tested. The outlier at this stage is your lack of knowledge about the very vehicles you're discussing.

During braking, the front loads up and the rear unloads. lets say at 1 G 20% of the load moves forward. If you start with 60:40, in a FF car, you will wind up with 80:20. If you have an RR car, starting at 40:60, you wind up with 60:40. The loadings are more even the more weight is towards the back.
How about instead of throwing around numbers you picked out of thin air, actually delivering real numbers.
Like the stopping distance of a mazda 3 (fwd) vs an RX8 (rwd).

Oh look at that, the mazda 3 stops better in the wet.
http://www.rx8.co.nz/Reviews/pr_brake_2904.aspx

Take a look here and you'll see many fwd cars pulling up faster than the rx8 too.:loser:
http://www.movit.de/rahmen/stoptbl.htm

You are as arrogant as you are ignorant, its a dangerous combination.

When you have some real experiance, can provide some useful and real world advice, then you might be in a position to question others on their choice of car.
In the mean time, as far as you are concerned, the Camaro is a very good car.
It sold in very large numbers, and there are thousands of owners who are very passionate about it.
I bet you have never even driven one.

It puts you in about the same class as the 15 year old kids who make assumptions about cars based on the car magazines their daddy brings home.

aaah but it is you who are over arrogant and if you think im ignorant, you are guilty of it worse. how else, without ignorance, can you claim i have no real world experience? i dont remember telling you my life story. i commented on my opinion of his car. if you think my opinion isnt valid you are more ignorant than i could ever be. sure the camaro sold in large numbers, and lots of people like it. so did such gems as the fiero, sunbird, taurus, pontiac 6000, and many others i could name. it doesnt make them good cars. theres a reason that auto manufacturers cheap out whenever they can on cars. sure there were versions of camaros that were better than other camaros, but GM among other companies, is guilty of using a bad cost cutting strategy of trying to make crappy platforms perform well enough to sell a sports car version. just because it can get from one stoplight to another faster than a buick doesnt mean its better. im sorry but straight line speed doesnt do much for me if it cant turn.

ding ding ding
we have a winner.

and guess what?
i actually really wanted one of those before i got my camaro
it was as simple as, i couldnt find one.

also, body build-quality is an issue too.
my camaro is rust free


whats funny is that from the right angles, they even look pretty similar
the daytona even has the "camaro" rear taillight triangles...
(if you havent noticed, when viewed from the side, the rear tailights form a triangle-esque shape
http://www.moparautos.com/images/84day2.jpg


uh huh i guess i see your point even though your camaro isnt 500 bucks anymore, and when it was, didnt run anywhere close to 12s. another car that fits your model? a foxbody crustang(wait, no ttops. why is this a big deal?). or a mkIII turbo supra, or a z31 turbo 300zx, or a swapped rx7, or a turbo 240sx(wait no ttops again. just me but ttops isnt all that.), how about such make believe cars as a volvo 240 wagon with a 5 liter bmw v12 in it? irocs get bad gas mileage, handle like shit, dont look good in my opinion, and have technology straight out of 1971(except for the fuel injection). theres cars that can do things your camaro never could. have you ever driven other stuff? ive been at the helm of a camaro with a turbo 3.8 and took it up to 150mph on the freeway, and tried to get it to turn on twisty roads. my old sentra could handle more confidently.

If you're claiming that sway bars are a bad thing, then you'd have some serious arguments with anyone who designs or tunes suspension. The drive traction you are soo concerned about is only an issue in two situations. One is traffic light racing, the other is the 1/4 mile drags. In all forms of racing other than stupid straight lines it is not an issue.
A lot of people who think they are 'tuning' their suspension end up making things a lot worse. If you know how swaybars work you will know that what I said about them is true.

Drive traction is an issue any time you can spin the wheels. If you are a professional racer, or someone racing a higher end car, it matters a lot of the time. If you are someone racing a small, FWD economy car, or any car without much grunt, not so much.


You should have mentioned that earlier.
See the problem with your theory is that it hasn't been tested. The outlier at this stage is your lack of knowledge about the very vehicles you're discussing.
Hahaha, jesus, these are not my theories. Why don't you mosey on down to eng-tips and tell all the automotive engineers they haven't tested their theories enough. Then tell them you know this, because a mazda 3 can outbrake an RX-8 in the wet!

