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Brakes & Suspension Forum sponsored by The Tire Rack |
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05-18-2010, 04:53 PM | #1 |
Former Vendor
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02/03 Impreza refresh – where to begin
Yes, this is going to be quite the wall of text. Read it while you’re at work (yeah, we know you’re surfing at work, but I’m writing this while at work so we’re all good). This is not a comprehensive document. While I will try to put a good bit of info in it, I know for a fact I will miss things. That doesn’t mean I won’t address it, just that I missed it or haven’t addressed it yet.
Lately we’ve been getting a lot of calls and emails from bugeye owners who now have an appreciable number of miles on their cars, and want to tighten it up. There tends to be two types of people who call about this. The first are the daily driver guys who just want to get that “crisp” feeling back. The second are the guys who bought the car for cheap as a weekend warrior toy. There is absolutely NOTHING wrong with either of these. Different people use the cars differently. What is common is that all of them need a place to start. In both of these cases you need to start from a stable base to get that crispness back, and here’s where we can offer some guidance. Now in either case we need to look at the items that wear over time, and look at their replacement. In some cases these will be upgrades over stock. Once we have that nailed down, we can look at the performance adders assuming you’ve built up a stable base from which to work. The most simple part:
Bushings When you think about bushings they certainly don’t seem all that glamorous, but these are a big thing that really affects how the car feels. They connect suspension pivot points, hold things in place, and cushion NVH (Noise, Vibration, and Harshness). Because these little guys are, well, little and they often get overlooked, but really, a good set of bushings can help really tighten things ups. If you are looking to getting that stock feel back in your car, and nothing more than you cannot beat the stock bushings with one exception. I’ll go over that one exception right now: Steer rack bushings – these little guys are the ones that go between your steering rack and the front subframe of the car. They really do two things. First is they isolate any vibrations from the rack to the chassis, and second, they hold the rack in place. Quite frankly, the stock ones suck. Yeah, they do a great job of isolating that NVH, but they are so soft that they allow the rack to shift in its mounts leading to the dreaded memory steer (steering wheel cocked to one side after making a turn) and also contribute toward that dead spot of feeling when you have the wheels straight. Even when new, they are too soft, and this is by far one of the first things that should be changed out for aftermarket. Now, let’s say you did these a LONG time ago way back in the day when the car was newer. Aftermarket parts are not magic. They will wear out over time. If it has been a few years since you’ve done these take a look at the ones on your car. If you’re rolling around on the stock bushings, even if you’re going for that stock feel, chances are pretty darn good they desperately need to be replaced.
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05-18-2010, 04:53 PM | #2 |
Former Vendor
Member#: 93646
Join Date: Aug 2005
Chapter/Region:
MWSOC
Vehicle:Many Track Records Let us help you go fast! |
Other bushings –
As I said before if you’re looking for a stock feeling car, and just looking to stabilize the platform with no concern to performance upgrades you can’t beat the stock bushings. Here’s an ordered list of the ones we see wear out the fastest, and need to be part of your inspection and upgrade path (more on the upgrades later).
As I said, this is an ordered list, and what we seem to see fail the most quickly over time. If you have an eye toward performance then the order to look at these is the same from a wear standpoint, but often people don’t upgrade them in that order (that’s just how it works). Either way, I’ll go into each one, and what they do to give you a bit of an idea of upgrades. As I’m trying to keep this document as brand and vendor neutral as possible I’m going to try and avoid naming names or pointing to vendors. For that I strongly encourage you to do some research in the car parts review and vendor review areas. Rear differential mount bushings – These are at the very back of the rear diff and attach it to the rear subframe. The bushings are there to isolate noise. They are subjected to twisting, compressing and stretching. The stock ones have voids at the top and bottom to further isolate noise, but this allows for movement. Combined with those forces, the voids, and environment these bushings wear quickly. This wear allows the rear diff to move around a good bit, and the more wear the more movement. This will lead to a disconnected feeling when trying to apply power and a bit of numbness from the back end. Upgrades for this are stiffer rubber, urethane of various stiffnesses, and even aluminum. Engine and transmission mounts – I’m lumping these two together as so many people look at them at the same time. These bushings hold your motor and tranny in place, and are subject to all sorts of stress, heat, and again the environment. When they fail the will start to separate the rubber from the metal portions or the rubber will start to soften. This will lead to poor control of holding the motor and transmission in place. This can lead to more than just unwanted driveline movement. You can actually start to overstress the CV joints on the front axles. Upgrades over stock for these are stiffer than stock rubber, and urethane based. While there are solid mounts you will hardly ever see me recommend those. Anti-roll bar bushings – it’s funny that I would address this one as hardly anyone talks about it, but it is one that needs to be addressed. Your anti-roll bar is attached to the chassis at two points, and in each of those points is a bushing that allows for the bar to twist (an ARB is simply a spring that works by being twisted). The effectiveness of that bar depends on those points holding