DIY || STi strut bar install onto BRZ (applicable to FRS)
 

I bought the STi strut bar a while back, and finally got around to installing it. I liked this strut bar mostly because of the clean design, but also was intrigued by the "flexible" design.

Contrary to popular belief, strut bars are meant to deflect/transfer loads from one strut tower to another to by tying them together but can be of virtually any design. Many OEM bars are cheaper hollow steel bars, while aftermarket bars often end up being a more intricate aluminum design (or prettier steel design).

After getting the STi bar, I wanted to look at how it was designed, so I pushed the STi rubber center cover to reveal the ball joint design:

http://i.imgur.com/CeQtG2V.jpg
http://i.imgur.com/CNL3EJ1.jpg

From what I can tell, it's just a simple ball joint socket with two rubber covers over it. The package and instructions specifically state to not put load on this joint past a certain angle (when handling the bar), and I can see why; if you were to bend the bar more than ~45 degrees or so, it will pop the ball joint out of the socket.

Having said that, when pushing the ends together there's absolutely zero play. After seeing this design, now I understand why it is "flexible".

Under hard cornering, the bar acts as a solid piece and any deflection from one strut tower is transferred to the other. However, when driving in a straight line the bar allows one side of the car to "sag" or "go upwards" depending on the road condition. This is hard to describe but I hope someone (or STi themselves) can make an animation showing how this works.

Anyhow, install instructions (for those wanting to buy):

Tools needed:

• 12mm deep socket (or wrench)
• 5mm hex tool
• Long ruler/leveler

Time: approx. 15-20 minutes

http://i.imgur.com/pUhdShV.jpg

Start by taking off the 12mm strut tower nuts.

http://i.imgur.com/h5UQWiq.jpg

Next, put strut tower bar onto shock towers, over the strut studs.

http://i.imgur.com/P0qZkj3.jpg

Tighten the 12mm strut tower nuts.

http://i.imgur.com/rdt6XSV.jpg

In this picture, you can clearly see the deflection the bar has shipped from the factory.

http://i.imgur.com/qk97cKo.jpg

(no picture for this step but it's self-explanatory)

Use a 5mm hex tool to loosen the hex bolt on the ends of the strut bar from the end plates. Using the leveler (or some type of string/flat edge as a guide), move the bar so that it is level with the measuring edge. Tighten the 5mm hex bolt on one side, then move to the other side.

After you are done with this step, the leveler should look approximately like this:

http://i.imgur.com/iKsJRja.jpg
http://i.imgur.com/Y8HcyCE.jpg
http://i.imgur.com/Fb3xcNU.jpg

Lastly: if you moved the rubber cover (or need to adjust it), there are white marks on both sides of the cover (and a corresponding white mark on the strut tower bar). Line these up on both sides to center properly.

http://i.imgur.com/r3SgfY3.jpg

Installation finished, go out and test drive!

http://i.imgur.com/TuOGhfr.jpg
http://i.imgur.com/ygyfRKW.jpg
http://i.imgur.com/AZjTJJe.jpg

-alex

That's kinda cool! It might be on my TO DO List soon

That's a lot of deflection on the bar without adjustment. When I installed mine I didn't have to adjust the four allen bolts at all (the STI video did show them adjusting it before closing the hood on the Forester). But at the time of the install my car only had a couple hundred kilometers. Same with my flexible draw stiffeners, both rods ended up having their lengths adjusted exactly the same down to the mm by chance during fitting (chassis by then had 2500km). I guess I just got lucky.

No two STi bars will be assembled the same from the factory... if they were, the instructions wouldn't need to be so detailed.

Just a byproduct of the design I suppose.

-alex

Where did you pick this up at?

How much?

@mav1178 ... any driving impressions?

@donoman I like how I'm reading your comment 3 months later... anyhow.

Driving impressions are... placebo effect. I could feel some stiffness over some surfaces, and the car overall is a bit more rigid than before (it's the most apparent when you are jacking up one corner of the car and three wheels come off the ground), but otherwise the normal driving sensation is about the same as without a bar on normal roads.

I think on a completely stock car it may make a bigger difference. My Ohlins makes it hard to tell.

At the track, I have no idea. I like to curb hop and run tight lines so perhaps it helps there.

YMMV.

-alex

Currently $260 at Japanparts
https://www.japanparts.com/parts/detail/40969