Why coilovers have softer rear spring rate than front?

[vroomevo]

Evo Spring Rates
Name
Lowering Springs:
...................................Front.......... ........Rear.............drop

Eibach Pro-Kit:**....165lbs(2.9k)....140lbs(2.5k)....1.2f / 1.2r
Espelir ASD:............263lbs(4.7k)....319lbs(5.7k)....79 f / .79r
Espelir GT:..............308lbs(5.5k)....330lbs(5.9k)....1 .7f/ .98r
Ralliart:...................280lbs(5.0k)....307lbs (5.5k)....0.5f / 0.5r
RSR:**....................224lbs(4.0k)....280lbs(5 .0k)....1.4f / 1.4r
RSR Ti2000..............280lbs(5.0k)....336lbs(6.0k).. ..1.4f / 0.8r
Stock(USDM):..........180lbs(3.2k)....225lbs(4.0k) ......STOCK
Tanabe GP210:.......256lbs(4.6k)....319lbs(5.7k)....1.5f / 1.0r
Tein High Tech:**...196lbs(3.5k)....268lbs(4.8k)....1.4f / 0.3r
Tein S Tech:**........212lbs(3.8k)... 291lbs(5.1k)....2.0f / 0.9r

Coilovers:

APEXI PRO:..............560lbs(10.K).....560lbs(10.K)... .Adjustable
CUSCO Zero 1:........392lbs(7.0K).....280lbs(5.0k)....Adjusta ble
CUSCO Zero 2:........392lbs(7.0K).....280lbs(5.0k)....Adjusta ble
CUSCO Zero 2R:......392lbs(7.0K).....280lbs(5.0k)....Adjustab le
HKS Hypermax II:....392lbs(7.0k).....336lbs(6.0K)....Adjustable
HKS Hypermax RS....336lbs(6.0K).....280lbs(5.0k)....Adjustable
HKS Kansai Tarmac:.448lbs(8.0K).....448lbs(8.0K)....Adjustabl e
HKS Kansai Track:....896lbs(16.K).....784lbs(14.K)....Adjusta ble
HKS Performer:........392lbs(7.0k).....336lbs(6.0k)... .Adjustable
HKS PRO:.................672lbs(12.K).....672lbs(12.K) ....Adjustable
JIC FLT A2:...............560lbs(10.K).....504lbs(9.0K)... Adjustable
OHLINS FLAG L:.............ANy ..............Any ...............Adjustable
OHLINS R/T:.............250lbs(4.4k).....310lbs(5.5k)....Ad justable
Ralliart:....................336lbs(6.0K).....336l bs(6.0K)....Adjustable
Tein Basic:...............392lbs(7.0k).....336lbs(6.0K) ....Adjustable
Tein Flex:.................504lbs(9.0K).....448lbs(8.0K )....Adjustable
Tein SS:...................392lbs(7.0k).....336lbs(6.0k )....Adjustable
Tein RA:...................672lbs(12.K).....504lbs(9,0K )....Adjustable
Tein HA:...................504lbs(9.0K).....392lbs(7.0K )....Adjustable
Tein HT:...................896lbs(16.K).....672lbs(12.K )....Adjustable
ZEAL:.......................336lbs(6.0K).....280lb s(5.0k)....Adjustable
ZEAL Also:...............448lbs(8.0k).....392lbs(7.0k). ...Adjustable

** = progressive rate
Pasted it from evolutionm.net spring rate chart.

why lowering spring/stock springs are stiffer in front and coilovers are stiffer in rear?

will it be OK to i put stiffer aftermarket spring in the front and softer stock spring in the rear?
:roll:

[JWest]

Companies spec springs based on achieving some balance between COST, SAFETY (them not having law suits filed against them) comfort, and performance (maybe).

So here are some options...

Plan A: Your best bet is to work with professionals that have way too much experience making your car do what you want it to do.

