I have purchased a set of Zeal B2 coilovers from AJ Racing with the street spring rates. Recently I have doubted my decision on spring rates. I am under the assumption that to achieve real handling out of the type r, the rear has to be stiffer. So I thought that I should switch the fronts and rears around (spring rates that is). I sent an email to them and got this response:

"In the question of spring rate settings. All of our own cars from experience (and all that we see in Japan) have stiffer spring rates in the front due to the fact that the cars under braking have severe "nose dive" problems with higher spring rates in the rear. The oversteer is then somewhat severe as the balance of the car is actually upset. Another fact is the weight in front is heavier on all FF cars and therefore the spring rates are to help give the 50/50 balance on the suspension. I do recommend staying with the given rates but if you want a lot of oversteer for autocross. The biggest problem is recovering from oversteer with an FF car as it is very difficult. Let me know what you want to do and we can discuss this further.

Thanks,
Alan
A&J Racing Motorsports http://www.aj-racing.com"

Is this true or should I make the rear stiffer or just leave it!? Now I'm confused! They are ready to ship with the stiff ones up front. Any advise?

PS: I hope Alan doesnt mind me posting this

 

.....well everything Alan said is true.

But what he didn't say is that in jdm land they use skinnier tires in the rear to induce oversteer...

What is your reason for purchasing the coilovers? If you intend to track them (roadcourse) or autox, then you might want some stiffer rates in the rear to suit your needs. Are you happy with the handling of the car right now? (It comes with softer rates in the rear from the factory...)

Without knowing more, I'd suggest you go with the rates that are suggested by the manufacturer for your car. You can always get different springs for the rear if you want more oversteer later, and they are relatively inexpensive (~$200)..... Playing with tire pressures helps too if you want to play with the handling characteristics of the car without having to change wheel/ tire combo or spring rates/ damper rates.....

 

All the succesful North American pro and endurance road racing G3 Integras run higher spring rates in the rear. The JDM thing with soft rates in the rear is a safe understeering approach - and often you see such cars running skinny rear tires to make them turn. If you can be happy with such a setup on a road course you aren't going fast enough. If you are mostly driving on the street leave them heavy in the front and light in the rear - it is much safer.

The idea that high rear rates contribute to nose dive is wrong. High rear rates reduce static deflection and in operation if you only have one inch of droop travel at the rear (what you get with 900 lb rear springs) that's the limit of how high the rear of the car will rise from it's static loaded position under braking. You cannot effectively run enough front rate to reduce brake dive to less than a couple inches in the front because the car would be too stiff and darty and you'd lose grip.

The idea that the heavy end gets the heavy rates is wrong. Slow FWD and slow 911 Porsche people say that all the time, and they can't figure out how the other guys cars can work so good when they're set up all wrong. This fallacy will never go away because, while wrong, it is intuitive to most people.

If you are lucky and can move some weight around you can acheive 50/50 cross weighting - and that's the only distribution you'll ever get 50/50 on one of these cars.

Recovering from oversteer on an FWD car is easy: 1) don't lift and 2) countersteer....

Scott, who used to wonder about rate bias too....but not anymore....go rummage thru what passes for an archive on the Competition board.....


[Modified by RR98ITR, 6:44 PM 1/15/2002]

 

I wonder if any of the AJR cars run smaller rear tires? I don't think they do, so in that case, how do they deal w/ inducing oversteer? Or do they just drive w/ more understeer and are used to it and can handle it just as well as someone who's used to a lil oversteer? This has been a debate that no one's been able to answer aside from japan racers using smaller rear tires. I personally wonder what AJR does since they track their cars but don't think they use smaller rear tires.

Someguy: do you mind asking AJR what they do to counter understeer since japan uses smaller rear tires and they do not (I'm assuming they don't, tho they might, but their pics don't look like it). Thanks.

 

Damn RR98ITR, that was a good post!

-ken r0cker, who is happy there are actually well thought-out posts like this still coming in from time to time.

Bhcvc, I guess he answered your question already - they aren't winning the North American Pro and Endurance Races...

Although, I would gauge that they feel that this is a decent setup for you and I'm sure it is an upgrade over stock all around... While you're at it though, ask A&J about wheel/ tire and brake setup too.....


[Modified by Black R, 9:32 PM 1/15/2002]

 

Someguy: do you mind asking AJR what they do to counter understeer since japan uses smaller rear tires and they do not (I'm assuming they don't, tho they might, but their pics don't look like it). Thanks.[/QUOTE]

Hrm, you could ease off the throttle. I don't know why you would want to induce oversteer though. Neutral handling is fine for me.

