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Old 09-15-2020, 12:10 PM   #1
OhThatHurt
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Default 8k/7k on FA500 '16 STI?

Anyone running 8k/7k springs on their Fortune Autos on a 2015+ WRX / STI? Currently running 7k/7k with a 22mm rear sway bar. Street driving only. Looking for a little more steering input response. Thoughts? Feedback?

Thanks
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Old 09-16-2020, 11:42 AM   #2
mitch808
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Not being familiar with that specific platform, typically you start with the soft gummy bits like anything made of rubber..

basically all bushings related to the suspension and rack get replaced to improve responsiveness.

Tire types can make a difference, as well as tire pressure.

The spring tuning is the last thing to do when all squishy bits have been addressed.
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Old 09-16-2020, 12:12 PM   #3
blurred
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Quote:
Originally Posted by OhThatHurt View Post
Anyone running 8k/7k springs on their Fortune Autos on a 2015+ WRX / STI? Currently running 7k/7k with a 22mm rear sway bar. Street driving only. Looking for a little more steering input response. Thoughts? Feedback?

Thanks
What does "steering input response" mean to you though...? Why do you think a small increase in spring rate will change that?
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Old 09-16-2020, 12:55 PM   #4
OhThatHurt
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Quote:
Originally Posted by mitch808 View Post
Not being familiar with that specific platform, typically you start with the soft gummy bits like anything made of rubber..

basically all bushings related to the suspension and rack get replaced to improve responsiveness.

Tire types can make a difference, as well as tire pressure.

The spring tuning is the last thing to do when all squishy bits have been addressed.
Good feedback. Running stock wheels and tires. Have already started stiffening from the middle of the car while trying to keep NVH down. I have installed Group N engine mounts, transmission mount, crossmember bushings and pitch stop. Perrin pitch stop brace and master cylinder brace. TS rear diff brace. SuperPro rear rear LCAs, rear diff inserts, 22mm RSB and endlinks, SuperPro bushings on the front SB mounts.

I guess it would make sense to upgrade the rest of the bushings on the F&R LCAs?

Quote:
Originally Posted by blurred View Post
What does "steering input response" mean to you though...? Why do you think a small increase in spring rate will change that?
Just looking to tighten the feel. I honestly do not know if the change from 7k to 8k in the front will do that or not. This is why I am seeking knowledge from those who know more about this than I do. This will help me decide if it is worth doing or not.
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Old 09-16-2020, 02:07 PM   #5
gtsilver944
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You can buy S209 draw braces. No experience with them but they supposedly improve steering feel.

I don't think the spring rate will change anything.
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Old 09-17-2020, 09:44 AM   #6
AndyRoo
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What is your alignment?
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Old 09-17-2020, 10:47 AM   #7
OhThatHurt
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What is your alignment?
Alignment is -1.7 F and -1.5 R and zero toe.
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Old 09-18-2020, 01:43 AM   #8
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its going to cause understeer. as you are going to not be able to transfer the weight of the car when you take your foot off the gas
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Old 09-18-2020, 07:08 AM   #9
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Quote:
Originally Posted by OhThatHurt View Post
Just looking to tighten the feel. I honestly do not know if the change from 7k to 8k in the front will do that or not. This is why I am seeking knowledge from those who know more about this than I do. This will help me decide if it is worth doing or not.
It sounds like what you want is for the car to 'turn in' a little more 'crisply'. For that, springs aren't going to be nearly as big a factor as front control arm bushings and any bushings associated with lateral location of the steering rack.

Turn-in response is what happens at the very beginning of a cornering maneuver, before the suspensions have moved much. Small amounts of suspension movement mean little change in spring force, so a change from 7 to 8 isn't going to buy you much help here.


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Old 09-18-2020, 07:32 AM   #10
Norm Peterson
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Quote:
Originally Posted by subaru_gc8 View Post
its going to cause understeer. as you are going to not be able to transfer the weight of the car when you take your foot off the gas
Understeer, yes. But the real reason is that changing the front from 7's to 8's and leaving the rear alone is going to make the front transfer load faster rather than slower. And once roll has fully developed, the share of lateral load transfer up front will be slightly greater with the 8's.



There seems to be this common misconception that suspension movement - roll, nose dive, rear squat in particular - is what causes load transfer. That's exactly backward because it's the load transfer that causes springs to compress or extend as load either shifts onto them or off of them.

IOW, it's load transfer that causes roll/squat/dive, and what you see is nothing more than visible proof that load transfer is happening (and that the suspensions are actually allowed to move in response to the changes in load).

On "load transfer" . . . car weight is pretty much stuck where it is and does not move around or transfer, except for fluids that slosh and cargo/passengers that get tossed around because they're not adequately restrained. Something else that's commonly thought but sometimes misleading (and always technically wrong).


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Old 09-18-2020, 10:03 AM   #11
OhThatHurt
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Quote:
Originally Posted by Norm Peterson View Post
It sounds like what you want is for the car to 'turn in' a little more 'crisply'. For that, springs aren't going to be nearly as big a factor as front control arm bushings and any bushings associated with lateral location of the steering rack.

Turn-in response is what happens at the very beginning of a cornering maneuver, before the suspensions have moved much. Small amounts of suspension movement mean little change in spring force, so a change from 7 to 8 isn't going to buy you much help here.

Norm

Yes. "Crisper" is what I am shooting for. That seems to be what @mitch808 said in post #2, also.
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Old 09-18-2020, 11:06 AM   #12
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For sharper turn in, more negative camber in front (which will require camber bolts or plates) with a tiny bit of toe out.

Tires also matter. While my PS4S's are overall excellent, their turn in isn't as good as the stock Dunlops.
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Old 09-18-2020, 11:17 AM   #13
OhThatHurt
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Thanks for all the feedback everyone. I will start by installing the WL steering rack bushings. I can do this without messing up my alignment.
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