STI Suspension Swap Project

[Crazy_pilot]

I posted this in the Megan Racing group buy thread, but thought I'd start a new thread to get more opinions. I'm planning on test fitting a v7 STi suspension in my SVX in the coming weeks. I've already found a way around the front sway bar endlink of the SVX. The rear endlink from an '05 Outback is the perfect length to fit a bracket welded to the control arm:

http://www.subaru-svx.net/photopost/data/570/IMG_2791.jpg

This removes the requirement to have the endlink attach to the strut. For the test phase I would just fabricate a bracket myself, but if this works I'll go to the machine shop and have a batch cut properly.

A member of the local Subie club has offered to let me borrow a spare v7 suspension he has since upgrading to coilovers. All I need it for is a mock up and fit test. He's confirmed that it uses the two bolt lower strut-to-knuckle mount in the rear (some Subies have a pillowball bushing in the rear).

To the best of my knowledge, if the lower strut will attach to the knuckle, this should work. If the top hat won't fit is it possible to swap the SVX top hat from a Koni/GC system onto another coilover system? If that's possible the only fitment requirement is the lower mount.

Is there any reason that the STi shocks won't work with the SVX's additional weight? I'm not worried about a two-year life expectancy or something, more a "will-this-thing-blow-up-if-I-hit-it-too-hard" sort of thing.

If this works I would like to go straight to an aftermarket STi suspension, coilovers etc. The heavy spring rates should help negate the extra weight, right?

I'm a rookie at all of this, so any of you more knowledgable types feel free to tell me I'm out to lunch.

[It's Just Eric]

talk to benebob.

[Hocrest]

You will need to use the SVX top mounts, or drill out different holes on the body of your SVX. If you decide to use the SVX top mount, you will find the top of the strut rod is slightly different. We used a small metal collar.

For the bottoms of the strut where they mount to the spindle. The spindle is thicker on an SVX than it is on the Impreza's. You will either need to spread open the flange on the borrowed STI struts or do what we did on the racer and use a grinder and remove metal from both sides of the spindle.

Looking at your picture posted, are you sure that there is enough clearance between the sway bar and the axle when the suspension drops? From that angle it looks fairly tight?????

[Crazy_pilot]

Looking at your picture posted, are you sure that there is enough clearance between the sway bar and the axle when the suspension drops? From that angle it looks fairly tight?????

Cool, thanks!

That's the normal position of the swaybar. The other end is still connected to the strut with the stock SVX link.

[Hocrest]

Cool, thanks!

That's the normal position of the swaybar. The other end is still connected to the strut with the stock SVX link.

Ok, but in the normal set up, the sway bar is attached to the strut and won't be dropping any lower, the axle in relation will be dropping away from it.

With your set up, the control arm will be pulling the sway bar down as it does with the axle.

I'm not saying that there will be a problem, just double check before you weld things into place.

[Crazy_pilot]

:confused::confused:

The sway bar is connected to the lower strut housing, which does move up and down. The bracket I would put would make the sway bar follow the movement of the control arm at that point, and the control arm and axle should remain roughly parallel as the suspension travels, so the sway bar should not come any closer or farther from the axle than it is right there. That's what my metal picture of the situation tells me anyway.

Once the bracket's on and the strut is out I'll move the knuckle as far up and down as it will go to confirm clearance.

[Crazy_pilot]

Yay free stuff!!:D:D

http://www.subaru-svx.net/photopost/data/570/IMG_2795.jpg

Some V7 STi takeoff struts from Japan. Brand freakin new too, only about 5000 miles on them.:D Time to start measuring.

[sicksubie]

well????????

[Crazy_pilot]

Well I've hit a roadblock. The raised part of the STi front upper strut mount is too large to fit through the hole in the SVX. Th hole is about 3.75", and the raised part of the mount varries from 3.8-4.1". Also, the studs on the mount are more widely spaced on the STI, and need as much as 0.5" more space, which I'm not sure the SVX has to spare. All this points to needing to use the upper mount for the SVX in the front.

I've also been doing some thinking about swapping the whole STI knuckle and hub into the SVX. They have different ball joints, but an adapter can be made to overcome that. The biggest problem I see is that with the STI knuckle, we will HAVE to run the Brembos. Nothing wrong with that, it's just a bunch more money, on the brakes and the rims to fit over them.

