so cutting springs is bad, huh? [Archive] - Zilvia.net Forums | Nissan 240SX (Silvia) and Z (Fairlady) Car Forum

Rennen

05-09-2004, 10:52 AM

From your article: "All stiffer springs do is make the car have a stiff ride. They have no capability to make a significant improvement in handling"

I think that this would be true.... if your car never ever had to transition its weight. Stiffer springs should keep your cars weight centralized, making it easier to shift the weight when turning/braking/accelerating/etc. The spring's ability to reduce body roll seems to be left out of this excerpt for some reason :confused:

Also, when talking about the cutting/torching springs he does not address dampening. And since "optimum road-holding demands the tires be in contact with the pavement" having an underdampened spring would be undesirable.

I have read a lot of textbooks in my engineering classes, written by accomplished authors, and I am sure you will agree that some of them are on occasion misleading or just plain wrong. I am not saying that he IS wrong, I am just saying there is a possibility. Some of those things make sense by themselves, but when you consider all the other parts of a car, his suggestions go against logic.

-Matt

s0ldats

05-09-2004, 10:54 AM

if you want ride quality why are you talking about upgrading suspension? go get a lincoln towncar.

Replicant_S14

05-09-2004, 11:11 AM

this "author" should go and have a debate with some REAL automotive engineer's (i.e. nismo, trd, mugen, etc) and see who's "right" and who's "wrong".

An engineer isn't going to argue that cutting a spring is "good" or "bad". It's a spring. There's no magic involved. There's even a formula to determine the rate based on how many coils, wire diameter, coil diameter etc.

I wouldn't cut stock springs just because of the way they are shaped but the notion that cutting a spring is universally bad is kinda silly. Just because the occasional redneck kid lops the coils on his cavalier without having a clue doesn't make the whole idea a calamity.

s0ldats

05-09-2004, 11:44 AM

cut springs aren't bad, but saying that they will out perform a coilover system is bullshit. a lot of research and development has been put into _quality_ aftermarket parts.

Kreator

05-09-2004, 12:27 PM

I think that this would be true.... if your car never ever had to transition its weight. Stiffer springs should keep your cars weight centralized, making it easier to shift the weight when turning/braking/accelerating/etc. The spring's ability to reduce body roll seems to be left out of this excerpt for some reason :confused:

weight transfer depends on inertia, not on how your car is made. No matter the design of your suspension, inertia will be the same, how you deal with it is what matters. Imagine you just have a steel tube in place of your spring that doesn't compress what so ever. You take a turn. you have only 2 choices of behavior. First, your car skids which is a big traction problem in itself. Second, your inner tire lifts provided your outside tires have enough traction not to skid. Sicne you read the books, u already know that having weight distributed between all 4 tires will give you more cornering force then having all the weight at just 2. So applying this to stiffer vs softer springs (given all the same characteristics) stiffer springs will provide less cornering force. BTW, he does talk about stiff springs effect on roll angle in another paragraph. He says that stiffer springs do reduce roll angle, but the additional understeer induced by stiffer springs cancel out the effect.

I have read a lot of textbooks in my engineering classes, written by accomplished authors, and I am sure you will agree that some of them are on occasion misleading or just plain wrong. I am not saying that he IS wrong, I am just saying there is a possibility. Some of those things make sense by themselves, but when you consider all the other parts of a car, his suggestions go against logic.

Maybe. But here I'm, being told by a lot of ppl that stiffer is better without any backup, and i read a book that says otherwise providing proof of why (which makes sense) and all of a sudden i'm thinking all these ppl have no freaking clue what they are talking about, because i seriosly haven't yet seen that stiffer springs do improve handling. I'm not trusting this guy 100%, hence my original question. But it makes perfect sense to me, that's why i was wondering what you ppl had to say.

And i'm not trying to tell that everybody is an idiot for getting coilovers. It's just that it seems to me some ppl are getting stiffer springs because "it improves handling" when all it really does is allow the car to not bottom out while sitting lower.

the 2 things i'm getting at are:

1. ppl bitching at those who cut their springs when lowering the car. Ofcourse if you cut off half the spring your car will handle like shit cuz u will bottom out on every bump. But if its 1 or 1/2 of a coil, it actually is ok. Basicly if you are lowering a car an 1", you don't need to buy aftermarket springs.

2. Every now and then i hear something like this in reference to buying coilovers: "if your car is only a daily driver get these spring rates. If you are going to occasionally autox, get these *stiffer* rates. If its an all out race car, get these *even stiffer* rates." Basicly an advice on deciding harshness vs better handling. This guy is basicly saying, if it's good for daily driving on this specified coilover, there is no need for stiffer springs, since there is no benefit handling wise, just a stiffer ride. If you can't bottom it out on hte street, i doubt u'll be able on the track, unless ofcourse u rally your car.

adey

05-09-2004, 12:32 PM

He mentions, in going on about soft spring rates, that one can go super soft, as long as they're still "stiff enough to keep the car from bottoming out". That said, on our cars with especially short front suspension travel, a stiff spring rate is required if you're going to be doing some very spirited driving with very sticky tires. Same could be said about the rear, though we have (afaik) more room to work with there.

Stiffer springs will, as I understand it, let your car transition faster, because you're not throwing the whole 2,600 lbs around like a rag doll (which would probably make transitioning reeeaallly unstable).
Speaking of stability, that's something that I think you gain with stiffer coils, too.

I would love to see the author post some skid pad #s with stiff vs soft springs... since he provides NO evidence (what good are a bunch of credentials when you don't adequately support what you're saying with evidence?), I will carry on running my 8/6 springs.

