Use late model STI front, lower control arms?

[Scargo]

I will be building an R and currently race a track only '08 STI. On it, I upgraded my LCAs to '11+ STI arms because they increased caster and have the new, beefier, rubber isolated "spherical bearing". This new design seems like a distinct improvement over the GD design.
Could modifying the mounting points and using this LCA be done without throwing the suspension geometry all out of whack? I don't have one of the earlier versions to measure.
Can discrepancies in pivot points and size be compensated for by how you place your new mounting points (without disturbing the basic frame)?

As a possibly related issue, I intend to use 5x114 hubs and matching spindles.

[Scargo]

Well, harrumph. My first thread and no response.
This is what I'd like to use. Can anyone provide dimensions for the GD STIs? Know the difference in offset or track?
3IkHDyc.jpg

[JeromeS13]

Glyn,

It's probably because this is all unknown territory. You may get some more feedback from NASIOC. I wouldn't mention that it was for an 818. If it can be adapted onto any GD platform without causing any suspension geometry issues, it *should* work on the 818.

[SixStar]

You'd have to do a fair amount of custom fabrication on the chassis to make those work. Short answer, no.

[fateo66]

Not to mention the newer design is far worse then the older style. Look at how many LGT's, 08+ wrx's and 08+ STIs HAD to replace the rear bushing because it crapped out in the first 60k. I have never seen a bad stock transverse link on the older style.

If you like the pillow ball design, which I can't blame you because I do too. Go out and find an original set of Perrin PSRS's or fork out the money for some MSI transverse links.

[D Clary]

cant you add caster with the older sti arms without modification?

[Scargo]

Perhaps there were problems with the first spherical parts. I talked to Joe Aquilante, of Phoenix Racing and SRRT, and he liked the 2011 arms and used them stock, with just a shim under the rear to increase caster. I have a pair of '08 arms and, if I use them, I would likely install the Whiteline KCA334M spherical racing bearings.

If I chose to use them I can set up the caster where I want and they might give me a wider stance. I'm trying to figure out exactly how they are different.
Why did Subaru change the arm in '08? There is something that seems compromised and unsophisticated about that bolt-on steel pin.

[SixStar]

The thing that everyone seems to keep missing about the 818 front suspension is it's no longer MacPherson - all the caster tricks for the WRX arms are moot when you can infinitely adjust the upper arm. You can dial in a TON of caster without ever having to move the lower arm. Also, if you use 05 STI lower arms those have the most caster out of them all FWIK.

[fateo66]

The thing that everyone seems to keep missing about the 818 front suspension is it's no longer MacPherson - all the caster tricks for the WRX arms are moot when you can infinitely adjust the upper arm. You can dial in a TON of caster without ever having to move the lower arm. Also, if you use 05 STI lower arms those have the most caster out of them all FWIK.

I disagree, if you only take caster out of the top the tire will move closer towards the center of the car and since we already know their is clearance issues with the tire hitting the firewall Imo builders should do everything they can to add caster via the lower control arm in order to clear bigger tires.

Edit: and 04-06 USDM STI arms are the exact same. Its the JDM and 07 US arms that are lacking the extra caster.

[Scargo]

The upper adjustment has not escaped me either. It is (to me), a given; part of the equation where there are a myriad of elements and options.
There is the adjustment on top and there is the fact that I am getting a bare frame that I have no reservations about modifying.
I am building a race car. I am TIG proficient and I can hack out parts in my garage-shop or have pieces made with laser precision. I am feeling inconvenienced by the fact that I no longer have machining centers to do my bidding.
I am hearing that '07 has less caster. Is that because of the arm or the brackets? All this reminds me of inflation: Relative to what?
I think I read that '08 and up arms increased caster (over GDs), and that in '11 they increased caster more and changed other geometry for the good (performance-wise). That was why I upgraded my '08 LCAs to '11 LCAs.

So, back to my original question of "how do the GD arms compare to the GRs?". If I used space available, and not cut any of the framework out, would I potentially move the wheel forward substantially and gain more clearance in the inner rear wheel well area? Would I possibly be increasing my stance? I will be pushing the boundaries on tire sizes relative to what's gone before.
I am just doing this guessing game because I don't have my kit and I don't have any dimensions from GD LCAs. I sure would like to know how the geometries compare.

[SixStar]

I guess my point was, the caster kits designed for caster challenged Subarus don't NEED to be installed on the 818. You don't see anyone offering caster bushings for Civics, they have a double a-arm setup and I've always set caster on those cars with the upper arms.

If more caster is needed and there are clearance issues then yes, use a caster kit and tip the back of that lower arm out. As far as using the GR/GV lower arms, I'm not sold. Every car I've worked on that has those arms has shot bushings, alignment issues, lack of travel, specifically droop. I personally think it's a poor design (most of that chassis is). I must amend this with I am definitely biased toward the GD chassis, I think it was the last thing Subaru got mostly right. I have a spare set of the Whiteline caster bushings pressed and ready to go. If we can't align the car where we want it they can be installed in minutes. I'm a long way off from there so for now it's all just theory.

[Scargo]

Six Star: Should be Six-Gun. I think you're starting to convince me that I'm just weird... I have some fatalistic attraction for the new design. But, I think you have to admit that with a solid pivot it can't be sloppy and tear apart. However, I don't know how to defend the poor droop. I didn't know it was droop challenged. More travel might be hard on that stock rubber isolated bearing.
I know I have been less than satisfied with the skimpy travel of my STi's coil-overs. I'm still waiting on RaceComp Engineering / GTWorx to come through with their new camber plates that allow more shock travel than any others.