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Registered
2006 Forester
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174 Posts
Discussion Starter #1
My 2006 stock Forester X needs less body roll for sure. I have heard posters here say that istalling a bigger sway bar will help.
Is this a drop-in install or do other components need to be changed?
Are there other things I can do without affecting the ride-height too much. I mean, a 1" drop isn't bad but I like having decent clearance for offroad forays.

If I could live with a 1: drop, are there better options. The funny thing is that I don't think the Forester drives particularly "soft" so why is there so much body lean? My Nissan Pathfinder with pretty stiff Old Man Emu springs and shocks and KYB struts drove smoother though it was stiffer than stock.

Maybe the Forester just transmits road vibes more.
 

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The Modfather
2019 Impreza 5dr Sport - Manual
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2006 Forester
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174 Posts
Discussion Starter #4
This seems like a good project this summer. I really like the clearance so I don't want to drop it much over an inch. If clearance was not a need/want, I may not have bought the Forester so I want to preserve that utility.
 

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Premium Member
2004 Forester XT MT
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1,433 Posts
Flyer said:
If I could live with a 1: drop, are there better options. The funny thing is that I don't think the Forester drives particularly "soft" so why is there so much body lean?
Short wheel base and relatively narrow track give the Forester a high polar moment of inertia. This gives us more body roll, squat, and dive. On the upside, it lets us rotate better.

You have 3 options(aside from lowering the car):
  • stiffer struts
  • stiffer springs
  • stiffer sway bars
Try the STi rsb with FSTi springs on the stock struts.

Contrary to popular belief, a really stiff sway bar will affect the straight line ride quality; it hampers the ability of the left and right suspension to work independently.
 

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Asphalt Surfers Unlimited
2004 Forester XT
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742 Posts
Northwest Tan said:
Short wheel base and relatively narrow track give the Forester a high polar moment of inertia. This gives us more body roll, squat, and dive. On the upside, it lets us rotate better.

You have 3 options(aside from lowering the car):
  • stiffer struts
  • stiffer springs
  • stiffer sway bars
Try the STi rsb with FSTi springs on the stock struts.

Contrary to popular belief, a really stiff sway bar will affect the straight line ride quality; it hampers the ability of the left and right suspension to work independently.
"Really stiff" meaning what? 32mm?

I have used a 29mm (solid) front sway bar on an STi with no discernable reduction in ride quality... it was coupled with a 26mm rear.

There are SUVs with 1.5in front sway bars... that's ~38mm.
 

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Premium Member
2004 Forester XT MT
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Porter said:
"Really stiff" meaning what? 32mm?

I have used a 29mm (solid) front sway bar on an STi with no discernable reduction in ride quality... it was coupled with a 26mm rear.

There are SUVs with 1.5in front sway bars... that's ~38mm.
really stiff as in stiffer than the STi bar or Perrin bar...the COBB bar set to the stiffest setting would be a good example (i think this counts as 25mm).

think about what the bar does to keep the car from rolling. then imagine going over a road surface where each tire is trying to its own thang. even in a straight line, the bar ends up increasing the effective spring rate seen at each wheel. the only aspect of ride quality not changed by a stiffer bar, is the suspension's response to an irregularity in the road which strikes both left AND right tires at the same time.;-)

so a stiffer bar will create stiffer ride but the change isn't as great when compared to a stiffer spring.
 

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Asphalt Surfers Unlimited
2004 Forester XT
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742 Posts
Northwest Tan said:
really stiff as in stiffer than the STi bar or Perrin bar...the COBB bar set to the stiffest setting would be a good example (i think this counts as 25mm).

think about what the bar does to keep the car from rolling. then imagine going over a road surface where each tire is trying to its own thang. even in a straight line, the bar ends up increasing the effective spring rate seen at each wheel. the only aspect of ride quality not changed by a stiffer bar, is the suspension's response to an irregularity in the road which strikes both left AND right tires at the same time.;-)

so a stiffer bar will create stiffer ride but the change isn't as great when compared to a stiffer spring.
The sway bar will have almost no effect on real-world ride quality.

Deflections that result in sway bar torsion are large... you would have to go over a rock or an obstruction with one wheel to induce enough sway bar torsion to make any significant difference in springrate... At that point you should be more worried about the rocks you're driving over than the smoothness of your ride experience, especially any obstruction large enough to make a difference in springrate that would result in a ride quality change.

"Ride quality" infers a constant condition, i.e. something you would notice as an ongoing annoyance or change in behavior. Swaybars, by their very transitory nature, have no discernable effect on that quality.

BTW... the Cobb bars are a rebranded Hotchkis. They are 25mm hollow... comparable to a 22-23mm solid bar like a Whiteline. Perrin bars are rebranded Progress swaybars, though they are solid bars like the Whiteline. A Whiteline 25mm solid bar is significantly stiffer than a 25mm Hotchkis.


Sway bar tuning is extremely effective on a Subaru, and unfortunately many of the manufacturers (*cough* Progress *cough*) don't seem to have an understanding of the chassis dynamics of the Subaru platform.

I have had excellent results on many, many Subarus (non-motorsport) with bar sizing of around 24mm front and 22mm rear. Motorsport applications will vary depending on the other suspension components and the specific surfaces on which the vehicle competes.
 

