Subaru Legacy/Outback 2005+

poisson · September 2005

The air pressure pushing up against the vehicle is a combination of the wheel itself and the airtight seal between the tire and wheel (the bead). Filling the tire with air raises the car via the wheel.

poisson · September 2005

same here - 2 bulbs :mad: . While my car is only 11 months old, I have ~ 22K miles on it. From what I undertand, the bulbs are not of high quality (even heard the term 'temporary'). I ended up having to replace one myself (never got around to submitting the receipt to SOA for reimbursement) and having the dealer do the other.
For the dealer service, I had to get into an argument as to whether it was covered. They said that it was the DRL and it wasn't covered. I said the DRL and the low-beam are one in the same. I finally spoke to SOA who contacted the dealer and explained the coverages.

c_hunter · September 2005

That's a good question. I have been looking at the P*A term pressing down on the ground, but there is an opposite P*A term pressing up on the wheel. It's the other half of the problem I have been considering. This is again a situation where the sum of the vertical forces has to equal zero since the tire is static. I cut through the sidewall and looked down, but you can cut through the sidewall and look up. We'd have W pressing down on the axle, P*A pressing up on any internal surface of the wheel/tire having a down-facing horizontal component of area, and then a vertical component of sidewall loads (T). Again we get the T ~ P*A - W balance.

This is what's interesting about a pressurized structure, you have that P*A force acting in all directions. When you start to break it into components (in any direction really) you see the forces that are there to balance it out. From there, it's a matter of book-keeping to pick out the information you want to isolate. I'll try to scan or draw a sketch later on.

CRaig

ateixeira · September 2005

Nice list, Eric. Keep in mind the '06s change slightly. The turbo Forester XT automatic actually gets 21/26 mpg, that matches the CR-V!

Plus we're talking 230hp vs. 156hp, though you will need premium.

Seems well worth it, though.

You forgot to mention the Suzuki Aerio, 24/29 with AWD, but just 155hp. The Matrix and Vibe make just 123hp with AWD, and that's just not even adequate.

Subaru makes the most efficient AWD vehicles at any given level of performance.

-juice

c_hunter · September 2005

Here's a schematic of the forces on a pressure vessel bearing a load W and resting on the ground:

Left image shows the whole system. Summing vertical forces gives G=W here; ie, the ground reaction force is equal and opposite the load W. The pressure effect does not come into play here for one of two reasons: 1) we only consider external forces on the tank or 2) we consider external and internal forces but the pressure cancels itself out. The interesting thing is that the internal pressure would cancel itself out no matter what the shape, as long as the pressure vessel is closed. Think about any closed shape and you realize that there is always an "opposite" side no matter where you are inside the shape. Since pressure acts the same in all directions, pressure loads summed over a closed loop give a net zero effect.

The middle sketch shows us cutting through the tank and considering the top half. Where we cut through the tank, we have to place reaction forces into the model, drawn here as a force T. The summation shows that T is equal to the difference between the pressure acting on the internal (horizontal) area and the applied load W. If pA is less than W, the sides of the tank are in compression and the tank is carrying part of the load. If pA = W, then the pressure balances out the load and the tank is not carrying any of the load. If pA is greater than W, the sides of the tank are in tension because the internal pressure force actually exceeds the load!

The right sketch shows an analagous version for the bottom half of the tank. Same conclusion is reached here.

This is a very general example, but you can simplify a tire down to the same sort of analysis. And looking at all the details and assumptions here, you can imagine how a real tire would differ from this basic model. Surprisingly, though, if the tire is in static equilibrium under a load, this same basic analysis gives you the right information. With a tire, the real question is what's the area "A", and that may be difficult to determine. My earlier experiments suggest that A is approximately the contact area within a range of pressure close to the design inflation. At low or high pressures, that is likely not the case.

Craig

robr2 · September 2005

Boy - you guys must be the life of the party!!

This is like a Texas Death Match involving Einstein and Goddard!!

dougb10 · September 2005

Is there going to be a test on this? As long as I know where to attach the air pressure hose, I will be just fine.
Now it's time to increase the dose of my medication...got a huge headache after reading all this stuff.

c_hunter · September 2005

Hey, just be thankful I was trying to keep it simple and brief! If I really got carried away, they'd probably have to lock down the forum to keep everyone from either falling asleep or entering math/physics panic!