How about instead of throwing around numbers you picked out of thin air, actually delivering real numbers.
Like the stopping distance of a mazda 3 (fwd) vs an RX8 (rwd).

Oh look at that, the mazda 3 stops better in the wet.
http://www.rx8.co.nz/Reviews/pr_brake_2904.aspx

Take a look here and you'll see many fwd cars pulling up faster than the rx8 too.:loser:
http://www.movit.de/rahmen/stoptbl.htm
I have already explained this in my first two posts in my last reply to moppie. You should also read the exerpt from the book given up there.

This is now lapsing into little attcks against each other.

i'll put this simply:

if you can't put your point across without being whiny and bitchy, and can't accept each others' points of view, regardless of right/wrong i will close this thread.

this applies to everyone.

ding ding ding
we have a winner.

and guess what?
i actually really wanted one of those before i got my camaro
it was as simple as, i couldnt find one.

also, body build-quality is an issue too.
my camaro is rust free


whats funny is that from the right angles, they even look pretty similar
the daytona even has the "camaro" rear taillight triangles...
(if you havent noticed, when viewed from the side, the rear tailights form a triangle-esque shape
http://www.moparautos.com/images/84day2.jpg

Very good points. I've never understood why the rockers love to rust out on Daytonas and LeBarons. I guess I'll have to take a look when I cut my 1/4 panel off.

A lot of people who think they are 'tuning' their suspension end up making things a lot worse. If you know how swaybars work you will know that what I said about them is true.


A swaybar can have a rate anywhere from imperceptible to stiffer than the chassis itself. To claim a sway bar "throws off bump handling" indicates a lack of understanding.

Again with reference to weight distribution. You need some data, not hand waving of what you think the weight distribution is.
It might help you understand why an audi A3 can stop harder than an RX8.


Hahaha, jesus, these are not my theories. Why don't you mosey on down to eng-tips and tell all the automotive engineers they haven't tested their theories enough. Then tell them you know this, because a mazda 3 can outbrake an RX-8 in the wet!

I have read your excerpt and many others form Milliken. I conclude that you are attempting to apply them outside their intended context. In short I don't think Milliken would agree with how you are trying to use his words.

I am an engineer, I am familiar with eng-tips.com and I don't think the engineers there would agree with your blanket statements on the handling of vehicles you admit to not having driven.

A swaybar can have a rate anywhere from imperceptible to stiffer than the chassis itself. To claim a sway bar "throws off bump handling" indicates a lack of understanding.
If you have 60:40 weight distribution, and lets assume suspension design holds the tyres at opimum slip angle and camber for their load, and you have to use an roll axis that slopes upwards as it moves forwards (this is what most cars use I believe, apparently a comfort thing), and you are already quite possibly using softer springs on the rear (as the mass on the rear is less), then that leaves you with a car with more weight up the front, and more roll hardness up the front. To make up for that (in an attempt to get neutral handling), you need to add a lot of roll hardness at the rear, and the way to do that is a stupidly hard sway bar.

When one side of this sway bar hits a bump, the other wheel gets pulled up as well, decreasing traction even on the previously unaffected side. You are ruining part of the benefits you used to get from independent suspension. Yes if you had a soft sway bar this wouldn't be such a concern, but when you ask a swaybar to fix poor weight distribution and suspension geometry that isn't helping, you may not be able to make it soft.

Again with reference to weight distribution. You need some data, not hand waving of what you think the weight distribution is.
It might help you understand why an audi A3 can stop harder than an RX8.
What data do you want me to get exactly? Apparently the new A3 has a weight dsitribution of 58:42, and the RX8 has 50:50. Please do not keep making me reiterate that there is more to it than just being FWD, and just being front heavy. That's why I'm not giving examples. Are you sure tread compound, the ABS program, the weight of the vehicle, and all those other things aren't influencing the results?

I have read your excerpt and many others form Milliken. I conclude that you are attempting to apply them outside their intended context. In short I don't think Milliken would agree with how you are trying to use his words.
Well, one thing that I did fail to include in the quite was that he was talking about race vehicles, but as you probably know, I am also talking about race vehicles/high performance ones, because like I have said, problems start occuring when you start trying to put down a lot of power through the front wheels.