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Premium Member
'09 STI
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I agree with Porter. The change in ride comfort is minimal if any with bigger bars. Bottom line is that there will always be a trade off for performance and in this case the possible slight increase in stiffness when hitting large bumps on one side only is the trade off for a much better handling car. Especially at or near stock height.

The tendency for the tires and suspension to roll over at stock height will always be a problem with handling. Controlling that massive lean and the inherent alignment changes is a worthy trade off especially when comparing to stiffer springs to control roll.

Just my opinion.
 

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Does anyone know of any springs that can replace the stock ones on an SF model without dropping it to much? Aside from the stock ones off a wrx, what is available?

Something like the Forester STI springs mod for the SG model, but for the SF. Something that only takes it down about an inch.
 

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#8 Post ho
1999 Subaru Forester
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2,441 Posts
Nachas said:
Does anyone know of any springs that can replace the stock ones on an SF model without dropping it to much? Aside from the oem ones off at wrx what is available?

Something like the Forester STI springs but for the SG model, they only take it down about an inch.
Only ones I've found will drop about 2-2.5 inches and run you about 275
 

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Premium Member
2004 Forester XT MT
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1,433 Posts
without diving into any textbooks, here it is...

Porter said:
The sway bar will have almost no effect on real-world ride quality.

Deflections that result in sway bar torsion are large... you would have to go over a rock or an obstruction with one wheel to induce enough sway bar torsion to make any significant difference in springrate... At that point you should be more worried about the rocks you're driving over than the smoothness of your ride experience, especially any obstruction large enough to make a difference in springrate that would result in a ride quality change.

"Ride quality" infers a constant condition, i.e. something you would notice as an ongoing annoyance or change in behavior. Swaybars, by their very transitory nature, have no discernable effect on that quality.

BTW... the Cobb bars are a rebranded Hotchkis. They are 25mm hollow... comparable to a 22-23mm solid bar like a Whiteline. Perrin bars are rebranded Progress swaybars, though they are solid bars like the Whiteline. A Whiteline 25mm solid bar is significantly stiffer than a 25mm Hotchkis.


Sway bar tuning is extremely effective on a Subaru, and unfortunately many of the manufacturers (*cough* Progress *cough*) don't seem to have an understanding of the chassis dynamics of the Subaru platform.

I have had excellent results on many, many Subarus (non-motorsport) with bar sizing of around 24mm front and 22mm rear. Motorsport applications will vary depending on the other suspension components and the specific surfaces on which the vehicle competes.
well said Porter.
  1. good to see you are on the same page with me regarding the increased effective spring rate.
  2. i don't agree with that the amount of suspension travel required to develop a significant or noticeable amount of "torsion" needs to be large.
  3. "ride quality" will always subjective.
  4. i have heard that COBB bars are made by Hotchkis but haven't seen any concrete evidence.
  5. basically a bar's spring rate can be calculated like this: K=[(coefficient for material used)*(diameter)^4]/[(arm length)^2*(bar length)]
  6. the formula makes it obvious that sway bar rates are not merely determined by diameter or the fact that they are solid or hollow. bar length, arm length, and construction material play a role in the K. the value for diameter has the largest impact on K due to the fact that it's taken to the 4th power. diameter can be a good way to get a rough idea of a bar's stiffness but is not entirely accurate.
  7. it's apples to oranges unless you compare each aftermarket bar to something like the stiffness of one thing like the stock bar. it would be great if the bar manufacturers provided useful data for the consumer. (COBB does compare its bar to the stock one but I'm not sure about the others)
  8. differences in construction material will also change the characteristic of the bar. for example, the change in K as degrees of twist increase.
great stuff mang;-)
 

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that was some good readin NW Tan, and Porter
 

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2006 XT
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Boy there are so many options. For the last three weeks I've lived with a stock strut/spring and Strano 32mm fsb and Cobb 25mm rsb. Yes straight line effect is minimal, but for sure there is an effect in NVH. Body roll was changed dramatically but all was not perfect. I've now installed the Megan Racing Coil Overs and the package is complete.

Strut/spring upgrade has to happen for a better overall package. Dive, squat and other changes are not going to happen with just a new set of springs. Strut/shock change is a must.

Megan Racing wants to see if the Forester community wants a setup just for us that has a "zero" drop. Use this thread to let them knowhttp://www.subaruforester.org/vbulletin/forums/showthread.php?t=2827
 

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Ze flying Russian
2007 STI
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2,008 Posts
Flyer said:
This seems like a good project this summer. I really like the clearance so I don't want to drop it much over an inch. If clearance was not a need/want, I may not have bought the Forester so I want to preserve that utility.
I can vouch for F-STI springs as well. I have them for a year or so and they definitelly improved the look and handling of my Forester. The clearance is more than acceptable, in fact in my opinion it looks more natural than stock height:

See it yourself:




 

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Premium Member
2012 camry se 6AT
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2,809 Posts
Nachas said:
Does anyone know of any springs that can replace the stock ones on an SF model without dropping it to much? Aside from the stock ones off a wrx, what is available?

Something like the Forester STI springs mod for the SG model, but for the SF. Something that only takes it down about an inch.
I will say this for the millionth time.

Use the JDM Forester STi springs but use it with SG struts and top hats. The SF struts have a much lower dampening rate and may not work well. The rear top hats are different too. My old set of 03 struts and top hats with JDM Forester STi springs lives on a 98 Forester right now. Bolts right up. Only difference is with the brake line bracket and mounts. Zip ties or wire ties are your friends. :)
 
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