adey

05-09-2004, 12:45 PM

So applying this to stiffer vs softer springs (given all the same characteristics) stiffer springs will provide less cornering force. BTW, he does talk about stiff springs effect on roll angle in another paragraph. He says that stiffer springs do reduce roll angle, but the additional understeer induced by stiffer springs cancel out the effect.With stiffer springs though you have more force acting UP on the outside wheels, and should therefor have more force actind DOWNwards on the inside wheels... or at least that's what my highschool physics classes imply to me.
Also, I see not why stiffer springs would increase understeer. Is it possible that you're only reading a chapter on FRONT springs? ... if you up the spring rates of the rear only, you're not going to get more understeer... this is something that's been proven. (although it's interesting... stiffen up rear springs = more rotation which translates into less grip in the rear. Interesting tangential discovery!! I imagine it's different when you have stiffer springs all 'round though)...
Ofcourse if you cut off half the spring your car will handle like shit cuz u will bottom out on every bump. But if its 1 or 1/2 of a coil, it actually is ok. Basicly if you are lowering a car an 1", you don't need to buy aftermarket springs. You realize that we have something ridiculous like 2" of suspension travel in the front, don't you? Cutting 1 (or even 1/2) a coil up front would, in my understanding, be terrible for our suspension travel.
[quote="Kreator"}if your car is only a daily driver get these spring rates. If you are going to occasionally autox, get these *stiffer* rates. If its an all out race car, get these *even stiffer* rates." Basicly an advice on deciding harshness vs better handling. This guy is basicly saying, if it's good for daily driving on this specified coilover, there is no need for stiffer springs, since there is no benefit handling wise, just a stiffer ride. If you can't bottom it out on hte street, i doubt u'll be able on the track, unless ofcourse u rally your car.[/QUOTE]
It's really easy to bottom out your stock suspension on some relatively sticky rubber on the street. It's even easier to do so on the track. If you run really sticky R compound or some super high performance tires (Bridgestone S02/S03 or Falken Azenis or similar), it'll be EVEN easier to bottom out our suspension. I'm not sure how the suspension of domestics (esp. those noted in the paragraph you scanned) is designed, but I imagine, partially given their 4*4 stance, that they have significantly more suspention travel than we do... hence their ability to work relatively well with cut coils.

The way I see it... stiffer springs + stickier tires = good... softer springs + harder tires = "good" and any other combination would suck.

Kreator

05-09-2004, 01:02 PM

I would love to see the author post some skid pad #s with stiff vs soft springs... since he provides NO evidence (what good are a bunch of credentials when you don't adequately support what you're saying with evidence?), I will carry on running my 8/6 springs.

Sure, keep doing that. But w/o those skidpad numbers how do you know your car IS actually doing better at those rates? I dont see any evidence in support of stiffer springs = better.

As for understeering, how do you think your car would behave if you take a a hard turn w/ no springs at all? Skid? Most likely. No springs = Springs with infinately high rate. So basically a spring that is stiffer then your current spring gets you closer to that skidding point.

As for spring cutting, you also got to realize that cutting off a coil does in fact increase your spring rate. So if there is some extra in the spring (as in it doesnt bottom out stock) you most likely can cut a little off.

again what i'm trying to get at is that some ppl believe that stiffer spring in itself improves handling. This is not true. It only needs to be stiff enough for hte car to not bottom out. Having it a bit stiffer WILL NOT have any effect on handling. if there is a coilover made, and u get a spring for it, that doesn't bottom out when u drive it, there is no point of getting a stiffer spring "for racing".

lol, and what 4x4 stance are u talking about? Corvettes, camaros and firebirds are way more of race cars than 240s are.

RPS13_SR20DET

05-09-2004, 01:44 PM

I'm not sure how the suspension of domestics (esp. those noted in the paragraph you scanned) is designed :D FYI: http://www.corvetteactioncenter.com/specs/2004/suspcomp.html

compare to the 240sx stock rates (which is around 112lb/in. from 90 fsm), covette spring rate are much much more stiffer.

DSC

05-09-2004, 05:39 PM

Sway bars can't do everything. What better way is there in a street car to reduce roll and dive than stiffer springs & shocks? Soft springs may be ok in nascar since they don't have to change directions.

Does the book even mention dampening other than you don't want them to bottom out?

This is what a book I have says...
lowering cg, widening track, and reducing load (either by losing weight or driving slower) is the only way to reduce weight transfer. - paraphrased
I think everybody would agree with this. but just because you can't reduce weight transfer with stiffer springs, you can still reduce the effect is has on the car which can have a big impact on handling.

"A quick caution about springs: While a softer spring should increase the relative grip of that end of the car, you have to keep in mind how the additional roll allowed by the softer spring affects the grip of the tire. Some suspension designs will be more sensitive to roll than others, and beyond a specific point, will start doing bad things to the contact patch. In an effort to imporve grip by softening the spring rate, you might result in losing grip due to the suspension's inability to deal with roll."

I think the author of your book just oversimplified it to the point of just being incorrect. I agree with his basic idea that stiff springs don't make the car faster alone...but I don't like the way he said it. Everything has to be in ballance. If you lower your car and make it just stiff enough to not bottom out, your not going to have a fast car "."

s0ldats

05-09-2004, 06:20 PM

Kreator

05-09-2004, 07:16 PM

is the author of this book your dad? why are you trying to defend him so much? are you from california? let's enter an autocross together and see who gets a better time? or how about we have one driver drive both of our cars to make it fair? deal?

dude, stop trying to insult me. I'm not defending anyone. I came up on something that confused hte hell out of me and trying to straighten stuff out. You have made 3 posts in this thread and they all contain exactly 0 information on the subject, so id really appreciate if u just STFU. Thank you.

DSC. I see what you are saying. Could you elaborate on "will start doing bad things to the contact patch". And the author says that "beyond specific point". I dunnow that sounds kinda vague to me. Is the author saying that having softer springs IS beneficial, up to some specified level? Is that level exactly the level of where the car bottoms out?

I might be wrong here, but from just looking at it from physics stand point, when the car "rolls" in corner (soft springs), it provides pressure on the springs from the top (as the outer body height, lets call it that, becomes higher then the inner), while when the car does not roll at all (stiff springs) the weight transfer is horrizontal not providing additional traction, but actually providing side force on the tires making them likely to skid. Am i wrong here?

Dream240

05-09-2004, 07:29 PM

To Kreator,

Okay well here's my 2 cents. Based on my current setup, KYB AGX struts & Eibach Sportline springs, my car HANDLES way better than it ever did with the stock setup. To be honest, the handling is noticably better when doing any of the following:

Changing lanes quickly on the freeway at high speeds. More stable transition.
Braking quickly.
Braking while turning through a sharp corner.
Acceleration while turning through twisting roads.

Now in your defense the following is noticably worse:

potholes or uneven surfaces at speeds in excess of 35 mph.
bumps in the road or hitting those damn sections of freeways where the road just jumps up 2 or 3 inches at high speeds.

The difference in the handling I've found is affected two ways, when I adjust the KYB struts to a higher-stiffer setting, I get the bumpiest ride ever. Obviously this higher setting is intended for the track. Also when I lower the setting to the lowest, only 3% stiffer in back and 5% in the front than stock, the springs still affect the travelling of the tire on any uneven surfaces. No bottoming out but still somewhat bumpy. I do feel the bumps more and sometimes it does affect the way the car takes certain roads. BUT there is no way to compare the stock spring setup to the aftermarket in terms or cornering and acceleration while cornering.

So I guess it really all comes down to, do you want to have a bumpier ride but be able to rip through country roads and take your car to the track whenever you want and have fun? Or do just want a smooth ride and suffer the consequences of longer braking distances, rolling through those mountain roads instead of driving through them, and no having 100% faith in the performance of your car when you ask or need it?

