Official Suspension FAQ - Swaybars - Struts/Springs - Coilovers - Alignment
The following is a collection of the FAQs for various suspension subjects.
Strut / Spring FAQ by fwa2500
Swaybar FAQ by jamal
Coilover FAQ by broknindarkagain
Alignment FAQ by broknindarkagain
Strut Spacer Templates
A few of us have spent a LOT of time writing these to help you out. So please, before you ask a question about anything suspension related read through this stuff. Chances are that the answer to your question is below.
For those of you who are new to the Legacy thing, this may be an EXCELLENT page to bookmark.
For those of you who posted a thread about something and were given this link and a smart @$$ answer, that means the answer to your question IS in this thread and you should read it all the way through.
Strut / Spring FAQ
This FAQ has been written by fwa2500. The original post can be found HERE
I am tired of the same questions being asked over and over again, so here is a FAQ that I have put together with the help of Reuben.
Will STi struts and springs work on my car?
Yes, but only '04 STi struts will be a direct fit because in '05 the hubs were changed from 5x100 (which is what your car is) to 5x114.5. '05-07 STi springs will work too, but also require the '04-07 top-hats. Additionally, any '02-07 WRX set-up will work since the WRX never changed away from the 5x100 hub.I found some '05 STi struts and springs, can I use those?
The springs, yes, but not the struts for the reason mentioned above.How much lower will STi struts and springs make my car?
Approximately 1 inch.What about WRX struts and springs?
As stated above, yes they will fit. Any '02-07 WRX strut, spring and top-hat combo will work on our cars. These will only lower half an inch at most with the stock WRX springs.Can I use just STi springs?
Yes, but you will need the 04-07 rear top-hats if you are using 04-07 springs. If you are using JDM springs meant for a bugeye (GDA) you should be able to use your stock top-hats.Isn't STi stuff really expensive?
It can be, but for a complete set of '04 STi suspension you are looking at about $300-400, which is a pretty good deal when compared to our stock set-ups.Would 3rd or 4th gen stuff work?
Unfortunately, no. Both have a completely different rear suspension set-up.
I want my car lower, what is the easiest way to do it?
Get a good set of aftermarket struts or springs, or even both. DO NOT cut your stock springs, not only does this decrease your handling performance but it can be very dangerous.I want my car slammed and heard S-Techs are the way to go.
No. Just no. You might as well cut your stock springs, just get a good set of performance springs and enjoy. You might not be quite as low, but you and your car will thank me. Please see THIS THREAD on NASIOC for more info.I've heard wagon and sedan rear struts are different, won't you get 'ass sag' with sedan struts in a wagon?
Generally it's chassis related. In most cases, second gen. Impreza (bugeye-hawkeye) suspension works just fine in our second gen. Legacy wagons and sedans. The exceptions being the 05-07 STi struts which don't work due to the different hub. GC/GF (first gen. Impreza) stuff also works in Gen 2 Legacy's, but GC/GF Impreza rear shocks and springs are shorter, and so you get the 'ass sag', regardless if it's from a wagon or a sedan.Is it hard to swap struts over?
If you've worked on cars before and generally know you way around, no, it's an easy job. I recommend having a friend help out when installing the struts, it makes things so much easier. Keep in mind that you must get an alignment done once finished.Ok, I installed some WRX suspension and now my wagon has a saggy butt. How do I correct this?
Spacers. Putting spacers in between the top hats and the top strut mounts on the car will help correct the sag.That is all good and all, but let's say I want to **gasp** raise my car.
In that case, your best bet is swapping on BD/BG Outback struts and springs or second generation Forester struts and springs.All that performance stuff is nice, but what about just replacing worn out OEM struts with stock-spec struts?
For that I would recommend KYB GR-2 struts, they are nicely priced and are excellent quality all around. Another option would be Monroe, they are also good stock replacements.While I have the car in the air, what else can I do to make my car handle better?
One simple thing you can do is install camber bolts. These will give you more available camber (can produce both positive or negative camber) to fine-tune your alignment.What about swaybars and endlinks?
Good question, please check out Zeus Marine's repost of Jamal's excellent swaybar FAQ HERE.What are you running on your car?
I currently have '04 STi struts with '05 STi springs, a 22mm adjustable Whiteline rear sway bar, Tribeca 25mm front sway bar, Kartboy solid front and rear endlinks, Ingalls camber bolts on all four corners and a slightly aggressive alignment (-2.3 degrees front camber with zero toe and -1.4 degrees rear camber also with zero toe).More will be added as is needed. I hope this helps some ;)
This FAQ has been written by Jamal
I've noticed a lot of swaybar related threads in the short time I've been around here, and I also have noticed a lot of misinformation and contradictory advice. So I thought I'd polish up my old legacycentral FAQ and post it over here.