Anyway, I have quoted a large exerpt and I don't think it needs more context (it's certainly not worth typing out the pages either side of it). What you take from it is up to you, I have been pointing people to it because I don't think there is much else you can take from it.

I am an engineer, I am familiar with eng-tips.com and I don't think the engineers there would agree with your blanket statements on the handling of vehicles you admit to not having driven.
I have said twice explicitly that I'm not making blanket statements, and many other times implicitly. I know that there are FWD cars that can outhandle RWD cars. The point I am making, again, is that them being FWD is not helping. I think it is very rare when someone decides 'making this car FWD will help lap times'. The only time I can see that happening is low friction surfaces where load transfer doesn't have much chance to take effect, so you can end up with more load over the drive wheels.

For the record, I have driven my fair share of FWD cars, but not in a performance situation. Even if I had, I can hardly trust the seat-of-the-pants measurements I would have come up with.

A lot of people who think they are 'tuning' their suspension end up making things a lot worse. If you know how swaybars work you will know that what I said about them is true.

Drive traction is an issue any time you can spin the wheels. If you are a professional racer, or someone racing a higher end car, it matters a lot of the time. If you are someone racing a small, FWD economy car, or any car without much grunt, not so much.

A lot of people think that lowering the car as far as possible will make it handle better but they end up going below the roll center and screwing up their camber and throwing the suspension geometry all off. Then they just add thick sway bars front and back with subframe connectors and strut tower bars not taking in to how the car handles at the limit. They also tend to buy dampers that aren't dampened properly for the springs and don't even pay attention to spring rates. Some people just heat their stock springs or cut progressive springs. Truth be told, most people should even try modding anything on their cars. SCC has a few good articles explaining how to do your suspension right. I thought they were very good.

Also, I do agree with you about limits to FWD. You really don't want to go much past 350 hp or you're asking for potentially asking for traction issues, shearing axles, and blowing up CV joints.

If you have 60:40 weight distribution, and lets assume suspension design holds the tyres at opimum slip angle and camber for their load, and you have to use an roll axis that slopes upwards as it moves forwards (this is what most cars use I believe, apparently a comfort thing), and you are already quite possibly using softer springs on the rear (as the mass on the rear is less), then that leaves you with a car with more weight up the front, and more roll hardness up the front. To make up for that (in an attempt to get neutral handling), you need to add a lot of roll hardness at the rear, and the way to do that is a stupidly hard sway bar. see, your problem is moderation.
lets say we take your example of a fwd car with a 60:40 f:r weight distribution.
now, lets say that instead of using spring rates as a comparison, we use spring frequency, or hertz. wheel hertz more specifically.
now.

your typical 4dr import sedan has spring frequencies in the 1.3-1.7 hz range.
typically, 1 hz is known as the "brown frequency" and makes people get sick, so it is avoided.

anyway, lets say that for fun, this car has a front spring frequency of 1.5 hz and a rear frequency of 1.6 hz.

this also makes sense as the normal practice for suspension tuning is to make the rear frequency slightly higher than the front frequency so that the cars oscilation front to back will not be un-checked.
if they were both 1.5 hz, the car would tend to rock front to back endlessly. the back is made higher than the front because it helps the rear end "catch up" to the front end after hitting a bump.

now lets assume that since the rear has a higher frequency, it must have a slightly higher roll stiffness.
knowing that understeer is considered safe, an anti-roll bar is fitted to the front of the cars suspension.
lets say for arguments sake that the arb contributes 75% of the roll stiffness of the springs.

this means that if the springs contribute 100 lbft of roll stiffness, the front arb contributes 75 lbft.
i dont know if this is exact, but following your gross estimations, i would not think that this is too far off.

this means that the front now has a much higher roll stiffness than the rear of the car and the car has a natural understeering tendancy built in.

if a rear anti roll bar is desired to add a bit of "sport" to the feel of the car, one may be added.
lets say that the bar on the rear also has a rate equal to 75% of the roll stiffness of the springs.

this means that the roll stiffness of the front is still higher than that of the rear, but the rear is higher, as a percent, with respect to weight.