Craig

kens · September 2005

Seeing the sum of forces = 0 makes me misty eyed in rememberance of my college level statics course. :-)

Ken

subearu · September 2005

Time for a real-life "How Stuff Works". We'll have Craig actually demonstrate on a real tire though, as us non-math dudes can understand better when we see something in real life. :shades:

-Brian

capriracer · September 2005

Great drawings - one of these days I will figure out how to do that. But in the meantime, words will have to suffice.

Referring to the drawings:

The force G obviously is where the ground is in contact with the tire and it is pushing up. And the force W - which balances out the equation so there is no acceleration upwards - appears to be pressing down on the top of the tire. Can that be right? What is connected to the top of the tire?

xwesx · September 2005

That is showing the directional force, not necessarily the point at which the force is applied to the structure. If this was a tire, the "top" of the vessel would be the nearest point on the rim, etc., directly opposite the point on the bottom of the tire.

Such literalists. :P

c_hunter · September 2005

In the case of the tire, it would look something like this:

The "W" is applied at the axle.

Craig

capriracer · September 2005

"The "W" is applied at the axle."

So if we go back to the drawing in your earlier post - (the circular one) - force W is not acting on the perimeter (am I allowed to call the perimeter a belt package?), it is acting where the "p" is (I'll call that point P) and the equation still is balanced. So what is it that connects point P to the belt?

stantont · September 2005

Exactly. We all probably suspect the diminishing returns part, but when you put it to numbers, it just jumps out at you. Of course if fuel get expensive enough, that diminishing return may be worth pursuing. That is, if fuel were $30 per gallon, I'd probably be looking pretty hard for a Jetta diesel or a Prius. And I'd be using my bike for short trips even more than I do now.

Stanton

ateixeira · September 2005

Fuel is still only a very small % of the TCO.

It would be interesting to use Edmunds' TCO tool to figure that out.

But I'm too busy to do that right now. :P

-juice

c_hunter · September 2005

Forces act on a point, while pressures act over an area. For this analysis, the exact location of the forces are not important -- we assume that the object acts as a rigid body and applied forces transfer through (this is a fair assumption since a real tire/wheel combo does come to rest in equilibruim and acts as a rigid unit).

If we were looking at a rotational balance, the location of the forces (and their lever arm) becomes very important. Here it's not important.

In real life, the axle force would be distributed as a stress over an area, like around a shaft or bearing, but it still adds up to the applied load W. Here we skip over the details and just apply the force W.

So in this case it's somewhat generic -- there is a load W pressing down (due to gravity) somewhere, there is an equal and opposite ground reaction, and then there is the pressure acting on the area. The pressure acts in all directions, we are just considering the component that results in a vertical force.

Craig

robr2 · September 2005

I'm taking up a collection to get these guys there own board so we can discuss something else. I understand going OT, but this tangent is about 30 miles long.

mitchyk · September 2005

Hello all - I'm new to this forum as the owner of a new 2005 Legacy GT Limited MT Wagon. I love the driveability of the car but knew I'd be taking a hit in the audio department relative to my old Audi A4 with Bose (and, as it turns out, my old 94 Altima with a Clarion system). I have ordered the factory subwoofer from an aftermarket parts dealer and am considering upgrading the door speakers and tweeters as well if the sub doesn't add the missing "punch". My question to anyone who has replaced or added speakers, particularly in the 05 Legacy or Outback - what tools and technique should I use to ensure that I do not damage door panels and center console side trim when I remove them to access connectors and speaker mounts? I've seen a tapered acrylic tool as well as advice to simply use a flathead screwdriver with electrical tape on it. Or should I just pay up and trust an installer? Thanks.

kens · September 2005

I'd try the subwoofer first to see if that alone makes a difference (it should). I caution against upgrading just the speakers since the stock headunit is tuned specifically for the stock speaker response with a loudness function.

If you change out the speakers alone, the stock HU's equalization curve won't match, possibly the impedance as well, and you may end up with something that sounds even less appetizing.

