[Az1aN]

hi all!

recently purchased a 05 STi that came equipped with Perrin Performance lowering springs, notice a rear knocking noise while driving. I assume the shocks/struts (i dont even know what is the difference between these two, care to educate lil girl ol' me ) are blown, put the car on the lift and notice they were OEM, what are my best compatibility with the Perrin springs?

PS: i tried to search but seems not many run with Perrin's springs, why is that? bad reviews? I've read they give the lowest drop.

Thank You!

[twiSTies]

STi Suspension Buyers Guide

[Az1aN]

Thanks, can't believe i missed the Sticky!

Since the thread is dated back in May, had Bilstein/RCE ever been released?

[evilSTi7]

^^^ twisties knows what's going on. More specifically for you knocking problem you most likely have a blown strut. It's pretty common on the sti. If you are still under warranty you dealer should replace it for you. If not your best option might be to pick up 06 or 07 struts to replace yours with.

also, the spring is the coil thing and the strut is that whole thing the spring sits on.

[Az1aN]

Originally Posted by evilSTi7

If not your best option might be to pick up 06 or 07 struts to replace yours with.

isnt it true that i'm better off going with aftermarket struts since I have aftermarket springs?

[twiSTies]

Originally Posted by Az1aN

Thanks, can't believe i missed the Sticky!

Since the thread is dated back in May, had Bilstein/RCE ever been released?

Unfortunately, nope. The Prodrive/Bilstein RB320 package is supposed to be here already, but hasn't arrived yet. I'd figure on yet another month.

[austinpike]

Since you have an '05, your options at the moment for replacement aftermarket struts are exactly one, the Ohlins for $2k. Neither the Prodrive/Bilstein nor RCE struts are out yet.

Most people who do aftermarket springs put them on stock struts, since there are no moderately priced strut options.

Don't know much about the Perrin springs. Pinks, Prodrive, and RCE are probably the most respected options around here, and they are designed to work on the stock struts. Dropping the car more than ~ an inch is not really recommended if you care about performance.

Now if you want to look into coilovers, there are a number of options out there.

[twiSTies]

Originally Posted by Az1aN

isnt it true that i'm better off going with aftermarket struts since I have aftermarket springs?

Yes and no.

Traditionally with many other cars, an aftermarket spring will have too high of a rate for the stock dampers (struts/shocks). This will cause the damper to wear at a much faster rate and eventually blow out. Or blow out after the first pothole if you're extra lucky.

On the STi, the stock dampers can handle a higher spring rate, but due to the internal construction, there isn't enough bump travel to support a spring that lowers the car significantly without the car riding on the bump stops, which causes corner entry understeer and other problems (most signifcantly, incorrect A arm geometry)...not to mention it'll ride like garbage over most roads in the U.S.

You're left with the option of getting springs, cutting the bumpstops one progression, dealing with the inevitable degradation in ride quality, or just skipping this route and going to coilovers.

Ohlins are your other option, but at $2k, you may as well go with coilovers if you want bump travel and spring rates that will make a real difference in handling.

Another route to take is to keep your stock springs, cut your front bumpstops one progression, then get RCE Lowering camber plates. This will give you the lower ride for looks/handling without decreasing your bump travel (actually increasing it with removal of the bumpstop progression), allow you to run more camber (alignment is the key to any setup), and not punish you over bumps.

So, to make this long summary shorter, you'll be ok with springs on the stock struts, but they're ultimately quite the compromise.

[holycow]

Originally Posted by twiSTies

Yes and no. On the STi, the stock dampers can handle a higher spring rate,

I disagree. I am running the RCE yellows on stock struts, and I am certainly under dampened now. I bounce around on the road like cut stockers on a civic.

[twiSTies]

Originally Posted by holycow

I disagree. I am running the RCE yellows on stock struts, and I am certainly under dampened now. I bounce around on the road like cut stockers on a civic.

Interesting. You sure its not just from you hitting the bumpstops?

[holycow]

Originally Posted by twiSTies

Interesting. You sure its not just from you hitting the bumpstops?

totally sure. using the shorter bumpstops supplied by rce, and it happens over all kinds of sizes of bumps/dips.. even the little ones. They aren't GROSSLY under dampened... but certainly are to a point.

[twiSTies]

Originally Posted by holycow

totally sure. using the shorter bumpstops supplied by rce, and it happens over all kinds of sizes of bumps/dips.. even the little ones. They aren't GROSSLY under dampened... but certainly are to a point.

I haven't heard that before, good info. I wonder if its RCEs rates (which are higher than most lowering springs on the market), or what.

I see Stretch lurking...

[jasonlee4180]

If RCE's seem to be too aggressive, would the prodrive or the jdm pinks be a more viable combination with the stock struts?

[stretch]

Originally Posted by twiSTies

I see Stretch lurking...

Don't run lowering springs on stock struts!
Don't run lowering springs on stock struts!
Don't run lowering springs on stock struts!

[thunderbird]

Originally Posted by holycow

I disagree. I am running the RCE yellows on stock struts, and I am certainly under dampened now. I bounce around on the road like cut stockers on a civic.

This might be off-topic: I don't know how many miles you have on your struts, but they eventually need replacing. One of the symptoms is underdamping. The stock ride is so bouncy that its hard to know if its tired shocks or what. The mechanic confirmed that my struts were shot when I replaced them with coilovers on my '04 with 75k miles on the odo.