Late Monday night 7/15, Wai posted a critique of the worksheets I wrote and posted sometime back. His post was laden with what many of you would consider fairly reciprocal insults. After some contentious posting by others the thread was deleted Tuesday morning at Wai's request. I was told that he was going to rewrite it without the personal attacks. I had already written a response, and have waited approximately 24 hours since his original post. What follows is a full copy of his original post, followed by my response. I've gone to this trouble because of the subject matter and for the benefit of the board.

Enjoy.

Scott, who enjoyed writing it....and who requests that any moderator tempted to delete it not do so. The subject matter is On Topic and no less important than anything else we write about....

 

Here's Wai's original post:

This post is directed to an analysis that was done by our fellow Honda-Tech racer RR98ITR (Scott Rinde). Readers please focus on the issue and try to keep all responses intelligent to avoid it being locked. To the moderators, if you see any post contains impropriate personal attacks, please ask the person to edit it or delete it instead of locking the whole thread.

A 10-page G3 Integra chassis analysis done by Scott was brought up during a discussion in this thread: Click . It was presented so that people can justify the knowledge Scott has towards suspension setup for the ITR, and the attitude he has towards certain Honda-Tech members. Many people/racers have gotten a copy of this. After reviewing this so-called analysis, I have the following comments.

--------------------------------------------------------------------

This set of analysis appears to be taken out from a section of a book. It is not ¡§original¡¨ as Scott repeatedly claimed it to be. By plugging A=3, B=4, C=5 into [A^2 + B^2 = C^2] does not automatically make me the ¡§originator¡¨ of Pythagoras Theorem. All Scott did was to look up the specs and measure off some dimensions of an ITR (track width, wheel base, suspension dimension, curb weight, weight distribution, etc.) and plugged them into the equations. I honestly don¡¦t see how it would be so original and unique that it could be used to attack and insult other people.

Despite the ¡§originality¡¨, we move on to the content of this analysis.

For those who have a copy of this, I can assure that 95% of them can not make a head or tail out of it. Although it ¡§looks¡¨ sophisticated, it lacks accuracy, organization, and most importantly none of the references were provided. By creating this kind of grey atmosphere, readers have difficulties to dispute the outcomes, in which case, they would just take it for granted. I am among the 5% and can tell you that this analysis contains a lot of mistakes and wrong assumptions that the outcomes are almost meaningless. I don¡¦t know if Scott is an engineer. I hope he is not because for an engineer who publicized calculations without checking for accuracy, his/her ethic is highly questionable. By calling it a ¡§crude calculation¡¨ at the end does not excuse it at all.

Mistakes everywhere:

Scott displayed his incompetence on performing basic engineering calculations. Numbers were rounded off randomly and inaccurately, and assumptions were inconsistent; all these resulted in substantial discrepancies throughout the analysis.

In the page titled ITR Dynamic Weight Transfer, under Lateral with the assumption of 2,500 lbs of vehicle weight:

1.2 x 2,500 x 20 / 58.2 = 1,000 lbs <http://images.zeroforum.com/smile/emarrow_right.gif> This should equal 1,031lbs.

By using the ¡§~¡¨ symbol, he rounded off the number to 1,000. Is 31 lbs significant? Try hanging a 15 lbs sandbag on one side of your front and rear spring and see if they make a difference.

On another page titled ITR Wheel Deflections , he assumed 750 lbs front corner weight and 475 lbs rear corner weight, which gives a total vehicle weight of 2,450 lbs. Why the weight assumption decreased from 2,500 to 2,450? Those 2 sheets are co-related in the later analysis so they can NOT be taken as independent assumptions.

Regarding the 750 lbs and 475 lbs of front and rear corner weight, this is assuming that our car is perfectly balanced left and right, which is very rough and conservative. But this can be excused by Scott¡¦s disclaimer at the end: it¡¦s a crude calculation.

At this point, some of you may think that I¡¦m trying to make a big deal out of some small insignificant things. Please be patient. More significant issues would be coming right up.

We¡¦re still on page ITR Wheel Deflections. It stated that,
Wheel Rate = Spring Rate / Motion Ratio^2
With a given Spring Rate and Motion Ratio (~1.5 for front, ~1.35 for rear, let¡¦s ¡§assume¡¨ that they are correct since there¡¦re no references on where Scott got those numbers from), the wheel rates can be easily obtained by a simple use of calculator. Then with the given corner weight and wheel rate, the Static Wheel Deflection can be calculated.

But I guess the use of calculator is not as simple as we think for Scott.
For front spring rate of 380 and a motion ratio of 1.5, the wheel rate should be 169, not 180.
For rear spring rate of 450 and a motion ratio of 1.35, the wheel rate should be 247, not 220.
For rear spring rate of 250 and a motion ratio of 1.35, the wheel rate should be 137, not 140.
On top of that, he rounded off the numbers on the correct ones randomly and inaccurately. Remember, this is based on the assumption that the unreferenced Motion Ratios were correct ¡V no similar mistakes like the previous ones were made during calculation. Then since the wheel rates were wrong, the Static Wheel Deflections were wrong. All these wrong information were then applied to the later analysis.

