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Old 03-26-2010, 06:19 AM   #1
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Default Help me pick springrates

Rather than tangent this thread anymore http://https://www.miataturbo.net/forum/t45188/ I thought I'd start a new one.

Firstly I know next to jack about suspension, I currently have NB KONI's (so only one perch choice) with Koni sport springs and OEM ARB's. The front is stupid low and the rear heights are inconsistant side to side. I have a set of eBay threaded collars, and want to pair those with a set of 2.5" x 7" or 8" springs.

I've started tracking my car about once a month, the last trackday was the first truely dry day and it showcased how much my car leans, compared to my old mans setup, (FM Springs KYB AGX FM ARB's), his car corners much flatter.

My car
8K9U2492.jpg?t=1269594576

8K9U1326.jpg?t=1269594578

Dad's Car
8K9U2499.jpg?t=1269595130

I'm not really inclined to increase the strength of my ARB's, from what i've read it'll keep the body under control at the expense of outright grip/more severe loads on the outside tyres.

My car is also my daily driver, and some of the roads i drive on are nasty with potholes etc, so DD comfort is also an issue, would the 'Ground Control' rates of 275/250 be sufficient for my needs? or should I go higher/lower? (FM's springs are 320/200?!?)

Whist I'm asking.... 'Front Roll Couple' as reference by Braineack in the linked thread above, why's that important? is there anywhere online I can read about this kind of stuff?
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Old 03-26-2010, 09:42 AM   #2
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I did exactly what emilio/949 told me to do:
10/7 springs
tein twin flex (running 6 clicks front, 10 clicks rear)
RB front sway
stock rear
2.75* front camber
2.5* rear camber
3.5* caster
0 toe
11.75" ride height at the fender front
12" ride height rear

The car feels AWESOME on the track, it slides perfectly. I'd run more camber if it were track only and I could get more. I have a lot of body roll too and I don't know if that's good or bad, other than the logic that more compression means more camber (right?).
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Old 03-26-2010, 11:51 AM   #3
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Forget ebay sleeves. For true adjustability, they're ****.
Thumper13 (he's more active on m.net) runs those things, but, even he runs only jamnuts without the sleeves.

Talk to Advance Autosports. They have 5" coilover sleeves that they use on their Spec cars (made by AllStar performance), which will work with Konis.

As far as springs, well, you WANT a soft spring for the street, and a stiff spring for the track.
Yellow Koni can handle no more than 450lbs front, and, with fleabay coilovers, you won't be able to run 7" spring. That's why that silly kit comes with 5.25" spring, which guarantees coilbind.
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Old 03-26-2010, 02:14 PM   #4
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Quote:
Originally Posted by richyvrlimited View Post
I'm not really inclined to increase the strength of my ARB's...
Tough ****. If you don't, the body will roll like a pig in mud unless you run spring rates high enough that they will be uncomfortable for a DD. Upgraded sway bars make a big difference in reducing body roll and have less of an effect on DD ride quality than the rate of your coilover springs. Everything is a tradeoff, but sway bars are one of the best upgrades to start with.

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Originally Posted by richyvrlimited View Post
My car is also my daily driver, and some of the roads i drive on are nasty with potholes etc, so DD comfort is also an issue, would the 'Ground Control' rates of 275/250 be sufficient for my needs?
You typo'ed, GC standard rates are 375/250. They are well within the range that Konis can control and shouldn't ride too shabby on the street either. I run 450/300 on my Koni Sports and I think they ride fine on the street (the roads I drive are a little bumpy but not too horrible) and on track they are a great match for RS-2s or similar summer street tires. When I move up to r-comps I will probably have to increase the spring rates a tad to deal with the increased lateral grip, which will require new shocks or at least a revalve since I'm already at the upper end of what the Koni Sports will handle.

Quote:
Originally Posted by richyvrlimited View Post
Whist I'm asking.... 'Front Roll Couple' as reference by Braineack in the linked thread above, why's that important?
FRC is a number that can give you a rough idea of how over- or understeery the car will feel. Play around with the suspension spreadsheet that Shaikh @ FCM made. Plug in different spring rates and sway bar sizes and see how the FRC changes. You can see how FRC is affected by the front & rear spring rates, and the diminishing effect sway bars have on FRC once you start increasing the spring rates, among other things.
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Old 03-26-2010, 02:22 PM   #5
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Quote:
Originally Posted by alik View Post
Yellow Koni can handle no more than 450lbs front, and, with fleabay coilovers, you won't be able to run 7" spring.

Pretty amazing that I was running 550# 7" springs on konis with ebay sleeves...




You want at LEAST 375/250.

