GD/GG Impreza (WRX/STi) springs on BC/BF/BJ cars: UPDATED

Struts, spring, anti-rollbars, braces and the like.

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GD/GG Impreza (WRX/STi) springs on BC/BF/BJ cars: UPDATED

Post by THAWA » Tue Jul 26, 2005 6:55 am

After some searching and quick logic we may have found that it is possible to use 04+ impreza rear springs on first generation suspension cars. First gen meaning bc/bf/bj/gc/gf/gm/sf/sg.

According to this thread:
http://forums.nasioc.com/forums/showpos ... ostcount=5
90-91 rear springs taper to 95mm at the top. We suspect this is the ID of the spring.

And according to this thread:
http://forums.nasioc.com/forums/showpos ... stcount=78
04+ Impreza rear springs taper to 100mm at the top using the ID.

The reason we suspect it's the ID is if you look at the other info from the first thread the rear spring top diameter is 125mm for non-tapered first gen springs and 130 for 02-03 impreza springs. In the other thread the rear suspension top diameter is listed as 100mm ID or 126mm OD. These rear springs wont fit with first gen rear spring perches, per this thread: http://bbs.legacycentral.org/viewtopic.php?t=21883 So the measurement has to be an ID measurement, which means the rear spring top diameter is 100mm for 04+ impreza.

Now, 95mm for 90-91 legacy rear spring top diameter, 100mm for 04+ impreza rear spring top diameter, the difference is 5mm. That is theoretically workable.

So what does this all mean? Well, it means theoretically you should be able to use 04+impreza rear suspension(including STi) if you use 90-91 legacy rear spring perches and top mounts. If 90-91 rear spring perches and top mounts are separate units you should be able to use sti gc rear top mounts. If they are one single unit, you'll have to use them, or find sti rear top mounts that are tapered.

Anyway, though this might be of use to someone.

EDIT: Psychoreo has confirmed this works.

EDIT #2:
I'm currently using 04 US STi struts with JDM GDB C-F Pink springs. The springs are listed as a 20mm/20mm front/rear drop for STi's. STi's are 10mm/10mm lower than WRX Sedans to start with, and 1mm/10mm lower than WRX Wagons. My hub to fender measurements are 343mm/311mm. Stock is 393mm/364mm. This setup provides a 50mm/53mm drop. This means a stock 04 US STi setup should be a 30mm/33mm drop or 363mm/331mm. A stock US WRX Sedan setup should be 20mm/23mm or 373mm/341mm. A stock US WRX Wagon setup should be 29mm/23mm or 364mm/341mm

These numbers are all based on my original measurements of my 90 Sedan LS 4WD so your ride heights may vary.

EDIT #3 by DerFahrer: Final clarification.

PLEASE READ THOROUGHLY before asking your question.


If you have a 90-91 Legacy, you can use 04-07 Impreza springs as direct replacements. The 90-91 Legacies have tapered rear springs like the 04-07 Imprezas do, so they will fit. Below are 04 WRX sedan part numbers as an example.

04 WRX sedan front springs: 20330FE861
04 WRX sedan left rear spring: 20380FE830
04 WRX sedan right rear spring: 20380FE820


From my post below, here are the part numbers you will need to have to use 04-07 Impreza springs on your 90-91 Legacy.

04 WRX front top hat: 20323FA000
04 WRX front rubber spring seats: 20325AA000
(all 02-07 Impreza front top hats and rubber spring seats are the same)
91 Legacy rear upper rubber spring seats: 20375AA011
04 WRX rear lower rubber spring seats: 20375FC001
(all 02-07 Impreza rear lower rubber springs seats are the same)
04 WRX front strut bearing washers: 20326AA000
(all 02-07 Impreza front strut bearing washers are the same)

You can use 04-07 Impreza rear tapered springs on your 92-94 Legacy, but you will need to switch to the 90-91 strut mount setup. To do so, or if you just want to replace your strut mounts, you will need these part numbers:

91 Legacy left rear FWD strut mount: 20370AA030
91 Legacy left rear 4WD strut mount: 20370AA010
91 Legacy right rear FWD strut mount: 20370AA020
91 Legacy right rear 4WD strut mount: 20370AA000

If you have a 92-94 Legacy, you can use 02-03 Impreza springs as direct replacements. The 92-94 Legacies do not have tapered rear springs, and neither do the 02-03 Imprezas. Below are 02 WRX sedan spring part numbers as an example.