Mistakes are ok, as long as you realize it soon enough and do not carry it along.
Crude calculations are ok, as long as you¡¦re 100% sure that the answers are accurate and valid.
However, this is not the case here.

On pages titled ITR Dynamic Weight Transfer Implications for 1) Braking, 2)Cornering, the wrong and inconsistent information were being carried through.

Under Braking for 380F/250R, Front Corner Weight of 1,050 lbs was used. It¡¦s the sum of 750 (2,450 curb weight assumption) and 300 (2,500 curb weight assumption). The dynamic deflection was calculated to be 5.83¡¨. Minus the static deflection of 4.20¡¨ from the previous page, the answer should be 1.63¡¨ Bump Travel, not 1.50¡¨ as shown. Maybe Scott likes 1.5¡¨ better so he decided to throw it in and pray for no one would ever find out? But all these mistakes do not matter much because all these numbers were start out wrong to begin with.

Under Cornering , the wrong and inconsistent assumptions were once again being carried through. In addition, new assumption was made, and once again inconsistently from the previous ones. He assumed that all weights came off of the inside rear so the f/r weight distribution was 525/475 under cornering. I thought previously the ITR f/r weight distribution was assumed at 61%/39%? When cornering, under the assumption that both braking and acceleration are not involved, this distribution should NOT be changed.

If the sole purpose of this analysis is just to ¡§get the point across¡¨ and accuracy is not a concern, then detail references should have been provided so that readers can focus on the subject, not the numbers. In this case, accuracy is none. Reference is none. Readers¡¦ understanding is also none (unless you have much free time and knowledge background as me to really look into it.) The only purpose I can think of is to tell the readers to look at the gibberish and take the conclusion for granted. Now THAT is more like the sole purpose of this analysis.

Now what¡¦s next after getting the bump/droop travel?
With the bump and droop travels, the amount of camber change can be estimated off of this page . To make the long story short, stiffer springs would yield less camber change, and kind of ¡§support¡¨ the following conclusion:

Stiff rear rates bring rear camber under control, allowing maximum use to be made of the outside rear within a wide envelope, allowing maximum distribution of lateral weight transfer to outside rear to minimize reduction of inside front dynamic corner weight & hence total front grip.

I¡¦m not quite sure how this analysis would lead to this kind of conclusion. This analysis merely explains a well-known fact in a greater detail that stiffer springs yield less deflection and by what amount; hence less camber change. It is quite irrelevant to what is being said in the conclusion because nothing about how camber change affects available grip was mentioned. Regardless, I know what Scott¡¦s bases of arguments are for using stiffer rear, and I would use his exact same concept and apply to stiffer front. I hope it would put all these spring bias debates to an end:

The above conclusion is true and desirable when exiting a corner under wide open throttle. No one, including myself, is disputing that. But when diving into a turn (ala trail braking), the same conclusion and concept from above can also be applied, but to the front wheels.[/b] During trail brake, the outside front corner weight would be the sum of both cornering AND braking. By using the same numbers from Scott¡¦s analysis on F600/R900 setup (even though they are wrong, I just use them for comparo purpose), outside front corner weight would be 750 + 300 + 525 = 1,575 lbs and would yield a 5.92¡¨ ¡V 2.82¡¨ = 3.10¡¨ of bump travel. True that it¡¦s impossible to obtain 1.2G lateral at turn-in, but hey it¡¦s a ¡§crude calculation¡¨. 3.10¡¨ is quite a lot of nose dive and would yield a broad range of camber change ¡V in Scott¡¦s words: it is the root of instability. So softer front springs introduce instability during trail brake. Imagine having an unstable front end when you need to slow down to make a turn, not to mention bouncing off the bumpstop with over 3¡¨ of wheel bump.

Besides this ¡§theoretical drawback¡¨ of rear stiff setup, there is a couple more:

1) The car has more tendency of lifting the inside rear at turn in. Is it good or bad? From the ¡§grip¡¨ standpoint, it was quite subjective based on the discussion from the other thread. For autocross, I think it is good. But for a road course, probably not depending on the individual¡¦s preference. But from the ¡§brake¡¨ stand point, lifting the inside rear would create unnecessary wheel lock-up. In Asia, AFAIK, most Honda race cars do not have ABS. But even with ABS, a setup that is more prone to wheel lockup is less desired.