The reason for that is that when Tom tried to fit the Brembos he found that the SVX, while having the same bolt pattern, has the caliper mounted farther out from the center of the hub. This means that to run Brembos on an SVX, you need larger rotors than an STI would, and the calipers really can't work properly with larger rotors. Mounting an SVX caliper on an STI knuckle would bring it closer to the center, and would not allow us to use our stock rotors. So unless there's a good substitute in the size that would require, it would be Brembos or nothing. (The Subaru 4-pots might fit, but I don't know if there's a 5x114.3 rotor that will work with those)

[Crazy_pilot]

lol, nice timing

[Seraphinwolf]

lol, nice timing

I take it that was in responce to something from SickSubi about just selling some Brembros?! LOL I would bet it is. See you should have sold them to me instead, Sickboy! LOL! To be honest I do feel sorry that you had that option slip through your fingers. Would have been nice to stop the Supercharger in less than 200ft. LOL Wow that's a lot of "L.O.L."s sorry, got carried away Let me know how it goes though I'd like to do something about my suspention and would like to know my plan like 6 months ahead of time.
-Gaddis

[Crazy_pilot]

I take it that was in responce to something from SickSubi about just selling some Brembros?! LOL I would bet it is. See you should have sold them to me instead, Sickboy! LOL! To be honest I do feel sorry that you had that option slip through your fingers. Would have been nice to stop the Supercharger in less than 200ft. LOL Wow that's a lot of "L.O.L."s sorry, got carried away Let me know how it goes though I'd like to do something about my suspention and would like to know my plan like 6 months ahead of time.
-Gaddis

Actually it was in response to Sicksubie saying "Well??????" at the same minute I posted a long ass blurb starting with Well:lol:

[sicksubie]

I take it that was in responce to something from SickSubi about just selling some Brembros?! LOL I would bet it is. See you should have sold them to me instead, Sickboy! LOL! To be honest I do feel sorry that you had that option slip through your fingers. Would have been nice to stop the Supercharger in less than 200ft. LOL Wow that's a lot of "L.O.L."s sorry, got carried away Let me know how it goes though I'd like to do something about my suspention and would like to know my plan like 6 months ahead of time.
-Gaddis

Nope.... I didn't let the brembos "slip through my fingers" I sold them so as to do my entire 6 spd swap for less than 1800.-. :D:D:D (gloating)

[Seraphinwolf]

Nope.... I didn't let the brembos "slip through my fingers" I sold them so as to do my entire 6 spd swap for less than 1800.-. :D:D:D (gloating)

But at the cost of selling the Brembo for way less than what they are worth and thus FAILING! You could have done you're 6-speed for around $800 instead. Or have atleast posted up on here for offers. I could have come up with the money. I know my Impreza would be cool with it(though I'd have to then convert again now that I did 02' Rex brakes in the rear) I supose it's okay. I would like to see getting a set of Impreza Coilovers under these cars (heavier duty ones) Makes it easier to find stuff.
-Gaddis

[redlinedeath]

I've also been doing some thinking about swapping the whole STI knuckle and hub into the SVX. They have different ball joints, but an adapter can be made to overcome that. The biggest problem I see is that with the STI knuckle, we will HAVE to run the Brembos. Nothing wrong with that, it's just a bunch more money, on the brakes and the rims to fit over them.

The reason for that is that when Tom tried to fit the Brembos he found that the SVX, while having the same bolt pattern, has the caliper mounted farther out from the center of the hub. This means that to run Brembos on an SVX, you need larger rotors than an STI would, and the calipers really can't work properly with larger rotors. Mounting an SVX caliper on an STI knuckle would bring it closer to the center, and would not allow us to use our stock rotors. So unless there's a good substitute in the size that would require, it would be Brembos or nothing. (The Subaru 4-pots might fit, but I don't know if there's a 5x114.3 rotor that will work with those)

im not incredibly familiar with suspension setups, so im sorry if what i say is just stupid:confused: anyhow, with these problems(not including top mount issues) you cant just swap out the whole suspension/knuckle/hub/brake system and new rims (off a stock sti maybe) and make it work? im sure that was just stupid, as i dont know suspension systems well, but is this not possible? i apologize in advance if it was that bad of a question:)