When one side of this sway bar hits a bump, the other wheel gets pulled up as well, decreasing traction even on the previously unaffected side. You are ruining part of the benefits you used to get from independent suspension. Yes if you had a soft sway bar this wouldn't be such a concern, but when you ask a swaybar to fix poor weight distribution and suspension geometry that isn't helping, you may not be able to make it soft. again, yes, but you are taking it to the extreme.

http://www.sfxperformance.com/parts/HOT804121.htm

this is a link to a sway bar kit for a toyota scion xb.
it is a relatively well mannered car.

notice that the front sway bar is 1.125" and the rear bar is .5"
i am willing to bet that you could twist that rear bar with your bare hands.
(well not necessarily you, but i surely could.)
if you go and look at kits for other popular import cars, you will see a similar trend.

in the case of the xb, i am willing to bet that the rear bar is nowhere near 75% of the roll stiffness of the springs. it is most likely nearer to 20%



another thing you are overlooking, especially in the case of a fwd vehicle, is the differential.
the differential, in my opinion, is responsible for more of the way a fwd car handles than the suspension its self.
a lsd with the right tuning (high torque under power, low torque under coast) can give the car LOTS of lift off oversteer.
if a car is understeering, all the driver has to do is give it a shot of gas and lift off while increasing the steering angle and voila, oversteer out whe wazoo.

on the contrary, a rwd car that has lots of power but is being set up "safely" for understeer, will have a low locking torque under power. this will let the driver have fun getting the rear end out.
the coast torque is set much higher though, so that when the driver lets off the gas in the middle of a tail-out turn, the rear will gain traction and come back into the correct line.



i recommend this program to you
http://www.vehicle-analyser.com/

go ahead and download the lfs version because it includes more car types.

play around with it and you will begin to understand what i, and others here are saying.

If you have 60:40 weight distribution, and lets assume suspension design holds the tyres at opimum slip angle and camber for their load, and you have to use an roll axis that slopes upwards as it moves forwards (this is what most cars use I believe, apparently a comfort thing), and you are already quite possibly using softer springs on the rear (as the mass on the rear is less), then that leaves you with a car with more weight up the front, and more roll hardness up the front. To make up for that (in an attempt to get neutral handling), you need to add a lot of roll hardness at the rear, and the way to do that is a stupidly hard sway bar.

Lets start with the errors in this paragraph.

Firstly, the roll axis slopes up towards the rear on every vehicle I've looked at. That is, the rear suspension roll centre is higher than the front.
The roll axis is the result of the roll centre, not the other way around.
This is another reason why many production vehicles have sway bars fitted to the front and not the rear.

Secondly, talking spring rates doesn't mean much without including the sprung weight at that end. You probably don't realise but the natural frequency of the suspension matters most and rear suspension is often tuned to have a higher frequency than the front. One of the goals is to prevent see-saw pitching.

You do not need a "stupidly hard bar" in the rear, I have no idea where you got this idea from, but it possibly stems from you getting the roll axis wrong above.
As I've said, normally you need no sway bar in the rear, if you do need to add one to tip the balance, it's rate does not need to be high at all. One of the purposes of a sway bar is to cause faster load transfer to the outside wheels.
The higher roll centre of the rear wheel already causes faster load transfer without needing additional roll-stiffness to acheive that.


There's a catch with applying theories, the catch is you need to understand them well enough to apply them correctly. I'm convinced that on this subject you don't.

I'm going to ahve tos plit my replies to you guys up into parts - there is a lot to say.

A lot of people think that lowering the car as far as possible will make it handle better but they end up going below the roll center and screwing up their camber and throwing the suspension geometry all off. Then they just add thick sway bars front and back with subframe connectors and strut tower bars not taking in to how the car handles at the limit. They also tend to buy dampers that aren't dampened properly for the springs and don't even pay attention to spring rates. Some people just heat their stock springs or cut progressive springs. Truth be told, most people should even try modding anything on their cars. SCC has a few good articles explaining how to do your suspension right. I thought they were very good.

Also, I do agree with you about limits to FWD. You really don't want to go much past 350 hp or you're asking for potentially asking for traction issues, shearing axles, and blowing up CV joints.

