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Old 04-29-2010, 03:27 PM   #1
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Default GD Suspension on a GC

I see this topic come up every once in a while and get lots of calls on it. Today I just so happened to have an 01 RS in the shop that I was installing a GD suspension on and figured I'd take a couple pics to show what is necessary to install it.

As some know, the front struts, springs and tophats front a GD simply bolt on to a GC. No problems there. The rear however is where the fitment issues come into play. The bolt pattern for the GC rear tophats is different from the GD. The GD pattern is larger than the GC and makes them not a direct swap.

Most people say that new holes have to be drilled in order to fit the GD tophats on a GC, but in reality it's much easier than that. The holes need to be slotted about 6mm towards the outside to be about to bolt the GD tophats in. The outside hole needs to be slotted slightly more than the inside holes. That's it though. Here are some pics to exemplify.

Stock without slotting.



After slotting. I did the slotting with a grinder and carbide burr bit. Takes all of 2 minutes to do.



That is all that is needed to fit the rear tophats.

The spring perches are in slightly different spots between the struts which will make the rear sit a bit higher on the new setup which can be seen in the following pic. This is on STI struts with Tanabe GF210 springs (05 sti spec) and Noltec front camber plates. It sits very even, but without the camber plates the front would be a bit lower than the rear. Not something that can't be fixed with some readily available spacers.



Tony
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Old 04-29-2010, 04:04 PM   #2
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Great info!!

I believe early 90's Legacy tophats can be used as well.

I am going to put my old WRX strut housings with Koni inserts on my GC. I am just trying to decide on some well matched springs for a compliant ride, light drop, and a little front rake. I am thinking RCE blacks...
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Old 04-29-2010, 04:58 PM   #3
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RCE blacks would sit pretty high. I think the GF210s would lower the car about .25" in the rear and .5" in the front over the blacks. Keep in mind the car above has camber plates in the front that without them would lower the front another 3/8" to 1/2". As it sits now it is 1/2" lower than stock height.

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Old 04-29-2010, 05:12 PM   #4
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That's interesting, but wouldn't it be easier to just swap the rear top hat to a GC top hat? The GC group-n tophats are expensive and hard to find, but stock are cheap and readily available.
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Old 04-29-2010, 05:20 PM   #5
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Quote:
Originally Posted by Suba_Roo View Post
That's interesting, but wouldn't it be easier to just swap the rear top hat to a GC top hat? The GC group-n tophats are expensive and hard to find, but stock are cheap and readily available.
The reason for doing this is there are better dampers and springs available for the GD than GC.

and the GC hats won't work with 04-07 springs
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Old 04-29-2010, 05:26 PM   #6
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Nice, I have a 99l that I swapped GD subframes in, I kept the rear GC knuckles, and struts, and used the GD front shocks and knuckles. Ive done ALK, Roll center kit, sphereical trailing links, hopefully some TIC LLs, and next on the list is a set of D specs, and ground control springs. What combination of tophat/camber plate fitment for the ground control springs would be appropriate in the rear?? I could just use GM/GC camber plates in the rear on groundcontrol springs right? I also gotta track down GD rear knuckles.

I also topmounted Noltec plates and replaced a bearing with an SKS unit. i had extra plates water jetted out and spacers to put them ontop of the strut tower. Want to maintain good bump/droop for DD as well as take advantage of the ALK/Roll center kit geometry.

Last edited by Dubstar112; 04-29-2010 at 05:33 PM.
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Old 04-30-2010, 12:07 AM   #7
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this is exactly what I did when I put 04 sti suspension on my 93 legacy.


... in 2005.


Quote:
Originally Posted by aboothman View Post
Great info!!

I believe early 90's Legacy tophats can be used as well.
yeah, 90-91 tops.

Last edited by jamal; 04-30-2010 at 12:16 AM.
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Old 10-30-2010, 08:01 PM   #8
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Sooo I decided to go with this method. I ended up installing 06 WRX struts with 05 STI springs and GD tophats on my 98L, along with 4/2 pots and 06 WRX hubs. Basically all of my OEM setup on the WRX.

I will get some pics up later, but doing it the TIC way ended up with the raised metal section misaligned with the hole that it is supposed to poke up through. I THINK it will work ok, but I will be seeking some older Legacy tophats in the future so that it works the way it should.

For those that reference this in the future, I would recommend slotting all of the holes a couple mm outward. Draw (or imagine) a line from the center of the tophat running out through each stud. If you line the center of the tophat up with the center of the hole, this should be the best way to go about doing this. It will be the same amount of work in the end, but the tophat should fit better.
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Old 10-30-2010, 09:17 PM   #9
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You know, you should have used fancyness to also finally settle the "how much camber do you lose on each end going from GC struts to GD-sedan struts" issue.
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Old 10-31-2010, 02:34 PM   #10
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Fancyness haha!!

Ya I should have also taken before and after pictures. As for the camber I would be able to determine this, but the car has not been aligned since I bought it, so I do not have an initial alignment spec. The fronts appear to have more positive camber, but the springs have not settled.