2) According to the racers in the US, the rear stiff (springs + sway bar) setup favors on-throttle oversteers. But from what I learned from the racers in Asia (it¡¦s only an opinion from certain individuals, doesn¡¦t represent ALL racers in Asia), they do not like it. On a race track, the driver has to be prepared to hit the brakes ANYTIME for a spin in front, patch of oil, another car, or car parts lying on the ground, even if it means that your car is in mid corner. Their races are usually VERY crowded and I definitely understand their concern. I also agree with this wholeheartedly based on my own experience. During EXPO ¡¥02, there were 2 incidences that the car right in front of me spun at track out while I was at mid-corner. Imagine what would happen if I was in the process of ¡§on-throttle oversteer¡¨. Should I hit the brakes or plow into the spun cars?

However, even with the above reasoning, it does NOT mean that the Japanese race cars are plowing out of every turn. With proper alignment settings, high locking ratio LSD, f/r different ride height, different f/r tire sizes, spacers, etc. a front stiff car can be tuned to have virtually no understeer at track out ¡V or if the driver prefers so, the car can also be tuned to be extremely tail happy, up to a point of being scary.

Nothing is perfect. Using stiffer front springs also have their drawbacks, mainly at track out. So it is important for the driver to find out a spot where HE/SHE feels most balanced and preferred.

I think I¡¦ve repeated myself about 500 times already that rear stiff setup is NOT WRONG. It is a different driving preference and just like everything else: it has tradeoffs in exchange of better front grip at track out. It depends on the individual to decide if the tradeoffs are worthy and applicable. Scott accused me of resisting explanation and spreading wrong information; hence deserve the ¡§****¡¨ from him. I guess Scott, as a bigger stubborn idiot himself, should then **** on himself for resisting the existence of ¡§the other setup¡¨ out there and spreading analysis with wrong numbers all over the place. Scott favors the Pythagoras Theorem and I told others that besides this Theorem, Law of Sines and Cosines also works. I am not denying Pythagoras Theorem and its proof. But since more and more people jumped on his back because of his attitude, he accused me of denying the fact so his attitude would look more justified. <http://images.zeroforum.com/smile/emthup.gif> <http://images.zeroforum.com/smile/emthup.gif>

Let¡¦s continue the discussion here.
Upping the rear springs to restrict rear wheel travel hence less dynamic camber change can only be done up to a certain point where the tail becomes too sensitive to bumps. That becomes the limitation. As for the heavy front rates for the purpose minimizing nose dive at trail braking, it has to be balanced out with static camber settings. Unless you are running on street tires, I really don¡¦t think how a ¡V3 or ¡V4 degree front camber would be an abuse for nowadays race tires. For what I¡¦ve seen in Japan, the front rates are often seen at as high as 26K (1500#), and the rear is highest at 20K (1120#). Both Spoon (R20K) and RTR (R1200# I think?) use about the same rear spring rate, so I guess that¡¦s pretty much the limit of the rear before it becomes too bump sensitive?

There is also another mysterious setup out there in Japan. The Gymkhana (autocross) setup that uses heavy front rate, but very soft rear rate (i.e. F16K/R6K, F900#/R340#). This is NOT a misinformation. Anyone familiar with the Japanese racing scene can attest to that. I brought that up once in a discussion but didn¡¦t get much feedback at all except for another personal insult. Now let¡¦s apply the same ol¡¦ concept again and see what happens (soft rate <http://images.zeroforum.com/smile/emarrow_right.gif> big wheel deflection <http://images.zeroforum.com/smile/emarrow_right.gif> wide range camber change <http://images.zeroforum.com/smile/emarrow_right.gif> instability):

When turning in (again trail braking), the stiff front springs allow maximum use of the outside front wheel. When radius gets smaller at mid corners, the rear wheel deflects because of the soft rate, yields camber change, and camber change affects available grip, tail becomes unstable (but predictable) and steps out. Rear end instability at tight turns. Isn¡¦t it preferable for autocrosser? I have autocrossed a few times and I think this behavior is quite preferable. Good grip at medium to small corners, then unstable but predictable (tire adhesion limit) at tight turns. It was funny how Scott couldn¡¦t apply his own concept to a different scenario like that. Instead of getting some of the functioning brain cells to work, he chose to insult. Man, you know, flame war takes a lot of energy.

Long post isn¡¦t it? Thanks for sticking around and read up to this point. I am just a person with way too much free time. Bad economy = slow work = more time on Honda-Tech. That¡¦s it. <http://images.zeroforum.com/smile/embeer.gif> <http://images.zeroforum.com/smile/embeer.gif>

Lastly, Scott needs a new calculator.

[Modified by Wai, 11:29 PM 7/15/2002]
_______

Stuff for sale:
ITR Stock Cat Converter (23K miles) -- $85
ITR Stock Front Strut Bar -- $120

 

This is to respond to Wai's latest post regarding the ongoing chassis dynamics argument. (Note: that thread was deleted this morning 7/16).

Wai's critique represents considerable effort, and I applaud his expenditure of time and motivation.