I'd like to start by talking about how our cars handle and what happens to our tires and suspension when we go around corners.
From a flat out, on-road performance standpoint, a subaru starts out at somewhat of a disadvantage. Off the showroom, these cars are set up to understeer, and understeer some more. And then keep on understeering. Understeer is when, in a corner, the front tires break traction and begin to slide.
One reason for this is the AWD. You have four wheels powering the car, and give the fronts the additional task of steering. That right off the bat means that while accelerating and turning, the front tires will lose traction first.
Another problem is the weight distribution. On top of asking the front tires to both accelerate the vehicle and steer, you've gone and put more weight on them. Guess where that leads.
Now we come to the alignment and suspension geometry. When the suspension moves, the alignment changes. This can be a huge advantage, or a big problem, depending on the suspension geometry. In our case, it's a big problem. A tire creates the most grip when the entire tread is in contact with the road. When you go around a corner with the stock car, the car leans over, the tire leans over, and you end up doing most of the cornering with the outside edge of the tire and sidewall. That's not good for grip. Additionally, when the suspension compresses past a certain point the tire will camber out, which makes the problem even worse.
On top of these inherent handling disadvantages, the cars are setup to push at the limit. This is because it's generally safer to go off the road straight than it is backwards/sideways, and inexperienced drivers tend to have trouble dealing with oversteer. There's also something called lift-throttle oversteer, and it's a common cause for crashed wrxes.
Okay so what do I do about it, and what does this have to do with swaybars?
One part of the solution is the alignment. Start with the tire leaned in (negative camber), and when the car rolls the tire ends up with more tread contact. More negative camber in the front means more cornering grip in the front and less understeer. I daily drive with over -2 degrees of camber and have not noticed any additional tire wear. However, it is important to have the toe set to 0 or slightly in, rotate tires frequently, and make sure all of your suspension and steering components are in good condition.What is a swaybar?
A swaybar (aka anti-swaybar, anti-roll bar etc), is a bar that connects the left and right sides of the suspension. It twists to resist the suspension on one side of the car from being at a different height than the other side. Swaybars exist to add roll stiffness without adding ride stiffness. On a stock Subaru, it's been calculated that the swaybars do about twice as much to resist roll as the springs.What is roll stiffness?
Roll stiffness is a car's resistance to body roll. Body roll is caused by cornering force. Cornering causes a lateral acceleration, and that force acts through the center of gravity about the roll center (that's a hint at why roll center height is important). Both the springs and the swaybars resist this rolling force.Why is roll stiffness important?
A car will more roll stiffness will have less body roll and the suspension will load and react more quickly. That is good for two reasons:Great... What does that mean for me?
Swaybars let you add roll stiffness efficiently and also adjust the front to rear handling balance of the car.So then I should buy a rear swaybar?
Yes, probably. To reduce understeer, you need more rear roll stiffness. But to improve grip, you need less body roll. Can you see the conflict here?How big is too big?
Well, that depends on the intended use, the tires, and the rest of the suspension.One thing to keep in mind is that bigger swaybars add spring rate that the dampers have to deal with. So if you have 100k mile stock struts, I'd be wary of slapping on some big bars without at least throwing on a set of fresh KYBs.
Okay, well, I think I have a good start. I need to expand on the last few parts a little and update the next post for the newer Legacies.
We've all heard the term that Subarus are like lego and you can interchange many parts between models and years. This mostly holds true for swaybars but there are some exceptions:
In the front, all Legacy swaybars are the same from 90-04, with the only difference being turbo vs. non turbo. There are also two different bushing and mount types, but bars are the same.
The FRONT 05-09 swaybars are different and do not fit on other legacies (although they interchange with 08+ imprezas).
Rear swaybars for an 00-04 Legacy must be specific for that model.
Rear swaybars for an 05-09 Legacy must be specific for that model.
Front swaybars for a '10+ must be for that model.
Rear swaybars for a '10 Legacy are the same as 08+ imprezas and foresters.
Turbo and non-turbo front bars are different
Because of the crossmember and exhaust differences, turbo and non-turbo bars do not interchange.Impreza rear bars don't fit any Legacies
Our Legacies have a little bump that sticks out of the spare tire well and interferes with Impreza rear swaybars. So while a Legacy bar will fit perfectly on an Impreza, things don't work the other way around. This also probably applies to Forester swaybars.The new wider-tracked WRX and STi front bars don't fit
The 02-07 WRX sedan has a wider track and therefore different control arms and lateral links. This means that the front swaybar has to be wider. WRX Wagon and non-turbo front bars DO fit on any 90-04 Legacy, following that you are not trying to mix turbo and non-turbo bars. Sti rear swaybars are also wider.90-91 and 92-99 rear swaybars are different.