 

Sorry can't agree with most of what RR98ITR said.
But I do agree with most of what AJ said.

Running stiffer fronts doesn't necessarily need skinnier tire in the back in induce oversteer. I personally have ridden in an ITR with 16K front and 6K rear (gymkhana setup), 4 identical tires, and the car still oversteered (with thicker rear sway tho). According to my friend who is a shifter-cart racer with trophies filled up all 3 walls in his office, and also a tuning shop owner:

CAMBER affects turning characteristics the most. It was provened on the above mentioned ITR with -3 front and -1 rear.

My friend was driving the car. I was surpised by how much speed that car could carry INTO a turn even with that high of spring rates in front. Then as the turn's radius decreased, the tail stepped out. My friend said it is what he expected because -1 camber is not enough.

 

"The fastest way to drive a fwd car is in a constant state of oversteer" - Some ITA driver whose name I've forgotten. Also I believe RoadRacer on this forum said the same thing before. In my experience, that is true.

 

Toe also has a great effect on the cars ability to turn and to be stable. Camber should be set for whichever tire you are running as some tires like more camber than others. Assuming camber is set correctly for said tires, RR98ITR's post is 100% true imo.

 

Correct. Conventional wisdom in FF racing setup is to use higher spring rates in the rear, as much as 1400# in some cars, with big rear sway bars to enduce as much oversteer as the driver can handle.

As others have pointed out, the setup of your car will highly depend on what you plan on doing with it. If you drive it the street alot, tool around with your friends, street race, drive fast on back roads, etc, I would highly consider staying with the stock neutral to understreer balance that most off the shelf kits provide. If you are going to AutoX, go to track events, and really learn to drive your car in a controled enviroment, you will want more oversteer.

For a street driven car, 300-400# in the front and 400-600# in the rear are quite streetable and can be done on off the shelf Koni Sports or other high end shocks. Anything more then 600# will need custom valved and possibly shortened shocks.

If the spring rates are high enough to handle the weight transfer under full braking, then there won't be much brake dive. The front to rear ratio has nothing to do with it.

Not really, if you know what you are doing. Don't lift, couter steer, full gas, hope for the best. The biggest problem is people who put oversteering setups on their street cars and don't know how to handle it. They usualy end up wrecking.

Again, it depends on what you want to do with the car. The Type-R already has a very neutral setup from the factory. A stiffer and lower suspension setup will inherently give you more oversteer then stock, no matter if the fronts are stiffer. The neutral to understeer characteristic of the car will remain, just the performance envelope will be moved up a bit.

If you are able to get custom spring rates for the Zeal stuff, then stick with thew off the shelf setup for now. Once you are ready to move up, get some custom spring rates for it where the rears are stiffer then the fronts.

I have been running Eibach Pro-Kits on track for the last year. They are around 320# in the front and 120-190# or so progressive in the rear. Understeer city, but the car was still my daily driver at the time. Now that it is race only duty, I will be going with a more aggressive setup.

Hope that helps. If you need more edvice on this topic, pop over to the competition forum.


[Modified by SPiFF, 10:34 PM 1/15/2002]

 

For those who promotes the idea of stiffer rear springs because the US championship ITRs did so, do you know the exact suspension setup of those cars??

It's kind of vague to suggest people to run stiffer rear springs but no data on alignment setup. I also don't see those ITRs sliding through a corner (oversteer) so it must be something about camber settings or the like.

 

Thank you for the responses. This board is full of knowledge! Since it will see only occassional track use, my car will have the stiffer front springs. I can always change them later. I called AJ and they are being shipped tomorrow.

Thanks again,
Alex

 

What Scott said.

stiffer front = blah.

There is oversteer and there is neutral. The goal is to have the car be neutral under power. Anyone can get a car to oversteer if you friggin lift, but who the hell wants to do that?

You want to know why you don't hear of winning road race Integras in NA is running stiffer front than in back? Because those cars keep losing to the properly setup ones

Warren

 

You mean the RealTime cars? They probably don't disclose their exact setup.

True. Alignmnent is the most import part of setting up a racing car. The thread was just talking about string rates.

Sliding and oversteer are 2 different things. You don't see race cars sliding becuase sliding is slow. If the car is sliding, it has lost traction and is not under control. Also keep in mind that with FF cars, the power is up front and the car is effectivly being pulled. Oversteer is used to get the car to rotate at turn in. Hense the name oversteer -- the car is turning more then the steering imput would normally dictate. Once the car is turned, it is under power and the rear of the car follows the front. At that point it is in a neutral state.