Me personally, I'll take the bumpy ride cause I know my car can take me through any roads I find with absolute certainty of the cars handling performance.

Dream240

05-09-2004, 07:39 PM

I might be wrong here, but from just looking at it from physics stand point, when the car "rolls" in corner (soft springs), it provides pressure on the springs from the top (as the outer body height, lets call it that, becomes higher then the inner), while when the car does not roll at all (stiff springs) the weight transfer is horrizontal not providing additional traction, but actually providing side force on the tires making them likely to skid. Am i wrong here?

Oh and to respond to this. I think you are on the right track with the weight distribution. But I'm thinking that your weight is still shifting from right to left. So whether the spring rate is high or low really only matters when you're talking about how much pressure and force you're putting on the springs at any given moment. There's alot more factor than srping rate when talking about weight shift. You've got speed, weight of car, condition of the entire suspension system, road conditions. I'm thinking that the label "progressive spring rate" has something to do with that. So say whikle sitting still your spring rate is, 125. then while turing at 35 mph it's 150, and while turning at 60 its 200. So basically the harder the turn the stiffer the spring gets to compensate for the force and weight shift. You can use progressive lowering springs on stock setups and have improved handling, but no matter how you slice it your car won't ever handle the same as stock. And someone corect me if I'm wrong but the stock springs aren't progressive rate springs so they don't actually fight body roll and weight shift while turning like say Eibachs do.

DuffMan

05-09-2004, 07:52 PM

There is some truth to what he's saying but I see 2 problems with it.

1. Since soft springs cause the transitions in weight shift to take longer. This means any difference between the front and back weight shift is exagerated. If a car is tuned towards understeer (like most passenger cars), the understeer is going to be even more exagerated with stickier tires on stock springs.

2. Cutting springs does make them stiffer in proportion to their decrease in length. However, most cars have springs that are a lot longer (even under the load of the car) than their shock travel, so cutting them sacrifices a larger percentage of of suspension travel compared to the percentage increase in spring rate. Also, a lot of cars depend on the sway bars for a large percentage of their rolling resistance. If you increase the spring rate by cutting them, but dont increase the sway bar as well, the total resistance to roll wont be proportional to the drop in spring height.

On a car with excelent roll geometry that doesnt depend on sway bars much for roll resistance like a Corvette, cutting springs a bit, and keeping the stock springs might work. But on most cars, its not going to help, and the stock springs are much too soft to maximize the cars handling potential.

The empirical results of people who race street cars (that arent exotic sports cars) disagree with this article.

EEdude

05-09-2004, 07:54 PM

Kreator

05-09-2004, 08:16 PM

http://auto.howstuffworks.com/question432.htm

ok makes sense, but doesnt answer the main question. Does having less of the roll produce larger side force on the tires, making htem more likely to skid then if there was body roll?

DuffMan

05-09-2004, 08:32 PM

ok makes sense, but doesnt answer the main question. Does having less of the roll produce larger side force on the tires, making htem more likely to skid then if there was body roll?

No. When the centripetal acceleration of the car and the springs resitance to compression reach equilubrium, the springrate does not effect anything. Spring rates only effect transitional forces. If you are turning at a constant rate, the spring rate doesnt matter, though the ammount the spring has compressed effects the suspension and wheel angles obviously.

Dream240

05-09-2004, 08:35 PM

ok makes sense, but doesnt answer the main question. Does having less of the roll produce larger side force on the tires, making htem more likely to skid then if there was body roll?

Generally, yeah I think so. But honestly you can't be general about this. Like I said before, there's alot of factors involved. You will probably be more inclined to skid with less body roll, but don't forget about these factors, suspension system condition, tire type and condition, road conditions, speed, and I'm sure there's a few more.

I know there's articles out there to back me up, but I really don't feel like finding them right now. :) This is just my logic behind body roll.

Also, I just remembered, body roll has some major disadvantages, bad tire wear, poor steering response during heavy turning, hard braking while turning becomes unstable, too much side inertia resulting in a higher probability of tailfishing or loosing control of the vehicle. And I think too much body roll causes unwanted understeer like previously mentioned.

Does that help?

Kreator

05-09-2004, 08:59 PM

No. When the centripetal acceleration of the car and the springs resitance to compression reach equilubrium, the springrate does not effect anything. Spring rates only effect transitional forces. If you are turning at a constant rate, the spring rate doesnt matter, though the ammount the spring has compressed effects the suspension and wheel angles obviously.

rethinking it and reading some additional stuff, i came to another thought: a. like DSC quoted, springs have 0 effect on weight transfer. b. they have effect on shifting the center of gravity, however unless the center of gravity is way up high from the axle of rotation or the springs are way too soft, the effect of this shift is minimal compared to weight transfer experienced in the turn, and does not outweigh having softer springs for general traction of the course (small bumps etc).

In other words, if the springs are stiff enough to not roll the car over, they don't need to be any stiffer, and additional stiffness might in fact bear negative effect overall. Basicly spring stiffness actually has very minimal effect on reducing body roll. Like what the author of the book is saying...

correct?

dream240, well take all other conditions the same. Does having a stiffer spring vs a softer spring in a particular setup have any more benefit in just turning. Not taking into account suspension conditions or tire wear :)

DuffMan

05-09-2004, 09:12 PM

Kreator

05-09-2004, 09:35 PM

You are correct in terms of softer springs not decreasing the ultimate turning grip of a car (not taking into account angle changes from more roll).

They can cause exagerated understeer, and also since the weight transfers slower, changes in direction are slower, which can slow a car down on courses that have quick switchbacks.

wait, i thought we just agreed on hte fact that spring stiffness doesnt affect weight transfer?

i can see your point about switchbacks, but that is case specific already :) i'm talking general all around driving/regular track.

adey

05-09-2004, 10:06 PM

I don't understand how spring rate would NOT affect weight transfer in real driving conditions.
It sounds like we've established that it would take more TIME for weight transfer to finish/completely occur on soft springs (stiffer spring rate means there'd be less travel, making the transition faster because less distance moved)...

Given that, wouldn't the force distributed on the wheels be different?

If you shift (hypothetically) 500lb from inside to outside in the span of 1 second versus if you shift it over in 1/2 second, the tires would react differently, no? (Time frame exaggerated.)

That's just something that comes to mind, it's not a thought I've given more than 3 minutes' worth of exploration.

DuffMan

05-09-2004, 10:18 PM

Spring rates effect the SPEED of weight transfer, but not HOW MUCH weight transfers.

