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Mach V Dan's mega suspension guide


Mach V Dan

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What are dampers, and what do they do?

 

Dampers = struts = shock absorbers ("shocks"). Three names for the same device. The shocks are paired with the springs, and serve to dissipate suspension energy, so the car does not keep bouncing once the springs have done their job.

 

--Dan

Mach V

FastWRX.com

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  • 2 weeks later...
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Which is a better first mod (aside from wheels and tires) if I’m looking to improve the suspension, cornering, and handling…

 

1. COBB Tubular Sway Bars or

2. COBBStrutTower Brace

Pros and Cons for these or should I use both?

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Which is a better first mod (aside from wheels and tires) if I’m looking to improve the suspension, cornering, and handling…

 

There's no one answer for that. It depends what you are looking for, and how much you want to spend.

 

Strut bars improve chassis rigidity. This has a positive effect on handling, although adding only front and rear strut tower bars won't have a dramatic effect. But strut bars aren't very expensive, weigh very little, and are simple to install, so the overall cost is also minimal.

 

Sway bars reduce body roll in corners, and can help move the car's at-the-limit balance more toward neutral (or even oversteer), compared to the Legacy's default understeer bias. But as I've said before, too much sway bar can make the car very snappy at the limit, and you can have some harshness when the car traverses a bump with one wheel -- your spring rate is effectively increased by the way bar during single-side suspension travel. Most aftermarket bars for Legacy aren't THAT much thicker than stock, so having too fat of a bar probably won't be a problem.

 

As for brand, you have many to choose from. Strut bars are going to be pretty hard to get wrong -- if they fit, they should work. But sway bar space is pretty tight on the Legacy, and many users of aftermarket bars have reported interference with the suspension, so choose carefully when considering sway bar brand.

 

--Dan

Mach V

FastWRX.com

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  • 1 month later...
Appreciate the post, and I just spent some time on SUBE555's sticky thread. An unanswered question for me is the abbreviation "BA" as referenced by H&R Springs on their Sport Springs for the '00 Legacy. They specify "BE/BA" however, I have not been able to find "BA" ANYWHERE in searching vehicle codes for my Subie. BE is obviously the '00 sedan, and BH is well documented as the Wagon, so what is BA? Thoughts?
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  • 2 weeks later...

Dampening ?

 

Forgive my ignorance but as I'm in the bicycle business and we seem to describe rebound dampening as fast or slow. How does this correlate to soft and stiff/firm when describing strut dampening adjustments? My best guess is fast=stiff and slow=soft. On a bike, we tend to adjust the rebound to be as fast as possible without bucking the rider off. With a shock with adjustable compression, we can tune what we describe as soft vs firm. I'm just trying to wrap my pea brain around the different terminology used in the auto industry.

 

To KISS:

Soft=?

Stiff=?

 

TIA

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Um...fast and slow refer to speeds, in my book. I'm not sure what that means in terms of shocks. But automotive people almost always talk about shocks in terms of firm/stiff vs. soft. Firm being like a stick in peanut butter, and soft being like a stick in water.

 

Some very high-end shocks have different dampening adjustments for high-speed and low-speed shock motion. Most don't, though.

 

--Dan

Mach V

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dan,

 

speeds-yes. we (cycling guys) are referring to how fast or slow the strut is allowed to return to it's extended state.

 

i certainly get firm vs soft but, for example: is a strut set at full soft adjusted to slow the return rate of speed or is it allowing the strut to extend as quickly as possible? does this make sense?

 

oh yeah, you are the perfect person to ask about my current set up. i installed my swifts (on oe struts) last saturday and would like to minimize the bounciness and hopefully the jarring when hitting a pothole or similar. the bouncy part is the most annoying. yes, the tokico's are on my shortlist but at that point why not sell what i have and get megan racing coilovers? i'll end up roughly at the same $'s. what would be the downside?

 

btw, for those who may think i'm speaking negatively about the swifts, i am not. i like the stance and the firmness the springs themselves bring. i'm just not crazy about how the struts are mating with the springs. here's an odd observation after installing the spring: my brakes feel better?! i attribute it to less movement in the suspension. in any case it's a nice side benefit.

 

thanks

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speeds-yes. we (cycling guys) are referring to how fast or slow the strut is allowed to return to it's extended state.

 

i certainly get firm vs soft but, for example: is a strut set at full soft adjusted to slow the return rate of speed or is it allowing the strut to extend as quickly as possible?

You seem to be talking only about REBOUND dampening, and not COMPRESSION dampening. MOST adjustable automotive shocks that I'm familiar with adjust both at the same time. The one exception I can think of is Koni yellow shocks, which adjust only rebound dampening. To answer your question, a shock set at full hard will tend to resist motion of the wheel in either direction, and full soft would allow more motion in either direction.