First let me say that the worksheets that are floating around were originally written up for Karl Shultz in haste one day last year. I acknowledge some small errors and inconsistencies some of which were pointed out long ago. The worksheets were never represented as professional quality. They are merely very useful to anyone with a real interest in what their G3 chassis does. The scope of the analysis is limited to the G3 Integra.

Let me say further that my posts are by nature serial. I don't rewrite from scratch each time I post on a technical matter. Most of what I've done is just typical chassis homework. The original part of my writing is the dissection of the basics as they pertain to Front Wheel Drive cars. It's really too bad that our archive isn't longer, and our search function more effective.

The origins of the sheets are in measurement. I did a reasonable location of all chassis pivots, did a tracking of wheel/shaft travel to come up with average motion ratios, ran front and rear bumpsteer with a typical dual dial indicator rig, ran the chassis pivot locations thru Mitchell Software to produce the data with which I constructed the Roll Center and Camber worksheets for ease of visually following behaviors thru operating phases. All of this is very standard stuff - you can read about it and learn to do it for yourself in Puhn, Smith, et al. What's funny is that I used a cg height of twenty inches (An assumption. I haven't ever tried to locate it - a real pain in the butt whatwith needing to lift the front end about 2 feet on the scales with fixed rigid front and rear suspension), which coincidentally is what Puhn's example uses.

I'm content to disregard the numerical criticism up to here:

QUOTE

Under Cornering, the wrong and inconsistent assumptions were once again being carried through. In addition, new assumption was made, and once again inconsistently from the previous ones. He assumed that all weights came off of the inside rear so the f/r weight distribution was 525/475 under cornering. I thought previously the ITR f/r weight distribution was assumed at 61%/39%? When cornering, under the assumption that both braking and acceleration are not involved, this distribution should NOT be changed.

ENDQUOTE

The biggest idea that one has to "get" in fundamental chassis dynamics is that we get to choose where the weight that is transferred under lateral acceleration comes from and goes to (up to the point an inside wheel lifts) thru spring rates, bars, roll centers, and damper settings to name the most important. Static F/R weight distribution does not define this. If it did there would really be no point discussing any of this. The magnitude of the wrongness of the last sentence in the quoted paragraph above is COLOSSAL.

QUOTE

"Stiff rear rates bring rear camber under control, allowing maximum use to be made of the outside rear within a wide envelope, allowing maximum distribution of lateral weight transfer to outside rear to minimize reduction of inside front dynamic corner weight & hence total front grip."

I'm not quite sure how this analysis would lead to this kind of conclusion. This analysis merely explains a well-known fact in a greater detail that stiffer springs yield less deflection and by what amount; hence less camber change. It is quite irrelevant to what is being said in the conclusion because nothing about how camber change affects available grip was mentioned. Regardless, I know what Scott's bases of arguments are for using stiffer rear, and I would use his exact same concept and apply to stiffer front. I hope it would put all these spring bias debates to an end.

The above conclusion is true and desirable when exiting a corner under wide open throttle. No one, including myself, is disputing that. But when diving into a turn (ala trail braking), the same conclusion and concept from above can also be applied, but to the front wheels. During trail brake, the outside front corner weight would be the sum of both cornering AND braking. By using the same numbers from Scott's analysis on F600/R900 setup (even though they are wrong, I just use them for comparo purpose), outside front corner weight would be 750 + 300 + 525 = 1,575 lbs and would yield a 5.92¨ V 2.82¨ = 3.10¨ of bump travel. True that it's impossible to obtain 1.2G lateral at turn-in, but hey it's a crude calculation¨. 3.10¨ is quite a lot of nose dive and would yield a broad range of camber change in Scott's words: it is the root of instability. So softer front springs introduce instability during trail brake. Imagine having an unstable front end when you need to slow down to make a turn, not to mention bouncing off the bumpstop with over 3¨ of wheel bump.

ENDQUOTE

The other way of saying what I say in the quotation above (that I use almost exclusively now since it's easier to say and for people to remember) is: Any weight on the inside rear is weight that could have been on the inside front.

There are two issues here. First, distribution of vertical tire forces (weight transfer), and second, the effect of camber change on traction. Understanding what's going on requires loading the camber worksheets into your head, and thinking about what you're asking the car to do at each phase of cornering. My treatment is neither comprehensive or exhaustive - it is up to the reader to wrestle with the data and form their own understanding. Anything less is letting someone else do their thinking for them. I pointed out a few of the major headings.

Front deflection (and camber change) is higher in pure cornering than in braking. A static front camber setting for peak lateral G is necessarily going to be suboptimal from braking thru corner entry - this is life, and a compromise is in order.

Since the number one problem with our type of cars is UNDERSTEER (thru all phases of cornering), we want to minimize weight transfer off of the inside front in all phases. The necessary implication of this is that we will unweight the inside rear. We can get all the rear grip we need thru the rear camber setting. My conclusion suggests that by minimizing rear deflection induced rear camber change we get a more stable rear grip envelope that is controlled more effectively by weight transfer alone. Remember that as the inside rear lifts and additional outside rear deflection ceases as the car continues to roll about an axis approximated by the front roll center and the outside rear contact patch, the outside rear will continue to decamber.

