Hey guys,

First off I dont have an ITR, just a Rs. I come to you because you guys actually put your cars on the track, and you seem to have a good understaning of how it all comes tougher.

I am looking into new suspension and I am getting a little confused on what springs rates to go with, and what it all means. I was looking at one set-up and they said it was 450 FT pounds F,300 FT pounds R. Then another setup said 11k F and 6k R. Now I am confused about the 11k and 6k. Is this in inch pounds??? I cant see the springs being 11,000 Ft pounds.

Now my next question, What are you guys running??? I am setting the car up for auto-x and as a back up "daily driver" Really this is my second car, and I hope to make it my thrid car soon (company truck coming soon i hope) Total comfort on the road is not a big deal, but i also want it to perform.

When you change spring rates how can this affect the car? If you only lower or raise the rear rate how does it change, same with the front. I know this is pretty basic info, but it is not something I have really reasearched. I have a pretty good grasp on sway bars, camber, toe, but the spring and shock still have me a bit lost.

Thanks for the help.

 

a quick google would tell you the difference...

kgmm and ft lbs

6k =~ 360 ftlb

frankly if you havent tracked the RS stock, i suggest you do so before you go about wasting your cash making the car a little more dangerous before making the driver a whole lot better.

all USDM production vehicles come with understeer which isnt a bad thing to begin with on the track. as you progress and feel more comfortable on the track, you may opt for higher spring rates, and/or for less understeer.

i used to track a bit on the stock itr suspension which had 240 F/180-240 R spring rates. (progressive). moved up to a little firmer setup - 360 f / 360 r H&R springs

now i'm on 400F/500R coilovers and havent looked back. Much more fun to drive, gives me the rotation I like, but alot less margin for driver error.

some people stand fast with the JDM spring setups for USDM cars, and argue its the best for multiple reasons (cuz its JDM y0...etc). others will say a stiffer rear spring rate compliments a ITR better in the states...

look at the faq and you will find a plethora of knowledge. I cant believe youre asking this sort of question after 1500 posts, but use the search.

road racing forum will help alot as lots of knowledgable people post there who have tons more experience and track time than any one of us.

 

Thanks for the reply. I actually did run a search here on HT and most of the answers where along the lines of " Just go low" "keep it jdm" "just get the cheap egay springs" I found very little usefull information. But then again I am the first to admit that i suck at searching.

Part of the reason i want to swap suspension out is the car came with tokico shocks and lowering springs. I have no ide what rate they are, who made them or anything. I know the fornt shock are blowen, as I need to change parts I figure i might as well upgrade and get a nice set-up. I do agree about making the driver better, but I wont be able to improve with totally crap suspension.

It sound like the 11k/6k would be way to stiff for what i need, and could make the car very unstable.

P.S. Where did you find the conversion for kg/mm to ft lbs?? I found a few conversion, but i still cant get 6k to equal 360 lbs. I know i suck at google also.

Thanks! and I will wonder over to the RR forum and start searching there also.

 

I would suggest getting a set of Koni Yellows and stock ITR springs, since it sounds like you're going learn how to drive on a track with this car. It shouldn't be too hard to find a set of ITR springs.

Later, when you have more seat time, you can have the Koni's revalved and get a set of Ground Controls.

 

Multipy the rate in "k" x 56 to get an approx rate in lbs. I used to have Tein susp that was 8k/6k but it was listed on US website as 448/336. I dont think its quite that same amount but thats ballpark at least.

If you are setting the car up for autox, you will almost CERTAINLY want higher rate in the back (and a big rear sway, 22mm at least). This is assuming you have some autox experience at least, b/c at first no amount of car setup is going to make you faster, its seat time you need.

Good luck

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by jetydosa &raquo;</TD></TR><TR><TD CLASS="quote">Multipy the rate in "k" x 56 to get an approx rate in lbs. I used to have Tein susp that was 8k/6k but it was listed on US website as 448/336. I dont think its quite that same amount but thats ballpark at least.

If you are setting the car up for autox, you will almost CERTAINLY want higher rate in the back (and a big rear sway, 22mm at least). This is assuming you have some autox experience at least, b/c at first no amount of car setup is going to make you faster, its seat time you need.

Good luck </TD></TR></TABLE>

I have allready done the 22mm in the rear. I did a couple small auto-x in my DA, but my DC has not seen the track. This summer i hope to get a few auto-x days in, jsut depends on my bike racing. At least going into this I allready have a good idea of hitting an apex, breaking into a corner, and not in the middle. You have to know a lot of this to hit a corner at 40mph on only 5mm of rubber. Not saying it makes me a good driver, but at least i have the general concept of it all.

The ITR springs are a good idea, I will start looking at the FS thread here, and in the marketplace.

Thanks again!

 

Well, to give you another data point. On my race car (a REAL race car, not a lapping car ) I run 500# front and 1100 # rear. I find it neutral, but then, I am always full throttle in the corners.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MightyMouseTech &raquo;</TD></TR><TR><TD CLASS="quote">Well, to give you another data point. On my race car (a REAL race car, not a lapping car ) I run 500# front and 1100 # rear. I find it neutral, but then, I am always full throttle in the corners.</TD></TR></TABLE>

Just curious, if you run 500# springs in front, your ride height would need to be quite high (might even need to be stock height with race tires?). What are your race rules regarding ride height?

If you don't take full advantage of the ride height, meaning that you didn't go as low as the rule allows, then you are sacrificing grip by allowing excessive weight transfer. Did you find that it is faster with such setup?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Wai &raquo;</TD></TR><TR><TD CLASS="quote">

Just curious, if you run 500# springs in front, your ride height would need to be quite high (might even need to be stock height with race tires?). What are your race rules regarding ride height?

If you don't take full advantage of the ride height, meaning that you didn't go as low as the rule allows, then you are sacrificing grip by allowing excessive weight transfer. Did you find that it is faster with such setup?</TD></TR></TABLE>

Why would running 500# springs up front affect my ride height? YOu don't want to go too low anyways. As soon as the lower control arms go past horizontal, you are designing in a very poor camber curve and excessive bump steer.

As for rules, my suspension mods are unlimited.

 

Racermech - I would suggest starting off in the 300/400 ~ 400/500 range with a set of aftermarket shocks. Koni Yellow or Tokico's would work well. Those rates will provide a dramatic improvement over stock and at the same time they aren't too crazy for the street or a n00b at the track. If you want a better ride on the street you can run the higher rates in the front of the car. If you want better performance at the track you would run the higher rates in the rear, although until you get a decent amount of experience the heavy rear spring may not really give you much.

MightyMouse - I believe Wai was referring to the large split in spring rate front to rear, not necessarily the nominal value. Since we don't know the rest of your set-up the discussion is somewhat mute. As for the camber curve comment.... you/we are always dealing with compromises in suspension set-up becuase that is indeed what it is - a trade-off - one thing for another. Are you setting up for a single critical turn, tire wear, stability, mutliple driver preferences, qualifying lap, etc..... all realtively different and all requiring a different approach.