Suspension FAQs - Coilovers - Springs - Swaybars - Alignment

John · Aug 11, 2011

I wrote this to be specific to BD, BG, and BK Legacys, but over the next few days I'll edit it to be directed towards WRX/STI. I will add the missing sections as well

COILOVER FAQ

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 Subaru. Read on and I'll explain in more detail.

What are some of the benefits of coilovers?

Just to name a few....Coilovers can allow more alignment customization, 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 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.

Another big thing is body roll. I currently have D2 Racing coilovers. I have almost NO body roll (and I'm on stock sway bars too!)

When driving my Subaru compared to other Subarus that are on stock suspension, I feel MUCH more planted to the road. As weird as it may sound, I feel connected to the road...instead of just driving over the road.

So all this information is cool and everything....but I can't find coilovers that are made for my Legacy!

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 for my Legacy....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.

Ghetto option #1

Zipties. Just ziptie your brake line to the coilover

Correct option #2

Swap brake lines. You can buy any 2004 STI or 02 - 07 WRX brake lines and clips to properly secure them. While you're out shopping for brake lines, I suggest picking up a set of stainless steel brake lines. They will help you maintain a nice pedal feel.

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 on the market?

There are countless coilovers out there. I'll highlight a few of the major ones.

Raceland USA

These are "budget" coilovers. Quality is questionable and spring rates are unknown. Some people love these, and some people hate them. This would be a good option if all you car about is being lowered.

Rokkor

I personally believe that all of the generic coilovers on the market are made by the same people, just marketed under different names. All of the "budget" sets are pretty much the same.

Godspeed

I have no experience with these. I have read both good and bad reviews on them. It seems like these may be good for someone who wants a little bit of performance and a lower ride height.

Megan Racing

These are the "cheapest" coilovers that I would personally buy. They have great reviews and I have personally driven several cars with them. They seem to handle well, and the ride quality is not that bad.

BC Racing

These have EXCELLENT reviews. I have driven on BCs before and I love them. If you want something that will give your car a good look, and help it handle extremely well, these are for sure a viable option.

D2 Racing

These are my personal favorite, but they are NOT cheap. My set was $2300, but was worth every penny. I have driven almost every kind of car on the road on every kind of suspension, and I still have yet to find a suspension system that performs like D2Rs coilovers.

John · Aug 11, 2011

ALIGNMENT INFORMATION

Camber

Camber is the measurment of how much the top of the wheel is tilted in or away from the center of the vehicle. Most FWD or AWD cars run slight negative camber to help combat excessive understeer.

On most cars, running excessive negative camber will wear the inner edge of tires VERY fast. However, for some reason Subarus tend to get good tire life when running excessive negative camber.

Stock adjustments will get you up to -1.5 degrees. With aftermarket camber plates, one can achieve up to -6 degrees of camber. Most Subaru drivers are happy with between -1.5 and -2.0 and notice no ill wear patterns on their tires. I personally run -3 degrees on all 4 wheels on my Legacy, and I've driven 10,000+ miles like that and I have had no abnormal tire wear.

Camber should match side to side (per axle). Generally, there is a tolerance of about .5 degrees before there is a drivability concern. Usually anything over .5 degrees split will cause the vehicle to pull towards the more positive side (wheel with the most positive camber).

On our cars, Camber is adjustable by an essentric bolt in the steering knuckle in the front.

Our cars do not have a factory rear camber adjustment, however I've been able to adjust rear camber by close to 1 degrees by loosening the knuckle bolts and manually pushing in or pulling out the entire knuckle, and tightening the bolts back up. There are aftermarket camber bolts and adjustable lateral links available to allow further camber adjustment in the rear.

Caster

Caster is the angle of the upper and lower steering pivots viewed from the side.

To best explain steering pivot, its the lower part of the suspension that turns, and the upper part that turns. In a Subaru, this is the lower ball joint and the strut mount (top hat).

Caster has a direct impact on steering effort and lateral stability.

Negative caster will cause the vehicle to wander at high speeds, reducing lateral stability. But on the plus side, it will reduce steering effort.

Postitive caster will help the vehicle retain lateral stability at high speeds, but in turn it will raise your steering effort a little bit. Most cars are set up out of the factory with about 5 degrees of positive caster. Some German cars have as much as 9 degrees of positive caster.

Caster has little to no effect on tire wear. Like camber, caster has a tolerance of about .5 degrees from side to side. If there is a split of more then .5 degrees, the vehicle will usually pull to the more negative side.

In a Subaru (and most other cars on the road) caster is not adjustable. If there are caster problems, its a good indication that there is a bent steering / suspension component from some kind of accident.

Toe

Toe is probably the single most important alignment angle. Toe identifies the direction a wheel is turned compared to the centerline of the vehicle. Postive toe is the wheel turned out, negative toe is the wheel turned in.

