How stiff can springs be before its too much?

[thechromecoyote]

Before the crash I was discussing replacing the springs from a mugen ss kit bc I sourced a great deal on some struts, but the springs werent available with them. I am def leaning towards getting a set off of Doug when his become available (and assuming they are in good shape), but I wanted to ask about what my other spring options were in the suspension Guru's recommendations.

So Ive been more and more checking out Eibach springs to pair with my showa shocks, but Im interested in just how stiff a spring I could run on them?

Originally the mugen SS had a spring rate of ((283 Front/439 Rear)) and it resulted in a 1.5-1.8" drop for USDM cars.

Drop wise, that puts it in the realm of the Eibach Sportlines (20-25% more than stock- 297 / 528 ) - Drop: (1.4in Front/1.5in Rear) But the rear is much stiffer than the mugen SS kit.

Additionally, if I went with 02-04 RSX-S versions of the springs, Id be looking at a (335 / 550) springrate. :mangel:

I had also been looking at the Tein S-Techs (280 /515) Drop: (1.4in Front/1.3in Rear) as a more closely matched option.

How would running much stiffer spring rates affect the struts? They were designed to be paired with a specific spring rate originally, but would they have the rebound characteristics to handle a stiffer spring? How would the drop be with the 02-04 RSX-S version of the sportlines vs the EP3 version, etc.

Thanks for you help guys! :hungry:

[jw1]

Stiff springs that are paired for shocks that are designed for stock type spring rates will result in blown shocks. I blew the stock shocks on mine when running the Sportline springs.

[MugsyTheGr8]

i know that when you put lowering springs on stock shocks they blow out after not too long because the spring rates of the lowering springs are much higher. as for how much is too much, i guess it would depend alot on how good your tires are.

[thechromecoyote]

i know that when you put lowering springs on stock shocks they blow out after not too long because the spring rates of the lowering springs are much higher. as for how much is too much, i guess it would depend alot on how good your tires are.

right, but I thought that was mostly bc the height differences, not the rebound strength of the shocks. I want to know what happens when you put stiffer springs but maintain the height the strut was designed for. ?? :mbiggrin:

[blackhatchsi]

How stiff can springs be before it's too much for what? I think that it's gonna depend a lot on what you want. I'm no guru so i won't go into details about what i think. I know that when I was trying to get details or suggestions, I waited until Zzyzx and mustclime posted before I made a decision. Do you already have upgraded sway/strut bars?

edit: I went with progress springs (280 front/500rear) and I think that they are a little soft.

[ep_hatcher_510]

I believe shocks have a range of what spring rates it can handle, going to high or too low outside the range is designed for will not be good for it. I think for the mugen SS you should keep the springs since it was paired up with the shock by the maker.

[thechromecoyote]

How stiff can springs be before it's too much for what? I think that it's gonna depend a lot on what you want. I'm no guru so i won't go into details about what i think. I know that when I was trying to get details or suggestions, I waited until Zzyzx and mustclime posted before I made a decision. Do you already have upgraded sway/strut bars?

edit: I went with progress springs (280 front/500rear) and I think that they are a little soft.

yeah, I have 21 mm rear sway with poly bushings and corsport v2 endlinks. Looking to go with the em2 front with poly bushings and endlinks soon too. :mtongue:

I was waiting for Zzyzx and musty too :mangel: How stiff can they be until they threaten the longevity of the struts, height matched of course.

What makes the progress too soft for you? Thats what Im afraid of picking a spring rate thats closer to stock.

I want springs that are great for spirited driving, match the drop of the mugen SS struts and wont destroy the shocks pre maturely.

[oldskoofame]

yeah, I have 21 mm rear sway with poly bushings and corsport v2 endlinks. Looking to go with the em2 front with poly bushings and endlinks soon too. :mtongue:

I was waiting for Zzyzx and musty too :mangel: How stiff can they be until they threaten the longevity of the struts, height matched of course.

What makes the progress too soft for you? Thats what Im afraid of picking a spring rate thats closer to stock.

I want springs that are great for spirited driving, match the drop of the mugen SS struts and wont destroy the shocks pre maturely.

u have the wrong concept in mind.

"How stiff can they be until they threaten the longevity of the struts, height matched of course."

springs can be as stiff as 2000lbs per inch and more. My springs are 750lbs per inch in the front and 700lbs per inch in the rear, planning to go 900 per inch in the front. My struts can go up to 1800lbs if I want to (JRZ coilovers). How much did it cost? 6000 dollars. It all depends on the company and how much research they put into it - of course u get what you pay for. If you goto a company to buy shocks that cost over 3000 dollars, and you request a custom set up that won't last long, the company willl surely let u know "that will not work."

it's not the height that determines the lifetime of your struts. It's really the heat.

You can get as high of a spring rate you want. But spring rates don't mean anything. If you really knew what you are looking into, you would be talking about the wheel to spring rate ratio.


right, but I thought that was mostly bc the height differences, not the rebound strength of the shocks. I want to know what happens when you put stiffer springs but maintain the height the strut was designed for. ?? :mbiggrin:

ummm...it's...good?

"Originally the mugen SS had a spring rate of ((283 Front/439 Rear)) and it resulted in a 1.5-1.8" drop for USDM cars.

