Tech Reference

Suspension is an area that really allows an individual to tailor the vehicle to their driving needs and desires. Some of the most common types of suspension components are listed below along with what they do and what kind of impact they make on handling or if they are basically just for aestetics.

 

Strut Tower Bars

While being pertinent to many vehicles to increase chassis rigidity, older models in particular, strut tower bars (which span from the top of one strut tower to the opposing tower, mounted over the coil-over assembly) have become less useful in the latest Impreza models as well as even the BE/BH (2000-2004) Legacy models due to the absolute strength and rigidity present in the newest chassis. The new Legacy should further improve over the last making STB’s virtually useless in sedan models unless you want the look, and functional basically in just the rear location for wagon models.

 

Sway Bars, Mounts & Endlinks

Sway bars are probably one of the best handling modifications available to reduce body roll and understeer (the tendency for the nose to keep going straight while you want to turn.) Choosing an appropriate sway bar size (generally 19-22mm without upgraded front bars, or up to 24mm with upgraded front bars) will make a very noticeable handling difference, and considered by many to be one stage one-type modifications. Some things that must be taken into consideration though is with bars set to 20mm and higher, the stock mounts may break, thus aftermarket companies are starting to ship hardened mounts with their bars to alleviate this problem. Otherwise, they can be found separately. Additionally, endlinks may want to be upgraded as well, particularly with going to a higher set sway bar diameter, as the increased stress could make these more prone to breaking and their effectiveness becomes reduced. (At press time I am unaware if the USDM models have upgraded to new steel units I have seen pictures of which may negate the need for upgraded end links. I am only aware of this on the Legacy models however.)

 

Springs, Struts & Coil-Overs

The chassis is really held up by two main components off the axles, springs and struts (also known as shocks.) The springs suspend the body of the car and everything attached to it, while the struts ensure the tires stay in contact with the road with a high-pressure gas. There are many different options with this setup, but it is highly recommended that the struts and springs be matched for optimal performance, safety, and to minimize chance of damage to the suspension equipment. This setup can come in the form of a ‘coil-over’ which is essentially a spring and strut in a unit, many of these aftermarket units are adjustable by spring rates (the higher the weight, the harder they will ride) and stiffness of the struts (known as dampening rates.) More widely used (particularly by OEMs) are a combination of springs and struts.

 

There is a growing line of sport springs available for the Legacy models while finding applicable struts is hit or miss for many model years. Most springs lower the chassis by about 1” giving it a slightly more level stance while increased spring rates give the car a more supple ride. There are many solutions available for the Impreza chassis currently, and we may see at least a couple of the better solutions available for the Legacy chassis within the next year.

 

As good as springs and struts are at reducing body roll and increasing agility, they work best when coupled with at least a heavier rear sway bar or matched set (designed for the perfect handling balance- not the same size as match may be interpreted as) of front and rear sway bars.

 

Control Arms, Bushings & Links

To keep the suspension of your vehicle as responsive, quick acting, and rigid as possible, upgraded bushings, rear lateral links, and aluminum front control arms are one of the best kept secrets in the book. Subaru uses softer bushing and heavier steel suspension components to keep cost and NVH down on their normal street cars. What many don’t know is that for many of the road going cars, FHI produced STi versions of these components that are more rigid, lighter, and have better bushings to reduce unsprung weight, help your car respond faster with better feedback, and track better with increased alignment precision. Sometimes it’s the little things that really count.

 

A good discussion and explanation of the Multi-Link Rear suspension found on the BL/BP gneration Legacy's can be found here LINK

 

Alignment

If you are planning on racing your Legacy or the alignment shop doesn’t meet your specs, you may want to check out aftermarket Strut Top Mounts and/or alignment bolt kits which allow you to tailor your alignment to your specific needs (like race days) and can help provide a more sturdy alignment with even greater range of settings.

 

Brakes

The brakes on the new Legacy GT incorporate vented discs front and rear. The front disc size is 12.3” x 1.18” thick while the rear size is 11.3” x 0.7”. Dual-piston floating calipers are fitted up front with single floating sliding calipers are out back. The combination of near STi-sized brakes up front and basically WRX-sized rotors out back, both vented, will assure fade-free (loss of braking due to excessive heat) driving, even on the most spirited drives. This setup should not require the upgrade of calipers unless under the most extreme race conditions such as extensive lapping days.