Toe being outside of specifications can cause a few different problems. The big ones are abnormal tire wear, vehicle pulling, and a crooked steering wheel. The ideal toe setting is 0 degrees on all 4 wheels.

On our cars, toe is adjustable on all 4 wheels. If further adjustment is needed on rear tires, aftermarket lateral links are available that allow more adjustment.

Steering Axis Inclination (SAI)

Steering Axis Inclination (also called SAI) is the angle of the steering pivots viewed from the front.

Like caster, SAI can help improve directional stability by reducing the scrub radius.

SAI is NOT adjustable on any vehicle. If SAI is outside of specifications, its a good indication that there is a bent or broken steering / suspension component. SAI is mainly used by alignment technicians to help them diagnose bent parts.

Included Angle

Like SAI, Included Angle (also called IA) is a diagnostic angle. Its the sum of SAI + Camber. It is also used to help diagnose bent suspension parts. IA is NOT adjustable.

Scrub Radius

Scrub Radios is the distance between the extended lines of the steering axis and the tires centerline where the tread contacts the road.

Scrub radius is NOT adjustable, however it can be changed a few different ways. Bent suspension parts will change your scrub radius. If this is the case, the vehicle will pull hard in one direction since the scrub radius does not match on each side. Another way scrub radius changes is by installing different offset wheels. This can have a negative impact on vehicle handling.

Setback

Setback is the term used when one wheel on an axle is positioned further back then the other wheel. There is generally a tolerance of about .25 inches. Anything more then that indicates that there is a bent / broken suspension component.

Thrust Angle

Thrust angle is the diection that the rear wheels are facing in relation to the center line of a vehicle. Thrust angle IS adjustable on almost all vehicles. On a Subaru, you adjust rear toe to correct the thrust angle.

If the thrust angle is out of spec, then the vehicle will "dog track". As well, it will handle differently when turning left vs right.

On a solid rear axle vehicle (like a truck), if the thrust angle is not in spec...then usually the vehicle must visit a body shop for frame repair. Sometimes the rear diff can be re-positioned to compensate for the thrust angle however.

Ride Height

If I need to explain this one, there are some problems lol.

Ride height is not adjustable on Subarus unless you have an aftermarket coilover system installed. You can get a lower ride height by installing lowering springs on your factory struts too.

Any time you change your ride height, you MUST do an alignment since it will affect your camber and toe on all 4 wheels.

Toe Out On Turn

During a turn, the inside wheel of the turn will turn sharper then the outside wheel will. This is the "toe out on turn". See the above illustration to understand.

If this is outside of specs, its likely cause by a bent tie rod or steering arm.

Offset

Zero Offset - The hub of the wheel is in line with the centerline of the tire
Negative Offset - The hub of the wheel is towards the inside of the vehicle
Positive Offset - The hub of the wheel is towards the outside of the vehicle

By changing wheels to a set with a different offset, you effect toe out on turn and scrub radius.

Alignment 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.

Stock Suspension - Daily Driver

Front Toe : 0
Front Camber : -.8
Rear Toe : 0
Rear Camber : .6

Stock Suspension (including WRX) - Aggressive Cornering

Front Toe : 0
Front Camber : -1.5 give or take a bit. Max out the camber bolts and make have 0 cross camber
Rear Toe : 0
Rear Camber : -1 max out having 0 cross camber

Coilovers - Daily Driving

Same as stock

Coilovers - Drag

Front Toe : 0
Front Camber : 0
Rear Toe : 0
Rear Camber : 0

Coilovers - Aggressive Cornering

Front Toe : 0
Front Camber : -3.2
Rear Toe : 0
Rear Camber : -3

Making your alignment work for you

Any alignment changes you make have a direct impact on the way your vehicle handles. One of the biggest things you can change is the handling balance of your car by reducing understeer or oversteer.

Reduce Understeer : run more negative camber in the front. This is probably the single most important thing that anyone can do to make their car handle better. This will bring the car to a more "neutral" steering car.

More Understeer : run more positive camber in the front. This will likely make your car undrivable if you start going into positive numbers though. BE CAREFUL with this. If you're in the rain, snow, or ice and you're running positive camber, you will likely crash into a big tree and have an airbag blow up in your face.

Getting your alignment done

Almost any automotive shop can do an alignment for you. "Stock" alignment settings for Subarus SUCK. Its better to walk in knowing the alignment you want. Ask to talk to the tech doing your alignment so you can explain to them what you want out of the car and they can help you decide what settings are best. Keep in mind though, that running a bit of negative camber on our cars WILL NOT wear out your tires like it will on most other vehicles, no matter what the tech tells you.

Make it VERY clear that you want 0 toe, 0 thrust angle, and 0 camber split on both axles. Make sure that they adjust camber on all 4 wheels as well. It blows my mind how many half ass alignments I've seen done where someone doesn't bother to touch camber....or they will get everything "in the green" and call it a day, but the car leaves with a .7 split on the front toe. If the tech tells you that camber is not adjustable, teach them something about your car. Earlier in this article I explained how both front and rear camber are adjustable. If for some reason the shop wants to charge you more to do this, walk away from them. This is part of a NORMAL alignment and does NOT cost extra to do.

