need help w/ spring???

[R2K]

so yeah im thinking of buying a spring... so can you installed it my self??? or some mechanic have to do it??? and which is good??? they have eibach, H&R, tanabe, tein, skunk2... or coilover???

[LexmarkX73]

well first you have to think what you want the sprigs to do. Do you just want to lower the car or actually improve the suspension? Generally if you have to ask if you can do something yourself you should let a professional. Do some searches on what springs/shocks other people have used on the same car as yours, and what people are happy with.

[R2K]

well i really dont want to drop my car, but all they have is lowering spring... unless i buy the coilover or the whole coilover system... well i already think about the spring and how i want them... i want to have a quicker respond but also a comfort when im riding im my car... so what you whould suggest a little stiffer, or something else???

[Ris4drift]

as usual on drifting.com it appears you have posted asking about something you know little to noghitng on.

the way a spring affects the performance is it gets higher/lower spring rates. a spring rate is basically how much force it takes to compress the spring. the higher the stiffer, the lower the softer.

the length of the spring also has a factor, as does the center of gravity , which affects performance. for this reason most aftermarket springs lower the cars ride to lower the center of gravity.

the ride will be affected if you increase the spring rate, but the trick to getting the car to ride well is getting a shock that is matched to the spring well. if the dampening is too high/low the shock/spring will not work together and make a harsh ride. some springs are designed for looks/ride, most springs are designed with the understanding of the possiblity of stock shocks being used, but most quality springs have a shock you can buy with it, to make a full coilover system. which is the best wayto go, however its not the cheapest, but if you wanna do it right the 1st time get a quality coilover system. it will lower the car as will most aftermarket springs/coilover systems. lowerin the car does not affect the ride, but if you lower it too much you can screw up the suspension geometry on your vehicle, most coilover systems are designed for the application though so you wont do this.

[R2K]

why dont buy the whole system??? and why is making your own is better??? and also how you figure the geometry to make the best coilover system???

[Craftsman]

Ok... here is the reason for the combination being better than the single spring with stock damper...

Single spring has a single constant for the amount of force that it will resist. Basically what a spring does is, it takes the force applied to the spring and stores it. That's why any force whether it be compression or expansion, the force from the spring is negative.

Ok enough about the springs. If you have a spring that is too strong for your dampers, you will come across a situation called Underdamped.



This means that your suspension will bounce to hell... This happens because of these equations that I'm about to show you...

wn (natural frequency) = k (spring constant) / m (mass)

So to with vibration control, the goal is to have critical dampening z (damping) = 1

BTW, w is lower case omega greek symbol and z is the lower case zeta symbol...

The equation to get the damping ratio is b (damping coefficient) = 2 * wn * m * z. I'm assuming that the damping ratio (z) is one for critical damping...

Remember to watch your units.

So here's what the time response of your suspension when it's critically damped.



If your damping is too high, this becomes a problem also. It takes a long time for your suspension to settle out... Here's a comparision of critical vs. overdamped.



Red is Critical dampening... It may look like over damping isn't too bad, but you also have to realize that it takes a long time for the suspension return to rest. i.e. You push your car down and it doesn't come back up for a long time.

The mass that you should use is the mass at each corner of the car.

Coilovers are a good idea because they do all these calculations for you and they package them in a good deal for you to own. You might think that $1000 to $2000 bucks is too much, but you gotta think about the after service that most of those companies provide also.

[Ris4drift]

ill make a mental note that a w is a lower case omega symbol lol

$2000 bux is too much considering you can get spl coilovers for nearly 1/2 that.


www.splparts.com

tien he arent bad either. i dunno what they retail for.

most aftermarket coilover kits are made so you dotn have to do work. and even if you wanna get a custom set theres much simpler methods than what craftsman posted. mainly just picking up the phone and making calls to suspension companies. but when youve never worked on a car and want people to think your smart, i can see why youwould post that

[R2K]

so yeah like i said before, which is better the whole coilover system, or just the coil over( spring w/ that round thingy)?

[Craftsman]

Originally posted by R2K
so yeah like i said before, which is better the whole coilover system, or just the coil over( spring w/ that round thingy)?

Complete Coilover and Damper. The math is already done from the factory so you don't have to. The damping and the spring ratios are already set optimally. Usually they come with adjustable damping also which is a plus when you change the weight of your car or doing some serious racing.

In racing, you might want higher damping in a certain side or corner of the car because of weight transfer. You might want to setup the car so it's setup optimally for a particular corner..

Suspension setup is a little more complex than people make it out to be. Just putting on lowering springs doesn't help your car... Or Just swaping out dampers doesn't help either. It's when you match them together that you get a sweet setup.

Ris4Drift. I was just explaining how difficult the setup actually is. Sorry if that was too technical for you. I could have told them to call a shop, but some people might want to do this on their own. I gave the variables tags to tell you what the symbols meant. This is actually the same symbols and equations that engineers use... So I hope you learned alot.

[R2K]

HEY!!! thanks for all your help... yeah its all good that you write so much... i try to learn in the web site but so hard to understand, well atleast you help me w/ the basic so thanks!!!

PS you make my brain cramp up!!!

[R2K]

umm.... so there's a 16 way level damping... so what is the best for daily drive and drifting???

[Craftsman]

It's personal preference. Some people like stiff suspensions. Some like soft. But for street driving, most prefer soft.

[Ris4drift]

Originally posted by R2K
umm.... so there's a 16 way level damping... so what is the best for daily drive and drifting???

the 16 is basically for fine tuning, daily drive your gonna want the softest but on race day (depending on spring rates , tires, car, a billion other things ) youll want to make it stiffer, but adjust the back/front accordingly for understeer/oversteer etc.

[GRiDRaceTech]

Not necessarily. My coilovers are too bouncy for me on the softest setting, so I run quite a bit stiffer.

On an autocross-style drift couse, I adjusted it to be about medium up front with full stiff out back. That led to long slides.