If you are going to go through the trouble of swapping out the speakers, you may want to considering getting something like a Clean Sweep and a new amp. This way, you'll be able to precisely control the sound going to your new speakers while still maintaining control from the stock HU.

Upgrading the speakers can be quite a bit of work -- I haven't done it, but you may find some people over at the "other" forum.

Ken

c_hunter · September 2005

Congrats on your new wagon! But what about your tires? Just kidding ;-) , inside joke.

If you are handy and careful, you will likely do as good or better work yourself. There are a few tricks to getting the door panels off without damage.

1) power the window all the way down

2) remove the small trim piece that is over the mirror gusset, normally you can just grab with your fingers and pull straight outward.

3) on the silver painted piece that surrounds the pull handle, push up at the top near where the handle is. You want to open up a 1/8" gap at the top of the handle. This should expose a little nub at the top of the handle cover, and allow you to pull the top of the handle cover out towards you, then work it off and release a larger nub at the bottom.

4) use a paint-can opener or similar tool to pry off the cover that is under the chrome latch lever (there is a small place to hook the tool).

Steps #3 and #4 expose screws that need to be removed.

5) slide a 1" putty knife (optionally wrapped in one layer of tape) under the bottom corner of the door panel, between the panel and the door frame, and give it a good hard (and sudden) yank towards you. This should free a couple of the fasteners holding the panel on. Then use your hands to work around the edge of the panel (sides and bottom) to pop out the remaining fasteners (be sure to properly account for these later on).

4) the door panel should be only attached at the top now, so tilt it away from the door and lift up to gently unhook the top. The panel will have the window/lock wiring harness still plugged in, so detach it at the connector. The latch lever cables will also still be attached to the panel; you can either unhook these or unscrew the latch cup assembly from the door panel and then just tape it to the door (I chose the latter).

These insructions are for the front doors, but the rears are very similar.

Now, one warning about aftermarket speakers -- they normally take a lot more power to drive than the wimpy factory speakers. While the aftermarket speakers will sound better, they will also not sound as loud because the factory radio is not providing a lot of power. So you gain a little and lose a little. I would recommend the factory upgrade speakers for this reason -- they will sound better and still accomodate the low power of the factory radio.

I have been pretty happy with the sound in my OB XT since adding the factory sub, and have kept the stock speakers. With the bass augmentation of the sub, you can re-adjust your tone settings and get better sound out of the door speakers (ie, not relying on them to handle a lot of bass). Overall, I don't really have any complaints. But then again, I weaned myself off of high-quality car audio many years ago after having a few awesome setups. The combination of theft wariness and aging means I get along OK with most factory systems now!

Good luck!
Craig

P.S. I can give details on the center console, but that should be covered in instructions that come with the subwoofer. One piece of advice -- you can avoid the step of removing the whole bin/armrest section -- in my experience that is not needed. The wire routes easily enough with it in place as long as you lift the parking brake boot off the console. And another piece of advice -- for a little more effort, you can route the sub harness under the carpet so it's not exposed. For some reason, the instructions route it on top of the carpet, where it sticks out like a sore thumb (it has a baby blue cover). The port was even installing them this way at first, but now they are routing under the carpet too.

c_hunter · September 2005

We could move the topic to the Subaru Crew cafe if needed, I agree it's off course here. I suppose we should have taken capri's suggestion and moved to the tires forum if we knew if would go this far. At this point it's kind of late to go over there, and I doubt the engineering statics analysis would appeal anyhow.... My apologies for the drawn out discussion!

Craig

robr2 · September 2005

No need to apologize. I think it's funny to see two engineering types duking it out. No verbal assaults, no personal attacks - just charts and graphs and formulas and facts.

ateixeira · September 2005

I'll see your formula, and raise you an e=mC^2!

-juice

kyfdx · September 2005

I kind of like it... It serves as a reminder that I don't know everything...

(not the host)

mitchyk · September 2005

Thanks Craig and kens - I will start with the subwoofer and see how that sounds. (The tire joke was not lost on me...can't wait to see how the treadwear progresses) A couple of follow-up questions:

I was not aware there were factory upgrade speakers available for the 05 models- are those the ones in the Outback VDC and where can I purchase? I was going to go BA or Polk.

