04 STi Struts w/ 245lb springs - Installation Conclusion

[skid542]

First off I want to extend a sincere thanks to Jamal, Chris, and everyone else who has been patient with my relentless questions as I got my new suspension modified and installed. It handles so much better and I saw distinct time reductions at Auto-X.

I am at work and will be adding to this thread throughout the day and next week. For now information is pretty basic and direct.


For those who haven't followed my pilgrimage, I have a 93' SS that I installed a set of 04' STi struts with 245lb King springs on all four corners.

In order to install them I had to make two modifications.

The first was slotting the lower front strut mounting hole. I slotted them approximately 0.090", moving the hole away from the body. This was done to provide the movement needed to obtain a proper alignment. I will provide final alignment specs at the end. Note that I am running Oakos camber bolts in the rear.

The second modification was changing the rear spring perches. The 04' stuff will fit if you are willing to file the mounting holes in the car. I am running a nice Cusco RSB and did not want to do this. The solution is to replace the 04' strut top with a 90-91 strut top as the 04' springs are tapered. I searched and searched for Grp N mounts but with no luck. FHI told RalliSpec (great guys btw) that they no longer produce these because the car is too old - so if you find some you'd be wise to snatch them up. Not being able to find Grp N's, I went to the stealership and got brand new tops. If I had thought ahead I would have contacted someone like Genuine Subaru or such and ordered my tops through them, from the dealership it was $200 for both. As a heads up, the new mounts did not come with the rubber spring seat. I was able to use the ones from the old struts for this, just cut them a little as the diameter is smaller. Once you replace the top hats, everything fits into the car just fine.

While I had everything taken apart I went ahead and regreased the struts. The 04' strut is an inverted design meaning you can pull out the damper from the housing. To do this all you have to do is take off the spring and remove the small nut that is on the bottom of the strut housing. Be aware that if there is paint on the threads, you'll want to wire brush the threads clean first. If the nut sticks, it can (did on me for one of the struts) rotate the shaft and there is no way to really hold the shaft still. The shaft is 'keyed' into the housing but once you get about 1/16" play, the shaft can fall out of the housing 'key' and just sit there and spin. Once the nut is off, you simply pull the damper out of the housing. Once it's out, I cleaned out all old grease and replaced it with some Mobil 1 synthetic chassis grease. Grease up the outside of the damper a little and then slide it back into the housing, put the nut back on and you're ready to re-install the springs/hats.

While I had the housings apart I went ahead and welded in some wedges between the housing and the hub mounting flange. The fronts were done when I got them so all I had to do was the back. This is far in excess for normal street driving but I do intend to make this setup my rally setup so I followed Chris's, Rally370, lead. It look cool and gives a very secure mental feeling when driving.

Putting the struts into the car is pretty straight forward. Being a sedan I had to pull the rear seats and also remove the seatbelt to get good access. This isn't hard, just another straight forward step. Some might be able to get the struts with the seatbelt in, but my fingers are too big so out it came... only three bolts. I did have to remove the rear window trim piece though, pretty easy. There are plastic snaps on the columns and the only screw is on the bottom and the bolt holding the shoulder 'pulley' to the car. One tip for those who haven't done this before, when putting the bolts through the hub and strut - if you put the bottom bolt in first you can place a screw jack under the wheel bearing/hub/lugs and screw it up a little and it will make it easy to get the top hole in alignment. Having a second hand would have helped but this little trick did make it easy to tensions the control arms and sways to get the hub where it is supposed to be. Taking one side of the sway bar loose will help as well.

Slotting the front struts gives some play that you have to pull out while tightening things down. Not difficult. Once everything is tightened down, it was off for an alignment.

I took it to the shop and had the most expensive alignment I've ever had - $150. But, the guys were great - went to Buck's Tire in Spokane - and they let me hang out and we did a lot of tweaking. Even had the alignment set with me sitting in the car - my weight changed settings about 0.3*. My final alignment was 1.6* up front and 0.8* in the back ***Note I will verify this after work***. Toe is zero all around, +/- 0.05*. Not as much camber as I wanted, but it was enough for now. Next time I take things apart to re-grease the struts I will slot the fronts even more and also slot the backs. I should have done this to start with as I wanted 2.5* up front and 2* in the back. However, I am running a 205/55/16 all season tire so they don't have the stick to really compress and push the suspension on the tarmac.


So all the work aside, time for the fun part - how does it drive?

