Strut FAQ

From WikiNASIOC

This is meant to be a fairly short FAQ devoted to all the wacky quirks of the STi struts in all their forms.^[1]

1 I have some red struts in front of me. Which ones do I have?
2 I want to put STi struts on my car. Will they fit?
3 My STi struts are making a clunking noise. I think it's in the rear. What gives?
4 Is the clunk of doom dangerous? Will it affect my car's handling?
5 What can I do to fix the clunk?
6 What springs should I put on my STi struts?
7 How stiff a spring can I put on the STi struts?
8 Can I put Koni WRX inserts in my 2004 STi struts?
9 Can I put Koni WRX inserts in my 2005-2007 STi struts?
10 References

I have some red struts in front of me. Which ones do I have?

The paint codes on the spring should help identify them. http://forums.nasioc.com/forums/showthread.php?t=361244&highlight=struts+dots+spec

I want to put STi struts on my car. Will they fit?

Check out the "Will this suspension part fit my car?" thread: http://forums.nasioc.com/forums/showthread.php?t=1303381

Short version: The 05+ STi's have different hubs, and the mounting points on the front struts are different. 05-07 front STi struts won't fit any other car (the rears did not change) because when the 2005 STi got the new 5x114.3 hubs the bolt locations changed. The rest of the details are covered in the thread including what you have to do to make 02-03 stuff fit 04+ stuff and vice versa.

My STi struts are making a clunking noise. I think it's in the rear. What gives?

There are many threads about the STi strut clunk. This is the most famous: http://forums.nasioc.com/forums/showthread.php?t=520870&highlight=strut

Is the clunk of doom dangerous? Will it affect my car's handling?

There is no definite answer. The strut may be sticking, which may be affecting the car's performance. (This link is okay, but I'm always looking for a better one.) http://forums.nasioc.com/forums/showthread.php?t=997640&highlight=clunk+stiction

What can I do to fix the clunk?

Greasing them can help make the symptoms go away. This thread discusses it: http://forums.nasioc.com/forums/showthread.php?t=1362104

So does this one: http://forums.nasioc.com/forums/showthread.php?t=1415706

What springs should I put on my STi struts?

Start here: http://forums.nasioc.com/forums/showthread.php?t=1383366

It discusses a lot of the issues related to the STi struts and MacPherson struts in general. The short version is - a lot of the lowering springs out there are too low.

How stiff a spring can I put on the STi struts?

waiting for a better answer to this question I know someone local who ran 325/300 lb/in Ground Controls on his STi and liked it as an autox setup. I'm not sure what the upper limit is but it's probably something in that range.

Can I put Koni WRX inserts in my 2004 STi struts?

Maybe (see below) but your best bet is to just pick up some WRX housings since they will definitely fit, and those housings will definitely fit your car.