 

Some ways to improve pedal fell and bite are to incorporate stainless steel brake lines and upgraded pads. While upgrading pads, if you desire OE-like dusting and sound characteristics (or lack-there-of), Ceramic-type compounds are desired which keep dusting to a minimum while having an increased pad bit, heat range, and few require any bed-in. If you desire/require pads that bite harder and have a higher temp range, semi-metallic pads are available. Do not though, most of these pads dust heavily, squeel when cold, do not operate well below summer driving temps and are optimal only during higher temps such as tracking days. This type of pad also wears rotors faster.

Edited August 29, 2009 by SUBE555

I've been compiling a list of springs with their drops and spring rates, here:

 

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

 

Enjoy.

First and foremost – brakes are a no joke thing on your car. If you are new to brakes have someone teach you how to work on them. Despite all the reading in the world on this subject this is something you should be taught to do instead of trying to figure it out yourself.

 

Second – If you are new to brakes get someone to teach you. Yes, it had to be said twice. It’s that important.

 

Now, this is by no means an all inclusive document on brakes. Instead it is a few tips and tricks I have learned over the years.

 

Some background on my brake experience: I started helping Dad work on the brakes on the family cars and trucks when I was seven by handing him tools. By 12 I was doing the disk brakes myself with his supervision. By 15 I had the arm strength to do the drum brakes on my own. By 16 I was doing brakes unsupervised by him. Now, this does not mean I am immune to learning new things. Far from it. Quite often I see someone with lots of experience post up a new tip or trick to working on brakes, and if it makes sense I try it out. Most of the time it works nicely.

 

On to the tips and tricks. I will try and keep this brand generic as we can cover that later.

 

Pads –

Run the proper pad for what you are going to be doing with the car!!! Do not run street pads on the track. They can’t take the heat.

Do not run high end track pads on the street. They need time to warm up to operating temp.

Do not run track pads and expect to get low dust and no noise. In a race environment dust and noise fall WAY down on the importance list.

Buy the best pads for your application that you can afford.

Be aware of the limitations of these pads, and don’t out drive them. Remember, no matter how fast you go eventually you have to stop.

 

Fluid –

Regular street level fluid on a NORMALLY driven street car – change every two years.

Good fluid that sees aggressive driving on the street – change once a year.

Good fluid that sees heavy autoX usage on a “race on Sunday drive to work on Monday car” – change a couple of times a season at the very least.

Good fluid that sees hard track use – fresh fluid for each event.

 

Rotors –

Buy good rotors. Not unknown cheapy ebay ones that you have no idea who made them.

Slotted – not really necessary unless you are heavily racing in the rain

Drilled – NO NO NO a thousand times NO!

Two piece, semi-floating or fully floating – there’s a time, a place and a budget for these. 99% of the cars on this board will never need this time place or budget. Quite honestly they are not necessary unless you're REALLY into autoX or the track, and chances are if you are into those things I'm not going to tell you anything you don't already know about them.

 

Turning the rotors – if you feel they need it then do it, but don’t fall into the “warped” rotor myth. If you can see pad impressions on the rotors then get them lightly turned after a bed-in (see below).

 

NEVER run a rotor that is below the recommended thickness spec. It’s just not worth the risk. Period.

 

 

General tips on pads, fluid or rotors –

Brake squeal – this is actually a vibration you are hearing. It’s the pad backing plate chattering against the pistons. Anti-squeal rubbery goop is supposed to help prevent this. I’ve never really cared for it. For many years I ran a good grease on the backing plates and it worked just fine. Until! I got a suggestion to run high temp anti-seize instead. I gave it a shot. I will never go back to grease.

 

Fluid – Use good fluid for your application. Please note – DOT 5 is NOT what to run in our cars. It’s a silicone based fluid made for preservation of lines in classic cars. DOT 5.1 is the stuff to look at for actual driving if you choose to use a DOT 5 series fluid.

 

Whenever you replace pads OR rotors, not both, but EITHER you should do a bed-in process. Here’s the process I have used for years:

45-10 using medium pressure 3-4 times

Drive to cool for a little bit

55-10 using medium pressure 3-4 times

Drive to cool for a little bit

65-5 using hard pressure but not locking them up 3-4 times

Drive for 20 minutes to cool them.

If you must come to a stop in that time do so gently, and just hold the car at the stop with the least amount of pedal pressure that you can (or use your hand brake).

 

 

Please note, you can do a bed-in process at any time. In fact, if you are starting to feel a slight vibration in your wheel during light braking due to pad deposits do a bed in process before thinking about getting your rotors turned.