Craig, I have reviewed the install instructions for the subwoofer in advance of receiving the unit- just want to make sure I know how to safely pop out those side trim pieces on the center console, if indeed the armrest bin does not need to be removed. I would like to consult you on hiding the sub harness under the carpet - if you can post the technique here please do. Also curious to know how you set the gain and crossover and whether that's difficult to tweak after installation as another poster mentioned somewhere. Thanks,

Mitch

c_hunter · September 2005

I couldn't find any speakers online, so maybe they're not offered for the 05 as an accessory. The parts manual for the 05 Leg/OB does show two different part numbers, however, one associated with 6 speaker systems and the other associated with 7 speaker systems. The 7-spkr part costs more ($73 vs. $50) so it's probably the VDC part.

I left gain and crossover in the middle positions on the sub and have not adjusted. You can adjust in place with a long screwdriver, if you want to tailor the sound.

There is a hole in the carpet under the seat. I passed a piece of stiff wire through that hole and up under the carpet to the console area (where the carpet is open). Then taped the sub harness to that and pulled it back through to the underseat area.

Once you get the shifter trim off, there are a couple screws holding the side trim pieces down. Remove the screws, and then gently pull the side trim pieces up and off. They should just barely clear the armrest console if you're careful (same goes for re-installation). You can flex the trim pieces a little to make them slide past. By the way, these trim pieces are a major source of squeaks in most 05 models; not sure if they improved that by the time they made your car. I ended up lining the trim pieces with cloth friction tape to eliminate rubbing and squeaking. You can study them and see where they would be making noise.

Craig

capriracer · September 2005

I think the group is right - this discussion needs to move somewhere else.

Suggestions?

(Darn and I was just about to demonstrate how the air pressure was tensioning the cords in the tire thus preventing compression and therefore buckling of the sidewall and thus the sidewall was actually holding the vehicle up.)

c_hunter · September 2005

Move it over to the Subaru Crew cafe:

KarenS, "Subaru Crew Cafe" #, 25 Mar 2002 1:33 pm

(hope that link works, if not, click on subaru crew above and then navigate into the cafe).

I won't argue with you about tension, I agree with that completely! It's the key to the whole pressure vessel concept.

Craig

hypov · September 2005

Like all is saying, go with the subwoofer first. It's not a big sound woofer, but it does fill in the gaps.

I was watching one for the guys @ AZP doing aftermarket speakers on a GT today.
The OEM speakers, they are the standard 5.25" front and 4" rear. Both are treated paper cones, but appear of better quality than the non-upgrade speakers on the Impreza.

The OEM speakers are rated @ 30 watts peak, and I'm guesstimating the RMS to be around 15 watts, no more.
The subwoofer is 6" poly materialed cone powered by an internal amp rated @ 120 watts peak. My RMS guesstimate is 50 watts. I've heard that the subs for the newer car models are powered differently in so that the wiring harness has two plugs going to the HU vs one for the older.

The HU is probably 20 watts per channel giving you 80 watts overall, so swapping the OEM speakers for aftermarkets might not be wise. Unless you can find a set of good speakers that can be driven @ as little as 5 watts minimum or less. The speaker's peak and RMS watt wouldn't benefit any if it would take 20 watts from the HU, it's max, to drive it.

Tip on subwoofer install.
When you get yours in, don't mount it on the passenger side. Instead, if GT seat hardware permits, mount on the driver side at the underside of the seat and not on the floor. When you're done, the speaker will be firing towards the floor and the bass quality is much better that way... at least on my WRX wagon. Why the driver's side? Well, I found that there isn't much on the underside of the passenger seat to latch the bungie cord(s) to

-Dave

c_hunter · September 2005

Dave,

The 05+ models have 6.5" speakers in the front and rear doors.

Craig

hypov · September 2005

6.5" speakers in the front and rear doors

That's interesting to know.
On this guy's '05 GT sedan, it is definitely 5.25" and 4".

-Dave

c_hunter · September 2005

That's wierd. My 05 wagon has 6.5" all around, as does a coworker's 2.5i Legacy sedan. The audio FAQ on the LegacyGT website and Crutchfield confirm the same thing. Even the parts manual only shows one size, so I am surprised that some cars would have smaller than 6.5".