 

oh yeah, you are the perfect person to ask about my current set up. i installed my swifts (on oe struts) last saturday and would like to minimize the bounciness and hopefully the jarring when hitting a pothole or similar. the bouncy part is the most annoying.

I experienced that, too. The stock dampening is (I think) not firm enough to control the stiffer Swift springs to an adequate degree. A firmer shock, or an adjustable shock that will allow firmer dampening, will fix that.

 

yes, the tokico's are on my shortlist but at that point why not sell what i have and get megan racing coilovers? i'll end up roughly at the same $'s. what would be the downside?

I don't have experience with MR coilovers specfically, but there are a few downsides to coilovers. One is simply the installation/adjustment hassle; if you have height AND dampening adjustment at all four corners it can be some work to get it all sorted out. Another is that many coilovers only allow the car to be a certain ride height, and no higher. If you don't want the car "dumped," you may not have a choice. Coilovers may also require a bit more care and feeding -- more cleaning to keep them from getting stuck permanently at one setting, and sometimes the shocks need rebuilding.

 

But if they're good coilovers, you may find you have a better/more adjustable suspension than with fixed-heigh springs/shocks.

 

--Dan

Mach V

FastWRX.com

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Not sure how to ask this but I'll preface this by saying I'm coming from a mountain bike background.

 

I like the ride height and I don't want to change that as I do have to do some dirt/rough road driving. However I don't like the amount of body roll and dive. I've got some cobb bars and that helps but does make the ride a little rough, but there's still the issue of dive.

 

On my bike I'd up the low speed/force dampening (e.g. use a thicker oil, or smaller hole), then lighten up the high speed/force so the big hits are less harsh. Spring rate seems fine since I doubt I'm bottoming out (dual rate with the same overall rate would probably help). I'd think this would prevent dive and roll yet still be compliant.

 

Are the OEM struts simple orifice compression/rebound dampeners? Do all coilover/aftermarket struts digressive (e.g. use shim stacks or position sensitive orifices)?

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Are the OEM struts simple orifice compression/rebound dampeners? Do all coilover/aftermarket struts digressive (e.g. use shim stacks or position sensitive orifices)?

I don't think you can make any generalization about type or design of OEM or aftermarket shocks. There are as many shock designs as there are brands of aftermarket shocks. One thing that ALL non-coilover struts have in common is that they're sealed assemblies. They are NOT user-modifiable or rebuildable in any way. If they have adjustable dampening, you get to turn a knob, but that's it. And if the seals blow out, you throw the whole thing in the trash.

 

Coilovers have separate dampening cartridges, and those usually ARE rebuildable, but I don't know anyone who rebuilds them outside the factory themselves.

 

--Dan

Mach V

FastWRX.com

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As will Koni, including shortening, or adding bounce adjustability to rebound.
06LOB2.5i MT, JDMRSB, GYTTs, HPS, LGT Mufflers & Leather Wheel, SubiMomo Knob, Inalfa Moonroof, Clutch Switch Bypass, DeDRLd, DeChimed, & Straight Headrest.
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  • 4 weeks later...

Ok, so I have rebuilt, swapped and fixed engines, restored a car, even been to racing school. I like to think I know cars pretty well. That being said, I'm a total NOOOOB when it comes to suspensions and suspension upgrages....which leads me to 2 questions.

 

1. These end links I keep reading about on the forum - WHAT DO THEY DO?!?! and are they necessary to upgrade with my swaybars (that better hurry up and get here).

 

2. I know you said they're essentially the same thing, but what is the REAL difference between shocks and struts? Also, are dampers something slightly different or is that really just another word for one of the above?

 

Oh, and awesome post, even though I'm about 2 years behind.....

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1. These end links I keep reading about on the forum - WHAT DO THEY DO?!?! and are they necessary to upgrade with my swaybars (that better hurry up and get here).

They connect the end of the sway bar to the suspension control arm. Depending on the sway bar you get, you may need to go with a shorter end link to make everything work or fit right. But the stock links aren't bad, so there's no need to replace them if they're working fine. On the WRX, the rear links are a plastic C-shaped thing that's quite weak. Replacing those can help the car handle better.

 

2. I know you said they're essentially the same thing, but what is the REAL difference between shocks and struts? Also, are dampers something slightly different or is that really just another word for one of the above?

 

Dampers are anything that dampens suspension movement, so shocks and struts are all dampers. A shock (short for shock absorber) is a device dedicated to dampening vibration, and serves no other purpose. It will not carry any sideways loading. A strut (usually we'd be talking about a MacPherson strut) is both a shock absorber and a structural part of the suspension, and will handle sideways loads at the same time as absorbing spring motion. The MacPherson strut basically replaces the upper A-arm, and serves as the steering axis as well.

 

--Dan

Mach V

FastWRX.com

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  • 1 month later...