DSC

05-09-2004, 10:41 PM

lowering springs only reduce weight transfer by lowering the cars cg.
500lbs moving onto 250lb springs will just make the car move 2" rather than 1" if you had 500lb springs. The weight transfer takes longer on the softer springs, but not only that...touch the brakes and turn the other direction now :o your cars body is about to move 4" with those soft springs. I'm no physicists but that 4" of roll is going to be less stable than 2".

Kreator

05-10-2004, 08:00 AM

ok so suppose it takes longer to transfer weight with softer springs... wouldn't that be in a sense beneficial since that would imply that weight is more evenly distributed for a longer time vs when the shift is immidiate?

dsc: But assuming springs only direct effect on body roll is the shift in the center of gravity, then if the center of gravity stays exactly the same, it won't matter how much travel there is (not taking into account weight transfer time). You won't feel right since it would feel like a boat, but as far as the car is concerned, it's all the same?

aznpoopy

05-10-2004, 08:26 AM

ok so suppose it takes longer to transfer weight with softer springs... wouldn't that be in a sense beneficial since that would imply that weight is more evenly distributed for a longer time vs when the shift is immidiate?

beneficial to who? i think that's a subjective question that depends on the driving style and the road surface. a drifter would want a stiffer car all around because he wants to quickly hit and exceed the cornering limit of his car, with really quick weight shift to link corners etc. if you were road coursing you would prob want a more gradual set up. even if the limit doesn't change, there's more sensitivity required on the part of the driver to control a car with a quicker shift, so its not so good for ur average driver (me).

a parallel: take two obscenely sized steering wheels. one is a like a astrovan steering wheel and the other is so tiny it could fit in your pocket. the car's steering doesn't change, however the speed at which you can give the car that input does. the larger one is much less sensitive and gives you greater control over tiny steering inputs. the smaller one turns super quick and makes the car feel very responsive, but you lose alot of small adjustability.

sykikchimp

05-10-2004, 09:50 AM

I wish I had got to this topic sooner...

I will agree that softer springs allow for more grip, under specific circumstances. A springs job is to absorb irregularities in the road 1st, and manage body pitch/roll 2nd. Obviously a softer rate spring will allow the tire to roll over larger bumps than a stiffer spring without loosing traction. So if the only thing we were concerned with was keeping the tires in contact with the road under any circumstance, than softer = better.

on weight transfer.. softer springs not only transition the weight slower, they also move MORE weight. Remember that spring rate is how much the spring compresses given a specific load. A softer rate spring will compress more than a stiffer rate spring given a specific cornering load. With the outside of the car compressed more, and the inside of the car released more, you have a 2 fold effect of not only more weight moving around, but more body roll b/c the springs compress more for the same weight load. Think about corner weighting a car. You decrease height of one side to increase weight on that corner. Same principal when your moving.

So, apply this to traction. Any given tire has a finite amount of grip that is directly proportional to the force being applied to it. Increasing weight over a tire will increase the force it sees. This can be good, and bad. Increased weight over a tire will increase it's contact patch (depedant on the pressure in the tire) and will increase available grip at that corner to an extent (think if tire had 0psi, and is mounted on a wheel. It will only be able to provide so much contact.) In a steady state, static cornering situation, you want the springs to soft enough to allow the weight to transfer as much as is necessary to reach the maximum available grip possible for the outside loaded tires. (see why this works for nascar?)

Now suspension travel is also very important. The springs govern this 100%. Remember the springs 2 jobs. 1st Bump absorbtion, and 2nd roll/pitch resistance. Travel must be split b/w the two. In a static cornering situation, you have used up some of your travel by the weight transfer from one side to the other. This will leave a very specific amount of travel left for bump absorbtion. If you hit a bump that is larger than the available travel, than you have lost grip b/c the tire just skipped over the bump as the car was pushed upwards. Running out of travel is very bad b/c it causes all sort of dynamic aftershock with all the other componants of the ultimate grip equation. So as far as travel specifically is concrend stiffer is better with the one exception of an infinite spring rate like a steel pole. This should also make a point that cutting springs on a car that already has travel problems will only exacerbate things. This is really the only problem with cutting springs.

Now, the maximum traction a car sees is at this static cornering load. In a max performance mind set, the max static load will occur just before the maximum available grip of the tire. (sometime a touch after due to slip angles, but that is another discussion.) So, it only makes sense that we want the car to transition to this maximum grip state while cornering as quickly as possible. If we don't, than we have to turn slower, or be going slower. One of the two. Both are slower. Wheel rate (spring rate + roll bar rate + tire compression rate) will determine how quickly the car settles into this static cornering situation. Here, the goal is accomplished the quickest with your steel bar struts. (infinite spring rate.)

So, all these (somewhat oversimplified) goals come together to form the compromise that define a cars handling characteristics. To oversimplify even more, one could state that the best spring for YOU is the stiffest one possible that still allows for the tire to roll smoothly over the LARGEST bump on the suface of the road you plan to drive on.

-charles

p.s. this is all very oversimplified for the sake of discussion. There are of course 1000's of variable which would cause for infinite difference in desirable suspension setups. Not to mention I completely left out alignments b/c I felt they don't really pertain to the question at hand.

DuffMan

05-10-2004, 10:27 AM

With the outside of the car compressed more, and the inside of the car released more, you have a 2 fold effect of not only more weight moving around, but more body roll b/c the springs compress more for the same weight load. Think about corner weighting a car. You decrease height of one side to increase weight on that corner. Same principal when your moving.

Thats a good point, I hadn't thought of that.

Kreator

05-10-2004, 11:19 AM

on weight transfer.. softer springs not only transition the weight slower, they also move MORE weight. Remember that spring rate is how much the spring compresses given a specific load. A softer rate spring will compress more than a stiffer rate spring given a specific cornering load. With the outside of the car compressed more, and the inside of the car released more, you have a 2 fold effect of not only more weight moving around, but more body roll b/c the springs compress more for the same weight load. Think about corner weighting a car. You decrease height of one side to increase weight on that corner. Same principal when your moving.

I'm still failing to see this. If you take a 10lbs object and put it on the spring that stands on the floor, the force exerted on the floor is the same, no matter how much the spring is compressed, and is equal to the force exerted by the object on the floor if the spring was not present at all (assuming spring weight = 0). Same with cornering loads. I understand how stiffness has effect on how fast it takes to shift, but when its completely compressed, the amount by which it compressed doesn't matter (not counting any shifting in the center of gravity!). As for body roll, if the center of gravity is on the axle or rotation, then the car body can be sideways, it won't have any effect on traction, since the center of gravity is still in the same exact place. If the center of gravity is not directly on the axle, but say very close, i would assume the weight shift due to change in center of gravity to be very minimal relative to the weight transfer due to inertia forces. In this case the positive of not having that shift at all might not outweigh the overall lost traction due to stiffer springs. If the roll center is high enough to actually have a notable effect, then yeah, stiffer springs would be better, but again UP TO A POINT where that effect becomes minimized.