To focus attention on roll control thru stiff front rates is to overlook the weight transfer story - at the expense of considerable speed. Furthermore, to talk of instability without considering the effect of overly stiff front rates is a bad thing. We can get away with nearly rigid rear rates in large part because of the lateral component of the front wheels tractive vector (we're literally towing the rest of the car around by the front wheels), and in part because rear grip is not what we're generally short of.

And you CANNOT simply add up the weight transfers under braking and cornering on the outside front wheel. There's a thing called Trig, and another thing called Mohr's Circle - even Ronnie Peterson couldn't drive that far outside the circle.

In the most general case it doesn't make a lot of sense to sacrifice corner exit (straightaway entry) speed for corner entry speed.

QUOTE

2) According to the racers in the US, the rear stiff (springs + sway bar) setup favors on-throttle oversteers. But from what I learned from the racers in Asia (it's only an opinion from certain individuals, doesn?t represent ALL racers in Asia), they do not like it. On a race track, the driver has to be prepared to hit the brakes ANYTIME for a spin in front, patch of oil, another car, or car parts lying on the ground, even if it means that your car is in mid corner. Their races are usually VERY crowded and I definitely understand their concern. I also agree with this wholeheartedly based on my own experience. During EXPO-02, there were 2 incidences that the car right in front of me spun at track out while I was at mid-corner. Imagine what would happen if I was in the process of on-throttle oversteer¨. Should I hit the brakes or plow into the spun cars?

However, even with the above reasoning, it does NOT mean that the Japanese race cars are plowing out of every turn. With proper alignment settings, high locking ratio LSD, f/r different ride height, different f/r tire sizes, spacers, etc. a front stiff car can be tuned to have virtually no understeer at track out, or if the driver prefers so, the car can also be tuned to be extremely tail happy, up to a point of being scary.
Nothing is perfect. Using stiffer front springs also have their drawbacks, mainly at track out. So it is important for the driver to find out a spot where HE/SHE feels most balanced and preferred.

ENDQUOTE

On a racetrack a racing driver is normally concerned with going as fast as possible. To set up a car to be tolerant of sudden braking in mid corner is to surrender speed before you turn a wheel. In order for a High Front Bias G3 car to exhibit a lack of understeer, it would be as incapable of sudden braking in mid corner as a significantly faster High Rear Bias G3 car.

I assume in all my writing that a driver wants to go as fast as possible on a Road Racing course - not be comfortable or feel that the car will protect them from every contingency. This isn't tiddley winks.

In summary, it is amusing to see a criticism of my work on the basis of small numeric errors that incorporates evidence of unfamiliarity with the literature on the subject on the part of the writer of the criticism and demonstrates failure of understanding of the most basic element of the subject. What's really too bad about all of this is the fact that a meaningful study of the subject will be undertaken by relatively few on the board, and without that the average reader has little basis for determining who makes the compelling and factually conclusive argument. That many of these people value political correctness for it's own sake above factual correctness is just the punchline of the joke.

Cliff's Notes: I have a few errors and inaccuracies in my numbers and my car goes really fast. The person who wrote the critique of my work demonstrated clear misunderstanding of some of the most basic concepts of chassis dynamics and advocates a configuration that is guaranteed to cost speed. Those that want to learn are advised to read Puhn's "How to make you car handle", and the Entire Smith series "XXXXX to Win" at the very least. Weight transfer is the drivers primary tool behind the wheel for the management of traction - understanding it on a well informed basis is essential to understanding what you're doing and methodically going about the task of going faster.

Scott, who altered Wai's post from last night slightly by fixing the scripting errors caused by notation. The content of the paragraphs is unaltered and no attempt was made to remove them from their context to alter their meaning.

 

hmmm.... all of this is still over my head for the most part,

my opinion probably doesn't matter a whole lot to you, but I applaud you for the respectful tone in your reply, and would hope that Wai will reply in kind.

 

Hmm. I seem to remember the info going around the first time. I thought that all "inconsistent" numbers, assumptions, etc. were pointed out by Scott at that time. Wasn't the info written to help Karl fiqure out shock (purchase) valving decisions?

Theories not being original.....duh! Never thought there was a claim as to that.

Can't understand why anyone would want to sacrafice corner exit speed for corner entry speed. I love it when someone dive bombs me....& then goes off roading @ track out. See ya, sucker.Go ahead & set your car up that way....just another car not to worry about.

Why does Wai have a hard on for Scott? Seems like he started the unpleasantness early this year. Or was it late last year? What are Wai's credentials? Engineer, student, avid reader?

