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Discussion Starter #1 (Edited)
Shortly after buying my Forester XT I started investigating what it would take to lower down to WRX or STI ride height (reference http://www.subaruforester.org/vbulletin/f70/sti-suspension-whats-needed-124773/). I did a fair amount of research, poured over schematic diagrams, called people who work on Subarus for a living, and finally found what I think works. There are plenty of write-ups on how to switch out suspension, I may revise this writeup in the coming weeks, but for now I present to you how I went about doing my idea of switching to WRX suspension ignoring the details of the swaybars and struts. There are more parts that you could go with like the front lower arm assembly, but the stock front arm seems to work just fine. I welcome comments on how to make this process easier / better... not that I'll be doing again any time soon.

I'll update with alignment specs tomorrow, but initial eyeball seems to tell me the rears don't have too much negative camber. I stood on the rear bumper of the car and it barely goes down. Driving around down is nice and smooth, no bounciness, with great turn-in (perhaps due in part to the new sways). Car drives straight now so things shouldn't be too far off.

WARNING:
I am not a mechanic, I don't do this for a living, and I am definitely not well versed yet in Subaru repair. Follow what I came up with at your own risk, you've been warned. When in doubt seek a professional.

Goal for the project:
I wanted to basically start the process of making my own version of a Forester STI. I had heard that these cars share a lot of components between models so I did my research. I identified all the parts that were different between an WRX and a Forester and bought the WRX version. I kind of went out on a limb not knowing if all the parts would go together correctly. So far it looks like my leap of faith is paying off, I'll know more tomorrow when I get it aligned. This wasn't the cheapest way to do all of this but I wanted to go with new parts since the car has all of 1000 miles on it.

All the goodies:

Sitting waiting for the surgery:

Before and after:

Springs and Struts I used:
GTWORX / Bilstein WRX struts with RCE blacks (GTWORX.COM : GTWORX/Bilstein Impreza WRX Cup Sport Kit). This setup isn't suggested by GTWORX, in fact I was advised against it. Which is understandable, without the WRX parts below I believe wholeheartedly that the rear upper control arms would hit the body. I went with these for a few reasons, 1) They are valved for higher spring rate, 2) They have a higher spring rate hopefully allowing me to still run with cargo, and 3) The rears have a height adjustment to help keep a slight rake going.

Note: Updated to RCE Yellows to add a little more height and stiffer springs.

Why Struts not Coilovers:
I didn't need adjustability and even if I used coilovers to get the drop I wanted I'd still have to deal with the upper control arm. So I went with a stiffer spring with a well matched strut.

WRX Parts I used for the switch:
Rear:
20176FG021 x4 Stopper-upper (replaces frame spacers)
901000343 x4 Flange bolt 14x131.5 (replaces long bolts once the spacers are out)
20252FG000 x1 Upper right rear control arm (replace straight control arm)
20252FG010 x1 Upper left rear control arm (replaces straight control arm)
20157FG000 x1 Support-sub frame, right (needed to support the subframe once its raised)
20157FG010 x1 Support-sub frame, left (needed to support the subframe once its raised)

Front:
20323AG000 x2 Spring seat-front strut, upper (needed to work with the RCE blacks)

Side by Side Comparisons:
Front Struts (new on right):

Front Springs (new on right):

Front Spring Seats (new on left):

Rear Struts (new on left):

Frame Supports (new on bottom):

Rear bolts and spacers (new on right):

Rear upper control arms (new on top):