[Crazy_pilot]

im not incredibly familiar with suspension setups, so im sorry if what i say is just stupid:confused: anyhow, with these problems(not including top mount issues) you cant just swap out the whole suspension/knuckle/hub/brake system and new rims (off a stock sti maybe) and make it work? im sure that was just stupid, as i dont know suspension systems well, but is this not possible? i apologize in advance if it was that bad of a question:)

At this point I would say that the STI front knuckle could be used with a custom ball joint adapter. Not sure about the rear, I haven't looked at the rear knuckle to see if it's compatible with out rear suspension links. To use the STI front knuckle you would have to use the STI Brembos and a wheel the right size to fit over those brakes. To fit into the SVX strut tower you would need to either do some cutting and drilling of the SVX body, or put the SVX top mount on the strut.

[Crazy_pilot]

I did some talking with Mychailo about this idea, comparing the basic dimensions of the SVX and Impreza/STI struts. The fronts are roughly the same length, but the rear STI struts are 1.5-2" longer than ours. That in itself is not a problem, a suitable drop spring setup(or adjustable coilovers:D) would bring the ride height back to normal. The problem is that the STI has as much travel as we do in the rear. So to drop the rear to normal ride height you would use up 1.5" of suspension travel, giving you less than the SVX has. So, my opinion on the swap as of now:

The STI suspension CAN be used, with modifications.

1. Both front and rear SVX knuckles will have to be thinned somehow to fit into the strut mounting flange. Either by machining or grinding. Or you can pry the flange open to fit onto the SVX knuckle.

2. SVX top mounts will have to be used, or the shock towers in the SVX body will have to be drilled and cut to accomodate the different bolt patterns.

3. A bracket will have to be welded to the front control arms, allowing an aftermarket swaybar endlink to attach to the control arm rather than the strut. A rear '05 Outback endlink works perfectly.

4. The rear STI suspension will have to be compressed. This will sacrifice roughly 1.5" of rear suspension travel. To prevent the shocks from bottoming out a higher spring rate will have to be used. This will obviously have an effect on the handling characteristics.

Cost for this way of doing it: STI suspension+machining cost for knuckles+SVX top mounts+2005 Outback endlinks+bracket+welding bracket to control arm.

The big ticket option: Use a custom machined balljoint adapter to use the STI front knuckle. This allows you to use STI Brembos, and any other BBK for the STI.

Cost for this option: All of option A (minus machining knuckle) + balljoint adapter+STI knuckle and associated parts+Brembos

[Crazy_pilot]

So.... I bought a set of Stance GR+ coilovers today. They are 2002-07 WRX fitment. It'll be a little bit before they're shipped up, but I'm excited! Every day I see my classmates' 240SX and Prelude, both of which are lowered, and I'm getting real tired of the high front end of the SVX.

[Crazy_pilot]

*manic laughter*

Gots me some stuff!!!!

http://www.subaru-svx.net/photopost/data/570/medium/SP_A0205.jpg

http://www.subaru-svx.net/photopost/data/570/medium/SP_A0206.jpg

[Ricter]

Get those things installed now!!

And document everything you have to do to make them work (assuming it's changed from your speculations and measurements prior).

[Crazy_pilot]

I most certainly will.

[Johnybeas]

pictures of adapted front end??? plans for the adapter???

[Nevin]

Why don't you just cut out the SVX body mount where the struts bolt to the body, and weld in your own piece that is the same fitment as the wrx top mount?

[Crazy_pilot]

Why don't you just cut out the SVX body mount where the struts bolt to the body, and weld in your own piece that is the same fitment as the wrx top mount?

Way too much work, if my measurements are correct all I will have to do is drill two new holes in the SVX to accept the different top mount bolt pattern and grind down the part of the knuckle the strut attaches to by ~1.5mm. At the end of the day I'll still be able to go back to stock suspension with a small shim for the knuckle.

Nothing installed yet, I've got to find some free time from school to get this done.

