Has anyone actually installed 05-07 stock STI suspension?

[elninoalex]

I can see where people have talked about it like it should work, but can't find where anyone actually did. Of the five SVXs I've owned, they've all had blown struts. I'm hoping #6 (94 Laguna) will be different without dropping a grand on coilovers. But I will if need be.

Steve

[Crazy_pilot]

Several people have now. I think I was first, but a few other have done the swap as well. I used the 02-07 WRX fitment coilovers but the 05-07 STI are better - they are built for the same flange thickness as the SVX so you don't have to spend several hours grinding your knuckles down.

http://www.subaru-svx.net/forum/showthread.php?t=41831

[elninoalex]

Thanks. I did read that thread as well as smc's. But I was wondering if anyone had done it with just the stock springs and struts and not coilovers.

[Crazy_pilot]

Ah, gotcha. I think you might run into issues with ride height. OEM STi struts are about 1.5-2" longer in the rear than SVX struts so you'd either have the tail sticking way up or need some drop springs to lower it back down (and lose an equal amount of suspension travel).

[elninoalex]

Someone guessed the front would go down about 1.5". Any thoughts on that? I'm more concerned with the front than the back.

[Crazy_pilot]

I think it's a toss up. The strut lengths are similar, we have a heavier nose but the STi has higher spring rates. I don't know how close that would come to balancing out though.

[elninoalex]

Would using the stock STI front struts negate the front sway bar?

[Crazy_pilot]

You'd lose the attachment points for it, the STi sway bar attaches to the control arms rather than the strut.

[elninoalex]

Thanks Chris. I'm going to be looking for some front Sti struts to try this out with.

[gearheadE30]

Some info on spring rates for the '05-'07 cars, if that's useful. Asterisk means it's an mfg-verified number, and the exclamation point means that it's just from a vendor's website.

2004-2007 STi Aftermarket Spring Rate and Drop

Spring: Rate (F,R, lb/min): Drop(F,R,mm):

Stock 224F/194R * 0F/0R *
Cobb Sport 280F/243R * -51F/-38R *
Crucial Racing 257F/217R * -12.5F/-9R *
Eibach Pro-Kit ???F/???R -30F/-20R *
Espelir GT 280F/230R ! -30F/-20R !
Ground Control 300F/300R * 0 to -38 F&R *
Perrin ???F/???R -48F/-38R *
Prodrive ???F/???R -15F/-10R !
RCE Blacks 285F/269R * -15F/-10R *
RCE Yellows 295F/275R * -23F/-20R *
RSR Ti2000 268F/194R * -41F/-36R *
STi Pinks 257F/217R * -20F/-20R
STi Arai 342F/286R * -15F/-15R
Swift Sport Mach 252F/224R * -30F/-30R !
Swift R Spec 285F/275R * -20F/-15R * (2004 Spec)
Swift R Spec 285F/275R * -25F/-25R * (2005+ Spec)
Tanabe DF210 263F/246R * -33F/-20R *
Tanabe GF210 241F/224R * -30F/-20R * (2004 Spec)
Tanabe GF210 324F/246R * -25F/-13R * (2005+ Spec)
Tein H-Tech 229F/196R * -26F/-9R * (2004 Spec)
Tein H-Tech 230F/196R * -29F/-17R * (2005+ Spec)
Tein S-Tech 252F/219R * -41f/-24R * (2004 Spec)
Tein S-Tech 252F/219R * -44F/-32R * (2005+ Spec)

[gearheadE30]

EDIT: this is for a 1992 SVX, from factory literature.

Stock SVX suspension information:

Front rate: 140 lb/in

Rear rate: 110 (LS) 116(LSL) lb/in

I don't have any info on free lengths, but I do have these numbers:

Front upper dia: 5.51"
Front lower dia: 6.3"

Rear upper dia: 5.31"
Rear lower dia: 6.10"

[EdWindows]

According to Nate, the stock rear STI struts should bolt in just fine as the spring perches and everything are the same (using the SVX top hats of course). He also mentioned the front struts can work but that the spring perches are different, and then you also have to grind out the lower bolt holes on the flanges where it attaches to the knuckle.
I plan on picking up some STI struts and using my old stock suspension for some compatibility testing, and once I do I'll make a thread and post results.

[gearheadE30]

Hey, another E30 guy!

I would expect that the stock suspension would bolt up fine since the coilovers do; I would be more concerned about how long the struts are. My -fu isn't strong enough to find that info, haha.

One thing I have read is that the STi parts cause a lot of positive camber in the rear, so you'd either want rear camber plates or camber-adjusting bolts. that's all secondhand knowledge, though.

[EdWindows]

Or you get adjustable lateral links, and increase your rear track width for more stability in the process of correcting your camber.

[Tireiron]

Originally Posted by EdWindows

Or you get adjustable lateral links, and increase your rear track width for more stability in the process of correcting your camber.

Be careful, you can't adjust it too far out or you will cause the rear axleshafts to pop out of the diff (ask me how I know). My fortune auto 500 coilovers have slotted upper holes in the rear to allow for camber adjustment and it is plenty of adjustment to pull it into where i wanted it keeping the lateral links at about stock length. I'm running 1.5 degrees negative in the rear and could easily go to 3+ with the slots.

The rear struts will not fit and bolt right onto the rear knuckle either. The SVX rear knuckle is 1.25" thick, all other Subarus, including the STi rear knuckle are 1" thick. Because I was making a permanent change to STi fitment, I removed my rear knuckles and had a machine shop mill them down to 1" thick. The rear STi tophat only requires a single new hole to be drilled into the SVX chassis per side.

The front requires 2 holes to be drilled into the chassis for the STi topmount fitment. The front lower knuckle mount for the strut on the SVX has the holes 1/4" closer together than the STi strut. To deal with this I notched the hole in the STi strut mount 1/4" closer together to match the SVX fitment as the steel of the strut mount was easier to machine myself than the cast knuckle.