02 WRX sedan front springs: 20330FE230
02 WRX sedan left rear spring: 20380FE630
02 WRX sedan right rear spring: 20380FE620


From my parts catalogue at work, here are the part numbers you will need to have to use 02-03 Impreza springs on your 92-94 Legacy.

02 WRX sedan front top hat: 20323FA000
02 WRX front rubber spring seats: 20325AA000
(all 02-07 Impreza front top hats and rubber spring seats are the same)
92 Legacy rear upper rubber spring seats: 20375AA030
02 WRX rear lower rubber spring seats: 20375FC001
(all 02-07 Impreza rear lower rubber springs seats are the same)
02 WRX front strut bearing washers: 20326AA000
(all 02-07 Impreza front strut bearing washers are the same)

You can use 02-03 Impreza rear non-tapered springs on your 90-91 Legacy, but you will need to switch to the 92-94 rear strut mount setup. To do so, or if you just want to replace your strut mounts, you will need these part numbers:
92-94 Legacy rear strut mounts: 20370AA200
92-94 Legacy rear top hats: 20373AA200

If you want to replace your front strut mounts, you will need these part numbers:

90-94 Legacy nonturbo front strut mounts: 20320AA100
90-94 Legacy turbo front strut mounts: 20320AA110

With the guidelines above, any 02-07 Impreza spring (RS/TS/OBS/WRX/STi) will work on any 90-94 Legacy.

Any 02-04 Impreza (RS/TS/OBS/WRX/STi) strut will also work. But 05+ struts will not work without modification.

This is all to the best of my knowledge, using the information already presented in this thread, and my Subaru parts catalogue at work. Some of the above part numbers may not be necessary, but all necessary part numbers are listed.

If your fitment or compatibility question isn't answered here, it's likely answered in the Suspension Information Compendium.

Finally, if anyone more qualified would like to correct anything above or has something else to add, they are welcome to do so.
Last edited by THAWA on Mon Jun 26, 2006 8:36 pm, edited 2 times in total.
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Post by jamal » Tue Jul 26, 2005 7:43 am

I was wondering about all this the other day. I would have really liked to use the GC group N tops I had. Brat4x4 should be able to shed some more light on this because he used his existing tops with 04 STi springs. I think he has a 93 SS.

Maybe turbo and n/a rear springs are different.
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Post by scottzg » Tue Jul 26, 2005 11:03 am

I have GC gN rear tops. The 90-91 stuff is separate perch and topmount.

Turbo and na springs are the same, the struts are valved stiffer.
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Post by jamal » Wed Jul 27, 2005 3:05 am

So then that would lead me to believe that there are two different USDM 04 STi rear springs.
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Post by ultrasonic » Fri Jul 29, 2005 6:42 pm

scottzg wrote:I have GC gN rear tops. The 90-91 stuff is separate perch and topmount.

Turbo and na springs are the same, the struts are valved stiffer.
On my friend's 91 SS we found that the top mount and upper spring perch were one piece. Have some people found them to be two pieces on any tapered spring cars? If there are some that are separate, then I could use the GC Gp. N mounts that I just acquired.

This is a good thing to figure out because I was also wondering about the USDM version 8 STi rear springs fitting the upper perch on the tapered spring bc/bf.

Ideal situation: separate upper perch from a tapered spring set up, combined with GC Gp. N upper rear mount, and USDM ver. 8 STi compatible rear springs--- all fitting nicely together.
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Post by Psychoreo » Fri Jul 29, 2005 6:49 pm

Now, 95mm for 90-91 legacy rear spring top diameter, 100mm for 04+ impreza rear spring top diameter, the difference is 5mm. That is theoretically workable.
There's nothing theoretical about it. I installed 04 wrx struts and spring with my 91 stock tops and it fits perfect.
stupid electrical work...

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Post by vrg3 » Sat Jul 30, 2005 3:30 am

Psychoreo - Sweet!

ultrasonic - Yeah; the pre-facelift rear strut tops include the perch and bearing as all one assembly. That's one reason they're so expensive.

The 2004+ rear strut tops seem to also include the little rubber spacer for the spring, too.