Now suspension travel is also very important. The springs govern this 100%. Remember the springs 2 jobs. 1st Bump absorbtion, and 2nd roll/pitch resistance. Travel must be split b/w the two. In a static cornering situation, you have used up some of your travel by the weight transfer from one side to the other. This will leave a very specific amount of travel left for bump absorbtion. If you hit a bump that is larger than the available travel, than you have lost grip b/c the tire just skipped over the bump as the car was pushed upwards.

But this would mean that for this particular situation, the spring is just not stiff enough. If this was the worst/biggest impact on the suspension on the entire track, and your spring is stiff enough to not bottom out at this particular moment, you would not need stiffer springs. True?

So, all these (somewhat oversimplified) goals come together to form the compromise that define a cars handling characteristics. To oversimplify even more, one could state that the best spring for YOU is the stiffest one possible that still allows for the tire to roll smoothly over the LARGEST bump on the suface of the road you plan to drive on.

But this is fairly vague :) Softer spring will always make your even smoother over that bump, so there is no such point at which it's just "soft enough". On the other hand with stiffness there is. You either bottom out, or you don't.

sykikchimp

05-10-2004, 11:39 AM

I'm still failing to see this. If you take a 10lbs object and put it on the spring that stands on the floor, the force exerted on the floor is the same, no matter how much the spring is compressed, and is equal to the force exerted by the object on the floor if the spring was not present at all (assuming spring weight = 0). Same with cornering loads.

Not the same with cornering loads. weight over the outside springs increase due to the springs compression. as an extreme put one side of the car on scales and weigh it. It will be about 1/2 the total vehicle weight. Now rotate the car up onto it's door, and put it on the scales. ALL the weight is now on that side. The weight over each side of the car is not static. the center of gravity is also not static.

But this would mean that for this particular situation, the spring is just not stiff enough. If this was the worst/biggest impact on the suspension on the entire track, and your spring is stiff enough to not bottom out at this particular moment, you would not need stiffer springs. True?

True. Another solution to bottoming out is using a longer spring with a modified strut, or changing the location of the top of the strut mount to allow for more travel.

But this is fairly vague Softer spring will always make your even smoother over that bump, so there is no such point at which it's just "soft enough". On the other hand with stiffness there is. You either bottom out, or you don't.

Sure, you could make it smoother by going softer, at the cost of additional time to reach those satic cornering loads, which translates into corner entry and exit speed losses. Stiffness of the spring shouldn't just be about bottoming out. It's about minimizing the time to reach the static load.

Kreator

05-10-2004, 12:21 PM

Not the same with cornering loads. weight over the outside springs increase due to the springs compression. as an extreme put one side of the car on scales and weigh it. It will be about 1/2 the total vehicle weight. Now rotate the car up onto it's door, and put it on the scales. ALL the weight is now on that side. The weight over each side of the car is not static. the center of gravity is also not static.

No no no no. You are measuring a wrong thing. Ofcourse if you just lift the 2 inner tires, you already have all the weight on the outer tires. A more right measure would be taking a car, measuring the weight on the right side, then putting softer springs on the right side, and stiffer springs on the left and measuring the right side again. If the center of gravity didn't shift due to the tilt of hte body, the weight on the right wheels is going to be the same as with equal springs on both sides, even though the right side is going to be compressed moer then in the first measure.

when u put the car on the side (or jsut 2 wheels) you are changing the FORCE acting up on the spring. But having a constant force, the amount of compression of the spring will have 0 effect on that force.

Sure, you could make it smoother by going softer, at the cost of additional time to reach those satic cornering loads, which translates into corner entry and exit speed losses. Stiffness of the spring shouldn't just be about bottoming out. It's about minimizing the time to reach the static load.

But, from my readings, having weight more equally distributed to all tires, results in higher traction/cornering power, then having more on one side and less on the other. In which case, having the weight transition slower from the balanced condition of equal weight at each tire to unbalanced condition of having more weight on the outer tires would result in actually more cornering power?

sykikchimp

05-10-2004, 01:13 PM

A more right measure would be taking a car, measuring the weight on the right side, then putting softer springs on the right side, and stiffer springs on the left and measuring the right side again.

Given that the springs are the same length, yes, the side with softer springs will weigh more.

But, from my readings, having weight more equally distributed to all tires, results in higher traction/cornering power, then having more on one side and less on the other. This would be correct.

In which case, having the weight transition slower from the balanced condition of equal weight at each tire to unbalanced condition of having more weight on the outer tires would result in actually more cornering power?
No. slower is bad for ultimate speed. Smoothly transitioning the car from one to the other is absolutly necessary, and is the task of the driver. The stiffer the springs, the better the driver must be to smoothly transition from one state to the other b/c it happens at a much faster pace. Any time you delay the time to reach the static state, you reduce cornering speeds. In the hands of an unskilled driver, softer springs would likely be faster b/c they would screw up a lot on the stiffer springs.

Replicant_S14

05-10-2004, 01:57 PM

In the hands of an unskilled driver, softer springs would likely be faster b/c they would screw up a lot on the stiffer springs.

*raises hand*
That would be me. :ugh:
Seriously though, a softer setup may not be the quickest, but it is easier to drive for me. I think that's probably true for any skill level.

Kreator

05-10-2004, 02:04 PM

Given that the springs are the same length, yes, the side with softer springs will weigh more.

ok maybe you are right.

No. slower is bad for ultimate speed. ... Any time you delay the time to reach the static state, you reduce cornering speeds.

How does that work? from the physics stand point?

sykikchimp

05-10-2004, 03:17 PM

Hmm.. I'm not real good with the physics of this stuff, it just makes sense to me that any time not spent at the maximum adhesion limit of the tire is time given up on that lap. It really all comes down to the friction circle and trying to stay as close to the edge of it as possible. Let me try to explain it how I visualize it.

Image one string tied from the top of your brake pedal, that slips around the bottom spoke of your steering wheel, and back down to the top of your gas pedal. There is just enough slack in the line to full depress either the brake or gas pedal (not both at the same time) only when the steering wheel is straight. If you turn the steering wheel, it takes up that slack, and reduces the amount you can push on either pedal all in a proportionate manner. So threshold braking for a corner you must have the steering wheels straight. As you start to turn the wheel, you smust let off the brake to allow the wheel to turn. As you are at the apex, all slack has been removed by the steering wheel. At corner exit, the wheel is relaxed, and you begin to apply throttle as slack in the line allows.

