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Old 08-20-2012   #1
Adam
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Mazda3 STF Build Thread

Well after a lot of consideration I've decided to make the move from HS to STF with my 2006 2.3L. Just a little background on the car, it weighs 2,750 in HS race trim with stock exhaust, floor mats and jack in car, and oem rear spoiler on. It currently has Bilstein B8 sport shocks and a Hotchkis 32mm rear bar. To initiate the change I will be running RTF at Nats in a couple weeks instead of HS and probably at Blytheville this Fall but that is yet to be determined. Prep for STF will begin late Fall and I hope to have the car pretty much ready for next Spring.

This is going to be a rather budget build and also is my daily driver so I'm not going to go too hardcore and I'll also use some parts that I already have (like the Bilsteins and RSB). I want to keep the budget around 5K for the whole deal, but can spend less or more depending on how things go.

First stage of the build is deciding which springs to go with. Instead of chopping off the perch and converting the Bilsteins into basically coil-overs with adjustable drop via ground control kit, I will use drop in springs. Right now the Eibach Sportline springs are my top choice as hit the drop I'm looking for (nearly 2 inches) and are progressively wound so they won't be too punishing to drive on the street. Spring rate is 97-280 front, and 114-280 rear. Stock springs are linear and are 150 front, and 130 rear. I'm open to suggestions/ideas if anybody has some, but remember, I'm on a budget and I want to keep the car daily driver friendly.

Here's the start of the build and what I already have on the car.



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Old 08-20-2012   #2
Emanuel
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Good luck.
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Old 08-20-2012   #3
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Good luck.
Thanks man....I really hope you get that Mini. Looking forward to racing in STF next year with you and keep you on your toes
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Old 08-20-2012   #4
mellephants
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I prefer linear springs. Progressive springs make the car less predictable near the limits.

Seems like sportlines are more of a lowering spring than a racing spring, anyway.
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Old 08-20-2012   #5
gary p
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Quote:
Originally Posted by Adam View Post
First stage of the build is deciding which springs to go with. Instead of chopping off the perch and converting the Bilsteins into basically coil-overs with adjustable drop via ground control kit, I will use drop in springs. Right now the Eibach Sportline springs are my top choice as hit the drop I'm looking for (nearly 2 inches) and are progressively wound so they won't be too punishing to drive on the street. Spring rate is 97-280 front, and 114-280 rear. Stock springs are linear and are 150 front, and 130 rear. I'm open to suggestions/ideas if anybody has some, but remember, I'm on a budget and I want to keep the car daily driver friendly.
Ride is often more a factor of damping than spring rate. I would highly recommend you reconsider the ground control coilovers. They don't cost that much more than the Sportlines and have MUCH more tunability down the road. FWIW, I suspect the low end of that variable rate is only on the extended-past-static side of the the stroke.
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Old 08-20-2012   #6
mellephants
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Bushing materials will play a big role in comfort also. Sticking with oe stuff there will keep it feeling softer over harsh road seams and potholes.

However the stiffer you go with springs, the more you will be deflecting the oe bushings, which causes undesirable geometry and premature bushing wear.
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Old 08-20-2012   #7
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Quote:
Originally Posted by mellephants View Post
I prefer linear springs. Progressive springs make the car less predictable near the limits.

Seems like sportlines are more of a lowering spring than a racing spring, anyway.
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Ride is often more a factor of damping than spring rate. I would highly recommend you reconsider the ground control coilovers. They don't cost that much more than the Sportlines and have MUCH more tunability down the road. FWIW, I suspect the low end of that variable rate is only on the extended-past-static side of the the stroke.
Hmmmm.... yeah Clark recommended the ground control kit as well. I wasn't crazy about chopping the Bilstein perch off. I'll research the ground control kit and come back, probably with some questions. I know the sportlines on paper are softer than OE initially, but yeah in reality once you count in sag that low rate isn't going to be into play...which will be the case with all progressive springs.
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Last edited by Adam; 08-20-2012 at 05:26 PM.
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Old 08-20-2012   #8
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Hmmmm.... yeah Clark recommended the ground control kit as well. I wasn't crazy about chopping the Bilstein perch off, but maybe that is going to have to be necessary. I'll research the ground control kit and come back, probably with some questions. I know the sportlines on paper are softer than OE initially, but yeah in reality once you count in sag that low rate isn't going to be into play...which will be the case with all progressive springs.
Do you have the o.e. shocks? Are they still serviceable? If I go STX next year I'll keep the stock struts/springs/top-hats around for winter duty.
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Old 08-20-2012   #9
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I told you that you don't "have" to chop off the lower spring perch as I didn't initially for the first 8 months but that doing so allows you to maximize drop. Get the GC and don't chop off the perch. Call them and tell them what you have and want to effect. Jay and his staff is very good at giving you a base line of information as to lengths of springs and rates. As it stands, if you go this route and change your mind on spring rates, between Pete, Dave and I, we have lots of these 2.5 or 60mm springs sitting around which can be swapped and tested.
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Old 08-20-2012   #10
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Quote:
Originally Posted by mellephants View Post
Bushing materials will play a big role in comfort also. Sticking with oe stuff there will keep it feeling softer over harsh road seams and potholes.

However the stiffer you go with springs, the more you will be deflecting the oe bushings, which causes undesirable geometry and premature bushing wear.
Yeah, bushings will come much later down the road. I'll be picking the low hanging fruit first then go to that later.

Back to springs, do you know of anybody that sells a drop in racing spring for the Mazda3? I saw that H&R sells some and I think you own them, but not for the 3 Maybe I can make the Focus springs work with slight modification...heck maybe they'll work fine as is?
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