I am tempted to drill the right rear the way I suggested above, but I think I should keep things the same between sides. Oh well, back to the die grinder!!
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Old 11-01-2010, 09:46 AM   #11
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Cool info, just saw a gc running full Sti gear here in CT

wheels were pushed out a bit, guess rim offset could negate that
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Old 11-01-2010, 02:27 PM   #12
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What changed between the GC and GD? This was 2001->2002 where the chassis was changed, right? But, 2004 is when the rear tophat changed. Now I'm curious what they changed for 2002 that wasn't the major tophat change to the new spring shape.

Just a p.s.
For any Forester owner, the redesign happened a year later 2002->2003 meaning the 2002 Forester is still of the GC body style. Interestingly, the newer geometry tophats seem to have been used on them either in the 2002 year or possibly from the start. I'm not sure. I just know that my 2002 Forester is built off the GC chassis but requires zero modification to run the GD tophats. I'm just tossing that out there, but it also makes me curious what the older Imprezas were using on the rear that the Foresters weren't.
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Old 11-14-2010, 06:46 PM   #13
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I am really wanting to do this on my 1996 Brighton. I have just bought some 2006 WRX struts and springs. I am really wanting to lower my brighton a nice drop to get rid of most wheel gap. What WRX springs would you all suggestion to drop my brighton? Tein S-techs, Tanabe DF-210s?
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Old 11-14-2010, 09:31 PM   #14
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Keep in mind the WRX suspension will actually raise the car if you keep the stock springs, or that is the consensus on RS25. I used 06 WRX suspension with STI springs and it lowered the car a little bit from stock. The word over there is the WRX suspension will raise the car almost an inch, but I think this is an exaggeration. Something to keep in mind though. A friend is also running a set of 06 WRX suspension on his 95L and he is running WRX springs and all. It does not appear to sit any higher, but we both swapped on some 17" wheels at the time of the suspension swap, so that may affect our view of the ride height...even though they SHOULD be the same height.

I like the STI springs as they are cheap, a little lower than WRX springs, and they are only a little stiffer. When looking at GD springs keep in mind we are working with cars that are 400-600 pounds lighter than the car that the suspension and springs are intended for.

After looking inside the wheel well today, I am not sure if it would be a good idea to pull the strut mount inward instead of out. There may not be enough room left between the springs/ strut and the inner wheel well, at least not without getting the sledge hammer out
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Old 11-14-2010, 10:33 PM   #15
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aboothman... thank you for your input. I am defiantly not putting the stock WRX springs on my brighton lol. I want to know what WRX springs would drop my 2400 pound brighton enough to make the wheel gap very small. I am seriously thinking about S-techs because i know they drop the WRX the most which in turn will probably be just right on the brighton. Am I right?
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Old 02-05-2011, 12:12 AM   #16
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Anymore info on my question? I am thinking about buying 2002 WRX struts with some Sprint lowering springs. I have no clue on how much they would drop my brighton. Any suggestions?
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Old 02-05-2011, 09:58 AM   #17
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bumps
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Old 02-05-2011, 10:10 AM   #18
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I directly swapped in complete 04 STi spring strut combo with no modifications to the rear tophat mounting holes. I took the combo off the STi myself and swapped out my GC specific JIC magics for them. I didnt do anything at all to fit them, everyone else says the had to open the holes, I did not. Again I took them off of the 04 STi myself and immediately swapped them.
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Old 02-05-2011, 10:22 AM   #19
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Quote:
Originally Posted by GC_Anthony View Post
I directly swapped in complete 04 STi spring strut combo with no modifications to the rear tophat mounting holes. I took the combo off the STi myself and swapped out my GC specific JIC magics for them. I didnt do anything at all to fit them, everyone else says the had to open the holes, I did not. Again I took them off of the 04 STi myself and immediately swapped them.
Awesome! So how was the drop? How was the ride quality?
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Old 02-05-2011, 11:42 AM   #20
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Quote:
Originally Posted by GC_Anthony View Post
I directly swapped in complete 04 STi spring strut combo with no modifications to the rear tophat mounting holes. I took the combo off the STi myself and swapped out my GC specific JIC magics for them. I didnt do anything at all to fit them, everyone else says the had to open the holes, I did not. Again I took them off of the 04 STi myself and immediately swapped them.
If you used GC springs, then you must have swapped over your GC tophats with them. That would explain why they swapped right over.
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Old 02-05-2011, 11:45 AM   #21
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Quote:
Originally Posted by emsmap View Post
Anymore info on my question? I am thinking about buying 2002 WRX struts with some Sprint lowering springs. I have no clue on how much they would drop my brighton. Any suggestions?
I would like to help, but I am not familiar with Swift springs. But if you look at my car, and estimate the difference in drop from STI and Swift springs, it might give you an idea.
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Old 03-24-2011, 05:36 PM   #22
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Sorry to bump this thread from the dead but I had no GC springs/tophats to use I had JIC Magic coilovers. I used 04 STi Prodive springs.

As for the drop there was barely any the car rides at 14" hub to fender at ride height, as for the handling and ride I love them both.
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Old 03-04-2012, 10:29 PM   #23
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Awesome thread, this should be a sticky! Is there any camber issues with the GD swap?

Last edited by LeeRSti; 03-05-2012 at 04:17 PM.
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Old 03-13-2012, 11:32 PM   #24
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Ya I think your camber will be a little on the + side, but nothing bolts cannot fix.

Here are pics of a 99L with STI suspension and red swift springs






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Old 03-14-2012, 01:11 AM   #25
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Nice, which aftermarket bolts are you using?
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