Stiffer Rear End

[JazzMunkyy]

hey guys,
So im in the possess of making my 3rd gen legacy more willing to rotate while improving overall grip.
So far i have installed 4th gen jdm bilsteins with stock springs, a tribeca 25mm front sway and a 20mm whiteline rear sway.
The car overall has become much nicer to ride in and body roll has been greatly reduced but the car still wants to understeer when approaching the limit (although not as bad as stock)
I understand stiffening up the rear will help but i dont know of any springs that are stiffer than stock without providing a drop in ride height.
is it possible to use a lowering spring with a spring spacer to maintain ride height but also stiffen up the rear or would i be better off getting a set of coilovers?

[dodik]

summitracing sells 3" springs in any length and stiffness. figure out what rate you have and go a little stiffer. They are not too expensive either.

[yaya]

The rear sway bar being softer than the front isn't helping that feeling.

[Yamazaki]

The rear sway bar being softer than the front isn't helping that feeling.
This. I'd ditch the Tribeca front sway bar. That should help the back end become stiffer than the front.
The S401 is actually set up like that from the factory for the same reason. It has a tiny front sway bar.

[JazzMunkyy]

This. I'd ditch the Tribeca front sway bar. That should help the back end become stiffer than the front.
The S401 is actually set up like that from the factory for the same reason. It has a tiny front sway bar.

ehhh i really like how the front bar has tightened everything up and made the steering input feel

i'll have to look into those custom springs though
i wonder if outback springs have different springs rates than legacys

[Yamazaki]

Fair enough. You were just asking about how to make a 3rd Gen more willing to rotate while improving overall grip and I cannot think of a better 3rd Gen to use as an example than an S401. Steering input and response is amazing on the S401, by the way. I am certain that has nothing to do with the spagetti noodle of a front sway bar it has.

[JazzMunkyy]

Fair enough. You were just asking about how to make a 3rd Gen more willing to rotate while improving overall grip and I cannot think of a better 3rd Gen to use as an example than an S401. Steering input and response is amazing on the S401, by the way. I am certain that has nothing to do with the spagetti noodle of a front sway bar it has.

what size is the front sway bar on the S401 if i may ask?
another reason i want to get the springs is to see the difference between small bars and stiff springs vs large bars and soft springs
i found a set of rallitek and king springs but im not sure how they pair with bilsteins

[Yamazaki]

what size is the front sway bar on the S401 if i may ask?
I'll check when I get home. I don't know it off the top of my head.

[Yamazaki]

Nevermind, I found it online (STI parts). It's 19mm and the regular RSK/GT-B is 20mm. Rear - S401 is 21mm while the RSK/GT-B are 19mm. So they put a smaller front and a larger rear on the S401. Having driven all the above, I can say it makes a difference.

[nepbug]

I say try to dial in more grip on the front in order to solve it, not lose grip in the rear. Mods to the rear won't necessarily help increase front grip. What are your alignment specs? Maybe dial in a little more negative camber in the front. If you get the camber right then as your camber moves positive you'll be gaining grip and hopefully at your limit you're close to the maximum possible contact patch for the tire.

Stock specs are like -0.5° to +1.0° if IIRC, which seems like it's not setup for aggressive cornering.

[JazzMunkyy]

i was actually thinking that my alignment may also have an effect too as well as my less than stellar tires!
when we installed the bilsteins we maxed the camber on the front and left the rear so with the sway bars im thinking there maybe too much camber because the roll stiffness of the car wont allow it to lean over on to the contact patch. it might also have to do with my driving as most of the understeer happens mid corner when i apply throttle

[rkrenicki]

Your setup is essentially the opposite of the s401. Huge front swaybar in relation to the rear, and soft springs. The S401 has a purposely small FSB, and stiff springs. I mean, Subaru sprinkled their STI magic pixie dust on other parts of the car to make it handle the way it does, but the springs and sways play a large part of it.

I do not have the spring rates for the 4th gen, but the S401 springs are about 20% stiffer in the front (37N/m vs 31N/m), and about 10% stiffer in the rear (61N/m vs 55N/m) than the 3rd gen RSK.

[JazzMunkyy]

i dont know much about suspension other than what i have read on here but id assume the front springs for the s401 would be stiffer to make up for the smaller sway bar.
to my understanding having stiffer springs is better then stiff bars but stiff springs make for a stiff ride so we use stiffer bars to achieve the same effect. so with that in mind it would be better to find the right springs then have swaybar sizes to match and fine tune the dynamics

I may actually try out a smaller front bar vs stiffer rear springs if i can find a set that wont lower the car.
edit: im not sure how these will pair with bilstein B6 shocks either

[rougeben83]

dial more neg camber in front.

I remember some engineer on nasioc doing an torsional analysis on the tribeca FSB, based on the bends and some areas not really being 25-6mm, its more equivalent to a 23-24mm aftermarket FSB.

Also stiffer bushings help with the weight transfer being more instantaneous - that may be affecting your feeling of unwillingness to turn.

Also, regarding spring rate. Theyre not equivalent when comparing a macpherson suspension (front) vs. multi-link (rear) Because the links have a multiplier effect, the rear doesnt need such a high spring rate vs. the front.

Are you using the stock 3rd gen springs or 4th gen? The 4th gen rear springs are softer and shorter than 3rd gens, thats why.

[JazzMunkyy]

im using jdm spec b bilsteins with the spec b springs
i thought the shocks were just physically shorter!
the only rear suspension bushing i was going to replace were the rear trailing arm bushings when i swap to disks

if i can figure out my spring rates vs sti springs i may just do away with the front bar and install a smaller one

[JazzMunkyy]

quick update to this
i have picked up a set of springs that fit 4th gen legacy's
they look pretty darn beefy, looks like these have more coils and thicker coils than the ones on the car now.
i dont know what these springs are or who makes them.
i think they are king springs because they are yellow