I agree with basically everything you say. People think that hardening suspension endlessly makes the car handle. It's why a lot of people worship the swaybar and think thicker is better no matter what.

The more I read this, the more I agree with Nereth on one thing:
For ultimate performance, RWD is better than FWD.
But that was estrablished right at the start of this thread.

From there things get a little lost.
Nereth you seem to be always arguing from the point of ultimate high performance.
Where it is valid and accepted that RWD is better.

What the rest of us are pointing out, is that it is not always better under less demanding circumstances, and in the average road car, FWD can be preform just as well as RWD, and sometimes better.
You don't need a degree in engineering to understand that, you simply need to go out and drive a few cars, or even read a few magazine reviews to see real world examples.

.....i commented on my opinion of his car.


You did nothing of the sort.
You insulted him, and used his choice of car as your reasoning.
Do it again, or call anyone else here ignorant and I will ban you for a week. :loser:

see, your problem is moderation.
lets say we take your example of a fwd car with a 60:40 f:r weight distribution.
now, lets say that instead of using spring rates as a comparison, we use spring frequency, or hertz. wheel hertz more specifically.
now.

your typical 4dr import sedan has spring frequencies in the 1.3-1.7 hz range.
typically, 1 hz is known as the "brown frequency" and makes people get sick, so it is avoided.

anyway, lets say that for fun, this car has a front spring frequency of 1.5 hz and a rear frequency of 1.6 hz.

this also makes sense as the normal practice for suspension tuning is to make the rear frequency slightly higher than the front frequency so that the cars oscilation front to back will not be un-checked.
if they were both 1.5 hz, the car would tend to rock front to back endlessly. the back is made higher than the front because it helps the rear end "catch up" to the front end after hitting a bump.

now lets assume that since the rear has a higher frequency, it must have a slightly higher roll stiffness.
knowing that understeer is considered safe, an anti-roll bar is fitted to the front of the cars suspension.
lets say for arguments sake that the arb contributes 75% of the roll stiffness of the springs.

Why are you using wheel frequency? To have the rear end 'catch up', you would want to be talking about sprung mass frequency, no? Assuming that is what you meant:

60/40 front to rear and a front natural frequency of 1.5 and rear of 1.6, given that natural frequency=sqrt(spring rate/mass) yields a front spring rate of 135 and a rear spring rate of 102.4. Roll hardness from the springs, assuming equal track front to rear, will be directly proportional to that. This means the rear end takes less of the lateral load transfer, and also is lighter.

this means that if the springs contribute 100 lbft of roll stiffness, the front arb contributes 75 lbft.
i dont know if this is exact, but following your gross estimations, i would not think that this is too far off.

this means that the front now has a much higher roll stiffness than the rear of the car and the car has a natural understeering tendancy built in.

if a rear anti roll bar is desired to add a bit of "sport" to the feel of the car, one may be added.
lets say that the bar on the rear also has a rate equal to 75% of the roll stiffness of the springs.

this means that the roll stiffness of the front is still higher than that of the rear, but the rear is higher, as a percent, with respect to weight.

These assumptions are all wrong assuming my calculations showing front spring rate to be higher are correct. Yes understeer is safer, yes they do want the car to understeer, and yes that means this whole thing doesn't really matter to the average consumer car. Again, I am talking about high performance/race cars, where the goal is to be quite close to drifting. If that is the case, according to my calculations, are large rear swaybar is needed to try to remove the understeering tendency.



again, yes, but you are taking it to the extreme.

http://www.sfxperformance.com/parts/HOT804121.htm

this is a link to a sway bar kit for a toyota scion xb.
it is a relatively well mannered car.

notice that the front sway bar is 1.125" and the rear bar is .5"
i am willing to bet that you could twist that rear bar with your bare hands.
(well not necessarily you, but i surely could.)
if you go and look at kits for other popular import cars, you will see a similar trend.

in the case of the xb, i am willing to bet that the rear bar is nowhere near 75% of the roll stiffness of the springs. it is most likely nearer to 20%

Yes I am taking it to the extreme, but every bit counts. I have a model of a car from a project a while ago. The tyre model comes from some graphs in RCVD (it's not exactly something you can google, so you take what you get). Don't be surprised at the extremely high gees the car can pull, the tyres are basically race tyres and there are no bumps or road contaminants to throw anything off.