Who's car/driver is kicking *** & taking names? Well if Scott's calculations are all messed up & his "theory" is all wrong.......Screw it! Better to be wrong & fast than right & slow!

Hey Scott. Do you remember my IM back then? I asked why we try to help people with the info we worked so hard to learn only to have them crap on us. I still apreciate it. I hope others do, too.

 

I respect Wai for the effort he has put out and his willingness to challenge an entrenched idea, but the whole bit about lateral weight transfer is the name of the game and it's a huge miss.

If you assume that the car's chassis has infinite torsional rigidity, until the inside rear lifts, high rates out back are controlling roll amounts at ALL 4 corners! (obviously the torsional rigidity is not infiinte, but it's high compared to the other spring rates we're talking about). <edit: to be more accurate, a high rate at either end dominates the roll amount at both ends> Because of this, the soft rear rates do NOT mean more deflection at the rear until the inside FRONT lifts! I don't like it when one of my drive wheels is off the ground. For lateral weight transfer, with the "no-twist body" assumption, the front roll stiffness and the rear roll stiffness are essentially springs in parallel.. check into it Wai-- if you've got Mathcad or Matlab I can see if I can dig up some worksheets I did a while ago (or find time to make a new one up sometime during my lunch hour).. that way, you can see what assumptions I make, see what effects occur.. and challenge whatever assumptions you wish.. we can do it by email if you want.

I don't know enough about Japanese setups to really challenge them, but your explanation isn't making sense to me..

(Maybe the Japanese are Jymkhana people are masters of the handbrake?)

Edit above for clarity..


[Modified by MechE00, 4:37 AM 7/17/2002]

 

No, if you had read the thread that preceded Wai's post (the one Scott repeats above), you would see that it was Scott who started the insults. But I think Scott has got it absolutely right this time - let's stop the insults, and concentrate on the technical information. So I would suggest that we all move on from the unpleasantness and stick to the facts and the theory, rather than dredging up the "he said, he said". And give Scott credit for doing so here.

 

Wow, I've never seen two people go to such lengths to discredit the other or, at a minimum, discredit what the other is saying. If you believe/know in your heart of hearts that what you're saying is factual, even when the other person consistently and repeatedly refutes what you're saying (whether or not there's good factual basis for his/her view point), then why continue the discussion? Seems senseless to me. This has gone on long enough that most of us (I'm willing to bet) familiar with this debate have formed our own opinion about the opposing perspectives here, and know which side of the argument we choose to side with. I'm really not sure what more is to be gained by continuing this "discussion."

 

As for opinions, there is definitely a point of diminishing returns.. Discussing engineering principles and mathematical expressions can continue to be fruitful among honorable people if people are missing/overlooking something.. or at least, that's what I believe.. I really don't know what Wai is like, but I have a vague impression that he's a reasonable guy, and his quoted post seems to be pretty much the work of a reasonable person.. so I'm guessing that he'll react to scientific/engineering/mathematical discussion in a reasonable way. As for Scott, I must say, I've been a bit... surprised.. at the amount of ... aggressiveness.. Scott has been showing the past few months... (his posts (that I saw) had usually been pretty much "just the numbers/science/engineering"

Anyway, I'm pretty sure Wai is correct about Scott's mathematical errors.. I'm pretty sure Scott will concede that.. If Wai has noticed errors that cause a substantive change in the numbers to the point that it alters a conclusion or a point Scott was trying to illustrate, then that's something that needs to be brought forth, I think.. (or even if it just weakens support for Scott's points)

Despite his recent aggressiveness (in my perception), I still believe Scott to be an honorable guy who will fess up if the numbers show something other than what he thought, and I still believe Wai to be a guy who is seeking knowledge, and will accept input from others on potential flaws in his position.

Then again, maybe I'm just naive..

 

Tonyxcom,

You make one of my points for me: You don't understand the subject matter, and have no basis for evaluating the argument of the subject matter. You only know if someone is being "nice" or not.

Wai misunderstood the point I was making in the earlier attack thread about the Pythagorean Theorem. I used that as an example of a hypothesis with a proof, the rejection of which by an individual would clearly demonstrate ignorance or incompetence (note: these words can be used without "insulting" - when you earn an "F" in a class you don't accuse the Prof of insulting you (well, I wouldn't anyway)). That he responded to this quite literally in this later post is more evidence of how hard it is to communicate with him, and how much difficulty he has with the subject.

Scott, who hopes this helps you see what he's up against....

 

James,

The high rear rate practice isn't properly an "entrenched" idea. It's emergence as the dominant setup on NA H/A's has been coming slowly over many years - especially at the high overall rate levels we've come to take for granted over the last couple of years.

Koni NA only last year dropped their objections to the kind of rates some of us now use. And why? Because their guys were getting their asses handed to them.

And yup, the vehicle has one roll angle, and the end with the higher roll stiffness gets the higher proportion of the lateral weight transfer - that is a huge miss on Wai's part.