it to the chassis being rigid (but allowing for rotation). Just about every bar for our cars out there uses a bushing, even stock, to accomplish this. Over time the hole for the bar will oval, and as such will allow the bar to move about instead of being rigidly held. This will make the bar less effective. Upgrades for this are typically urethane, but I have not seen any urethane ones that cover the stock size so you may be stuck with rubber for stock bars. I need to see if stiffer rubber is available. Strut top hats – these guys get banged on every single time you drive down the road. If you look at the stock ones in good shape you’ll notice that the top has a concaved surface. We’ve seen them to the point when they are domed or even separated. The stock ones have rubber in them, and from a performance standpoint are rather soft. One thing I want you to think about is how the suspension works. In a perfect world the only thing taking the forces of the tire moving up and down is the springs and dampers because that’s what they are for. The problem with soft rubber is that it acts like a spring. The softer the rubber the softer this spring, and the more it will allow movement. In a perfect world all springs should be damped to control their motion. As my bank account will easily show, this is not a perfect world. So a good solution to helping control this is to go with something stiffer. There’s a couple of ways to go on this one. Stiffer rubber, stiffer urethane, or something solid (really lets the suspension work) like a camber plate. Now, rear camber plates depends on a number of things, but pretty much all of those rely upon your having coilovers. More on those later. Front control arm forward and rear bushings – Your front control arm attaches directly to the chassis at two points, the front and the rear. In these places are bushings, and these bushings see a tremendous amount of stress. These do wear out, and as such you’re car will be subjected to some poor control in both the straight line and in turning due to their flexing and allowing things to shift. When these things shift you run into a dynamic toe problem in that the wheel will toe in or out depending upon the direction of forces. This will lead to tire wear, impression in handling, and bad feeling. Upgrades are varied. Rears are the easiest as there’s stiffer rubber, urethane, or even a spherical bearing. The fronts are a little more limited as not a lot of people have done anything with it just yet. Upgrade options are stiffer rubber, urethane, and I know of one company currently working on a spherical bearing that will press into the stock control arm. Trailing arm forward and rear bushings – these hold the rear suspension in place to keep it from shifting forward and back. Since the whole rear suspension moves up and down these not only see rotation, but also stress from pushing and pulling on them as you apply power or brake. Being soft rubber they’ll move around a good bit, and as they wear it gets worse. When these start to go you get a disconnected feeling, and again poor dynamic control of where the tire is depending upon forces applied. Upgrades are stiffer rubber, urethane, and in a couple of cases spherical bearings. Lateral link bushings – on your 02/03 there are four arms in the rear that go from the rear subframe to the upright (the big heavy cast iron part that holds the wheel and brakes, and all that stuff). These see twisting forces and forward and back motion. When these wear you will not so much have a problem with twisting as you will with that dynamic toe problem. Again, we’re talking about controlling the car here, and anything that’s going on without input from you can lead to sloppy handling. Upgrades are stiffer rubber, and urethane. Spherical bearings as far as I know require that you change out the arms themselves. Shifter bushings – These control how the shifter feels while still isolating NVH. As these wear it can lead to trouble “finding the gears.” With as many times as you move that stick around during a drive it’s good to be able to find those gates so you can get into each gear. Upgrades to the shifter bushings are by far one of the most popular upgrades to these cars out there. There are options to do rubber, urethane, and in a couple of cases aluminum or bronze. There are bushings that address the feeling of the forward back motion, and there are bushings that address the side to side motion. |
05-18-2010, 04:53 PM | #3 |
Former Vendor
Member#: 93646
Join Date: Aug 2005
Chapter/Region:
MWSOC
Vehicle:Many Track Records Let us help you go fast! |
reserved 2
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05-18-2010, 04:54 PM | #4 |
Former Vendor
Member#: 93646
Join Date: Aug 2005
Chapter/Region:
MWSOC
Vehicle:Many Track Records Let us help you go fast! |
reserved 3
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05-18-2010, 04:54 PM | #5 |
Former Vendor
Member#: 93646
Join Date: Aug 2005
Chapter/Region:
MWSOC
Vehicle:Many Track Records Let us help you go fast! |
reserved 4
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05-18-2010, 04:54 PM | #6 |
Former Vendor
Member#: 93646
Join Date: Aug 2005
Chapter/Region:
MWSOC
Vehicle:Many Track Records Let us help you go fast! |
reserved 5
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05-18-2010, 11:05 PM | #7 |
Scooby Guru
Member#: 71092
Join Date: Sep 2004
Chapter/Region:
MWSOC
Location: Licking County, Ohio
Vehicle:2005 2.5RS Wagon Regal Blue Pearl |
Did you say "AH AH AAAHHHH!" after you typed each of those?
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05-19-2010, 09:17 AM | #8 |
Scooby Newbie
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South East
Location: charleston, sc
Vehicle:2002 Subaru WRX Wgn White |
suscribed
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05-19-2010, 12:08 PM | #9 |
Scooby Specialist
Member#: 149890
Join Date: May 2007
Chapter/Region:
NESIC
Location: Somewhere in CT
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def subscribed.
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05-20-2010, 12:23 AM | #10 |
Scooby Newbie
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Join Date: Oct 2009
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Vehicle:2003 WRX Sonic Yellow |
Subscribed!!