Lets take our earlier example car. 900kg front 600kg rear (60:40), with 1.5hz body frequency front, and 1.6hz rear. Toe and camber will be set to 0, and we assume the car doesn't roll, for simplicities sake. Wheelbase will be 100 inches, track will be 60. CGH is 20 inches. We will assume a perfectly rigid chassis. Using the springrates calculated earlier (front 135, rear 102.4), the TLLTD is 56.7% front, 43.3 rear, without swaybars.

In this configuration, the car understeers at 1.093 gees.

If the TLLTD=50:50, the car understeers at 1.103

Trial and error reveals neutral lies at approximately TLLTD=45.74% front, where the car understeers at 1.1071 gees. For a bit of spare drive traction for turn exit, lets pretend that equals 0.46 (it pretty much does, for the accuracy of this program :P). Anyway, to get the 56.7:43.4 to 46:54, the minimum rear swaybar hardness is 23.16 units. Considering that is more than half of the current rear spring rate, I think that is significant.

Anyway, I don't know if you will accept that analysis, since you don't have any reason to trust the program or numbers, but at least it makes me feel a bit more confident.

another thing you are overlooking, especially in the case of a fwd vehicle, is the differential.
the differential, in my opinion, is responsible for more of the way a fwd car handles than the suspension its self.
a lsd with the right tuning (high torque under power, low torque under coast) can give the car LOTS of lift off oversteer.
if a car is understeering, all the driver has to do is give it a shot of gas and lift off while increasing the steering angle and voila, oversteer out whe wazoo.

Lift off oversteer, to the best of my knowledge, will at best temporarily (for a fraction of a second), fix the problem. You cannot expect to be able to get through a long corner, by continuously adding and removing drive torque. If only for the penalty you get every time you add it.

i recommend this program to you
http://www.vehicle-analyser.com/

go ahead and download the lfs version because it includes more car types.

play around with it and you will begin to understand what i, and others here are saying.

Thanks for the program. When I get time I will have a play around with it.

Jesus, I hate this kind of "my $500 car is better than your $500 car" BS

With skill, tools and knowledge, I can make ANY $500 car absolutely kick ass in any category. I am so NOT impressed if you prefer one over another for some arbitrary reason

You really think an Iroc can't handle? Do you know where the "iroc" name came from?

thats to slideways, btw

Lets start with the errors in this paragraph.

Firstly, the roll axis slopes up towards the rear on every vehicle I've looked at. That is, the rear suspension roll centre is higher than the front.
The roll axis is the result of the roll centre, not the other way around.
This is another reason why many production vehicles have sway bars fitted to the front and not the rear.

I had always thought that it was the other way around, but, if you say so I will strike that from my list of arguments.

Secondly, talking spring rates doesn't mean much without including the sprung weight at that end. You probably don't realise but the natural frequency of the suspension matters most and rear suspension is often tuned to have a higher frequency than the front. One of the goals is to prevent see-saw pitching.

I am aware of that. See my post above, even with the rear natural frequency slightly harder, the lack of weight is enough to make the rear springs rate softer in terms of force per distance.

You do not need a "stupidly hard bar" in the rear, I have no idea where you got this idea from, but it possibly stems from you getting the roll axis wrong above.
As I've said, normally you need no sway bar in the rear, if you do need to add one to tip the balance, it's rate does not need to be high at all. One of the purposes of a sway bar is to cause faster load transfer to the outside wheels.
The higher roll centre of the rear wheel already causes faster load transfer without needing additional roll-stiffness to acheive that.

If the roll center is indeed higher in the rear, then admittedly you could soften the sway bar somewhat. However, how much? It would probably go beyond my interest in this discussion to try to make a similar analysis to the above while including suspension geometry.


There's a catch with applying theories, the catch is you need to understand them well enough to apply them correctly. I'm convinced that on this subject you don't.

And I'm convinced I do. Without going through and checking everything, the only new peice of information I ahve been introduced to here is that the roll axis usually slopes upwards rather than downwards. Other than that, all the disagreements have either been 'I have driven a car that drove better than another car', or corrections that winded up not correcting anything (saying the rear wheel needs a higher natural frequency, while ignoring the fact that the rears reduced mass makes that happen at a lower spring rate). Oh, and questions of magnitude, which really have nothing to do with the understanding of the theory.