ALWAYS ask for a before and after printout of your alignment.

If possible, watch the tech do your alignment. That way you can at least pretend you know what he is doing, and he is less likely to half ass it.

A fair price for an alignment is anywhere between $75 - $100.

Your alignment will likely come with a warranty. However, this warranty is void if you "race" or "abuse" your vehicle. Meaning if on your way home you go through the corners like a bat out of hell, it will void your alignment warranty if the shop finds out. So when you take your car back, don't mention that you have raced or "abused" your car. Some shops offer a "lifetime warranty" on their alignments. This usually runs about $150. If you plan on keeping your car for a long time, this may be worth it. If you do this, I suggest taking your car back about every 3 months to have everything checked.

John · Aug 11, 2011

reserved for swaybar faq

John · Aug 11, 2011

reserved for springs/struts faq

John · Aug 11, 2011

reserved for further information

John · Aug 11, 2011

reserved

John · Aug 17, 2011

I have been busy the past several days. I'll get this finished soon

Grinder34 · Apr 26, 2012

So i'm gonna take a preliminary stab at the spring/struts part:

Everything i'm going to discuss is assuming NO swaybars. That's the subject for another write-up.

Springs:
Springs are a very important part of your suspension. They're largely responsible for how stiff or soft your ride is, and the stiffness is measured in either g/mm or lb/ft, and is called the spring-rate. Basically, how much weight do you have to put on the spring to get it to compress? A higher number means a stiffer ride. It also means the car will corner flatter. Coversely, a softer spring will mean a lot more body roll, but a more forgiving ride.

Struts (Dampers):
The struts are what keep your springs from bouncing indefinitely. Have you ever ridden in an old car that seemed to just keep bouncing after you hit a speedbump or a pothole? That's because the struts were gone. Struts resist motion. Think of silly putty: When you pull it slowly, its quite easy to stretch out...however if you are to try to pull it quickly, it becomes quite tough and hard to pull. Struts have the same effect. Due to springs, your car will want to bounce--but the struts will try to prevent the movement of your springs. It sounds like they're fighting eachother! And they sort of are, but its to your benefit.

Imagine you're travelling in a straight line, and turn sharply to the left. At this point, your car will lean sharply to the right. You've loaded up the right side springs with the weight of the car, and they've compressed. Lets say, for the rest of the example, that your springs should have compressed 1.0" on the right side.

Imagine for a moment your car has no dampers (or blown dampers). Your springs might over compress (momentum!) to 1.5", then bounce back to nearly level, then to 1.5" again! That would make the car extremely upset and cause all sorts of problems. Luckily for you, your car DOES have dampers. Ideally what you'd want is for your car to gently, but quickly approach 1" of compression and STAY there. This is called critically-damped If you have too much damping, it'll take a long time for the car's springs to compress the 1" because the shocks are preventing that motion. This is called over-damped. If you don't have enough damping your car will surpass the 1" compression and then bounce around for a while. This is called under-damped.

So now we have the concepts down individually, lets look at how they interact with eachother.

Each spring rate has it's own damping value that will result in critical damping. I'll leave out the theory here, but i'll just tell you that you do not always want critical damping. In fact, you often want DIFFERENT damping values for compression and extension (called rebound).

When setting up a car, one usually starts by picking a spring rate. This may not be the same front-to-rear or even side-to-side (certain race cars. For you it should ALWAYS be the same side-to-side!!). But spring rates are the first thing to decide on. From there the valving will be picked. Valving is what determines your compression and rebound damping. Most struts have non-adjustable damping, but can be re-valved by professionals (eg FEAL) to suit aftermarket springs.

Coilovers:
Coilovers are, most simply, a matched set of struts and springs, and a few extra features. One of the most usual set of features is the adjustability aspect. A single adjustable set of coilovers, will have a single knob that you can turn to make both compression AND rebound stiffer at the same time. A good set of single-adjustable coilovers, will have the compression and rebound damping rates change in a complimentary manner. That is to say, compression will get proportionally stiffer with the rebound. With a bad set of single-adjustable coilovers, the rebound might "overpower" (for lack of a better word) the compression, or vice versa.

Next come the double-adjustable coilovers. These will have two knobs. One knob will adjust the rebound, and the other will adjust the compression. This gives the user the ability to fine-tune a setup in a way they would not normally be able to with a single-adjustable coilover. However, with more options for adjustment, comes more room for error and creating a bad setup!

I think i covered most of the basic topics here. Potential additional topics would be:
Height Adjustment
Shock Dynos
3-way, 4-way, etc... adjustable coilovers
Tender springs

Suspension FAQs - Coilovers - Springs - Swaybars - Alignment

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Grinder34

Track Monkey

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