Springrates - understeer and oversteer


Ok! Educated guess is alright, we can al learn from discussion :)
 
What you mention also relates to anti-ackerman steering geometery on race cars now I think of it, where the inside wheel turns less than the outside for any given steering input. This allows the inner tyre to run at a lesser slip angle relating to its lower load, as opposed to road cars where the inner tyre turns more for ease of turning. The offside of this is that the inside tyre gets dragged at an above optimum slip angle in high speed corners, lessening grip and increasing tyre wear.

So yes, you were right on that one. :)
 
hey i have a type ha tein coilovers on my ek9 and I love them. try full stiff for the rear and 3 clicks to full on the front very nice handling!! :)

p.s. let me know if you try and and what you think :)
 
Very usefull thread have to say!

Balance is the key. Stiffer is not always better. I have found this when i oppted for the Tein super street setup for my EG6 front 8k rear 4k what i would call a back end safe setup, at first i couldnt understand why i was getting so much understeer until i looked into suspention geometrys and weight transfers.

At the moment im still in the adjustment stage as i have oppted for 5k rear springs and an ITR rear anti roll bar to increase the front end grip but sacrificing with a more oversteer prone back end. The balace is improving but still not optimum as in the Isle of Man there is i wide veriety of road surfaces so im finding it difficult to get the settings right with different springs, adjustment of dampers and different ARB combinations. Think investment in more different spring rates is needed

Also the correct understanding of suspension "balance" and actual "grip" in the is thread as i could put it, would explain alot to why people rate tyres so differently as i have noticed some poeple will swear by a sertain tyre brand and type where as others would totaly grade them as useless, as in a way different tyres with softer or stiffer sidewalls will react differently to different suspension setups.
 
Most intelligent thread I've seen in YEARS on suspension theory. I was always taught that you wanted the stiffest suspension that was possible while still maintaining grip because after a certain point you fail to allow for imperfections on the road surface and you start "micro-hopping" the tires. Suspension = Actually interesting physics.
 
Well, there more things to consider. Lowering the car to a point where it's too low well cause the suspension arms to be in the 'upward' position where Suspension travel is limited/shortened. Eventually, it'll bottom out if it's too soft. You want to try to maintain the orginal suspension geometery while the spring rates are somewhat stiffer.

And consider this....not all spring rates are the same even though it's written the same through each manufacturer. Depending on the material, how thick the coil is, how many 'coils' are wounded up, and length of the spring will change dramatically.

Example:
oldnew1.jpg


Same goes with Stabilizer bars. Even though it might say, "22mm sway bar", they aren't nessarily the same with all makers. Most Aftermarket ones are hollow tubing design; some exceptions though. There are benefits to having Hollow tubing design and solid bar designs. Weight reduction, depending on the material the 'memory' might be better(metalurgy), and etc.
 
JunY said:
And consider this....not all spring rates are the same even though it's written the same through each manufacturer. Depending on the material, how thick the coil is, how many 'coils' are wounded up, and length of the spring will change dramatically.
Click to expand...

I have wondered if this was the case. My Tanabe GF210 springs are 4.1K/2.8K, yet feel much much stiffer than a friends car on Eibachs at around 5K/4K.
 
Thats rubbish about spring rates from different manufacturers being different, a spring is rated by how much force is required to compress it by a certain increment, this should be universal for all springs.

Although on different applications there may be more or less preload on the springs, this combined with different dampers/damping settings/tyres will make similar spring rates on paper feel different in reality

For instance a mate of mine has the same coilovers as me, but on a DC2. If you try and push his car from the side then you can move the car a bit

My car on the other hand is rock solid (not very comfy on the go), i run my rear springs slightly preloaded and also run R888 which have a stiffer profile than his hankook RS2, alot of factors to consider


One thing that does annoy me is people thinking that their suspension is too soft, but then yank it up to full damping then think wow it's so much stiffer this is better....... If you feel that the car rolls too much/is too soft then the springrates need uprating, yanking up the damping just makes the suspension rebound faster and is more likely to cause the car to skip about on the road
 
stevenEK9 said:
Thats rubbish about spring rates from different manufacturers being different, a spring is rated by how much force is required to compress it by a certain increment, this should be universal for all springs.

Although on different applications there may be more or less preload on the springs, this combined with different dampers/damping settings/tyres will make similar spring rates on paper feel different in reality

For instance a mate of mine has the same coilovers as me, but on a DC2. If you try and push his car from the side then you can move the car a bit

My car on the other hand is rock solid (not very comfy on the go), i run my rear springs slightly preloaded and also run R888 which have a stiffer profile than his hankook RS2, alot of factors to consider

One thing that does annoy me is people thinking that their suspension is too soft, but then yank it up to full damping then think wow it's so much stiffer this is better....... If you feel that the car rolls too much/is too soft then the springrates need uprating, yanking up the damping just makes the suspension rebound faster and is more likely to cause the car to skip about on the road
Click to expand...

And you are wrong. NOT all springs are calculated the same way. If it's a linear type spring with consistant width material is coiled together, then "Yes" it's possibly measured and preloaded in a same way.

There are springs that are "progressive" and "Double Truncoconical" types. They are measured completely different. Here's proof.
Double truncoconical spring of wire ... - Google Patent Search

Vogtland were the first to use this method.
 
stevenEK9 said:
Thats rubbish about spring rates from different manufacturers being different, a spring is rated by how much force is required to compress it by a certain increment, this should be universal for all springs.
Click to expand...
Are you an engineer? Do you understand the inner workings of the Automotive Spring Manufacturing Industry? Just from seeing what he's written and the link he just posted I think you might, in fact, be "rubbish".
 