CRaig

hypov · September 2005

Now that you've enlighten me, I'm :confuse: too.

Is the output max. 35 watts on those 6.5" speakers?

-Dave

kyfdx · September 2005

That 6.5" and 5.25" are the same speaker... Outside vs. inside measurement?

It has been a long time since I bought the 8-track player for my '77 Cobra II

, but I think the same assumption was being made then...

I'm almost positive those are the same.....

regards,
kyfdx

c_hunter · September 2005

I have no idea about the output or rating; I haven't actually looked at the specs on the speakers. The shop manual doesn't give any details on that either.

Subaru actually calls the speakers 6.1" which may refer to the opening or hole. But off-the-shelf 6.5" models fit right in.

Craig

locke2c · September 2005

a 6.5" speaker is considerably larger than a 5.25". they are different.

most 6.5S speakers used in many new cars are just 6.5" with a custom basket (I don't know why) and aftermarket 6.5" usually have the necessary hardware to mount in a 6.5S hole. many 5.25" speakers also come with hardware to mount in a 6.5" or 6.5S bracket, also.

my Evo originally came with 6.5" speakers front and rear and now I have 6.5" Memphis M-class coaxials up front and 5.25" JBL coincident source coaxials in the rear-- in a plastic adapter bracket.

btw, older Bose original equipment systems were often weird ohm ratings which prevented the use of aftermarket equipment unless you replaced everything. 10-12 ohm speakers was typical, whereas everyone else uses 4 ohm car audio speakers. (subwoofers can be all kinds of ohm ratings, though.)

~Colin

beanboy · September 2005

Quiet in here nowadays!

Coming up to a year of owning my unlimited LGT 5MT wagon. Glad I got it when I did! No more MT in the wagon...BOOO! No more unlimited version...DOUBLE BOO!

Mods have been minimal so far:
OEM subwoofer
Stainless steel brake lines, ceramic brake pads, synthetic brake fluid
Cobb Accessport Stage One

Here in about a week: shorty downpipe (will go to Stage 2 with Accessport), catless uppipe and MTL-R trans/diff fluid

Starting to look into springs/struts as well, Japan-spec LGT struts/springs seem to be the only set-up that doesn't lower the ride height, which is what I am looking for. Price is very high however, hoping some aftermarket company (maybe an Aussie one?) will offer stiffer springs/struts that don't compromise ride height.

Been to a road track school, dyno, and placed second in my division at my first rallycross. Need to hit up an autocross before the end of the season, and looking forward to a winter rallycross/ice racing event.

Car has been great so far, exceeded my expectations. Fits three others and hiking gear without any problem, handles unimproved dirt roads with aplomb, and cruises well on the highway. Have carried Christmas trees, multiple bikes, and a single bed inside the car with the seats down. Have hit 27+ mpg on highway stints where I stay within 5 mph of the speed limit, not too shabby for the power on-hand. Looks good, but doesn't stand-out too much.

I do wish it came a little sharper from the factory (brakes, suspension especially) but the aftermarket still is ramping up for these cars, and the prices are reasonable.

Anyway, off to do some elbow-bending. Cheers!

-B

c_hunter · September 2005

Coming up to a year of owning my unlimited LGT 5MT wagon. Glad I got it when I did! No more MT in the wagon...BOOO! No more unlimited version...DOUBLE BOO!

Congratulations! I guess a bunch of us are right around the 1 year mark now. Still loving my OB XT with 19600 miles on the clock.

I agree with you 100% on the double boos!

Craig

kens · September 2005

Still around too with 20,700 on the odo. Even over at LGT.com things have sort of slowed down in terms of interesting topics as well. I think it's just a normal part of the lifecycle.

I think the upside to the recent changes in the LGT/OBXT line up is that there weren't many changes with respect to performance. Aside from the deletion of the pre-cat for a secondary airpump, things seem generally the same. The last thing that any owner would like to hear is a big bump in power or handling as was the case with the 2.5i/base OB.

Ken

ateixeira · September 2005

That's the only real news so far for '06, unless they bring the Spec B model this model year.