Plan B: Ride in as many cars (that are the same as yours) as possible. Then you can try to copy the ones you like. ?You've set up suspension systems before right? When that doesn't work, take it to someone who knows how to do it, have them laugh and poke fun at you as they hand you the parts they had to remove from your car. Then have your car work the way you want it to.

Plan C: Pay someone who doesn't have a lot of experience (with your car), to set up your car. Then after they take your money and you don't get what you want. Then take it to someone who knows how to do it (right), pay them more money, have them laugh and poke fun at you. Then have your car work the way you want it to.

yust my .02

oh ya, there are many books available to explain how to make chassises work, they would be much more helpful than the internet.

only .01 worth :wink:

JW

[rammsteinmatt]

Plan A: Your best bet is to work with professionals that have way too much experience making your car do what you want it to do.

Plan B: Ride in as many cars (that are the same as yours) as possible. Then you can try to copy the ones you like. ?You've set up suspension systems before right? When that doesn't work, take it to someone who knows how to do it, have them laugh and poke fun at you as they hand you the parts they had to remove from your car. Then have your car work the way you want it to.


i vote for this

[all stock]

I don't have that much experience with AWD vehicles or their suspension setup, but typically, nearly all cars have stiffer springs in the front. This can be justified by several reasons.

1. Spring rate is the amount of force necessary to compress the spring 1 inch. This means that a 12k spring needs 12 kilograms of weight to compress 1 inch. Because most cars, Evo included, have their engine in the front, the car is front heavy or biased. A higher spring rate in the front will cause the car to compress less in the front than in the rear. Similarly, the rear contains less weight and requires a lower spring rate than the front to compress.

2. Not everyone is an expert at driving with oversteer. Most people can control a car much easier with understeer than with oversteer. The dynamics of the car becomes much easier to handle with an understeer setup.

3. It all depends on your driving style. Autocross or road race? Autocrossing requires a sharper angle during turns and quick turning. This may be better to have stiffer rears so the tail comes loose easily in order to setup for the next turn. Road racing is much different, with faster sweeping turns in which the rear shouldn't come out as much, or at all.

My .02

[Tarmac02]

all the reason posted here are justifiably correct in some way shape or form...

but the most obvious reason MOST CARS have stiffer springs in the front... is because the engine is RIGHT THERE... look at spring rates on some mid engined and rear engined cars and you'll notice the difference betwen f and r spring rates is a smaller ratio

[all stock]

all the reason posted here are justifiably correct in some way shape or form...

but the most obvious reason MOST CARS have stiffer springs in the front... is because the engine is RIGHT THERE... look at spring rates on some mid engined and rear engined cars and you'll notice the difference betwen f and r spring rates is a smaller ratio

i said it first! :p where's my prize?

[trannb]

1. Spring rate is the amount of force necessary to compress the spring 1 inch. This means that a 12k spring needs 12 kilograms of weight to compress 1 inch.

...to compress the spring 1mm (when giving a numerical value in metric). It can also be measured in pounds-force per inch....whatever.

[Blak94GSX]

Basically the spring bias front to rear controls the balance of the car. The more spring rate, the less grip. If you want the car to understeer more, put more spring up front... Is as simple as that...

As to why most vendors have their springs backwards, I don't know...


-Springs control balance front to rear
-Sway bars control balance with lots of steering input (low speeds)
-Shocks control ride quality and should be matched to the springs
-Tires control grip and steering response

Oversimplified yes, but these are the fundamentals.

[vroomevo]

thanks for the info guys.
now i am using espelir ASD for the front and stock spring for the rear.
I got the RRE sway bar at the same time and car feels alot more neutral now. maybe i will try with stiffer espelir spring in rear later.
i am still newbie in suspension and can't really tell the difference between different spring rates.

[JWest]

heh...

if you want to worry about such things... consider where the force of the spring is applied. if it doesn't attach dirrectly to the hub, there is some sort of leaverage type ratio you need to tink about. also the angle the force is applied at can give you another ratio. and then...

still, seems better to let someone else think about these things, so you can consentrate on driving ;-)

JW

[erikgj]

Evos have a 60/40 weight distribution.