Scott, who says again "damn our archive and search function"....

 

Nsxtcjr,

The problem I have with your perspective on this is that I was there when Wai and I first encountered each other last year some time. Wai was not then susceptible to explanation, and alluded to "my theories" as if I make this stuff up out of my ***.

You have committed the error, assisted by our woeful archive and search function, of landing in the middle of a timeline and forming an inaccurate conclusion on the basis of the events most proximate.

I only "started" the insults in the context of that one thread - not in the context of continuity.

Scott, who fully explained why he was insulting....

 

Neo,

It's this simple: I continue the discussion for the benefit of the board and for the excercise.

What's to be gained is the education of the next person.

Scott, who isn't making like education is some mission for him....beyond what I've written in the past about community....

 

James,

Wai is trying. I'm frustrated with his lack of progress and what it means to the board when he writes. The aggressiveness I've shown that has surprised you is reflective of that - I don't think it should be surprising. How many chances do you give someone who keeps getting it wrong? And as I've said before: Do you just stand aside and let them take the podium?

Uh, I addressed the mathmatical errors (I fessed up - and there was no praying) - sorry. But they are small trees in an enormous forest. Wai literally misses the forest for the trees with regard to lateral weight transfer as you noted in your previous post.

Scott, who is capable enough of being an ******* that I could prove James naive, but it should be obvious that that's not what's happening....

 

Heh.. I was actually saying "entrenched" with respect to this board (most everyone on this forum that I notice hold with that idea).. and I was applauding the spirit of "standing up for what you believe in, in the face of the majority".. of course, I don't believe in refusing to acknowledge engineering principles of mechanics, statics, and dynamics.. but I guess I missed out on the whole Scott/Wai history enough so that I still operate under the assumption that he's a reasonable person (since I've seen nothing yet sufficient to prove otherwise..)

As for the emergence of this car setup approach, I actually think I remember the first time I heard about the "stiff rear" school of thought.. it was on this board, and it was a post by you, discussing some VW racers who had pioneered it (if I recall correctly..)

James, who also curses this board's impotent search and archive, many, many times...

 

James,

The rear stiff thing on H/A's predated those posts of mine - there were plenty of smart people rallying Saabs and road racing Minis thru many decades. Jason Saini was trying to share what he'd learned from King and RTR with the VW guys who were running a front high setup advocated by Shine. Their story isn't directly relevant because of different front and rear suspension designs and roll centers - though the basics of the weight transfer story must be the same. He started some vigorous debate but that kind of thing appears to have died out on that board since his departure for S2K-ville.

Scott, who reminds you that SAE is selling Maurice Olley's papers now.....

 

While I am a relative n00b poster to this particular section of the forum, I have been a lurker for some time:

I must admit that much of this argument is not low enough to skim across the top of my head.....

But at a very fundamental level, I can appreciate (and have done so for quite a while) the arguments that both Wai and Scott present.

At the most basic level, I am trying their setup suggestions out for myself: higher f than r or higher r than f and seeing what "feels" better to me... but what feels better is often betraying, and sometimes I'm finding that almost out of control feeling is after all faster... So I've got to take people's word that certain setups are "safe" for the rookie driver like myself.

But just like anything on these boards (or in life), I like to experiment with different setups and see what works best for me. Part of the enjoyment is in the discovery, in this "hobby" after all..... right?

to you both. I haven't seen much more than a polite jab here, and although I understand only a small portion of it, am thankful of the information shared herein nontheless. I guess you are agreeing to disagree?

 

[QUOTE]...What's to be gained is the education of the next person...[QUOTE]

Big honkin'

Due to the explanations of vehicle dynamics in this discussion, I'm better able to visualize what my car is doing when it is doing it, and why. And what I can do as a driver, and as a mechanic, to influence its behavior.

 

for clarification, the setup scott was describing as far as i can tell goes 600lb fr springs (i whole heartedly agree), front sway bar??, big rear sway bar, and 900lb rr springs. is there a front sway bar in use?? as i see it, each end of the car can be dealt with in an essentially individual manner. ie; assuming front grip is maximized, tuning to the rear suspension is done to attain a certain "feel" and can therefore me dealt with as seperate. therefore, if your rear roll resistance is stiff enough to take dominance in controlling dynamic weight transfer, having a front swaybar will be of little detriment because it will control the attitude of the car (less camber change) more then it will dynamically transfer weight. i do not feel that a high front spring rate, low rear spring rate setup is good. at a bare minimum they should be equal (talking wheelrate, not actual spring). i have not taken my car on a track yet, but my setup seems to work well on autocross courses. my rear roll stiffness is high enough that my inside front tire is weighted enough that i get no wheel spin in 2nd gear in a hard turn. my front roll stiffness gives me plenty of turn in and keeps the front tires, with a relatively low static camber of 1.5 degrees, planted. so i'm thinking that for roadracing, were mid-corner and track-out rotation is at a premium, i'll just add 400lbs to my rear springs.
nate-who enjoys techno-babble more then anyone

 

To look at all of this as neutral as I can, I see where Scott backs up his reasoning with fact and logic, but I don't see Wai doing the same. All I see him doing is attacking calculation errors (which have since been addressed) and saying "that's how they do it in Japan". Dunno... maybe I missed something.