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05-21-2010, 05:29 AM | #11 |
Scooby Specialist
Member#: 134272
Join Date: Dec 2006
Chapter/Region:
HIIC
Location: Kahaluu, Hawaii
Vehicle:2007 Sti, UGM Rotated EFR 6758 |
Really need to do this.....
Subscribed! |
05-21-2010, 08:06 AM | #12 |
Scooby Specialist
Member#: 85905
Join Date: Apr 2005
Chapter/Region:
Tri-State
Location: Staten Island
Vehicle:2004 WRX |
My 125k mile 04 WRX needs a major refresh in terms of bushings and brakes. Getting a little worn and she feels like poop.
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05-21-2010, 09:16 AM | #13 | |
Scooby Specialist
Member#: 180570
Join Date: May 2008
Chapter/Region:
South East
Location: Orlando, Florida
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Quote:
http://www.energysuspensionparts.com...p?prod=19.5101 rear 20mm: http://www.energysuspensionparts.com...p?prod=19.5102 rear 17mm: http://www.energysuspensionparts.com...p?prod=19.5104 Energy Suspension hasn't exactly been too aggressive in the Subaru market, I've never been able to figure out why. In the past, I've been pleased with their products on other cars, but haven't tried them on my WRX yet. I just wanted to contribute to a great write-up. Nicely done. -Mike Last edited by Dentt42; 05-21-2010 at 11:06 AM. |
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05-21-2010, 12:41 PM | #14 |
Scooby Specialist
Member#: 126684
Join Date: Sep 2006
Chapter/Region:
MWSOC
Location: Lima, OH
Vehicle:02 wrx PLATINUM silver baby |
once i get my wheel bearings done ill be gettin in touch with u guys for the bushings an hopefully rear lat links.
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05-21-2010, 02:43 PM | #15 |
Scooby Specialist
Member#: 75081
Join Date: Nov 2004
Chapter/Region:
BAIC
Vehicle:2003 WRX WRB |
You're right. That is Definitely a "wall of text".
Very Good stuff though. |
05-21-2010, 03:10 PM | #16 |
Former Vendor
Member#: 93646
Join Date: Aug 2005
Chapter/Region:
MWSOC
Vehicle:Many Track Records Let us help you go fast! |
I have more I've been working on, but not much time. I will add to this though so don't lose faith.
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05-21-2010, 03:12 PM | #17 |
Scooby Specialist
Member#: 171293
Join Date: Feb 2008
Chapter/Region:
MAIC
Location: Frederick, MD
Vehicle:2021 WRX Premium Ice Silver Metallic |
I have to chime here, b/c as usual TIC hits a homerun again. I have pretty much done everything on this list (minus the trailing arm and lateral link bushings) on my '05 WRX (has over 82K miles) and the difference is amazing. Of course I got all this stuff through TIC and Tony's/Clint's wonderful guidence.
Thanks TIC for all your hard work and support to the community and I know for a fact my car would not be nearly as fun w/o all your help. |
11-27-2010, 07:59 PM | #18 |
Scooby Newbie
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Join Date: Oct 2007
Chapter/Region:
MAIC
Vehicle:2002 WRX MBP |
anymore updates this kind of stuff is right up my alley
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11-28-2010, 08:30 PM | #19 |
Scooby Specialist
Member#: 63328
Join Date: Jun 2004
Chapter/Region:
SCIC
Location: Tokyo, Japan
Vehicle:02 WRX Blaze Yellow |
Do the US WRXs have the steering column link with the huge bushing in the middle? We just changed one out for the the solid link from JDM STis and I was pretty surprised at how much play the stock ones had in them. That in conjunction with steering rack bushing must make a world of differences, right?
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11-28-2010, 10:12 PM | #20 | |
Former Vendor
Member#: 93646
Join Date: Aug 2005
Chapter/Region:
MWSOC
Vehicle:Many Track Records Let us help you go fast! |
Quote:
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11-29-2010, 05:17 AM | #21 | |
Scooby Guru
Member#: 126441
Join Date: Sep 2006
Chapter/Region:
SCIC
Location: TPE
Vehicle:03 bugeye |
Quote:
I swapped in a sti one and it made a big difference, much more than the steering rack bushings. It is also easy to install, same process as installing the steering rack bushings. I don't think that many have done this mod, although I feel more should try |
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11-29-2010, 07:54 AM | #22 |
Scooby Specialist
Member#: 149890
Join Date: May 2007
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NESIC
Location: Somewhere in CT
Vehicle:09 Forester Green |
What is this mod? I will give it a try.
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11-29-2010, 12:50 PM | #23 |
Scooby Guru
Member#: 71092
Join Date: Sep 2004
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MWSOC
Location: Licking County, Ohio
Vehicle:2005 2.5RS Wagon Regal Blue Pearl |
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11-29-2010, 12:59 PM | #24 |
Scooby Specialist
Member#: 180570
Join Date: May 2008
Chapter/Region:
South East
Location: Orlando, Florida
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11-29-2010, 01:02 PM | #25 |
Scooby Guru
Member#: 71092
Join Date: Sep 2004
Chapter/Region:
MWSOC
Location: Licking County, Ohio
Vehicle:2005 2.5RS Wagon Regal Blue Pearl |
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