The faster the car is traveling, and the more grip you have (weight + coeficient of friction), the faster the movement b/w the actions of braking, steering and accelerating have to happen. How taught the string is represents how close you are to the edge of the friction circle. Now if your springs can't allow for the car to transition that quickly, then there will be slack in the string for that brief moment while the suspension catches up to you the driver. Anytime not spent at the limit of the circle is time lost.

This also sort of shows how smoothness is absolutely necessary. Remember its a friction CIRCLE, not a friction square. lol :) I know not the best explanation in the world. In a effort to get you what you were looking for a quick google search turned up this jewel of a site:

http://www.miata.net/sport/Physics/index.html

There's a lot there, but I'm sure those articles (written by a Phd in physics) would likely outline it much better for you.

Kreator

05-10-2004, 06:30 PM

this was a bit confusing but i think i see what u are saying... lets say i'll take your word on it (for now :)) since you prolly have been racing more than me.

I do want to get back to the question about car weighing more on the side with softer springs. The only way this is true, is if the center of gravity is not directly on the axle of rotation (which is probably true for most cars, but not what i was assuming when arguin this point). If the center of gravity does not change due to the tilt, then the weight is still equally distributed on all 4 tires. As far as my physics education goes, this is true. If not, you are welcome to draw the side forces i'm missing here :)

Now considering almost no cars have the center of gravity at the axle of rotation, but somewhat above, this would shift the weight. But like i said before, this force is most likely minimal in comparison to the inertia weight shift, and would not have any notable effect. Unless ofcourse your spring compresses alot and your center of gravity is up high (which i doubt is true for most of the performance cars).

AceInHole

05-10-2004, 10:17 PM

Sorry if someone said this, i just skimmed through:
Stiffer springs = less suspension deflection = less body roll.

Although as your suspension is compressed, the camber will increase (in negative camber, of course), there is usually not enough compensation to keep the tire perpendicular to the ground, let alone keeping negative camber to keep an even force distribution over the tire footprint. Stiffer springs = better handling by keeping your ideal suspension geometry intact.

FWIW: I cut a coil off my old sportlines (in front) on the softer portion of the progressive side to increase the springrate. Won a Solo II class championship with them, too.

Kreator

05-11-2004, 08:08 AM

Sorry if someone said this, i just skimmed through:
Stiffer springs = less

well yeah we got that far on the first page already :) question is, is the reduction in body roll effect positive enough to outweigh the negative effect of the car not being able to follow the irregularites of the road as well.

FWIW: I cut a coil off my old sportlines (in front) on the softer portion of the progressive side to increase the springrate. Won a Solo II class championship with them, too.

cutting the coil lowered the cg which had a much more positive effect on handlin (i would guess) than actually increasing the spring rate.

Rennen

05-11-2004, 08:26 AM

I do want to get back to the question about car weighing more on the side with softer springs. The only way this is true, is if the center of gravity is not directly on the axle of rotation (which is probably true for most cars, but not what i was assuming when arguin this point). If the center of gravity does not change due to the tilt, then the weight is still equally distributed on all 4 tires. As far as my physics education goes, this is true. If not, you are welcome to draw the side forces i'm missing here :)

A stiffer spring, by definition, resists compression more than a softer spring. So if the weight is evenly distributed across a stiffer spring and a softer spring, the stiffer spring will resist compression more, creating a force like this:
^
| ^
| |
----------

and the weight is evenly distributed across the car, like this:
----------
| |
V V

add those forces up and you will find that the scale sees a more negative force (weight) on the soft side.

Thats the way I see it anyway, if I am violating any laws of physics, let me know :)

-Matt

EDIT: well so much for ghetto text drawings, it seems to ignore my spaces between lines, just imagine that the second arrow is on the edge of the horiz line, not the middle. ;)

Kreator

05-11-2004, 09:27 AM

Thats the way I see it anyway, if I am violating any laws of physics, let me know :)

Wouldn't matter how much is the spring compressed. The spring expands both directions so the up force exerted on the body on top of the spring will cancel out the exact same force it exerts on the ground. In which case the amount of force does not matter.

Lets go back to my old example for simpler setting. A 10lb weight on a spring that stands on the floor. No matter how much the spring is compressed, the force exerted on the floor is the same.

Same way this works for a car... considering weight is evenly distributed between left and right and doesnt shift when the car tilts.

KA24DESOneThree

05-11-2004, 12:04 PM

I am extremely disappointed that this thread has gotten this many replies. I didn't read much because, well, I don't trust anyone whose name I've never heard before.

sykikchimp

05-11-2004, 12:11 PM

If you had read the thread you might have learned something. so RTFM.

sykikchimp

05-11-2004, 12:28 PM

when corner weighting a car, if your goal is to increase the weight over a wheel, you raise the spring perch for only that corner. B/C none of the other corners heights are changed, you increase weight on the raised corner, as well as the adjacent corner. (think of taking a see-saw that is attached to the ground, and pushing upward on one side until the other side is force into the ground.) Now, if you raised the height of both left side springs, the weight would still be increased on their adjacent springs, but because it's neighboring spring was also raised, the additional weight they would have seen has been shifted to the both the lower springs.

It's the height of the spring that shifts the weight around the car. Not the rate of the spring. The rate only dictates how quickly the weight moves.

Putting equal length springs on the car, one side stiffer than the other creates the same effect on weight over each corner as does using the same rate spring with one side being shorter.

is the reduction in body roll effect positive enough to outweigh the negative effect of the car not being able to follow the irregularites of the road as well. I'm going to contradict something I said earlier b/c I wasn't thinking clearly. There is a point where a softer spring no longer allows for the car to maintain a better contact patch. That point is where the spring can absorb the upward force of the largest acceptable bump on track without compromising the size of the contact patch.

I say acceptable b/c in racing, all things are compromises. If you happen to have one large bump on a perfectly flat course, and you are fast enough on the rest of the course with stiffer springs to make up for the small amount of time lost on that one bump, then you will compromise, and go stiffer, and juggle the car over that one bump.

adey

05-11-2004, 12:29 PM

Wouldn't matter how much is the spring compressed. The spring expands both directions so the up force exerted on the body on top of the spring will cancel out the exact same force it exerts on the ground. In which case the amount of force does not matter.

Lets go back to my old example for simpler setting. A 10lb weight on a spring that stands on the floor. No matter how much the spring is compressed, the force exerted on the floor is the same.

