Spring Rates

[HellsBells]

So I know there's a lot more involved in tuning the suspension and all that.

But I was just wondering purely on spring rates, what spring rates are you guys running front and rear, preferably for a street driven vehicle / weekend racer.

I'm seeing 8kg front and 5kg rears to be more or less a "standard".

Do you guys find this undersprung or oversprung for the ~3600lbs weight of the car?

Anyone know the rough weight distribution front/rear without a driver?

This is strictly about coilovers and with adjustable dampers. The dampers will be valved accordingly to the spring rate of course.

Thank you!

 

[peetiewonder]

u must be looking at the BC Racing or one of the many coilovers taht are rebadged BC's such as saleens and megans. the 8/5 can be a tad rough on shitty roads especially if you're slammed thanks to the stick axle out back but overall its pretty manageable. The adjustable dampening will be your friend for really tuning your ride quality in. I have eliminated a lot of the bounce on my setup. Also as far as handling goes These rates work pretty well. Handles like its on rails as compared to stock and I don't get hardly any understeer, actually slight oversteer at the limit. I would recommened a good set of sway bars to go with the coilovers however because when you drop the car and raise the roll center, you will still get some pretty decent amounts of body roll.

Long story short I daily drive mine 2.5" off the ground on these coilovers and often go from San Diego to LA and vice versa with no major issues. If you are not planning to run slammed the ride will improve exponentially, cuz I raised my car a up a quarter inch in the rear and the added travel made it quite a bit better. Overall I would recommend these without a doubt and have been pleased with the quality. Just make sure u get your camber plates.

 

[HellsBells]

u must be looking at the BC Racing or one of the many coilovers taht are rebadged BC's such as saleens and megans. the 8/5 can be a tad rough on shitty roads especially if you're slammed thanks to the stick axle out back but overall its pretty manageable. The adjustable dampening will be your friend for really tuning your ride quality in. I have eliminated a lot of the bounce on my setup. Also as far as handling goes These rates work pretty well. Handles like its on rails as compared to stock and I don't get hardly any understeer, actually slight oversteer at the limit. I would recommened a good set of sway bars to go with the coilovers however because when you drop the car and raise the roll center, you will still get some pretty decent amounts of body roll.

Long story short I daily drive mine 2.5" off the ground on these coilovers and often go from San Diego to LA and vice versa with no major issues. If you are not planning to run slammed the ride will improve exponentially, cuz I raised my car a up a quarter inch in the rear and the added travel made it quite a bit better. Overall I would recommend these without a doubt and have been pleased with the quality. Just make sure u get your camber plates.

Sounds good. I had BCs on a previous vehicle (~2400lbs) and ran 9kg/9kg which was horrendously stiff but quite nice at the track.

So the Saleens are just BCs eh? I know a lot of companies rebadge from BC but I didn't think Saleen would.

If you could do it all over, would you change the springs rates knowing what you know now?

Do you bottom out or scrape on any of those giant dips and bumps on the 405 by any chance, especially in LA?

And did the BC's not come with camber plates? Which plates did you get?

I think I'm just going to mimic your set up. If it survives the 405, then it's exactly what I want. Thanks!

 

[peetiewonder]

Yeah those big dips on the 405 can be kinda rough but if i slow down to like 65 its dealable. Ill be in la after next week if youd like we can meet up and you can check them out.

 

[o2sys]

Spoke to BC racing and they come with front 7kg/mm (391lbs/in) and rear 5kg/mm (280lbs/in) as standard. Though I asked them if they recommend a softer rate for daily driving, the rep suggested that I stay with the 7/5 and just soften the damping on the shocks.

What do you think of the rates? I initially wants to go one step lower 6/4 (336/224).

 

[csamsh]

Spoke to BC racing and they come with front 7kg/mm (391lbs/in) and rear 5kg/mm (280lbs/in) as standard. Though I asked them if they recommend a softer rate for daily driving, the rep suggested that I stay with the 7/5 and just soften the damping on the shocks.

What do you think of the rates? I initially wants to go one step lower 6/4 (336/224).

Maybe 7/4? The thing about changing rebound to softer just sounds like you'd still have the stiffer springs, but they'd be underdamped...not too sure what they're getting at there.

 

[o2sys]

How is your ride with 550/250?

Do these car like a softer rate for the rears?

 

[Whiskey11]

Spoke to BC racing and they come with front 7kg/mm (391lbs/in) and rear 5kg/mm (280lbs/in) as standard. Though I asked them if they recommend a softer rate for daily driving, the rep suggested that I stay with the 7/5 and just soften the damping on the shocks.

What do you think of the rates? I initially wants to go one step lower 6/4 (336/224).