The 90-91 uses a droplink setup that goes into a hole in the rear trailing arm. 92-94 uses the C-links that are found on most newer Subarus. Swaybars might be interchangeable. More details of the differences can be found here:Some legacies do not have rear swaybars
None of the 92-94 L models came with a rear swaybar. I don't think Brightons or some L models did either after 95. Adding one is a really good idea. To do so you need mounting brackets, lateral links, and endlinks. More details here:Sizes
Okay finally we're here. Regardless of the car you have, there are different swaybars out there. Here's a list of sizes that came on different models of Subarus that will fit 1st and 2nd gen Legacies.
These may not all be correct and it would be great if people could confirm the stock sizes
Legacy90-94: 18mm (19mm air suspension?)
ImprezaRear93-01 L sedan: 18mmTribeca: 25mm
LegacyWhiteline Aftermarket90-92 non-turbo sedan: 16mm
BSF18 - 20mmNon-turbo front
BSF19 - 20mmrear 90-91
BSR17 - 18mmrear 92-99
BSR19 - 18mmOther Aftermarket
Rallitek - 22mm non-turbo front barBushings, mounts, and endlinks
The bushings in the endlinks and on the swaybars are made of rubber and they flex. That reduces the effectiveness of the swaybar. Replacing them with urethane or spherical endlinks is generally a good idea and really improves responsiveness because the bushings and endlinks aren't flexing as much before the swaybar loads, and will cause the swaybar to load more quickly. The only thing you need to keep in mind is that urethane bushings need to be well greased or they will bind and pop and possible tear apart. Whiteline makes urethane bushings in most sizes. Spherical bearings will also wear and eventually start to make noise.
The rear swaybar mounts have been known to break with larger swaybars. Whiteline, Perrin, and Cobb all have stronger mounting brackets available. The cheapest replacement option, however, are the 04-07 Impreza mounts, which are reinforced. They use a new bushing, and that Whiteline part number is W0406-[mm].
As far as endlinks go I'm partial to Kartboy and Whiteline but pretty much anything will work.
^Courtesy of Jamal for all his hard work documenting his experiments ^
What are coilovers?
Coilovers are an alternative to your stock McPherson strut setup. There are advantages and disadvantages of using a coilover system. If you're even reading this thread, you most likely want better handling out of your Legacy. Read on and I'll explain in more detail.What are some of the benifits of coilovers?
Just to name a few....Coilovers can allow more alignment custimization, lower ride height, stiffer suspension, less weight, better spring rates, adjustable rebound and dampening, etc.Sounds like coilovers are the way to go! What is the down side?
The biggest factor is cost. There are some "affordable" coilover kits that start at around $450. The quality of these kits are questionable. A "good" set of coilovers will cost you well over $1000. The other downside to them is ride quality. To many, coilovers on a daily driver car are a little too rough. Most coilovers (even on the softest setting) are considerable stiffer then stock Legacy suspension....Therefor your ride will be much rougher.I just want to slam my car, and I've heard that coilovers are the way to go!
If you want to lower your car more then lowering springs will allow you too, then coilovers are your only other option. If lowering is all you car about, then I suggest a cheap set of generic coilovers.I don't need coilovers to slam my car! I can just cut the springs! You're an idiot!
Go right ahead and cut your springs. I won't stop you. I'll just point and laugh at you when I'm riding in traffic behind you and I see your car bouncing around everywhere. As well, good luck with any kind of "aggressive" driving on cut springs.Can you explain a little bit about the benefits of how a Legacy handles with coilovers?
My favorite thing about my coilovers is the fact that I can run excessive negative camber. I frequently go on mountain runs and track my car. Running about -3 degrees of negative camber helps my handling in corners A LOT. I wouldn't be able to do this with any kind of stock suspension. The camber plates that are on most coilovers allow up to -6 degress of camber. Your caster and toe angles are not affected by coilovers however.So all this information is cool and everything....but I can't find coilovers that are made for my car!
You can use any coilovers that are made for 95 - 99 Legacy / Outback. As well, you can use any 2004 STI or 2002-2007 WRX coilovers. You will find the most options shopping for WRX coilovers. They are a direct bolt on mod.So I bought WRX coilovers....but I cant clip my brake line now? What gives??!??
The WRX/STI uses a different brake line...and a different clip. You have two options to solve this problem.I want stance....yo
Then please go buy another car. Don't destroy a Subaru. Most Subaru enthusiast are function over form. You will find little to no help destroying a Subaru around here....or any other Subaru site that I know of. If you want "stance", then maybe you belong in a Honda.Can you explain cambler plates?