Nice tech write up! Very informative. This leads me to ask a question about front and rear sways though. I currently have a Perrin adj. rear sway on my '05 GT wagon with a stocker front sway. I have not upgraded the front as all the info that I have been able to read has told me that switching to a bigger rear sway will increase oversteer, (which I want), and using a bigger front sway will increase understeer, something I don't want.

 

The problem is, I'm still not totally happy with the handling characteristics of my car and I'm trying to figure out how to get it closer to the way that my '98GT wagon handled, (KYB AGX's, Whiteline Control Springs, and Whiteline adj. rear sway with Toyo T1-S rubber). Maybe its just because at Stage II power levels, my '05 has tons more power than my '98 and I can't drive it through the corners like my '98 but jeez, I could just rally the hell out of that car through the twisties like it was on rails and I'm just not feeling that with my '05. Anyone out there care to comment on whether beefing up my front sway will help this situation without bringing back the understeer that I just rectified by going to the bigger Perrin rear sway? My current '05 set up: Whiteline Control Springs with Bilstein Rev A struts, Perrin Rear Sway, Bridgestone RE 750's, Stage II AP, Perrin mid and y-pipe, Endless SSS pads, w/stainless lines...

 

Thanks for any comments!

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...all the info that I have been able to read has told me that switching to a bigger rear sway will increase oversteer, (which I want), and using a bigger front sway will increase understeer, something I don't want.

 

That's a generalization, but isn't always true. If the car is rolling a lot (which the factory suspension definitely does), adding a sway bar to the front can help to reduce roll and INCREASE grip at that end of the car. That will DECREASE understeer. This is because when the car rolls a lot, the front tire experiences positive camber -- leaning out away from the car -- and isn't parallel to the road. Reducing that roll will make the tire more parallel to the road during cornering.

 

So basically the effect of a sway bar upgrade is going to depend on a lot of other factors.

 

I have had MUCH better results on my cars (DSM, Legacy GT, Evo) with upgraded front AND rear bars. The car corners flatter and behaves more predicatably. THEN I can dial in oversteer/understeer behavior with tire pressure adjustments, alignment changes, end link changes, or other tweaks. (On the Evo, more front camber resulted in a HUGE increase in front wheel grip, and a big change in cornering behavior.)

 

In my experience, upgrading only the rear gave the car uneven front and rear roll stiffness, which made for a car that did not behave as predictably, at least from my perspective. But that's just my opinion. Plenty of other people seem to feel that a stock front bar with an upgraded rear is the way to go.

 

--Dan

Mach V

FastWRX.com

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  • 2 weeks later...

Lots of great info. One thing I would like to see, somewhere, is a list/writeup/manifesto on combiantions of srpings/struts for various applications.

 

IE:

 

-You're going for cosmetics over perf. You want to lower, improve handling a bit but a pliable, non fatiguing ride is paramount. What are the options?

 

-Ride not so important, but it is still a daily driver. Want more of an "on rails" feel, less nose dive on braking. But you don't want a bruised ass and a busted spleen when you hit a pot hole.

 

I tried the k-sport coil-overs for a few weeks. Buold quality was good and once I got them setup the car handled great but long trips were just not fun. I switched back to stock. OVer all a costly experiment. Now, not so sure which way to go. A lot of opinions up here and the instant I think I've groked it I read something new that makes me go "oh noes! foiled yet again. I am teh newb."

 

:-)

 

-Ian

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I collected the drops and rates for standard springs (not coilovers) from various sources online, and compiled them all on this wiki page:

http://www.subiwiki.com/wiki/index.php/BL_%282005-2009%29#Handling_Modifications

 

There's some data missing, for example I suspect more of them are progressive than those I've marked with a (p). If anyone notices anything wrong or missing, update the wiki yourself. :)

 

That's all numbers though, and those are only what the manufacturer claims, not necessarily what the springs really are. And with progressive springs, a single number isn't really enough to describe "the" rate. It would be interesting to see if anyone's subjective impressions of ride harshness for two different springs are any different from what you'd expect given the relative rates on that page.

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  • 1 month later...
I would be interested in opinions on ride with aftermarket springs. Like some others have said, I dont want to wear a kidney belt to go to work everyday, but I would like to lower the car a bit. I'm thinking Pinks or H-techs, but which is closer to stock ride, which I think hits the soft/stiff issue just about right. Opinions? Redirection? And what about the driveshafts, any angularity issues here?
You're just jealous that the Voices talk to Me. :cool:
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Well I just put Cobb springs and sways on the LGT and am very happy with the results.

 

The ride is a bit firmer, but not overly so. Typical road obstructions like manhole covers, speed bumps are well modulated and do not jar the ocupants of the vehicle. With the k-sports every bump was trasnmitted into the cabin, it was not fun.

 

The look is great, the "right" amount of drop IMHO.

 

For someone like me who has no intent to track this thing the results are perfect. A slightly firmer ride, and with the sways in there as well much better handling and a surer feel all around without the added noise and harshness of the coilovers.

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