 

If you are changing shoes as in on drum brakes (remember your handbrakes are drums in the rear. They just happen to be in the hat of the rotor) do each side one at a time from start to finish. This way you can go and look at the other side in case you forget how it goes back together (and you will forget).

 

Couple of general points –

Use brake cleaner spray to clean machining oil and finger oil from rotors

Use brake cleaner spray and a rag to clean up stuff in there.

If you use an airgun for spraying dust out don’t breathe it. While pads are no longer made with asbestos I’m sure breathing that crap still isn’t exactly good for you.

Wipe things down so you can see what you’re doing.

Apply grease or anti-seize to the slider pins on the frame that holds you pads in place.

Apply grease or anti-seize to the backing plates of the pads

Apply grease of anti-seize to the clips that hold the backing plate tabs

Bleeding process –

Now, this is the part I know there’s a good bit of interest in. This is my thoughts and experience on bleeding. It is by no means all inclusive.

 

Why we bleed brakes –

Pushes air out of the system. Air is bad because it is compressible. That means energy is going into squeezing bubbles instead of brakes.

Flushes old fluid out of the system if you are replacing it.

 

NEVER let the reservoir go below the min mark while bleeding. Doing do and you risk pushing air into the master cylinder, and getting air out of the MC is a total pain.

 

Now, onto the bleeding. There are a few ways you can do this – traditional 2 man system, 1 man system using something like speedbleeders, 1 man system using a pressure pump or vacuum pump.

 

Let me cover the 1 man systems first. I don’t like them. Why? I just don’t. Now, don’t take that as gospel. There are MANY MANY people who prefer one system over the other, and their brakes work just fine. It comes down to personal preference on this. Mine just happens to be the 2 man system.

 

The two man system –

You’ll need a box end or flare wrench that properly fits your bleeders on your brakes. DO NOT use an open ended wrench. That’s just asking for trouble. Me? Trouble is good at finding me so I don’t invite it.

You’ll need some clear plastic tubing that fits tightly over the nipple on the bleeder. You could use something that’s not clear, but I find it’s easier to use clear as you can see what comes out.

A container to catch old fluid.

A buddy or hottie with a strong leg and a good bit of patience.

Roll down the windows of the car so you can talk to each other and communicate what is going on.

 

The actual bleed–

Top off the brake fluid

ABS systems work on diagonals so you want to bleed on the diagonals. The Subaru service manual calls out FR, RL, RR, FL.

Get on the first corner. Put your wrench on the bleeder, put the tubing on the nipple, and put the end of the tub in your catch container

Have your helper get in the car, and with it off pump the brakes. This is NOT a stabbing motion, but strong steady pumps.

When the pedal will not sink any more the vacuum has fully been evacuated from the booster, and the system is under pressure.

Do not let them remove their foot from the pedal.

At this point have your helper press the pedal with firm, smooth, steady pressure.

While they do this open the bleeder ¼ to 1/3 turn. Fluid, maybe some air, and on occasion some kind of alien will start to come out.

When the pedal is close to the floor have your helper warn you.

When the pedal hits the floor, have them call out floor, but do NOT let them release pressure.

Close the bleeder. Please note – you do NOT need to he-man these. Do not over tighten them.

Once closed call out for them to pump the brakes.

When they are hard have them call out they are ready, and repeat the bleed.

Do this a few times at this corner.

TOP OFF THE BRAKE FLUID before moving to the next corner.

Repeat for each corner in named order above.

 

If you are replacing fluid go around and do this a few times. Don’t try and get each corner in one go.

 

If you have replaced lines or caliper give the lines and caliper a few taps with the end of your wrench to dislodge any air bubbles. This is kinda like the bubbles on the inside of your glass of beer.

 

If replacing calipers the bleeders go UP!!! That’s where the air goes. I know this sounds dumb for me to mention, but believe me it does happen.

 

 

Overall, this is not all inclusive, and I am sure I and others will post other tips below, but I do really feel I must reemphasize my very first point. If you are new to brakes have someone who knows what they are doing teach you.

When the pedal is close to the floor have your helper warn you.

When the pedal hits the floor, have them call out floor, but do NOT let them release pressure.

Don't let the brake pedal go to the floor when bleeding. That can cause damage to your master cylinder seals. That is not the normal range of motion, and there can be corrosion on the shaft that can rub against the seals, potentially damaging them.

A heads up for everyone when you install the Cusco Front Strut bar on the 2005 Legacy GT Wagon.