-juice

mchalmers · September 2005

I have been following this post for a few months. Can anyone tell me if the new 06 2.5i Limited is a good car for highway cruising? I drive 2K+ a month on major highways and often cruise around 75-80 mph. Is the four cylinder comfortable at this range? I wonder if the mpg would be the same as a 6 cylinder due to the fact that the 6 is not working as hard. I like both models and would rather deal with better mileage but don't want an engine that is being pushed to hard on the highway (4 cylinder).

Matthew

c_hunter · September 2005

Hi Matthew,

I've owned two Subarus with the base H4 engine, and they cruise fine on the highway -- the engines are fairly relaxed at legal speeds. The 05+ Leg/OB are very refined, and cruise nicely no matter what engine, but the base H4 is quite good. For 06, you get a slight boost in power too.

In the previous generation Leg/OB I would have no problem recommending the H6 engine for economy -- I often got 28-30mpg in my 02 LL Bean Outback with the H6, which was as good or better than my previous 4 cylinder Outback. That was the 212HP H6, which was a nice engine. The 250HP H6 in the 05+ models is also a great engine, but a bit thirsty. I have my doubts that it could get up in the 28-30mpg range on a regular basis. In fact, at 75-80mph, I know it will not be able to. At lower speeds (55-65mph) even my Outback XT with the turbo gets decent mileage, but I would get run over on most highways...

Definitely take a test drive, I think you'll be pleased.

Craig

ateixeira · September 2005

Unless you are climbing long, steep hills, or driving at very high elevations, the base 2.5l engine should be just fine, and easily the most efficient choice.

To me the H6 is the best near-luxury choice, if your alternatives include quiet cars from brand like Lexus.

If you live a mile high, and climb mountains regularly, then get the turbo.

-juice

mchalmers · September 2005

Thank you for the information. Helpful to have real world experience. I am going to test drive both engines but I think I will have a hard time justifying the 6. If I have to buy the 6 to get a sunroof, climate control, etc.. then it would be an easy choice. With the 2.5i Limited seems like all the good things are part of the package. I like the larger wheels that come with the 06 2.5i package. Last year that was my excuse to lean towards the 6. Did not like the smaller wheels on the 05's.

Kind regards,

Matthew

mchalmers · September 2005

Hi Juice,

What is the spec B model?

Thank you, Matthew

woodshop28 · September 2005

I have an 05 Legacy 2.5i Wagon with a manual transmission. Driving a mix of hwy/city I have averaged 28-29 MPG, but I only have 2000 miles on it. The car moves right along at 75-80 MPH, and does not seem to strain at all to cruise at that speed. If legal, I think it'd do fine at 90 MPH. Yes, the turbo or 6 cyl. will get to speed more quickly, but at speed, the NA engine does quite well.
The cost of -5 MPG and the requirement of premium fuel in the turbo and H6 models (I think the H6 requires premium) made my decision.
You will likely be pleased with any of the engines, so enjoy whichever one you end up with.
I would note that the Outbacks, and even the non-OB "limited" weight a bit more, so the base engine in them may feel a tad more sluggish than in the base 2.5i, however the 06 has a little more power.

locke2c · September 2005

averaging 28-29 mpg??

surely your highway / city mix is heavy on the highway. even then your mileage is quite exceptional... atypically so.

~Colin

ateixeira · September 2005

For that model, so it's possible if you drive more highway than city miles, sure.

Spec B is a model in Japan, B for Bilstein shocks that it has. 18" rims, and there it's on an H6 model with a manual transmission, a powertrain combo that we have not seen here yet.

However, the US might see only the suspension and rims, looks like ours will be a turbo, since those have proven popular here.

-juice

mitchyk · September 2005

Hi - I posted earlier about subwoofer install and need some advice after making my first "mistake" - before even getting the thing out of my house!! I connected the 8-pin connector to the sub, to see how it would seat, only to find that it is now locked in. I'm looking for for advice on whether I'll have sufficient space and the right angle to thread the cable UP from the mounted sub to the exposed head unit, or whether I should cut the cable to the sub connector and thread it back down from the head unit. I could also disassemble the sub to see if I can free the locked connector but that seems risky. Any thoughts are appreciated.

Subaru Legacy/Outback 2005+

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