Lift off oversteer, to the best of my knowledge, will at best temporarily (for a fraction of a second), fix the problem. You cannot expect to be able to get through a long corner, by continuously adding and removing drive torque. If only for the penalty you get every time you add it.


Ever tried it?
I can tell you from experiance it works, and it works very well.
That experiance both driving a FWD car, and chasing one on a race track.

Your quoting a lot of theory, and lovely results from computer models, but theory can only ever take you so far.
At the end of the day there are always variables involved that a computer model can not test for, all allow for in a realistic way.

I spent the other weekend at the Taupo round of the A1GP, and got to spend a bit of time talking to some of the teams engineers.
They have all sorts of data logging, computer modeling, degrees and experiance to work with.
Yet most of their chassis work was done the same way its been done since people started racing cars.
Tweak, drive it, and see what happens.

Oh, and questions of magnitude, which really have nothing to do with the understanding of the theory.



Nothing wrong with your theory, just your application of it :)


If you want to be a really great engineer, then the first thing you need to understand is when and where to apply your theories, and how much to apply them.
You also need to understand that a theory is not a fact, and so is open to being proven false at any time.
Then you need to understand how those theory work out in real life, and just how realistic they are.


An alien with no knowledge of automotive engineering could easily conclude that FWD was better than RWD because there are more FWD cars produced that RWD one's, and be correct in his theory.

What the rest of us are pointing out, is that it is not always better under less demanding circumstances, and in the average road car, FWD can be preform just as well as RWD, and sometimes better.
I'm aware of that. I am also aware that in adverse conditions (Icy roads, mud, etc), FWD can routinely get more drive traction than RWD.

Allow me to quote myself a few times, in chornological order, and with a few bolded parts to help make my point:

From a performance perspective, it's useless in almost all cases.
And yes, they do handle fine for everyday road use. Obviously we are talking about beyond that.
Sorry if it sounds like I'm making a blanket statement. I know there are FWD cars that handle well. The point I am making is that being FWD isn't helping any.
I am talking about the limits - thats where you are supposed to be for high performance driving, and I thought that was what we were talking about
Drive traction is an issue any time you can spin the wheels. If you are a professional racer, or someone racing a higher end car, it matters a lot of the time. If you are someone racing a small, FWD economy car, or any car without much grunt, not so much.
I have said twice explicitly that I'm not making blanket statements, and many other times implicitly. I know that there are FWD cars that can outhandle RWD cars. The point I am making, again, is that them being FWD is not helping. I think it is very rare when someone decides 'making this car FWD will help lap times'. The only time I can see that happening is low friction surfaces where load transfer doesn't have much chance to take effect, so you can end up with more load over the drive wheels.

Your quoting a lot of theory, and lovely results from computer models, but theory can only ever take you so far.
At the end of the day there are always variables involved that a computer model can not test for, all allow for in a realistic way.

I spent the other weekend at the Taupo round of the A1GP, and got to spend a bit of time talking to some of the teams engineers.
They have all sorts of data logging, computer modeling, degrees and experiance to work with.
Yet most of their chassis work was done the same way its been done since people started racing cars.
Tweak, drive it, and see what happens.
That is absolutely true. The problem is, those variables should have nothing to do with our discussion. Yes you can make FWD handle very well, but it probably won't be as easy as doing the same with RWD (remember I am talking about the limits), and quite possibly the potential of a RWD car will be greater. There isn't really much advantage to be gained by switching your RWD car to FWD, on the other hand, I think we can all name a handful of advantages for switching your FWD to RWD (assuming, in both cases, you can do some relevant tuning afterwards).

If you want to be a really great engineer, then the first thing you need to understand is when and where to apply your theories, and how much to apply them.
The theories have been proven accurate at a far higher level than what I am using them at now - while it obviously will be innacurate because I am using such simplified models, it is good enough for qualitative discussion. As long as I put enough weasel words in (generally, usually, in most cases), the theories are accurate enough. :biggrin:

The chief advantage of them here is that they simplify the model down so that you can look at FWD versus RWD without including a bunch of irrelevant extras. By using the theories, I got to remove the effects of different suspension geometry, aerodynamics, wheelbase, track, tyre compound, road quality, etc etc.