Same way this works for a car... considering weight is evenly distributed between left and right and doesnt shift when the car tilts.
This seems to be a sticking point for you.
It DOES matter how much the spring is compressed. On a car if one corner compresses more than the other 3 (let's say there's just 1 soft spring on car) then that spring will see LESS weight than the other 3 springs. To exaggerate it, this is like a table with 1 shorter leg; the other 3 legs see more weight.

So yes. 10lb on 1 spring regardless of the spring rate will exert 10lb on the floor, but distribute 10lb evenly across 4 springs, and shorten (i.e. lower spring rate) one spring, and the other 3 will see MORE than 2.5lb each. The aggregate force pushing down on the ground is still 10lb, but it's split up UNEVENLY when there are different spring rates.

edit: damn! sykikchimp beat me by <1 minute. -_-;

TNathe

05-11-2004, 02:13 PM

I've been reading this thread and I must say I have learned alot. Good post Kreator! And damn good questions and answers from everyone!

andrave

05-11-2004, 04:27 PM

don't limit yourself to one book, especially one that is contrary to every other book on handling I have read.
go read some more, since you are so fond of reading.. there are plenty of good books out there on the subject ranging from very simple to very complex...

Var

05-11-2004, 04:45 PM

looks like he was basing most of his logic on theory and not taking into consideration the 1000's of variables that factor in to the equation when you actually go drive the damn thing..one more thing..handling to me isn't merely defined as how much grip your car has. You could soften your car up to a point to have a lot of grip on the skidpad but wont actually "handle" well when put through a series of turns. It's a delicate compromise . You lose here, you gain there. and that's why race car drivers are constantly tuning their suspension to find the better compromise.

Kreator

05-11-2004, 05:45 PM

edit: damn! sykikchimp beat me by <1 minute. -_-;

yeah, and he said exactly the OPPOSITE of what u just said.

ok lets go back to the drawing board (sorry for lack of drawing skillz):

Perfect world (from the point of which i was saying):

http://www.wam.umd.edu/~smolyar/pics/pi.jpg

http://www.wam.umd.edu/~smolyar/pics/pt.jpg

No matter how much u'd want to believe that F1 is actually bigger than F2, its actually not. And a block on an incline (which came to my mind when i tried to analyze this) is a wrong analogy. If you think i'm wrong here, please go ahead and draw the forces i'm missing.

Real World:

http://www.wam.umd.edu/~smolyar/pics/ri.jpg

http://www.wam.umd.edu/~smolyar/pics/rt.jpg

So yeah, in real world it will shift. But, pulling some number out of my ass:

Assume:
- center of gravity to spring mount distance = 4 feet = 48 inches
- spring compression = 2 inches
- distance between center of gravity and axis of rotation in balanced condition = 5 inches

Horizontal shift of the center of gravity (this is rough, and i might be wrong but it makes sense to me) =

2 * 5/48 = .2" = 5mm

now stiffen the springs to twice the rate and u end up with only 1" of movement. Result:

1 * 5/48 = .1" = 2.5mm

so, by stiffening the car twice, you lessened the shift by only 2.5 mm...... my guess is, the difference between a 150lbs driver and a 200lbs driver would have a bigger impact. I'm not even talking about all the weight shifting due to inertia. Even if cg is 10" above the axis of rotation,
the horizontal shift is only 5mm less with stiffer springs.

citizen

05-11-2004, 06:20 PM

uhhh, if there F1 and F2 are the same then the springs deflect equally,argue all you want. So your diagram is wrong. The springs will resist with the same amount of force applied to them. Springs resist changes in weight distribution caused my intertia when accelerating from a constant state. Stiffer springs react to weight transfer quicker because they don't need to deflect as much to have their resisting force equal that of the downards acting force from the weight of the car. There is less "body roll", hence less force acting unequally upon either side of the car. Hence less distortion in all four contact patches around the car. Its best to have a car the stiffest possible.

DuffMan

05-11-2004, 09:08 PM

I dont think anyone was trying to say the increase in weight on the outer wheels is huge, just that it exists. On passenger cars the center of gravity is always above the roll center by at least a few inches. But even if its wasnt there would still be more weight on the outside from more roll. Heres my crappy attempt to show it in picture form.

S14DB

05-11-2004, 09:44 PM

How to Make Your Car Handle (http://www.amazon.com/exec/obidos/tg/detail/-/0912656468/102-7904259-9587309?v=glance) is a much better book.

Kreator

05-11-2004, 09:49 PM

citizen: if u bothered to read throught the whole thing, then you would've seen what we were talking about. The tilted car in my pictures has a softer spring on the left side.

duffman: ok, but wouldnt the right wheel still be on the red line on the right? remember, left upper side gets shifted left, but right lower gets shifted right. so in a sense, if the right wheel started out right under the right corner, the bottom right of the car would end up closer to it during the turn. right?

as for the amount of that shift, i'm not trying to argue here. Just saying that as far as i'm understanding all of this, this is the only beneficial factor of having stiffer springs (outside ability to lower center of gravity by running shorter springs and the *unproven* :) factor that having the weight shift faster results in better stability) and is it turns out this benefit is fairly vague, especially in the light of much larger shift due to inertia forces that would make the car tilt like that...

s14db: and you are stating that as a fact because...?

DuffMan

05-11-2004, 10:00 PM

No, in the pic I lined up the wheel with the bottom corner. In reality the inside (relative to the turn) wheel actually goes out relative to that corner, and the outside wheel goes in, which would cause even further weight imballance.

It gets complicated when you start figuring in camber and control arm angles, but the principle demonstrated by the pic is true.

I designed the Nissan Rectanglemobile control arms to have 0 camber at all times. :hahano:

adey

05-11-2004, 11:25 PM

yeah, and he said exactly the OPPOSITE of what u just said.
What's up with the attitude, Kreator? You ask a question we all try to answer... then you flame people who don't reply with what you want to hear. It's like Bush going into Iraq.
I went back and re-read what Sykikchimp said and what I wrote, and don't see how it's the exact opposite.

edit:
if your goal is to increase the weight over a wheel, you raise the spring perch for only that corner. B/C none of the other corners heights are changed, you increase weight on the raised corner, as well as the adjacent corner.
To exaggerate it, this is like a table with 1 shorter leg; the other 3 legs see more weight.

sykikchimp

05-12-2004, 07:42 AM

The inertial forces are the main problem. On a track where you must change directions in a fairly dramatic manner such as a road course this is a very important thing to consider. A lot of those inertial forces can be made up for with properly sized anti-roll bars, thus allowing you to keep those wonderfully grippy and forgiving soft springs. Unfortunately you can only raise sway bar size so much until the two wheels stop working independently.

