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RIP: MY00 BRP 2.5RS Sedan 4EAT
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Discussion Starter #1
For the past 6 months, I was able to test new prototype springs made specifically for GC imprezas. A local shop, Mann Engineering, was able to bring over some prototype springs from Japan made by Swift. We, Mann Engineering and myself, went through a couple revisions to get the correct ride height and spring rates to match the GC body. Our goal was to have a spring setup that can have both drive ability on the streets and have performance. For testing, we matched the springs using KYB AGX adjustable struts with various settings. I was able to compare this setup with my previous suspension: Tein s-tech’s with version 5/6 inverted struts. The final ride height was adjusted so the bottom control arms are “flat” or parallel to the ground as it would give a good compromise for the dynamics of suspension travel and looks. The car is not slammed that it would have problems scraping like my previous setup, yet it is not high like a stock setup. Since the height was higher than the s-techs, I definitely noticed that bumpsteer was greatly reduced while going over bumps and the dynamics of the car feel completely different as the suspension has more travel to move. It did not feel as if it was hitting the bump stops anymore. So far the ride comfort in general (for all dampening settings) felt comfortable and smoother in comparison with my previous setup for daily driving. The stiffest setting for dampening was noticeably rougher, but still bearable for driving while the softest setting felt amazingly more comfortable than the stock RS setup. I was able to get other people to ride in my car with the prototype setup and they confirmed it was smoother and comfortable in comparison to their setups. One person even noted that it was not “choppy” and felt the suspension had more travel. Even the local alignment shop that I went to said the setup on my car felt “borderline to a coilover setup.” Performance-wise, I was able to bring the car to Thunderhill Raceway to test out how well it would perform on the race track. The car felt very smooth and controllable. It also seemed predictable and well planted while on the track Other people that got rides confirmed that my suspension felt more planted than their P1 setup with AGX’s on the turns. This setup overall definitely feels like it has the good combination to be a good daily driver with some performance like handling occasional track events.

So so far so good with this setup. I believe Gary at Mann Engineering might start bringing some springs over soon so be on the look out.

heres some phots of them installed showing the drop:




how the front and rear steering rods and lower control arms look after the springs were installed... flat!




and a pic of the setup right after i installed dba rotors and mintex pads that I am tried out for the subydude track day
 

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The Silverback Mod
05 Black OBS
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Gary @ Mann got me into the set for my '05 OBS... It was the 1st set of Swift installed on an OBS at the time. I mated them with the KYB GR-2's and I am soooooo happy with both the ride/handling AND the drop (it's lowered just the perfect amount!).

+1 to Swift and Mann Engineering!!!!! :bump:
 

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2000 Subaru Impreza Silver (1
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271 Posts
what the front and rear ride height? (middle of center cap to fender) let hear what those are, that will tell us how the car really sits, and if possible how about a rang or the exact number if you can give it of the spring rates in k's or lbs is fine. this is what the suspension geeks wanna here.

jason
 

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So do you know what rates they are or what they are equivalent to? I know that Swift springs tend to be on the softer side when comparing rates to another manufacturer. I might try some softer springs with my Prodrive struts since the P1 springs weren't designed for the strut. Keep us posted.

cheers

garrett
 

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RIP: MY00 BRP 2.5RS Sedan 4EAT
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Discussion Starter #7
totally forgot to put the spring rates up. the final ones are 3.4kg/mm front and 3.1kg/mm rear. I don't remember what that is in american units. my friend with P1's said they do feel more comfortable than his yet still feels more planted than his P1's. Garrett is right on that Swifts are a bit softer than other springs, but the difference is the materials used in the spring and how they are made as the springs are within 3% of their specified rate.

My measurement with my cheap tape measure looks like around 37mm front and 35mm rear from centercap to the top of the arch of the fender opening with plus/minus 5mm for my inaccuracy haha. I feel how level the control arms and steering rods are more important for adjusting ride height from what i've experience in some of my auto classes as it adjusts how the dynamic camber works and the effect of bump steer. The springs were designed more for performance and comfort in mind.

I also forgot to mention that the Swift springs are about 1 lb LIGHTER in comparison to my old Tein springs. The Swifts weighed at 5.50 lbs for the front spring while the rear was 4.75 lbs. Since Swift uses different metals to make their springs, the springs are usually thinner, lighter, and stronger to achieve their specific rate WITHIN 3%!

for those that don't know about Swift's technology, heres the link that explains it:
http://www.swiftsprings.com/advantage.html
 

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01 stm sedan w/v4 sugar
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Which springs are you using since there are none listed for GC's in the PDF file? Only GD's and up are listed, along with Legacy's and Forester's.
 

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Nice! Mabbe I'll buy a set and see how they work first instead of going with a coilover just yet. P1's are good and all but I can't help but wonder if there aren't higher quality springs available. When will these be available?

cheers

garrett
 

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2000 Subaru Impreza Silver (1
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271 Posts
Here are some conversions and some numbers to compare to...

3.4 (kg / mm) = 190.39121 pounds / inch FRONT rate
3.1 (kg / mm) = 173.591985 pounds / inch REAR rate

Stock GC8 Spring Rates
157 Front rate
149 Rear rate

P1 Aprrox rates
215 Front rate
195 Rear rate

i think he meant cm here...

37 centimeters = 14.5669291 inches FRONT height
35 centimeters = 13.7795276 inches REAR height

stock height for GC8
14.61 inches FRONT
14.29 inches REAR

p.s. im not passing judegment on the setup just trying to present information to everyone so that we can make a educated choice and a direct comparision to things out here that we know...
 

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04 Outback H6 aka old man car
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ATIC... said:
Which springs are you using since there are none listed for GC's in the PDF file? Only GD's and up are listed, along with Legacy's and Forester's.
If you read the original post, you'll see he mentioned they're prototypes for the GC.
 

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RIP: MY00 BRP 2.5RS Sedan 4EAT
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Discussion Starter #14
oh yes i mean cm instead of mm for ride height.

I am running proxy4's with 205/55-16's on stock MY00 wheels for daily street driving and Potenza RE011's with 215/45-17's on my P7's that I use on the track.

If anyone is in the bay area, I can give rides to see how they compare.
 

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01 stm sedan w/v4 sugar
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Yeah... I'm in the market for springs and have sort of changed my mind on P1's... I would like to give these a go!
 

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Discussion Starter #17
I believe Gary at Mann Engineering is getting the first production sets in by the end of this week. Right now I'm not too sure how he will go about it since he is not a member of RS25, but his shop sells parts in NASIOC so you might have to keep an eye out over there for these springs. I don't really know how much they will go for and how many will be available for first batch since I just test the springs.

If you are interested, Gary @ Mann Engineering is the guy to talk to. I'm sure NW OBS will chime in for him and how the service was.
 

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There's a group buy up on NASIOC.

I think I'll check these out, everyone I know who had them for their WRX raved about them. Not super performance oriented, but a great ride.
 

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01 stm sedan w/v4 sugar
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I'm doing the group buy! I need to swap out all my suspension later this summer... my rear passenger strut is shot, and the rear sits a bit too low for my liking with my current Tanabe GF210's.

Plus, they go well with AGX's!
 
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