First, separate the silver bar from the blue mounting plates. Then after removing your top nuts from each strut tower, position the blue plate over the exposed bolts. The one on the passenger side is easy to line up.

When you find that you can not get the blue plate over the bolts on the driver's side, stop cursing; do not pick up a sledge hammer or crow bar. Believe me I found it maddeningly frustrating when it would not drop over the bolts and into place.

Go and get your trusty hydraulic floor jack and slowly lift the front of the car and wheels off the ground; this will permit the strut to drop down. Now with the exposed bolts lower in the frame, you can very easily position the blue plate over the 3 slightly lowered mounting bolts.

Lower the car to the ground.

Caution: do not lift the car so high that your hood/bonnet hits the ceiling, also do not lift the car so high that you drop the strut out of the tower and position.

Use a torque wrench and you are finished.

The instructions are in Japanese which I can read, and this method is not discussed even in the Japanese directions. Damn it!

Edited August 3, 2008 by big ears
clarity

If you use different front pads/rotors at the track, you will have much more confidence in the brakes, so you will have a much better day. You will always have pads & rotors to drive home.

You still have to put cooling ducting in even if only for the CV joints & wheel bearings.

My brake pads up front just started chirping last night (pad sensor I am guessing) and I was thinking about changing out my brakes this weekend. I have observed many brake changes and have done it myself on my wife's forester turbo and on my old 01 LGT and I replaced pads and rotors each time. In the past I have simply changed both out because of the cost savings of doing it myself. I did a quick visual inspection and the rotors up front seem clean still, so it is my takeaway from your writeup that there is no need to swap, or even turn the rotors.....is that right? That would be a huge cost savings for me and would be awesome if the rotors are still good. My 05 legacy gt is my baby and I want to do what is right, but also only spend money on what is necessary. Any advice would be appreciated.

Here is my tip;

 

Before opening the hydraulic system, depress and hold the brake pedal with a block of wood against the seat cushion. This closes the ports in the master so when you open the system the master will not run dry.

My brake pads up front just started chirping last night (pad sensor I am guessing) and I was thinking about changing out my brakes this weekend. I have observed many brake changes and have done it myself on my wife's forester turbo and on my old 01 LGT and I replaced pads and rotors each time. In the past I have simply changed both out because of the cost savings of doing it myself. I did a quick visual inspection and the rotors up front seem clean still, so it is my takeaway from your writeup that there is no need to swap, or even turn the rotors.....is that right? That would be a huge cost savings for me and would be awesome if the rotors are still good. My 05 legacy gt is my baby and I want to do what is right, but also only spend money on what is necessary. Any advice would be appreciated.

 

If your braking is smooth, and the rotors are in good shape I don't see any problem with doing what I call a "pad slap".

In response to the tip you gave, are you saying depress the pedal with a block of wood prior to compressing the calipers??? I have always just opened the cap on the master cylinder reservoir and pumped the brakes a couple times until the air has been bled. Also, just in case I do need to replace the rotors, do you have any buying advice. I prob going to use duralast ceramic premium pads, but dont know how crazy to go with rotors if they are necessary. They range in price from about $30 to over $100 each. You are the second person to say avoid the drilled rotors, and I dont think that I am going to need slotted. Any buying advice in addition to my above question would be appreciated. thanks

Here's a quick guide for showing the percentages of torsion rigitity when upgrading your sway bar...pretty cool!

 

http://www.whiteline.com.au/docs/bulletins/BL-281.pdf

I,m looking for a brake hyd part 92 legacy wgn. this part is bolted on the rt front shock tower and has 4 brake lines that go to it but no electrical connections, has a round cylinder on one end about2 inches long and about 1 inch in diameter. no body at the parts house knows what I am talking about. Hopefully someone here can give me a part name or number and where I can get one.

I,m looking for a brake hyd part 92 legacy wgn. this part is bolted on the rt front shock tower and has 4 brake lines that go to it but no electrical connections, has a round cylinder on one end about2 inches long and about 1 inch in diameter. no body at the parts house knows what I am talking about. Hopefully someone here can give me a part name or number and where I can get one.

 

That sounds like the brake fluid distribution block.

 

https://parts.subaru.com/a/Subaru_1992_Legacy-4-L-GRADE--LS-WAGON/_54106_6021400/ANTILOCK-BRAKE-SYSTEM-FRONT-MADE-BY-NIPPON-ABS/B10-267-A1.html