The weight transfer we have been talking about is definately a small issue, but one you must consider on certain cars. Especially cars where the roll center is moved dramatically as you lower them. For example most mustangs roll center goes below ground when you lower them. I wish I had more info on the geometry of the 240sx so that we could directly apply all this information. Most of the time this kind of weight transfer is lessened by adjusting the suspension geometry so that CG is lower, and roll center is higher.

I will say that weight shifting faster does not make a car more stable. It does make the car faster, IF the driver has the skills to keep everything smooth with the increased speed.

Kreator

05-12-2004, 07:54 AM

What's up with the attitude, Kreator? You ask a question we all try to answer... then you flame people who don't reply with what you want to hear. It's like Bush going into Iraq.
I went back and re-read what Sykikchimp said and what I wrote, and don't see how it's the exact opposite.

edit:

sykikchimp: "Given that the springs are the same length, yes, the side with softer springs will weigh more."

you: "On a car if one corner compresses more than the other 3 (let's say there's just 1 soft spring on car) then that spring will see LESS weight than the other 3 springs"

duffman: ok looking at your pic again. The way you drawn it, makes it look like the axle of rotation is not in the middle of the car, but on the right side at the point where the body sits on the spring. In other words, the spring on your right side never goes up. which actually would be true if you only soften one spring, but don't raise the stiffnes of the other spring. During the turn though, the compression of the spring on hte left is exactly proportional to the decompression ofthe spring on the right (given equal rates), meaning it would actually rotate around the center line...

if the axle of rotation was in the middle of the car, then due to that rotation the top parts (left and right) would shift to the left and bottom parts (left and right) will shift to the right. Right? Wrong? Maybe?

sykikchimp: yeah, what you said is what i'm arriving at :) Basically get it not to bottom out, and then make it stiffer by your feel of the car.

sykikchimp

05-12-2004, 08:10 AM

sykikchimp: yeah, what you said is what i'm arriving at :) Basically get it not to bottom out, and then make it stiffer by your feel of the car.

This is a very common approach. Start with the softest spring that keeps you from bottoming out over bumps while cornering. Now add the largest sway bars possible without limiting the independent motion of the arms. After you add the sway bar, a lot of times you can drop that spring rate a good bit. A setup like this will afford a lot of grip, and driver forgiveness.

Another appraoch that I've seen more and more people go to is using very high rate springs without any anti-roll bars. With modern suspension technology/geometry, this can often afford much faster lap times on smooth, tight courses like auto-x's.

Those tend to be the two extremes for race car setups. In the real world they work well only in specific environments. Soft springs work well on bumpy courses with wide corners. The stiff setup works well on very tight smooth courses. Given that most racers have a limited budget and go to many different tracks, setup is usually compromised so that you can work the car consistantly on just about any race track you go to.

Dream240

05-12-2004, 10:51 AM

This is a very common approach. Start with the softest spring that keeps you from bottoming out over bumps while cornering. Now add the largest sway bars possible without limiting the independent motion of the arms. After you add the sway bar, a lot of times you can drop that spring rate a good bit. A setup like this will afford a lot of grip, and driver forgiveness.

Another appraoch that I've seen more and more people go to is using very high rate springs without any anti-roll bars. With modern suspension technology/geometry, this can often afford much faster lap times on smooth, tight courses like auto-x's.

So there's no third approach?

Here's a question: Am I hurting my setup (AGXs with Sportlines) by upgrading my sway bars to whiteline bars? Are the upgraded sway bars going to counteract the stiffness of the spring/strut setup and make each wheel handle the weight transfer worse than before? Or will the sway bars add to the weight transfer and stability of the car and increase the response of the already stiff spring/strut setup?

My car does have the stock sway bars already, are whitelines really an improvement? Or do I just need Poly bushings in there? OR should I remove the sway bars altogether and try that setup?

Var

05-12-2004, 11:10 AM

for auto-x remove the front sway. for road racing run upgraded sways. i got whitelines sways, they will improve steering response

Dream240

05-12-2004, 11:12 AM

Cool thanks for the tip!

DuffMan

05-12-2004, 07:20 PM

duffman: ok looking at your pic again. The way you drawn it, makes it look like the axle of rotation is not in the middle of the car, but on the right side at the point where the body sits on the spring. In other words, the spring on your right side never goes up. which actually would be true if you only soften one spring, but don't raise the stiffnes of the other spring. During the turn though, the compression of the spring on hte left is exactly proportional to the decompression ofthe spring on the right (given equal rates), meaning it would actually rotate around the center line...

You are missing the point. The whees dont stay in the place relative to the center of a car when it rotates.

Picture a huge bus. When the bus isnt rotating the wheels are about even with the windows, in terms of how far to the outside they are. When that bus leans over making a fast turn, the wheels dont shoot out to be even with the windows. They stay close to the bottom corners. Its the same with a car, just less exagerated.

In order for the car rotating NOT to shift weight to the outside wheel, the wheel would have to be as tall as the car.

Dream240

05-13-2004, 07:53 AM

[QUOTE=DuffMan]When the bus isnt rotating the wheels are about even with the windows, in terms of how far to the outside they are. When that bus leans over making a fast turn, the wheels dont shoot out to be even with the windows. They stay close to the bottom corners. Its the same with a car, just less exagerated.[QUOTE]

HA!...it would be funny if they did though!!! Great analogy.

Kreator

05-13-2004, 08:20 AM

You are missing the point. The whees dont stay in the place relative to the center of a car when it rotates.

Picture a huge bus. When the bus isnt rotating the wheels are about even with the windows, in terms of how far to the outside they are. When that bus leans over making a fast turn, the wheels dont shoot out to be even with the windows. They stay close to the bottom corners. Its the same with a car, just less exagerated.

In order for the car rotating NOT to shift weight to the outside wheel, the wheel would have to be as tall as the car.

yeah ok. I was pretty much ommitting the presence of the control arms.

sykikchimp

05-13-2004, 11:43 AM

So there's no third approach?

Here's a question: Am I hurting my setup (AGXs with Sportlines) by upgrading my sway bars to whiteline bars? Are the upgraded sway bars going to counteract the stiffness of the spring/strut setup and make each wheel handle the weight transfer worse than before? Or will the sway bars add to the weight transfer and stability of the car and increase the response of the already stiff spring/strut setup?

My car does have the stock sway bars already, are whitelines really an improvement? Or do I just need Poly bushings in there? OR should I remove the sway bars altogether and try that setup?

Sway bars will help your car handle in any situation.

and as for the "third approach" my last paragraph talks about intermediate setups b/w those extremes. There are of course other "approaches", but those involve completely reworking the suspension with new pickup points, and geometry.