 

hehe my car oversteers under power sometimes.. damned bumpy sebring pavement

lol

 

But why are they running stiffer front springs in japan? There must be a reason for this too

PL

 

Their setup is quite a bit different. First they run slicks, not DOT approved competition tires (r-compound). There is a big difference. As big as from street tire to r-compound.

They also run smaller tires in back. Why? I don't know. They have some great parts, like the Mugen N1 shocks, but for whatever reason they choose to take a different approach. I'm betting that our setups are faster. What can I say, I'm patriotic Besides, if you've had the chance to drive both setups, you'd agree.

Warren

 

Dudes.....first let me say: ....peace.

Next: With respect to what the Realtime team runs for springs and dampers: IT IS NO SECRET. I was personally at two SVWC races in the last 2 years. I asked Peter, Jerome and the rest of the crew tons of questions about their setups, I was invited to crawl all over and under the cars. The partnumbers are painted on the springs and the wire diameter and coils were there to be measured. The dampers are off the shelf Mugen N1 - they told me this, Scott Zellner tells me this, and I have circumstantial evidence that that is true (as if I might think so many nice people would all lie about it). One reason none of this is a secret is because the key competitive advantage is the DRIVERS.

Wai - You are wrong about camber being the most important thing. You can balance a front high rate G3 by abusing camber adjustment, but you do it at the expense of absolute grip. Spring rate bias is about control of dynamic corner weighting - the distribution of lateral weight transfer. THAT is the most important thing. All of my suspension posts in the last year have pointed to the relative stabilization of rear camber in conjunction with keeping weight off the inside rear and on the inside front. Cars set up like your friends - JDM style - typically push, and when overcooked the rear as you said "steps out". This is a type of instability is rooted in the broad range of camber the rear of such a car works thru as it uses 2 to 3 times the rear wheel travel of a high rear rate car. Granted a stiff car (however arrived at) restricts the dynamic camber range, but front high will sacrifice total grip. And a big rear bar isn't the answer all by itself because you still have all that pitch motion.

If you take your example setup and the car is balanced, the rear tire temps will show a huge gradient. That would also explain the JDM cars misbehavior over the limit. A rear high car is very forgiving. And if you watch SVWC carefully you'll see that Pierre and Hugh drift out of the turns real nice - they don't push like all the JDM cars in the BM videos.

Scott, who didn't know what was true about all this a year ago....I worked hard at this by talking to the right people, looking at the fast cars, and crunching alot of numbers in Mitchell software.....

 

Scott knows the science behind all this . I'm just another driver that borrows working setups

Oh yeah, this setup also very well for some rwd cars. Take my E30 M3 for instance. I run about 300 and change up front and 700 progressive in back. Ask any winning BMWCCA J-Stock driver what setup they are using. I bet they are almost all going to say Turner Motorsports E30 M3 J-Stock setup, which is what I run.

Warren

 

I'll throw in my 2 cents. and i've mentioned this couple times before in other threads.

- track surface in general is very different between Japan and US. Japan has excellent glass smooth surface while US is bumpy. thus they can run the high spring rate up front and we run softer front rates. a setup that works good in japan will probably not work well in US with out tweaking... a lot. there IS a reason why US FWD cars usually run much heavier rates on rear.

- they also have more tire brand, and compound choice, as well as they frequently run different widths too.

 

I would like to know this as well. My gut feeling is that they are probably not. Does any1 have info on the setups of real FF race cars in Japan? I am not talking about show cars or display cars from Spoon and the like.

 

I respect all the input from anyone. I won't call anyone right or wrong. It's always good to accept different ideas then come up with your own. I believe that there is no *ultimate fastest setup* on this planet. It's all about driver's preference.

Based on my personal experience, stiffer front springs showed me the magic on a nose heavy car with proper alignment setup. On the other hand, stiffer rear springs would tend to "jack the rear end up" when braking into a turn, especially if the dampers don't have extension adjustment; thus causing oversteer, in which I would percept as being "unstable".

In response to frank@b16a.com's comment about crappier track surface in the US, I rode in the ITR on even crappier public road in Hong Kong. So the pavement difference can not convince me of why we run stiffer rear springs here.

I would have to say that amatuer racing in Japan, in general, is much more professional than in the US (amatuer/professional, ironic isn't it? ).
Pick up a Japanese magazine, you would see numerous articles on those "Sunday racers". Pick up a US magazine, you would see numerous articles on those "Everyday ricers".
That's the biggest difference I see between the 2 countries.

Number of tracks in Japan is amazingly large. Going to a track becomes a pretty general hobby; therefore, their general knowledge and experience are pretty trustworthy. So, honestly, I would count on their opinions and expertise more based on the theories behind their setup. And I wouldn't say if the US or Japanese setup would be faster than the other. After all, it all comes down to the driver.