If the opening question had been 'is a [FWD car] better than a [RWD car]', then the complicating factors become relevant, and the theories at my level become a lot more useless.

at this point all i really have to say is...
does it really matter that much?

the original question was asked by a NOOB and we are now all sitting here aruguing with more NOOBS who enjoy knocking heads...
lol

but as for lift off oversteer, it IS a big factor.
any idiot knows that once your tires are sliding as opposed to rolling, they have less grip.
once you get your rear tires sliding slightly a larger radius than the optimal line of the front tires, you can begin to "drift" although you arent applying any opposite lock.
btw, drifting in a powerful FWD car seems fun.
smack a "stupidly stiff" sway bar on the rear, disconnect the front one, and go.
if you get out of control, floor it and it will tighten up your line.
much easier than RWD drifting possibly

And I'm convinced I do. Without going through and checking everything, the only new peice of information I ahve been introduced to here is that the roll axis usually slopes upwards rather than downwards.

That "new" piece of information is something that could be deduced with 5 minutes of crawling underneath a car to check the suspension geometry.
It's a major mistake and one that shoots down completely every other assumption you've made on the topic.

This quote sums it up quite succinctly.

These assumptions are all wrong assuming


Too much assumption, absolutely no checking of the facts before posting assumptions and misplacing otherwise valid theories.

That "new" piece of information is something that could be deduced with 5 minutes of crawling underneath a car to check the suspension geometry.

Not really, no. I for one don't intend to put a car on a lift just so I can check that kind of fact.

It's something I picked up somewhere along the way. I had no reason to doubt it and no feasible way to check it.

It's a major mistake and one that shoots down completely every other assumption you've made on the topic.

It only partially reduces the need for a swaybar. Other than that, nothing. Remember I did my calculations assuming no roll axis inclination, and there was still plenty large enough need for a rear roll bar.

Too much assumption, absolutely no checking of the facts before posting assumptions and misplacing otherwise valid theories.

You are the one who assumed higher rear natural frequency equals higher rear spring rate. Should I now pretend that all of your posts are based on faulty assumptions?

You are also assuming that because one FWD car can outperform one RWD car, FWD is better.

I have been posting disadvantages of FWD cars compared to RWD... most of the replies comes down to 'its not that bad', which is really quite a weak argument. I would like it if you people could then tell me some of the advantages it has?

Moppie seems to be the only one who understands I am talking in terms of high performance/racing situations. It would be nice if everyone else could understand that before replying as well.

Not really, no. I for one don't intend to put a car on a lift just so I can check that kind of fact.

It's something I picked up somewhere along the way. I had no reason to doubt it and no feasible way to check it.

It can be checked by sticking your head underneath. No lift needed. Checking such things avoids looking like an idiot on public forums.

BTW all calculations based on a faulty assumption quickly become worthless. I suggest you reread my posts, your interpretation of my comments is not accurate.

It can be checked by sticking your head underneath. No lift needed. Checking such things avoids looking like an idiot on public forums.



I have stuck my head under cars before. It isn't as easy as you say to eyeball RCH, especially considerin the difference front to rear of the RCHs is only a few inches. What about with strut type suspensions? Are you claiming you can eyeball a line out a couple of meters perpendicular to a strut? And then intersect it and a couple of other lines and points? And do all this within a few inches of accuracy? And then, moreover, while lying upside down, and with a bunch of other components in the way?

I can barely fit my head under the couple of stock-ride-height cars we have over here, and even if I do, there are fuel tanks and the like in the way.

BTW all calculations based on a faulty assumption quickly become worthless. I suggest you reread my posts, your interpretation of my comments is not accurate.

I didn't base any calculations on a RCH that rises as it moves forward. I made assumptions, yes, but being an engineer, you would know that you have to make assumptions if you want to get anything done in a reasonable amount of time. If you want to remake the only calculation I made and include roll axis inclination with it, be my guest. I for one don't have the time.

I would rather you start naming the performance advantages of FWD though, as I asked in my last post.