sti springs

[justaddwater]

hey what's up, i'm a new guy with a question. does anyone know if aftermarket sti springs will work on a wrx. both cars are 2004. thanx

[Dean]

Should be fine. Spring rates may be to high for the WRX struts to properly damp though.

[Kevin M]

Sedan springs don't work quite right on a wagon actually. The length of the rears isn't quite right.

[JonnydaJibba]

Another wagon, I like wagons, I would say what up, but this is the tech chat forum so I won't.






(what up?)

[cody]

Originally Posted by BAN SUVS

Sedan springs don't work quite right on a wagon actually. The length of the rears isn't quite right.

Really? I thought the spring rates were just slightly higher in the back for wagon specific springs.

[sperry]

Originally Posted by cody

Really? I thought the spring rates were just slightly higher in the back for wagon specific springs.

Which makes them a different length under static load than the sedan springs.

[cody]

Well THAT'S true, but plenty of people run sedan springs on their wagons. The only difference between the sedan and the wagon, that matters for this application, is ~80 extra pounds in the rear of the wagon. I don't think that's a big deal.

Still, I run wagon specific Eibach springs.

[sperry]

Originally Posted by cody

Well THAT'S true, but plenty of people run sedan springs on their wagons. The only difference between the sedan and the wagon, that matters for this application, is ~80 extra pounds in the rear of the wagon. I don't think that's a big deal.

Still, I run wagon specific Eibach springs.

Apparently the difference is significant enough to those that design the springs or we wouldn't see two different springs for sale for Imprezas.

[cody]

I think most spring manufactures offer one spring for both the wagon and sedan.

[sperry]

Originally Posted by cody

I think most spring manufactures offer one spring for both the wagon and sedan.

Says the guy with wagon specific springs.

[cody]

Yah, well I'm pretty anal like that, but if the original poster wants to use sedan springs, I don't think he'll notice any problems. That's all.

[AtomicLabMonkey]

Originally Posted by cody

Well THAT'S true, but plenty of people run sedan springs on their wagons. The only difference between the sedan and the wagon, that matters for this application, is ~80 extra pounds in the rear of the wagon. I don't think that's a big deal.

Back of the envelope calc, assuming a high motion ratio from a strut coil-over spring:

Using a typical OE spring rate of around 125lb/in, an increase of 40 lbs per side equals a changed in loaded spring length = 0.32". Which means ride height will drop approximately 0.32".

A "performance" spring of say, 300lb/in would see a loaded length change = 0.14" with that same 40lb/side weight gain.

[tysonK]

http://www.i-club.com/forums/showthread.php?t=114396

[Kevin M]

I don't think those work without the older strut tops Tyson.

And it's not just the extra weight of the wagon body over the sedan body. It's the extra weight you may or may not carry inside the wagon compared to what you fit into a sedan.

Anyways, yes you can bolt STi springs into your wagon and drive around perfectly happy. It's just not as good for your struts as proper springs would be. If you buy coilovers with threaded strut bodies, then it doesn;t matter as you should be able to get correct adjustments to it.

[cody]

You might as well throw some struts on while your doing springs anyway. KYB AGX's will add some level of adjustability.

[justaddwater]

thanx guys. i guess i'll throw them in and try it out. worst that could happen is putting the stock springs back in.

[Kevin M]

KYB doesn't make wagon-specific struts, at least not in AGX or GR2. Sedan struts cause excessive positive camber in wagons near stock ride height, and blow out faster when lowered a lot.

[cody]

Hmm, maybe that's why the alignment shop disregarded my instructions and used the camber bolts in the front instead of the back. The thing is, I had a guy I know check my camber a year after the alignment and things didn't add up. The original alignment results showed ~-1.4 in the front and ~ -1 in the rear (which is pretty much what I asked for). But when my buddy checked it with his fancy new alignment tools, he showed I was running -1.1 on both front wheels and -1 in the rear. He forgot his breaker bar, so that's what I'm still running today.

And you're right, AGX will blow out prematurely if you couple them with Tein S-Techs (I think those are pretty low) or the like, but they are designed to work with a moderate drop and mine still dampen like a mofo 2 years after the install. They'd work great with STI springs.

[MattR]

.3 difference in the front is no big deal, could be attributed to settling. That is hardly any difference over a whole year. And why do you run so much negative camber on the street? Do you race the car?

[cody]

Yah, but settling would add negative camber, I thought. It doesn't wear out my tires unevenly so I think it's fine. I don't race, but I hope to start autoXing next season.

[Kevin M]

Negative camber isn't so bad on a McStrut car for the reasons explained by Austin- when your camber curve sucks, every time you get some decent body roll in a turn you're evening it out anyway. I ran -2.0 up front and -2.5 rear for almost 2 years with no ill tire wear effects, even on my snow tires that saw little hard driving and obviously no track or autocross action. I also had a ton of toe out too , so maybe there's something to Dean's "cone" theory. :shrug:

[sperry]

For you guys running a ton of negative camber... remember that it is a trade off. Sure the tire flattens out in the curves, but the drawback is that you don't have all the tire to brake with.

For example, I was running my usual -3.5 deg of autocross camber at my 1st trials event. The car handled the corners great, but the excessive camber (and associated toe out) meant I had very little contact patch for the heavy straight line braking sections of the course. By dialing back to about -2.0 deg of camber, I picked up a lot more traction in the braking zones allowing me to go much deeper into the zone which lowered my times far more than increase in time from the lower traction in the corners.

In addition, my tire wear on the first few runs w/ the -3.5 deg of camber was horrible. The braking was *way* overheating the inside edges of the front tires, and the uneven wear was visible after just 2 or 3 runs.

Using a tire pyrometer is a great way to figure out the balance between cornering and braking with regards to camber. By taking inner edge, middle, and outter edge tire temps, you can emperically determine if you need more or less camber, and more or less air pressure.

[AtomicLabMonkey]

Originally Posted by sperry

For you guys running a ton of negative camber... remember that it is a trade off. Sure the tire flattens out in the curves, but the drawback is that you don't have all the tire to brake with.

Also very dependant on the tire's internal construction and width. Some tires can tolerate more static camber than others & maintain braking performance due to these factors. Just a tidbit to think about if you're ever comparing chassis setups with other people... what works best all depends on what tire you're using.