I think you should look at higher end coilovers that use a naming convention that actually has meaning. One of the first tip-offs to "Cheap" coilovers is this 7k/5k nonsense. Give me spring rates in inch/lbs like everything else I use.

As for what rates. I ran 200/175 with Steeda Sports and wanted more rate because I was rolling over too far even with a mild drop. I upgraded to 440/200 and wanted more rate because I was rolling over too far at -3.0º of camber. 440/200 was NOT a bad riding setup because I have a decent set of dampers with my coilovers and not some cheap imported coilovers. I personally felt it rode better than stock (and so did my dad who hates rough riding cars).

I now run 550/275 and it really isn't that bad. If you don't mind a firmer ride it doesn't get much worse than 440/200 does. FWIW, 450/225 is what I think most people are going to say is their "upper limit" for spring rates. Rough stuff in the winter torn roads of Nebraska with 550/275 requires a fair amount of slowing down to avoid excessive head toss but that is the price I am willing to pay for a well handling car. It is buttery smooth on stuff with 1" or less bumps.

 

[o2sys]

I don't get how 7k and 5k and etc is non-sense? Other high end manufacturers use kg/mm rather than lbs/in as well.

Well I'm not trying to start another debate whether this and that is good or bad.

Back to the the topic.. So high rate springs don't necessarily mean poor ride as long as the damping is right? And soft rates doesn't mean soft ride if damping is too hard?



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[csamsh]

I don't get how 7k and 5k and etc is non-sense? Other high end manufacturers use kg/mm rather than lbs/in as well.

Well I'm not trying to start another debate whether this and that is good or bad.

Back to the the topic.. So high rate springs don't necessarily mean poor ride as long as the damping is right? And soft rates doesn't mean soft ride if damping is too hard?



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Remember kids..."cheap imported" is all relative. GC (an import) is cheap import compared to AST, and AST (also an import) can be cheap import compared to $10k Penskes...

Anyway, yes you're correct. Hard springs don't necessarily mean hard ride, if the dampers are up to the task of dealing with a spring like that. My 550/250 setup is quite comfortable.

 

[sheizasosay]

The human head weighs 8 pounds.

 

[jayel579]

I now run 550/275 and it really isn't that bad. If you don't mind a firmer ride it doesn't get much worse than 440/200 does. FWIW, 450/225 is what I think most people are going to say is their "upper limit" for spring rates. Rough stuff in the winter torn roads of Nebraska with 550/275 requires a fair amount of slowing down to avoid excessive head toss but that is the price I am willing to pay for a well handling car. It is buttery smooth on stuff with 1" or less bumps.

Yeah no, "isn't that bad" is an understatement. I have 575/250 linear springs and it is terrible on local roads but then I have fixed back race seats in my car as well. Its not a street driven car anymore though, on the track the car is amazing. I would never suggest anyone have linear rate springs on a street driven car.

 

[Whiskey11]

Yeah no, "isn't that bad" is an understatement. I have 575/250 linear springs and it is terrible on local roads but then I have fixed back race seats in my car as well. Its not a street driven car anymore though, on the track the car is amazing. I would never suggest anyone have linear rate springs on a street driven car.

What coilovers are you using? I don't think it is bad at all. It's not worse than my buddy's EVO IX SE on 800/700's and that car is brutal on the street. Head toss and the whole nine yards. My car is really tame compared to that. The city I live and work in is comprised of something like 75% brick roads made sometime in the late 1800's and even with the large unevenness and dips and bumps at every junction it doesn't ride poorly at all. It's FIRM, yes, but it doesn't punish you when you drive the car. I do NOT have fixed back seats, nor do I have any seats with any real lateral support so maybe that is something worth keeping in mind.

A lot of aftermarket springs are linear rate so that isn't an issue either... infact some are progressive rate and some are bi-linear in rate.

At any rate there is a high level of subjectivity here because what I think is unbearable, others might find tolerable and what I find tolerable, others might find bearable. I wouldn't say either set of coilover springs I've had (440/200 or 550/275) has been unbearable to the point where I'd give up driving it for another vehicle even in my town on winter torn Nebraska roads.

Does 7k/5k really have meaning to you? Do you operate in the metric system? I don't. I have a hard time operating there so when you say 7kg/mm do you really think, "Man, 7kg's will compress this spring 1mm" or are you converting in your head all of those numbers? I have a hard time chosing a +/-1mm difference at a distance by eyesight but I can definitely see a one inch difference when I put a 391lb weight on that same spring.

Then start going into the "maths" behind the spring rates. Do you think of your car in terms of kg or in terms of lbs? Do you think of it's track width and ride height in inches and feet or mm or meters?