[sowise]

Way too much work, if my measurements are correct all I will have to do is drill two new holes in the SVX to accept the different top mount bolt pattern and grind down the part of the knuckle the strut attaches to by ~1.5mm. At the end of the day I'll still be able to go back to stock suspension with a small shim for the knuckle.

Nothing installed yet, I've got to find some free time from school to get this done.

I agree way to much work but also why drill the holes in the SVX? I have been looking at doing a similar set up and rather than put holes in the car just press the mounting studs out of the mount, mark your hole pattern for the SVX on the top mount plate, redrill the mount plate and press in the studs. That way the only thing you modified was the suspension.

[Crazy_pilot]

I agree way to much work but also why drill the holes in the SVX? I have been looking at doing a similar set up and rather than put holes in the car just press the mounting studs out of the mount, mark your hole pattern for the SVX on the top mount plate, redrill the mount plate and press in the studs. That way the only thing you modified was the suspension.

Eh, still more work. Besides, I have very little intention of going back to stock once I have these installed. If anything I'll be going from one WRX suspension system to another and I'd rather be able to just bolt the new system in. Also, the studs holes are all counterbored into the plate, so I would have to disassemble the pillowball to get at the back of it. Two small holes in the shock towers are a small price to pay.

[sicksubie]

Maybe a dumb question but why not swap SVX camber plates onto the coilovers?

[Crazy_pilot]

It's an option (as long as they bolt up), but it's just more money.

To give you an idea of just how minor the hole drilling will be:

http://www.subaru-svx.net/photopost/data/570/SVX_vs_WRX_front_strut_mount_holes.PNG

[sicksubie]

I would be concerned with how close those holes are to each other...

[StatGSR]

^ what he said, honestly, if possible, i would re-drill all 3 holes to space them away from the existing as much as possible.

[Crazy_pilot]

Why would that be a concern? The studs on the struts are barely structural (they're tiny little M6 or M8 bolts) and all the load is upwards. The top mount of the strut is a circular aluminum plate that distributes the load into the strut tower. All the studs do is keep the strut where it is.

[Crazy_pilot]

TADA!!! 50% done. I only have the fronts installed at the moment, not enough time to get to the rear.

Before and after:

http://www.subaru-svx.net/photopost/data/570/medium/photo_4_.jpghttp://www.subaru-svx.net/photopost/data/570/medium/photo4.jpg

The drill plate I made to locate the new holes in the shock tower:

http://www.subaru-svx.net/photopost/data/570/medium/photo_3_.jpg

Camber plates!!! And pillow balls!

http://www.subaru-svx.net/photopost/data/570/medium/photo_2_.jpg

And voila, installed:

http://www.subaru-svx.net/photopost/data/570/medium/photo_1_.jpg

WOOO!!! I'm happy. I still have to install the rears, so I haven't yet felt the full effect, but so far this is awesome. Of all the coilover-equipped cars I've ridden in this one is by far the best. The ride is firm but not jarring and there's zero "bouncy-ness". There's minimal body lean when cornering. Specs on this system is 8kg/mm front and 6kg rear, or ~450lbs front/335 rear. If I try to bounce the front end of the car by hand... Nothing happens.

There's no rubbing, no odd clunking... And LOTS of height adjustment left. I could drop the car another 2-2.5 inches if I wanted to. Kind of ridiculous actually.

Now, the installation. If you have an aversion to grinders, drilling holes in your car, and making a set of coilovers non-resellable, this modification in not for you. Here's what I had to do:

1. Drill 2 holes in each shock tower
2. The Stance camber plate is a circle. I had to grind the sides down in 2 places (rear and outside) where it didn't fit inside the shock tower. The SVX top mounts are very triangular and the shock tower doesn't fit much more than them.
3. Grinding the knuckles heavily. The section the strut attaches to is a few mm thinner on the WRX. I took the knuckles right out of the car to do this, it would have been almost impossible to do on the car.
3. Oval the holes of the coilover lower mount. The two bolts on the SVX are more widely spaced than the WRX.