Here's what I did on the front (more or less):
  • The front really goes on with out much trouble.
  • I followed a WRX writeup on how to switch out the struts and everything went well.
  • I hadn't purchased the spring seats before starting this so that was an unpleasent surprise when the Forester ones didn't fit the new springs, causing me to have to wait a few days with the car up on jack stands.
  • The GTWORX front struts don't come with dust boots, and the Forester dust boots are too wide to fit correctly with the new spring seats. Since the rear struts came with new dust boots, I re-purposed the old rear ones for the fronts and they fit nicely
Here's what I did on the rear (more or less):
  1. I removed the exhaust from the cat back. Others may not have to do this but I used an ATV jack to hold up the subframe while I switched out spacers and having the exhaust on there would have made that difficult.
  2. Removed the sway bar
  3. Removed the struts
  4. Separated the upper control arm from the hub (leaving the two rear bolts left)
  5. With the struts, exhaust, and hub out of the way I had enough room to get to upper control arms. If I didn't have this room, the procedure actually calls to disconnect a lot of things including the propeller shaft... I didn't want to do that so I made due. One thing to note those things are on there seriously tight (seemed above torque spec, but no matter). I used a breaker bar with the handle of my jack as an extension, only then could I break them loose.
  6. Switched out the upper control arms
  7. Supporting the sub frame from underneath I loosened the 4 sub frame bolts and lowered the sub frame slightly, just enough to get the spacers out.
  8. With the original spacers out, I set the new spacers in place (more like big washers really)
  9. Removed the subframe supports
  10. Lifted the sub frame up using the ATV jack and hand tightened the rear most subframe bolts
  11. Put the new subframe supports on and hand tightened the forward most subframe bolts
  12. Once everything was where it should be I lifted the subframe the rest of the way up and tightened everything down
  13. I then checked torque for the upper control arms before putting the struts back on
  14. Put the new struts on
  15. Put the rear sway bar on
  16. Put the exhaust back on
Edit (4/6/2014): After re-reading this post I realized I left a minor note out. When you switch out the upper control arms there's a wire that bolts onto the control arm. The bracket doesn't fit the WRX control arm, and a new bracket (has to come with the wire) was crazy expensive when I asked about it. I put in one of the two bolts then used a zip tie through the hole twoard the back around the loose end of the bracket. It's been solid for over 16k miles now.

Alignment Values
Code:
[B]Front[/B]        [B]Right[/B]        [B]Left[/B]      [B]Specification[/B]
Caster       6.87         7.18      6.50 to  6.50
Camber      -1.59        -1.16     -1.33 to -0.33
Toe          0.0          0.0      -0.04 to  0.04
[B]Rear[/B]         [B]Right[/B]        [B]Left[/B]      [B]Specification[/B]
Camber      -1.79        -1.89     -2.33 to -0.83
Toe          0.01         0.0      -0.04 to  0.04
 

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Excellent write up. That looks as low as all the photos of people on STI takeoffs in RAPTRS thread. I always thought STI takeoffs sat about an inch lower?
 

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Discussion Starter #4
Excellent write up. That looks as low as all the photos of people on STI takeoffs in RAPTRS thread. I always thought STI takeoffs sat about an inch lower?
Thank you. I think it is about as low as the Foresters in that writeup. I started with RAPTR's writeup and was planning on STI take-offs (or new ones). Then I saw the GTWORX struts and since they were for WRX they'd be a "direct" bolt on with out modification to the mounting holes. The RCE blacks drop a WRX 5mm or so, making it closer to the STI stance.

I agree about the excellent write up. What do the sub frame spacers do and why change them?

Sent from my mind using ninja telepathy.
Right now it's theory, I'll find out today when I get aligned but my theory is 1) by swapping out the spacers and associated parts I'll be able to maintain better / correct geometry and 2) changing out the upper control arms keeps me from bottoming out on the body.
 

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In your opinion how much of an issue do you think the control arm controversy really presents? Did you just replace them for peace of mind or did you find some hard evidence there is a problem? Don't get me wrong, I am just trying to figure out why there is so much speculation about this when there have been 10+ members do the WRX or STI takeoffs swap with no reported problems that I have read about anyway.

Sorry, I don't want to hijack this thread I just thought maybe you found some real evidence on this that I have not come across before. I'll be putting on my STI takeoffs this spring so any info you can share is much appreciated.

Thanks
 

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Discussion Starter #7
In your opinion how much of an issue do you think the control arm controversy really presents? Did you just replace them for peace of mind or did you find some hard evidence there is a problem? Don't get me wrong, I am just trying to figure out why there is so much speculation about this when there have been 10+ members do the WRX or STI takeoffs swap with no reported problems that I have read about anyway.

Sorry, I don't want to hijack this thread I just thought maybe you found some real evidence on this that I have not come across before. I'll be putting on my STI takeoffs this spring so any info you can share is much appreciated.