Kozy said:
I have wondered if this was the case. My Tanabe GF210 springs are 4.1K/2.8K, yet feel much much stiffer than a friends car on Eibachs at around 5K/4K.
Click to expand...

What strut/shocks are you using? And, what is your friend using?

It could possibly be that reason alone.
 
Yes i'm an engineer

I was reffering to straight linear springs, I do realise there are other types of springs when it comes to cars, progressive rate ones and some race suspension come with tender springs which affect the spring rates (these can be mistaken for helper springs which are fitted to some coilovers to prevent the springs dislocating from the seats when the car is jacked up)

My comment was perhaps a bit generalised, but i'm quite happy to be proven wrong :)
 
There are too many factors in the suspension of a car to base "how it feels when I push it down" solely on springs, especially with adjustable suspension.

I dare say a 14k spring will feel different in a BuddyClub Racing Spec Damper, than if that same spring were installed in a Tein Super Street. They are for two totally different applications, and springs should be carefully selected to suit the application they are being used for.

Take this example:

My setup is 16k F/14K R, and on a dry track will totally waste my friends EF9 Honda Works rally car (that's setup for Targa type touring rallying). However in the wet his 4K F/3K R will hand me my backside, even when I'm running wets. I have yet to find a spring/damper combo which works well under both conditions without changing springs. Our cars have almost identical 0-100 times, and 1/4 mile within .1 sec, so I think its safe to assume that the performance (engine wise) is identical.

Most of the above posts make complete sense, especially those about slip angles! I researched lots with both data logging and G meters to try and find a really high performing setup, and found that for my car the setup was about optimum with no sway bar (roll bar) and the above spring rates. Camber is 3deg front and 2deg rear. Bugger I just gave my whole setup away :lol:

Bear in mind that this is with aerodynamic ground effects and quite a wide tyre.

I have got the car handling as well (if not better) than a Porsche GT3 RS cup car, although he gets me on the straights :lol:

The key is to find a combination to suit your driving style. Many Jap track cars are set up for trail braking (which I personally don't like), and to be able to control the tail (oversteer) of the car with the go pedal mid corner. US Honda Cup cars are set up similarly, to have oversteer in order to control the nose of the car so the driver can see the apex and exit of a corner earlier and so corner faster. Then the diff in the car comes into play and so opens another discussion which we won't go into here, as you can corner much, much faster with an aftermarket LSD than you can with OEM if you choose the right one.
 
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blinx9900 said:
Dont forget tire compound and camber angle play a huge role in all of this, understeer can be combated with tire pressure alone sometimes even.
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Best advice at a cheap price :D

Fiddling with my tyre pressures alone on my old MR2 was fun!
 
I have learnt a lot in the past week on this subject, at some point I will sit down a type out some kind of understandable guide on how the whole system works, it would seem I could have been fundamentally wrong on a few key areas, and if not wrong, then perhaps simply understood it wrong but got the right outcome.
 
Hi, I am an EK4 driver of Gymkhana as Japanese original competition,and interested in
UK civic(EK#) circumstances and settings.
My set up is below,
-Fr coil:20k or 18k
-Rr coil:6k or 8k or 9k
-Absorber:GAB(KYB product and my original set up)....I want Bilstein in reality.
-body reinforce: sus tower bar(Fr & Rr), Adding Spot weld for Door part
-Others:Rr lower arm pillow ball, rigid Engine mount, hard suspension bush
I think suspension set up is deeply related to body reinforcement(adding spot welding,
swaybar,etc)
I have repeated try and error for set up and achieved best settings.
But my setting is for Japanese circuit condition, so This set doesn't necessarily meet the UK condition. Would you tell me UK civic condition for EK4&9, if you can.
Sorry for my bad English(laugh)
 
Sorry for the late reply. (Judging by the number of posts I doubt this will get read, but anyway...)

Looks like you use the typical JDM gymkhana/autocross setup, very stiff up front and soft in back, I would guess you probably use a staggered tyre set up also, maybe 225/235 up front?

Seems a popular setup with some people, others prefer the stiff rear setup and even tyre sizes all round, which is more of a US favourite. No idea on why the different setups are favoured in different coutries, and when pitted against each other often yield similar results in course times, so essentially it just boils down to driver preference.

I use my EK4 in gymkhana events, but being a dual purpose daily driver/track car, I am using 6.3kF/5.5kR. I think it would be fairly safe to say that most people here favour the fairly even setup for front and rear rates, as it keeps the handling balance similar to that of the standard EK9.
 
With relation to the original point of this thread, I missed out the most crucial point in the relationship between spring rates and under/over steer.

Tyre grip is related to vertical load. More load = more grip, but at a decreasing rate. So if 100lb of load can hold 100lb of lateral force, 200lb only results in 175lb lateral force 300lb results in 200lb and so on. This is called the tyres load sensitivity. It varies from tyre to tyre, and is one of a multitude of reasons why some tyres work better on one car than they do another.

This means for two tyres evenly loaded at 200lb can produce 350lb of lateral force. Throw the car round a turn and the weight is shifted to the outside, and off the inside tyre. The outside is now loaded with 300lb vertical load, resulting in 200lb lateral force, and the inside only gets 100lb vertical and 100lb lateral force = 300lb total.

From this we can see that the tyres on a given axle produce the most grip when evenly loaded, as the inside wheel will always lose grip faster than the outside can gain it. Fitting stiffer springs to an axle means that the chassis is less able to distribute the load evenly, the outside tyre sees more load in a turn resulting in less overall grip at that end of the vehicle.

This also goes to show that stiff does not automatically mean better.

Hopefully that clears up some confusion from earlier in the thread!
 
Rep added to Kozy!
I think i actually understand it all now:)
 
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