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Discussion Starter · #1 ·
Alright I got the damn mod bug. I have been reading about quality suspension setups. I know I dont want coil overs because I commute 35miles/each way to work and don't want most of my driving to be back wrenching. However, I'd love to fix some of the high-speed dampening in the STI.

The stock suspension I admit, is pretty good.

Here's what I'm trying to solve
1. The small amount of dive/squatting on braking and accelerating
2. The sometimes unsteadiness of suspension when in turns or high-speed in general (say 65 or 70+) when hitting unsteady patches in the road.


In pretty sure 1. Is solved by springs. I'm looking at the RCE yellow.

It also seems that Koni yellow shocks aren't made for 2015+?? (Please prove me wrong and I'll close this thread because that's probably the ideal).

Does anybody have experience with the bilstein/gtworx valving? They are pretty pricey and I can't really tell if they are THAT much of an improvement over the stock dampeners. $1100 is a lot to spend on something that probably is just as good...

Thoughts? Attached is the shock dyno if the bilsteins. Obviously huge improvement for a WRX, but an STI?

What about retaining stock dampeners with the yellow springs?

I don't like to half ass anything so if stock dampeners need to be replaced with rce yellows, let it be known.

Thanks all


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A couple of questions:
1) Do you understand the difference in compression and rebound in the chart?
2) Do you understand how to read the curves of the graphs in terms of what they mean?
3) Do you understand how the curves will affect handling of the car?
 

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Damn the low-speed rebound damping of the OEM strut is untouchable. It's probably what makes the modern STI so damn good in slow speed sweepers and transitions like found in AutoX.

I can see why most people complain about the jarring ride, though. The comparitive lack of low speed rebound damping in the WRX limited would certainly give the car a more supple feel.

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the bilstiens look super linear and predicable.
Look closer.

There are only a few data points with which to interpolate.

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The GTWorx has a much better defined "knee" like found in many high performance struts. It would certainly be a better riding strut with capability to support big spring rate.

I feel that the GTWorx is a good option for those who complain about a rough ride but still want a lowering spring with a stiffer rate, but I don't see it offering performance benefit over the OEM strut based on the shock Dyno.

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Discussion Starter · #9 ·
A couple of questions:
1) Do you understand the difference in compression and rebound in the chart?
I do to some extent from the bike world. Basically Rebound is how fast the shock will move up and down, and how fast the suspension will return to its appropriate position. Compression is how "mushy" it feels and how much Pressure is given to the shock. In Dirtbikes, rebound and compression are tuned in a manner to absorb bumps and such, but not cause a pogostick when landing off jumps.
2) Do you understand how to read the curves of the graphs in terms of what they mean? - If I understand correctly basically N force is applied to the shock and then its measured how the shock responds. various Dots = where the shock settled at? for varying forces/pressures?
3) Do you understand how the curves will affect handling of the car?
to some extent. So the STI stock handles low speed curves etc really well, but high speed stuff not as well and seems to bounce significantly more. However the bilstein should reduce the "Low ride jarring" that causes the STI to be so responsive at low speed, and seek to improve at the high speed.

am I off base?
 

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Discussion Starter · #10 ·
The GTWorx has a much better defined "knee" like found in many high performance struts. It would certainly be a better riding strut with capability to support big spring rate.

I feel that the GTWorx is a good option for those who complain about a rough ride but still want a lowering spring with a stiffer rate, but I don't see it offering performance benefit over the OEM strut based on the shock Dyno.

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This is what I gathered too. especially after reading the reviews of people.
basically there were 2 sides,
those who wanted a smoother ride loved it..those who did auto x/track etc were pissed they spent the money.

Thanks for the input. I think until the R&D is done more for 2015+ I'll probably go for an AOS instead of suspension upgrade...(maybe a front sway)
 

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The Bilstein shock Dyno results to not have enough resolution to draw any conclusion on that front.

The GTWorx offer minimal high-speed damping enhancement on compression or rebound.

Everyone seems to focus on Compression but I think Rebound is often more important -- it's what is keeping your tires on the road. Look up shock Dyno results for Rally suspension. You'll see low compression damping at low speeds and somewhat low at high speeds but high rebound damping... They achieve this with external gas reservoirs and clever valving.

I'm not sure the strut should be your focus right now. Stiffer spring rate and sway bars may achieve your goals.

Also... Have you changed your OEM tires?

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Discussion Starter · #12 ·

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Discussion Starter · #13 ·
The Bilstein shock Dyno results to not have enough resolution to draw any conclusion on that front.

The GTWorx offer minimal high-speed damping enhancement on compression or rebound.

Everyone seems to focus on Compression but I think Rebound is often more important -- it's what is keeping your tires on the road. Look up shock Dyno results for Rally suspension. You'll see low compression damping at low speeds and somewhat low at high speeds but high rebound damping... They achieve this with external gas reservoirs and clever valving.

I'm not sure the strut should be your focus right now. Stiffer spring rate and sway bars may achieve your goals.

Also... Have you changed your OEM tires?

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I'm on all-seasons right now for the winter. I'm planning on selling the stock yoko's sitting in my garage and picking up a pretty set of Michy PSS for the summer.

do you think you can do RCE yellow springs on the stock dampers and not be dissapointed?
 

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I think you need to get on proper rubber first, then make the assessment.

Yes, I think RCE yellows and a good rear bar will improve a bit.

Tires and alignment will improve the most. OEM alignment is really conservative. STI is set up to understeer at the limit from factory.

I apologize that I keep referring to shock Dyno plots in my posts as that's not really what we are looking at here... We are looking at the force vs. velocity graphs which are established using a shock Dyno.

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Discussion Starter · #15 ·
I think you need to get on proper rubber first, then make the assessment.

Yes, I think RCE yellows and a good rear bar will improve a bit.

Tires and alignment will improve the most. OEM alignment is really conservative. STI is set up to understeer at the limit from factory.

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got it. Yeah I'm planning on doing alignment - and specs I saved from you way back when I mount the nice tires.

Thanks zax!!
 

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My question to you... Do you intend to stay within the rulebook for SCCA?

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Discussion Starter · #17 ·
My question to you... Do you intend to stay within the rulebook for SCCA?

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Ah the end all be all question.

Idk. Is the answer.

To be honest, I should probably stay within scca rules for the time being until I drive the damn thing in a performance environment. Upgrading blindly without truly feeling in a 10/10 environment is a credit card racer move anyway.

A front sway and AOS would not disqualify me from street class B. However, obviously springs/shocks would.

Targeting July at the latest for a track day. Is basically turning into my bachelor party. However if money works out, I may do one earlier too. I believe scca street allows for any brake pads right? Would like to change those pads out.

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