The ride is very noticeably stiffer. Which is to be expected. It has taken a little getting used to but now that I have, it doesn't bother me. Around town there are a lot of rutted intersections from studded tires in the winter and you don't want an open cup of coffee in your lap going across them. It has a pretty solid bounce when you hit a bump and I hear a lot more noises coming from the front end than I used to. However, when hitting a big bump it still damps right now and the car feels much more planted on the road. Steering turn in is nice and crisp and the car has a much more 'prepared' feel to it. I did wedge the struts so I can take the car to Rally-X without any fear of bending struts. Consequently I have been hitting some bumps a higher speeds than I normally would and the car just takes it and keep going, doesn't seem to mind.

On the Auto-X I've seen a huge difference. I've increased my times about 2-3 sec. on a 70 sec. course so far. Keep in mind though that I got the struts installed thursday, aligned friday and raced sat. so I was still getting used to the new feel during the race. I am anticipating reducing my times even more. Body roll is still noticeable but much much less. I am still running stock sway bars and I know that'd an upgrade would help but I also want a viable off road machine too. The biggest difference though is in the tight 30'-40' slalamon (sp?). It cruises through much quicker and feels all around more secure. Tight L-boxes are a lot better and two consequtive L-boxes (essentially a 180*) are not as exciting but much faster. I had several people tell me that I was pulling both inside wheels up a couple of inches on the old suspension coming through the 180*'s. Now people tell me the car is boring to watch, but it's a lot 'safer' and much faster through the corners. I haven't had a chance to do any high speed sweepers but the few curved interstate on-ramps have been very solid and stable.

Rotation with the car is still fairly neutral. If I come into a corner hot and heavy on the brakes I can kick the back out pretty easily and if I'm still on the brakes and give a steering input the back will swing out a little. So far I haven't destroyed a set of cones but it has gotten a little exciting. Again though, most of that rotation has been due to heavy braking and initiating a turn while the car is still unsettled. Through the corners it's pretty neutral and the only rotation I've really had is due to being heavy on the throttle. If I enter a corner hot and start powering through it, once the wheels start slipping additional gas will start it rotating. But I haven't had it rotate on me just coasting through a hard corner. I'll play with this some more though and see just how neutral the car really is.

The car also squats a lot less during take offs and dives much less during braking. This has added a lot to the car's feeling of being fast. Obviously it didn't add any power but somehow it just feels faster. It does reduce my times coming out of corners though as I can apply more power and still keep the car balanced.

Ride Height - Well, overall it's a little lower and I'm happy with it's stance. It dropped it about 1/2" in the front but actually I think it raised it in the rear. Like an idiot I didn't measure before and after. However, it is now has a very slight rake to it. Measuring from the ground up to the bottom of the runner board, the rear is about 3/8" higher than the front. I attribute this to replacing the STi tophats with the taller 90-91 tophat assembly. I figure if nothing else, it gives me a little extra clearance on my muffler. I'll get some pictures up soon to show how it rides now.


So all in all, I'm very happy with the setup. It should last me a long time. Some day I may move to a set of Koni inserts, right now it does get a little bouncy on undulating highway surfaces, but moving from the stock setup to this has been night and day. I think I'll see even more improvements when I start running a 215 or 225 tire.


Below are some links that were helpful in getting all of this together. Hopefully the next guy who takes on this path will find them useful and answer some questions.

Slotting/Alignment - http://bbs.legacycentral.org/viewtopic.php?t=37245

http://bbs.legacycentral.org/viewtopic.php?t=36544

Other 04' STi experience - http://bbs.legacycentral.org/viewtopic. ... hlight=sti

Other 04' STi experience - http://bbs.legacycentral.org/viewtopic. ... hlight=sti

My initial rebuild questions - http://bbs.legacycentral.org/viewtopic.php?t=36985


So thanks again to those who helped out with answers and advice.

If anyone has any other comments, questions, please feel free.

[skid542]

Ride Height -

[jamal]

whoops all my pictures are broken. I'll fix that one of these days.

I've got the sti suspension installed on my new car, except I slotted the front struts, replaced the inserts with fresh ones from an 06, and cut a nub off the front bumpstops.

The car feels much, much better. Ride is less jarring thanks to the valving revision and shorter bumpstops, and the thing really grips with more front camber. Now all I need are some swaybars.

[skid542]

I take it Subaru changed their STi valving between 04' and today. All still the same ID on the housings so it's all interchangable?

And the bumpstops, I've heard a few people say they've done this. I guess I haven't really been paying attention if I'm hitting the stops but I thought they were there to prevent an "over-limit" situation on the damper?

[n2x4]

I've heard about cutting the bumpstop nub as well. I believe there's a thread over on RS25 or NASIOC that talks about some math you can do to see if you're on the stops. I'll see if I can dig it up.

EDIT: found it! http://www.rs25.com/forums/showthread.p ... t=bumpstop