This took me an entire afternoon to install these (~7 hours) with the car on a hoist and air tools. A fair amount of it was the grind-test-grind-test-grind process, and a good hour was lost getting the two ABS sensors out of the knuckle. This job is not for someone who has only done oil changes. If you're not comfortable with fabrication work and custom modifications just get someone to build you a Koni/GC system.

[Nevin]

Lookin' good! What are the springrates on these units?

I would't be afraid of doing any of the things you had to do! haha

[Crazy_pilot]

8kg/mm front and 6kg/mm rear (about 450 lbs front/335 rear).

[Nevin]

Gotcha!

Sorry if you said that before and I missed it.

[Crazy_pilot]

Installation complete!!!!

Decided to change it up a bit and modify the camber plate instead of the car, since only one hole had to be moved. Press out stud, drill 5/16" hole, press in stud, done.

http://www.subaru-svx.net/photopost/data/570/medium/IMG_0054.JPG

Took the rear knuckles off, ground them down, bolted everything together aaaannnnd:

When the car is in the air and the wheels are already at stock ride height you know you're in for something interesting.

http://www.subaru-svx.net/photopost/data/570/medium/IMG_0060.JPG

On the ground:

http://www.subaru-svx.net/photopost/data/570/medium/IMG_0063.JPG

This thing is LOW. The picture doesn't really convey just how close to the ground it sits. I can't get my baby finger between the front tire and the fender. It feels very strange walking up to the car now, and even weirder when the hood's open. I'm very accustomed to having the engine at a certain height, and now that it's 2-3" below that... Weird. I also tagged my exhaust on a small speed bump on the way home. :lol: The insanity begins!!!

The trunk is still full of tools and parts, so I haven't been able to give it a good drive to figure the handling out yet. Tomorrow!

[StatGSR]

^ lol you have a baby finger?

besides that, looking good!!!

[Mike621]

Good work, Chris, but damn that's LOW!

[Ricter]

Wow. I'm in love with the new ride height.

Have you reattached the front sway bar endlinks yet? You referenced how you might do it in the first post , but I didn't see you go back and say you actually followed through with that yet, or maybe you did and I missed it.

[Crazy_pilot]

:lol: Thanks guys. I'll grab a few pictures when I get back this afternoon, it looks even crazier in the sunlight.

Wow. I'm in love with the new ride height.

Have you reattached the front sway bar endlinks yet? You referenced how you might do it in the first post , but I didn't see you go back and say you actually followed through with that yet, or maybe you did and I missed it.

lol, I didn't mention it here? Well let's fix that. I used the Outback rear links, cut them in half and threaded the shaft. I made a coupler in the machine shop, put them together, and welded a tab onto the control arms.

shotgunslade and I had a good discussion about this in another thread. Modifying the endlink mounts like this effectively softens the swaybar a fair bit, but I do have another version in my head that may take car of that.

http://www.subaru-svx.net/photopost/data/570/IMG_0524.JPG

http://img.photobucket.com/albums/v252/crazy_pilot/Car%20stuff/IMG_0704.jpg

[92 SVX]

That looks very good, I can't wait to see the pictures in the sunlight.

[Crazy_pilot]

Pardon the iPhone shots, I don't have access to a proper camera at the moment.

http://www.subaru-svx.net/photopost/data/570/photo_6_.jpg

http://www.subaru-svx.net/photopost/data/570/photo_7_.jpg

http://www.subaru-svx.net/photopost/data/570/photo_5_.jpg

[NikFu S.]

Man that's awesome.

[92 SVX]

Yes, im very jealous.

[1986nate]

Looks Great!
No way I could get away with having a car that low where I live though.:(

[httrdd]

Looks really good with the BBS on there too!

[TomsSVX]

I guess you failed your geometry class?:lol:

The ride height is too low, thus actually making the handling worse except maybe better dampening control... Can you raise it up more or are the struts maxxed?

Tom

[Crazy_pilot]

:lol: I know, the control arms are no where near level like that, I just wanted to see what I could do with it. I can raise it to at least stock levels, probably quite a bit higher if I really want to. One thing that's great about Stance is that they're dual height adjustable, meaning I can lower the car without touching the spring perch: (not my picture)

http://www.ziptied.com/Coppermine/albums/userpics/10464/stance1.jpg

[mkud28]

Wow that is low, I thought mine was low lol.