I'm running 400/250 now, had been running 550/300 and 318/233 all on the street. The 550/300 combo was harsh due to improper installation where I lost a lot of travel but it felt great autocrossing. The 400/250 combo isn't even an issue, I'd start at least at those rates. Only driving on it a few weeks I'll say the ratio gives it a little more oversteer but today even in the rain I can give it gas through a corner and it gripped right on through it. Might be a good place for you to start.
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Old 03-26-2010, 03:34 PM   #6
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First you have to have good sway bars to control the leaning in corners, second you have to have a proper spring rate for your driving. Pick out the sway bars first, then pick the correct sping rates to get your FRC in the 57-58 range. An example would be a 50% would tend to oversteer and a 65% would tend to understeer. I'd say for the front spring rate 300 or less is more street, 350-500 is a good mix for street track, and 550-850 is more track only. Your choice of shock will dictate how high you can go and stay within the shocks valved range.

Use this link to get your setup 95%, then fine tune from there.

90-93
FCM_MSDS_1_6NA.xls
94-97
FCM_MSDS_1_8NA.xls
99-05
FCM_MSDS_1_8NB.xls


Oh, and FYI there is nothing wrong with ebay collars. I actually just did my 5th ebay collar install on my Dads new Bilsteins. Please don't give advice on products you've never tried.
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Old 03-26-2010, 03:41 PM   #7
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The stock front sway bar won't cut it for track duty. RB hollow in the front and keeping the stock rear is a hugely popular way to go. Well proven set up. You'll wonder why you didn't do it earlier.

Here's the place to learn about roll couple. Fatcat has a ton of info and this xls program to plug numbers into. There is a tutorial and other info on his site. This link is direct to the spreadsheet which may not mean much to you without more research.

FCM_MSDS_1_8NA.xls


Dammit. On the phone with a customer and didn't get my post up before Jacob with the FCM links. Now I look like a reposting doucher.
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Old 03-26-2010, 03:49 PM   #8
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lol, at least you have the link and know how to use it. newbs
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Old 03-26-2010, 06:24 PM   #9
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Cheers for the replies and links, I'll get reading/playing with that spreadsheet!

alik, I can't really afford to buy replacement threaded collars, from what I've read on here and m.net they should offer what I need. If money was less of an issue I'd have just bought the GC setup

Sounds like I'm best going with the GC rates (apologies for my typo!) or slightly higher and then if I'm still not happy saving up and purchasing a front ARB.

Hustler: I get that amount of lean from standard road tyres, at least you're running wider and stickier track tyres

Everyone else, thanks again for the advice, great food for thought
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Old 03-26-2010, 08:47 PM   #10
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Not that it matters seeing as you already have the flea-bay's, but FYI koni makes threaded perches and all the shiz u need to run adjustable height coils for cheaper than ground control.

BTW love the brg
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Old 03-27-2010, 07:19 AM   #11
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Quote:
Originally Posted by Chapman View Post
Not that it matters seeing as you already have the flea-bay's, but FYI koni makes threaded perches and all the shiz u need to run adjustable height coils for cheaper than ground control.

BTW love the brg
I searched the KONI's threaded perches, but they worked out almost as expensive as the full GC kit!

Thanks on the complement too it's Metallic BRG!
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Old 03-27-2010, 01:52 PM   #12
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Koni sleeves and collars should run $90 for all four.
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Old 03-03-2015, 08:27 AM   #13
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Quote:
Originally Posted by jacob300zx View Post
Use this link to get your setup 95%, then fine tune from there.

90-93
FCM_MSDS_1_6NA.xls
94-97
FCM_MSDS_1_8NA.xls
99-05
FCM_MSDS_1_8NB.xls
I will recommend this tutorial if you are new to Shaikh spreadsheet => FCM_MSDS_TUTORIAL.xls
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Old 03-03-2015, 12:46 PM   #14
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Bumping a 5 year old thread with useless info?

What are you trying to buy from the classifieds?
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Old 03-03-2015, 01:55 PM   #15
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Quote:
Originally Posted by aidandj View Post
Bumping a 5 year old thread with useless info?

What are you trying to buy from the classifieds?
Already received a pm from Braineack with a similar message. So friendly it was almost a flirt.

I dont think it was useless info. It was missing.
And for us noobs that are wandering on the endless path of "search and shut-up" its nice that even five years old threads have missing info added.

But I was carried away and posted the missing tutorial from Shaikh, which everyone should read first.

When it comes to buying things from classified, the only thing I found tempting was also in a five year old thread.
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Old 03-03-2015, 01:57 PM   #16
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Not bad, firm but not aggressive, backing up your points with research, and to top it off good punctuation and grammar. You might do ok here.
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Old 03-03-2015, 02:10 PM   #17
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Quote:
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When it comes to buying things from classified, the only thing I found tempting was also in a five year old thread.
I LOL'd.
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