Amen.

John -- who's just a innocent bystander, but a closet Scott Rinde fan



[Modified by johng, 10:11 AM 7/17/2002]

 

Actually, I'm not sure if I'm understanding what you're saying, but you can _not_ think of the front and rear as separate. It is the _balance_ of front and rear roll stiffnesses that determines the balance of lateral weight transfer. If you want most of your lateral weight transfer to take place at the rear, you need your rear roll stiffness to be large in comparison to your front.
The roll angle of the car is the same in the front and rear, assuming the chassis is not twisting and the road surface is level (as mentioned in previous posts). Camber and deflections might be different between the front and rear due to pitch from acceleration and braking forces, but the _roll_ of the car (the only thing that anti-roll bars have an effect on) is going to be the same (so long as all four wheels are still in contact with the road.

Whether you want a front roll bar or not depends on how you want to balance spring rates (since roll bars boost your roll stiffness while trying to minimize the effect on the car's behavior over bumps) and front/rear roll stiffness balance.

 

Ken,

Absolutely not. Everyone is free to think what they want. If they venture onto this board, post something erroneous, and I'm interested enough to contest it, I will take the subject apart. I may again indulge myself in making fun and may even hurl insults and invective if it seems useful - that being the online equivalent of knocking on somebody's skull - "hello....hello.....anybody home?"

Agreeing to disagree is on a slippery slope to "there's no right answer - all opinions are equally valid". That's why I like racing - winning is tough to argue against.

Scott, who thinks you might be asking/expecting too much of me....remember: this is the Road Racing / AutoCross board, it's a tough place....

 

okay guys keep it on the technical angle. i don't remember who started what first but i do remember both have you have in one point in time gotten very personal and called each other names and such before. there will probably always be some grudge inside but... oh well.

just sitting back and reading (man it's hard stuff to read sometimes!) i rather just drive... run a spec series! then you have a lot less chassis setup to worry about. ;-) spec miata is looking mighty good to me. i'm hoping to go wheel to wheel next year with some good competition to prove/improve myself.

ohhh I FOUND A MEATY PART of this thread (for me atleast). i believe what's below clearly explains the ideas/theories behind a rear stiff setup. read carefully and absorb it! BTW i'm totally unbiased! I run 560 lbs/" (10 kg/mm) springs all around.

wow, lifting the inside rear is done purposely... i always wondered with super rear stiff springs already why they STILL add a fat swaybar... it is to pick up the inside rear of course.

good point on the rear grip... FWD racing = *** dragging.



[Modified by ghettoRacer, 11:40 AM 7/17/2002]

 

i'm on drugs. what the heck was i trying to say??? leave out the "seperate" part, i don't know where that came from.

essentially, what i'm doing is running lots of spring AND lots of front sway bar. however, i'm keeping the spring rate of the swaybar lower then the main spring spring rate, preventing a situation were the swaybar can compress the main spring even a little. this allows me to run the maximum spring for the weight of the car, and then get even more roll stiffness out of the swaybar. (i do this because i only have 1.5 degrees of negative camber and anything that keeps the car flatter is better, imo). now leaving the front grip alone (i've maximized my contact patch with complete disregard to dynamic weight transfer), i can increase my rear roll resistance to the point the car begins to rotate, ie; i increase the dynamic weight transfer to the outside rear tire enough to overload it's contact patch. to me this seems like a better approach because i've maximized front grip even more now by reducing the amount of roll resistance it HAS to do, plus it was already setup to maximize the tire.

my current setup has not seen really high rear spring rates yet. for autocross, my car barely lifts the rear inside tire off the ground, and when it does it is usually under hard turning and braking at low speeds. my alignment specs are very mild and my car exhibits no understeer. for autocross, my setup seems to work damn good, as i had a 2nd place finish at rome ny on only my second event with the suspension and tires. since then i've done some more refining and at the last autocross, i had 2nd fastest pax time on sat. and the fastest pax time on sunday. both days the courses favored race tires and rwd because they were very tight, constant radius turns, many of them off camber. i figure if my car doesn't push in these kinds of turns, then it shouldn't at higher speeds, but i could be wrong.

 

You did a 10 page set-up sheet for Shultz?!?!

You're a fuggin' bastard .
Wait... Shultz keeps finishing last. Nevermind. Go ahead and keep helping him with his set-up .

Scott, who has had progressively higher rates on the rear of his car this year, and finds that it rotates a little better with each increase, and who now has a bigger rear bar in the works.