Thanks
I thought about that as I was doing this. I was tempted to leave the control arms on, lower it, then see how close it is to the body. After that, put on the new control arms and see the difference. I didn't have the time to do that though. I did look at the stock upper control arms before dropping and played with the hub once the strut was off to see how close it got at various hub height. It looked close, probably usable, but for my piece of mind I wanted to go for it. The new upper control arms have plenty of space. The other factor was my thoughts on geometry. I heard with the stock control arms I'd be looking at -2 or more camber, again probably not a huge issue (I run -3 on my other car...) but I wanted to keep this as a daily driver not an autocross car. So in my unprofessional opinion, can you drop without doing this? Sure. Could you bump the control arm if you did? Probably. Would it matter? Probably not for 80% of the use cases. Alignment is at 2 today, I'm crossing my fingers for the numbers. Car handles great at 70mph already, just wondering about geometry at this point.
 

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I hadn't purchased the spring seats before starting this so that was an unpleasent surprise when the Forester ones didn't fit the new springs, causing me to have to wait a few days with the car up on jack stands.
I had the same surprise when I went to install my 2011 WRX suspension. I bought a set that didn’t come with the top hats. The rears bolted up but the fronts did not. I did not find this out until AFTER I had finished the rears. Talk about major buzz kill. At any rate I now have top hats and waiting for Winter to pass to start the install all over again.

Great write up. I can’t wait to see the numbers from your alignment.
 

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Discussion Starter #12
Alignment values added to the first post. In all I'm pretty pleased. In fact I could have less negative camber in the rear if I wanted (started out at -1.5) but I had them dial it in for WRX alignment. The front camber is almost within spec which may indicate the front arms may be needed. Or perhaps I didn't get the spring seat just right (would that effect camber?). Anyway there you have it :Banane35:
 

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Discussion Starter #13
After seeing 2010subieforester's post I thought I would add the 2012 WRX specifications that I was using.
 

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Cool,

It's looking like you need a rear camber kit as well. It looks like my assumptions may be correct in that none of the additional parts that you installed made much difference. My alignment numbers first starting out were a little bit worse than yours but not much and they will be within specs it appears with just a camber kit. It's looking that way thus far anyway. We shall find out next week.

Sent from my mind using ninja telepathy.
 

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Discussion Starter #16 (Edited)
Cool,

It's looking like you need a rear camber kit as well. It looks like my assumptions may be correct in that none of the additional parts that you installed made much difference. My alignment numbers first starting out were a little bit worse than yours but not much and they will be within specs it appears with just a camber kit. It's looking that way thus far anyway. We shall find out next week.

Sent from my mind using ninja telepathy.
The car drives great so no rear camber kit for me. The numbers I have are all within spec (that I was going for) except for the front right camber. I added the 2012 WRX specifications I was going for to the post. The rear camber actually started out pretty much dead center of specifications at -1.65 L and -1.56 R for some reason a little more got dialed in, but I'm not going to sweat it unless I see odd tire wear. Since I was going for a WRX alignment I'm fine with the numbers. So I think the parts I installed did make a difference both in clearance and geometry (perhaps minor). Since you were shooting for -0.3 vs me shooting for -1.5 the comparison is made more difficult, to make it more similar I'd have to request a Forester alignment which isn't what I want :)

When I saw your post I didn't think the original numbers were too bad, I'm surprised the Forester specifications are so boring (so little camber for those fun turns). I figured your rear toe was off and could use a little less camber say in the -1.5 range, but the front looked alright. It's sucks having a mod go south, but it sounds like you're getting close. I was going to go with the powerflex bushings or Cusco adjustable lateral links if my numbers were not good enough.
 

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Did you end up using the WRX tophats in the front or the Forester ones?

I am in the process of doing the same swap, and also did not get top hats or the spring perch with my 2011 take offs. Ordered the spring perches today, and was wondering if the Forester top hats worked or not.
 

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Discussion Starter #18
Did you end up using the WRX tophats in the front or the Forester ones?

I am in the process of doing the same swap, and also did not get top hats or the spring perch with my 2011 take offs. Ordered the spring perches today, and was wondering if the Forester top hats worked or not.
The Forester spring seats won't work with WRX springs but the strut mount will. I bought #7 on the following diagram and reused the Forester version of #4 http://opposedforces.com/parts/impreza/us_g12/type_7/suspension_and_axle/front_shock_absorber/illustration_1/
 

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