Camber plates allow you to adjust camber from the top of the coilover, instead of using an essentric bolt in the steering knuckle. Using this method allows for much more adjustment in either direction, as well as an alignment that will not get "knocked out" as easy.I just got my coilovers and I don't know what I should set them to? Can you tell me?
No I can't tell you. However, I can help you get started. Its best to set them in middle. If they are too soft, then you can adjust them a little to the firmer side. If they are too firm, then adjust them softer a bit. Its a trial and error thing that each person has to figure out on their own.What are the available coilovers for the Legacy?
There are countless coilovers out there. I'll highlight a few of the major ones.
http://img.photobucket.com/albums/v2...lign/toein.jpgSteering Axis Inclination (SAI)
If I need to explain this one, there are some problems lol.Toe Out On Turn
http://img.photobucket.com/albums/v2...ign/offset.jpgAlignment images from http://www.anewtoronto.com/wheel%20alignment.html
SUGGESTED ALIGNMENT SETUP
I will give my person reccomendations here based on a few different setups and driving styles. This is not a "one size fits all" chart, however its a good starting point. You will likely have to tweak the following numbers slightly to find something that feels good to you. These numbers are just what I have found works for me.Making your alignment work for youStock Suspension - Daily DriverFront Toe : 0Stock Suspension (including WRX) - Aggressive Cornering
Getting your alignment done
BY : Jac Wagon
Hey Zues, I found this on a 240 site. Good info for those who are new to the world of suspension.
There are 2 kinds of springs. Progressive, and Linear.
With progressive springs, as they compress the lighter rate coils compress, and force higher rate colis into action. Effectively increasing spring rate as they are compressed. Stock 240sx springs are progressive. (most stock springs are.) This type of spring is good for street driving b/c they are comfortable over small bumps, but tighten up as you start turning, or braking harder.
Linear springs are the same spring rate no matter how much they are compressed. Almost all coilover systems come with linear rate springs. Linear springs are much better for sport driving, b/c they are much mroe predictable, and make tuning your suspension much easier.
You can only preload springs with threaded shock body coilovers.
To preload a spring, you compress it b/w the upper and lower spring perches by adjusting the lower collar with the spanner wrench.
With linear springs:
When you put the weight of a corner of a car (probably around 700lbs) over your spring it compresses to absorb that weight. With 400lb spring, it will compress about 1 3/4". So, if you start with the lower collar so that it is just tight enough to hold the top of the spring against the upper perch this would be 0 preload. Raise the collar 1 3/4", and you now have 700lb's of preload. (arbitrary #'s for the sake of illustration.) Since you have preloaded the spring, the same weight as the car's corner, when you put the car on that spring, it will not compress at all, and will simply sit on top of the spring. If you were to hit a bump, the force would still compress the spring the same amount it normally would if you had set the spring to 0 preload. Now if you set the spring to say 900lbs of preload, when you hit the bump (say its a bump that generates around 250lbs of upward force), the spring will compress much less b/c the spring is already beyond the load specified to absorb the bump. Since there is only 50lbs beyond the preload, the spring will only compress about 1/8th inch, and the car will likely be launched over the bump.
You will likely never ever preload a spring beyond the weight of the corner of the car it is on for that exact reason. Springs are there to absorb bumps, if there are any bumps at all, this is a bad idea.
What good is preloading the spring then?
It can provide you with more suspension travel in certain situations. In the ideal world, having the spring at 0 preload would place the piston inside the shock exactly halfway through it's stroke (middle of shock) once the car's weight is resting on the spring. This is almost never the case. by preloading the spring, you can adjust the amount of rebound, or compression travel you have in the shock. If you preload like 200lbs, this will give you more compression travel, and will help keep your car from bottoming out when cornering. You have to be careful though, b/c you don't want to sacrifice too much rebound travel, or you could cause all sorts of other problems.
With progressive springs, preloading the spring does all the same things as linear springs, but it also increases the initial rate of the spring. So say you have a spring with a 200lb/in initial rate, and a 400lb/in max rate. (all progressive springs are rated this way.) Preloading 200lb's will compress the spring just under 1". Since the rate goes up with a function, it will have increased to probably somewhere around 250lb/in by the time you reach a 200lb preload. So now your initial rate is 250lb/in, with a max 0f 400lb/in.
You will likely never deal with this though, b/c very few coilover systems come with progressive springs, and remember you can't preload without adjustable spring perches. (coilovers)
also should quicklink to the post # on the first post so ppl dont have to scroll
My e-mails with Rallitek
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