Were you able to find out the alignment settings on those cars? That comes to my point again: alignment settings affect turning characteristics the most. Springs are there to keep the car as level as possible under braking, accelerating and turning. Alignment should be the key to decide turning characteristics of the car.

In the US, the purpose of each suspension component seems to get mixed up sometimes. For example, the main purpose of a sway bar is to reduce body roll, not to induce over/understeer. People put stiffer rear springs and thicker rear bar for oversteering behavior, but keeping the alignment setting stock. Yeah they could achieve what they wanted, BUT in reality the car is riding on the tire sidewall in a turn. I found that people here ignores the importance of alignment settings, and focus on changing other components to achieve their desired behavior. Again, it's not wrong, just a different approach.

My other guess on those SV cars is that by having stiffer rear suspension elements, the rear tires would attract more motion; thus, higher temperaure in the rear and the front would run cooler. Well, just a guess, maybe I'm way off.
And sure there're secrets that we can't see on every race cars!

Another theory is that no matter what's going on on your car, after all, it would all come down to the TIRES, which are what actually touching the road. Having aggressive camber may sacrifice braking distance in a straight line, but once the steering wheel is turned, the contact patch and the adhesion of tires matter most, not the springs. So now, it's like they're saying apple is red, and you're saying banana is yellow. Different theories and both work. But I still stay with my original belief: stiffer front than rear because of the heavy nose, change alignment settings to make the car turn the way I like it to.

That car did not push at all. That's different driver's preference. He wanted his car as planted on the ground as possible, hence the -3 camber in front and was still dialing in the rear alignment setup.

Since the dynamic camber range is restricted as you stated, the "static" camber has to be set more agressively so that total grip would not be sacrifice. I agree that big rear bar is not the answer because the main purpose of it should have nothing much to do with grip. If I want oversteer, I would consider less rear camber, rear toe out, or even stiffer rear damper setting instead of having a stiffer rear spring and thicker bar. Still work, wouldn't it?

Why would it? Whatever tires scrab the ground the most would have the highest temperature right? Oversteer would eat rear tires while understeer would eat fronts. Correct me if I'm wrong here: you have an impression that my example setup (front stiff, rear soft) would induce too much understeer for track use. With that said, the front tires should show a huge gradient, not the rear, right?

Hmm... that I have no comment. Dunno how you define "misbehavior".

That I have to correct you. 85%+ cars in BM are stock cars so understeer is what should be expected. I don't remember seeing the JTCC Accord or Civic plows through a turn tho. And the Group N Spoon EK9 does run higher rates in front than rear.

Definitely not doubting Scott's knowledge on this whole thing.
But I also give great respect on the data that KYB has put together for competition use. They even recommend F20K (1130#) and R8K (450#), along with some alignment settings for the EK9 application. That's a HUGE front and rear difference. I can't really figure out their logic behind this.

 

Well, if all is opinion and every idea is valid, then there's really no point in talking about it.

Absolutely love your idea about high rear rates causing the rear to jack - that renders the fundamental portions of my Physics and Mechanical Engineering curricula effectively just a set of opinions about the physical world.

Next time you look at a North American pro ITR race car in the pits look at the front camber (it's about 2-3 degrees), then look at the rear (it'll be less - but still negative). Ask Jerome what they run for toe - he'll tell you what he told me: a bit of out in the front, about zero in the rear. IT"S NO SECRET. Endicott's King ITR in Grand Am runs similar setup and Scott Zellner will tell you all about it. And again the reason: because he thinks you can't beat Bob anyway. You are putting too much emphasis on alignment. Camber settings are adjusted based on tire temps and car balance - in an iterative tuning cycle tied to track conditions. Toe settings are somewhat dependent on the speed of the track but the amount of variance from day to day is relatively slight.

You are subtley wrong about what sway bars are for, but I'll give more time to later.

Scott, who will quit explaining this stuff some day....and you can all study Puhn, Smith and M&M for yourselves if you want to know what you're talking about.....don't mean to sound ty about it but it goes beyond amusing how some of guys have no understanding of basic physics and you then want their opinions to be as valid as science......

 

Heheh. I agree, let these people study up and draw their own conclusions.

 

It's funny how I backed up my beliefs with evidence and experince but still got criticized as "goes beyond amusing" plus "no understanding of basic physics and you then want their opinions to be as valid as science......"

Never mind. I guess those statements also apply to Showa (Spoon & Mugen) and KYB as they both list higher spring rates up front for competition use.