This is from the 90-91 Legacy parts catalog:

http://www.graphics.cornell.edu/~v/pics ... _strut.png

This is from the 2004 Impreza service manual:

http://www.graphics.cornell.edu/~v/pics ... _strut.png

One should note that it's also possible to use later Impreza rear strut tops on our cars if we slot the three holes in each strut tower. Chris (rally370) said he only had to file his out about a quarter of an inch.
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Post by THAWA » Mon Aug 01, 2005 7:53 pm

Psychoreo wrote:
Now, 95mm for 90-91 legacy rear spring top diameter, 100mm for 04+ impreza rear spring top diameter, the difference is 5mm. That is theoretically workable.
There's nothing theoretical about it. I installed 04 wrx struts and spring with my 91 stock tops and it fits perfect.
Great, I just said theoretically because it wasn't confirmed.
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Post by Psychoreo » Tue Aug 02, 2005 3:10 am

not trying to bite your ***, but i'm confirming they fit... no disrespect.
stupid electrical work...

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Post by THAWA » Tue Aug 02, 2005 3:33 am

Word. I'm not offended :)
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Post by jamal » Tue Aug 02, 2005 3:40 am

Well, I'm still confused as to how Brat4x4's 93 perches fit on his STi springs. Or maybe they were different springs. The SPT setup or something like that. Or else he LIED TO ME!.

EDIT: brat4x4 is using 02-03 (ver7) suspension, which is what caused my confusion.
Last edited by jamal on Tue Feb 19, 2008 4:19 am, edited 2 times in total.

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Post by wes_ej20t » Fri Aug 12, 2005 1:38 am

I will be changing my rear struts this weekend. 91 Series 1 Liberty and I have 04 STi struts. Will let you all know just what I find, will take some pics and measurements.

I know it won't be quite a simple as doing the fronts but we shall see.

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Post by DerFahrer » Mon Apr 10, 2006 1:28 am

I just put these springs on Patti this weekend, and I'm VERY VERY happy with the results. I haven't had this big of a dorky grin on my face in YEARS! :lol:

The car does sit what looks like about an inch lower (I was gonna actually measure the ride height before-and-after, but I got impatient). So it looks noticeably lower, but doesn't looked slammed or anything.

Assuming you get all the parts necessary (there is a full list of part numbers at the end of this post), you should have absolutely zero fitment issues. Everything bolts up.

If it weren't for the fact that I'm on bald Michelin Symmetries (which I learned come as standard equipment on Cadillac Devilles :roll: ), that aren't balanced anymore, I'd be really impressed with the handling. I got a chance to get on a highway entrance with no one in front of me, and the turn-in is much much crisper, which is to be expected thanks to the significantly-decreased body roll. I was squealing tires all over the place, but damn it was fun! :lol:

Anyway, part numbers:

The springs themselves (04 WRX)
20330FE861 for the fronts
20380FE830 left rear
20380FE820 right rear

Front top hats (04 WRX)-
20323FA000

Front upper rubber spring seats (04 WRX)-
20325AA000

The numbers following this are not confirmed to be NECESSARY, but I got them anyway.

Front washers (04 WRX)-
20326AA000

Rear lower rubber spring seats (04 WRX)-
20375FC001

Rear upper rubber spring seats (91 Legacy)-
20375AA011

If Hardy is able to get his site back up where I can upload pics, I'll do that to show the differences between the Legacy and WRX springs, as well as before and after shots of the car.

Thanks for all you guys' help, especially Phil!
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Post by DerFahrer » Fri Apr 14, 2006 1:55 am

EDIT: Okay, I signed up for Hardy's new gallery, so here goes:

Here's what she looked like right after the wheel bearing project. Up in the air!!!
Image

The WRX springs are on the left, originals on the right:
Image
The WRX springs on the right, originals on the left:
Image

Here's what she looked like after the springs, MUCH better:
Image

And just today with the XT6 wheels and Yoko Avid H4's:
Image
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Post by DerFahrer » Fri Apr 14, 2006 11:05 pm

By the way, here's the list prices for those parts:
20330FE861 $75.73 apiece
20380FE830 $75.73
20380FE820 $75.73
20323FA000 $13.68 apiece
20325AA001 $13.68 apiece
20326AA000 $3.87 apiece
20375FC001 $7.97 apiece
20375AA011 $13.68 apiece
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Post by DLC » Sat Apr 15, 2006 2:41 am

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Post by jamal » Thu Apr 20, 2006 2:41 am

cool. My post from somewhere else would probably be helpful in the thread then:

There are two different 90-94 Legacy rear suspension designs, and two different 02-06 Impreza rear designs.