Drop wise, that puts it in the realm of the Eibach Sportlines (20-25% more than stock- 297 / 528 ) - Drop: (1.4in Front/1.5in Rear) But the rear is much stiffer than the mugen SS kit."

it's not so wise to calculate the drop by looking at spring rates. the company should actually let u know much you need to lower to get a certain drop. spring rates, majority of the time - if not, ALWAYS - be taken into consideration when the car is moving.

for instance if u lower the car, and u come to a strong stop; the car will lean forward. The rear strut will decompress, the front will compress. If your vehicle is lowered, you'll have less leverage to lean your vehicle forward (lower mass - or whatever u wanna call it.)

shocks don't support weight as a spring does on their own. A 200 lb per inch spring requires 200 lbs to force to compress it one inch.. Adding a shock absorber to a spring suspension doesn't support any additional load while the car is standing still. The car will settle to the same ride height as it did without the shock in the system. WITH a shock absorber in the system, if there is very little resistance to compression, the load gets to the tire relatively SLOWLY. If the shock has alot of resistance to compression, the load gets to the tire quicker (basically bypassing the spring and going directly through the shock).

A stiffer bump setting slows down the motion on its corner and speeds up the load quicker. A softer bump setting does the opposite. If allows the suspension to move fraster and spreads the changes in loading out over a longer extent of time.

If you have money to buy a preset coilover, then get it.
If you have more money to buy a custom built set up, then get it.

It's all in the money and knowing what you want.
Be wise and make sure u take the quality of your daily drive streets into consideration.

Performance-wise, I would just got with thinner front sways in general, and about 25mm sway in the rear. That was my intentional set up, but i never ended up doing the thinner in the front. I had 10kg front springs and 12kg rear springs on my ep3 with 25mm rear comptech sway bar on meganracing coilovers - excellent coilovers to beat up.

If you want 10kg or 12 or 14kg in the front
AND up to 18 kg in the rear

mix match meganracing's struts.
Buy the front struts that can run 10~15kg (meganracing's track version) that's compatible with ep3 (don't ask the meganracing guys, they don't know shit).
Then buy the rear rsx track version struts that can be compatible wtih around 14 to 80 kg.
as far as the knuckles go, ur gonna be using the meganracing ep3 fitment knuckles and top camber.
i'm not sure if this will completely work.

[blackhatchsi]

yeah, I have 21 mm rear sway with poly bushings and corsport v2 endlinks. Looking to go with the em2 front with poly bushings and endlinks soon too. :mtongue:

What makes the progress too soft for you?

I think what makes me feel like the progress springs are too soft is that it tends to be a little bit "swquishy" in turns. I really notice this in long sweeping turns that have a few bumps in it. Also, the nose tends to dive a little more than I want it to when braking heavily. I don't think that this is entirely because of the springs but I do think that if they were a little stiffer, then it woulde make a difference. I also need to install my CTR rear sway and i have D-specs and need to do a little tweaking on those as well. Don't get me wrong, the progress springs are a LOT better than stock and they ride GREAT and the drop looks really good but I wouldn't have minded having a little stiffer springs, especially in the front. I'm still learning. :mbiggrin:

[mustclime]

I put this thread togather on another forum, It might help....

http://forums.clubep3.net/showthread.php?t=565676

Here is a brake down of coilover kits and there spring rates on another forum.....

http://forums.clubep3.net/showthread.php?t=564642

Look, your spring rates should be determaned by you tires, and your dampers are determaned by your springs. Before you start messing around with your strut spring combo, you have to decide what you want from your car. My advice is decide on a wheel tire combo, then a spring rate, then dampers for those spring rates and finaly a swaybar combo to match all of the above....:mangel:

[Zzyzx]

Suspension tuning dictates that you should be running the softest springs you can that keep you off the bumpstops at full cornering loads... And this can be acheaved through a combination of spring rates & anti-roll bar rates, both with their own pro's and con's.

So... are you hitting your bumpstops? or are you looking for something that feels more sporty?

[v1c10us]

for a daily driver your rear should not exceed 620, i have no clue about the front but the same is probably true, although at that stifness steering would suck.
the reason being, you take a corner and there are a few little bumps and the wheels will have a tendency to hop over it. also on launch if the road is not very smooth you're going to have wheel hop bouncing all over the place.
Your spring rates need to be low enough that they will absorb average dips and bumps without you going 80 miles an hour

For a car that is strictly autocross you probably wouldnt want to go over 800 with our cars because then you are making it quite possible that the car would tip over before the springs would compress, assuming your tires dont lose traction first.

edit: there is a calculation that can be made for handling characteristics of your suspension by first finding your tires maximum g rating sideways, they might call it a lateral skid pad or something weird. Then you' want to determine the weight of your car and a bunch of other stuff.. well nvm, im not gonna turn into one of those people who posts stupid equations that no one will use.

To oldskoolfame: nice Yokohama A048 avatar

[oldskoofame]

Suspension tuning dictates that you should be running the softest springs you can that keep you off the bumpstops at full cornering loads... And this can be acheaved through a combination of spring rates & anti-roll bar rates, both with their own pro's and con's.

So... are you hitting your bumpstops? or are you looking for something that feels more sporty?

more sporty duh~ :smile:

[Zzyzx]

more sporty duh~ :smile:

Then get dampers that have stiffer bump valving!.... Though not too stiff, as skipping across road irregularities is a great way to make less traction.