If you DO operate in metric then fine, and good for you, I just think the terms 7k/5k involves too much extra work to get to terms that are usable to me. To add insult to injury, 99.999% of your cheap Chinese/Taiwanese import coilovers (BC, Megan, Tein, etc) list rates in "kg/mm" rates. There are a few high end coilover companies (Ohlin comes to mind) which probably still use that naming convention but I think the rest that have their own complete coilover setups are in lbs/in in the US because the metric system is more foreign to us than it probably should be.

 

[Pentalab]

What coilovers are you using? I don't think it is bad at all. It's not worse than my buddy's EVO IX SE on 800/700's and that car is brutal on the street. Head toss and the whole nine yards. My car is really tame compared to that. The city I live and work in is comprised of something like 75% brick roads made sometime in the late 1800's and even with the large unevenness and dips and bumps at every junction it doesn't ride poorly at all. It's FIRM, yes, but it doesn't punish you when you drive the car. I do NOT have fixed back seats, nor do I have any seats with any real lateral support so maybe that is something worth keeping in mind.

A lot of aftermarket springs are linear rate so that isn't an issue either... infact some are progressive rate and some are bi-linear in rate.

At any rate there is a high level of subjectivity here because what I think is unbearable, others might find tolerable and what I find tolerable, others might find bearable. I wouldn't say either set of coilover springs I've had (440/200 or 550/275) has been unbearable to the point where I'd give up driving it for another vehicle even in my town on winter torn Nebraska roads.

Does 7k/5k really have meaning to you? Do you operate in the metric system? I don't. I have a hard time operating there so when you say 7kg/mm do you really think, "Man, 7kg's will compress this spring 1mm" or are you converting in your head all of those numbers? I have a hard time chosing a +/-1mm difference at a distance by eyesight but I can definitely see a one inch difference when I put a 391lb weight on that same spring.

Then start going into the "maths" behind the spring rates. Do you think of your car in terms of kg or in terms of lbs? Do you think of it's track width and ride height in inches and feet or mm or meters?

If you DO operate in metric then fine, and good for you, I just think the terms 7k/5k involves too much extra work to get to terms that are usable to me. To add insult to injury, 99.999% of your cheap Chinese/Taiwanese import coilovers (BC, Megan, Tein, etc) list rates in "kg/mm" rates. There are a few high end coilover companies (Ohlin comes to mind) which probably still use that naming convention but I think the rest that have their own complete coilover setups are in lbs/in in the US because the metric system is more foreign to us than it probably should be.

Tires are all in metric....like 255-45-18..and 285-40-18

 

[Sky Render]

Tires are all in metric....like 255-45-18..and 285-40-18

Seriously? The width is in millimeters, but WTF do you think the 18 stands for?

 

[sheizasosay]

Seriously? The width is in millimeters, but WTF do you think the 18 stands for?

Liu Kang Wins. Finish him!

 

[JesseW.]

a good set of shorten struts sure cured a lot of my ride problems, with a 600f 250r spring rates. for you metric guys thats around 10.7kg and 4.4kg. i will probably back off the fronts to 550 or 500 pretty soon since i have an s2000 i autocross now.

linear rate springs are relatively cheap and easy to find a good set used, why not just get several and test which you like, then sell the rest. i see hypercoils floating around for $80/set used all the time, buy a range, try them all out, sell the other sets that you didn't like for the same $80/set you got them for.

for the street, turning the rebound down and running the front swaybar on the softest setting it rides pretty nice. the swaybar seems to make a huge difference in ride quality between full soft and full stiff. if you want a good ride you only have a few options. softer spring, not much lower than stock with appropriate valving, or stiff springs with $$ shorter dampers that can be adjusted between "street" and "track".

250 pound force/inch = 4.464492 Kilogram/millimeter
300 pound force/inch = 5.35739 Kilogram/millimeter
450 pound force/inch = 8.036085 Kilogram/millimeter
500 pound force/inch = 8.928984 Kilogram/millimeter
550 pound force/inch = 9.821882 Kilogram/millimeter
600 pound force/inch = 10.71478 Kilogram/millimeter

 

[o2sys]

"things that come in kgs is always more exciting than things that come in LBS"

- Jeremy Clarkson, Top Gear

Or something of that nature lol

 

[Pentalab]

"things that come in kgs is always more exciting than things that come in LBS"

- Jeremy Clarkson, Top Gear

Or something of that nature lol

194 countries on the planet...... and 193 of em use metric.

 

[SoundGuyDave]

And the one that doesn't happens to be one of the largest markets for high-performance aftermarket equipment...

"Down with Metrics, we don't want no foreign rulers!"

The bottom line here is that whether you measure in kg or Lbs, you need to use the system that MOST of the people you're talking to understand...

So, I was approaching a standard 1.5705 radian right-hand corner the other day... Or maybe was it closer to 350,000 arc-seconds... ;-)