[LetItSnow]

Although I wasn't as low as that (and dag, you're in the weeds!) Tom told me the same thing about my Pearly, and from my experience he's definitely right.

[Crazy_pilot]

I had some skidpad fun using my iPhone and Dynolicious software. Around a 300ft skidpad the car hit .96 lateral G.

Test conditions: (this was an impromptu thing, so hardly ideal setup)

Temperature: 7* C (45* F)
Coilovers: Full soft.
Ride height: low.
Tires: General Exclaim UHP, 40 PSI front, 35 PSI rear.
Car load: 1/3 tank gas, myself (165 lbs) and 145 lb passenger.

Observations:

I was told the car cornered very flat from people watching, it certainly felt like it. There was some rubbing in the front outside wheel well, but nothing extreme. The parking lot we used was quite bumpy, as you can see in the graph from all the jumpyness of the line. The main limiting factor at this point is my tires. The Exclaims were fine with soft stock suspension, but can't handle the extra demands of the coilovers, the sidewalls are just to soft. They were my first set of "performance" tires and my initial thoughts were good, however now that I've had them for a while and have more varied experience with tires I would certainly not classify them as "Ultra High Performance" as General claims. Rather I would call them an aggressive touring tire.

Graph: (there's a high res version in my locker)

http://www.subaru-svx.net/photopost/data/570/medium/96_Lateral_G.JPG

[LetItSnow]

Is that with the car still slammed? All told, a skidpad queen is nifty until you get into turns that will throw your camber out the window and make performance mods cost performance!

[Crazy_pilot]

Yep, still slammed. I know, I know. The car hasn't even been on the alignment rack since I put the coils on. When I did the alignment this summer the specs were on factory all around, which are very conservative. Not even a full degree negative on camber and zero toe all around. I haven't bothered because I've only put about 60 miles on the car since then and it's about to go to bed for the winter.

Right now I'm just having fun with this coilover thing. I doubt I'll be bringing the car to a track for a while, but when I do it'll be at proper ride height, aligned, balanced, etc. What are you running for alignment specs Rob? The local Subie guys go for -2* camber all around and zero toe.

[LetItSnow]

I've had it set to whatever it was like when I got it! :lol: I'll do something with it next season, for sure. I'm not quite sure what yet.

[dynomatt]

Did you happen to get any photos of the rear?

[Crazy_pilot]

Woops, sorry I missed that question...

No real pictures of the rear, but there's nothing much to show, the process is almost the same as the front but doesn't involve drilling new holes in the car.

-Remove old, rusted out strut.
-Remove knuckle from car (remove axle nut, trailing arm bolt, lateral link bolt, wheel speed sensor, brake caliper, rotor, and parking brake cable)
-Go to town with your grinder on the knuckle until the coilover bracket fits.
-Put everything back together with your shiny new awesome parts.

The only reason this part takes longer is because you have to strip out the whole interior in the rear of the car to get at the three nuts holding the struts to the car. Seat, sides and rear shelf.

[sowise]

Outstanding thanks for the link to this from the other thread!

[Crazy_pilot]

Just a fun little bit of info: I had to raise the front of the car to get it onto the U-Haul trailer that brought it home the other week (1200 miles in a POS U-Haul cube van does not make for happy Chris). There's still adjustment left, I didn't try to max it out, but this is how high she's currently sitting:

http://www.subaru-svx.net/photopost/data/570/medium/photo_5_1.JPG

I haven't touched the rear, didn't need to adjust anything to fit the trailer. Raising the front was about 20 minutes work with hand tools and a floor jack. Amusingly, I had to drive the front wheels onto 2X4's AND remove the gripper thing from the jack to get it under the side of the car.

[Nemesis Destiny]

Nice job. If you're ever in my neck of the woods we should meet up and compare notes ;)

[Crazy_pilot]

Actually I passed through Sault Ste. Marie a couple weeks ago on the way home. I'm done with school for good now though, so I don't know if I'll be passing through that way again. Possibly if my girlfriend ends up moving out to Toronto with me, but not likely with the SVX.

[Crazy_pilot]

By request, I've attached a drawing of the difference in STi and SVX front top mounts.