The 90-91 Legacy has a tapered rear spring with an integrated spring perch and top, like this:

Image
thanks for the source image, THAWA

The 92-94 Legacy has straight spring and a separate top and perch, like this:

Image
(This is also identical to the 93-01 Impreza)

The 02-03 Impreza has a straight spring and an integrated top and perch, like this:

Image
(guess where I got this picture)

From what I can gather, the 95-99 Legacy rear tops, if not identical, have the same bolt pattern and will fit the same springs.

The 04-06 Impreza has a tapered spring and an integrated top and perch like this:

Image

The neat thing is that the tapered springs and the straight springs have the same respective top diameters so you can switch tops.

A 90-91 Legacy top/perch will fit on an 04+ Impreza spring.
A 92-94 Legacy (and 93-01 Impreza) perch will fit on an 02-03 Impreza spring.
Pretty much any spring and top will fit on any strut, so there are many different combinations that will work.

All front springs will fit on all front struts, and all you need is the upper spring perch that corresponds to the springs.

Also, 95-99 Legacy and 02-06 Impreza rear strut tops have the same bolt pattern. I am pretty sure 95-99 Legacy springs are straight like 92-94 Legacy and 93-03 Impreza springs.
Last edited by jamal on Wed Aug 22, 2007 7:41 pm, edited 2 times in total.

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Post by Murphy » Fri Jun 09, 2006 5:10 am

i wish i had known all of this alot sooner.....
now ill have to wait 3 or so years for my new stock Gabiel struts to wear out before i can do anything...

**begins thinking of excuses to get rid of them**

"aw yeah, you should have seen it, this crazy guy came from nowhere and shot all of my struts! it took him a while because all he had was an airgun, but i knew better than to try and stop him, people are crazy these days!"

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Post by DerFahrer » Sat Jun 10, 2006 1:36 am

Murphy wrote:**begins thinking of excuses to get rid of them**
The excuse that you can probably get GR2's cheaper than you paid for your Gabriels.

I had Monroes on my car before my wheel bearing project last year, and they were only a couple years old. I didn't care, I bought GR2's, and threw my Monroes out. I don't regret it in the least bit either.
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Post by Legacy777 » Sat Jun 10, 2006 1:41 am

subyluvr2212 wrote:
Murphy wrote:**begins thinking of excuses to get rid of them**
The excuse that you can probably get GR2's cheaper than you paid for your Gabriels.

I had Monroes on my car before my wheel bearing project last year, and they were only a couple years old. I didn't care, I bought GR2's, and threw my Monroes out. I don't regret it in the least bit either.
Ditto.....had monroes, and they suck monkey nuts compared to the GR2's.
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Post by Threshld1 » Tue Jun 13, 2006 7:24 pm

so reading this i have come to the conclusion that if i wanted to put 05 STI springs on my 93ss. The fronts would swap right over but i would need a different tophat for the rears? Is this correct? What tops would i need to make the rears work?
Now if i were to get say 03 wrx springs those would work with my stock tops, front and rear?
Last edited by Threshld1 on Tue Jun 13, 2006 11:42 pm, edited 1 time in total.
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Post by Murphy » Tue Jun 13, 2006 9:41 pm

if i dont get a new top hat can i just move the mounting holes?
so the 95's would bolt on the front of my 90' right?
i know the guy above just asked this but im not sure if 90' and 93' are the same

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Post by scottzg » Wed Jun 14, 2006 2:31 am

Image

jamal, the image you posted of the rear topmount and perch is not what my stuff looked like on my 90. My stuff looked like the 92-94, except the perch was smaller.

90 and 93 fronts have the spring seat welded to a different part of the strut body. So, you swap both strut and spring, everything else will be fine, but if you just do 1, your nose will stick up in the air.

There are other fitment issues with sti stuff. Jamal and brat4by4 have posted about them.
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Post by jamal » Mon Jun 26, 2006 3:20 am

huh. so my tops would be interchangable with 90 perches?

wish I'd known what I do now before I did that swap.

I'm having some neat plates made as soon as next week to make everything fit a bit better though.

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Post by THAWA » Mon Jun 26, 2006 4:25 am

This is what scott says, however I can't find another set of 90-91 rear top mounts separate from the perches. I wish we could though. Or at least the part number for the perch.

Are the plates the ones you talked about a while ago? Are they being made for First gen bolt pattern or for Second gen bolt pattern?
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