Subaru Forester (up to 2005)

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Comments

  • ateixeiraateixeira Member Posts: 72,587
    paisan put one in his SVX, that experience might help a little.

    I've seen engine oil coolers, which are standard on the auto, being put in the 5 speeds.

    John: yes, Imprezas get a donut. I'll take the full-sizer any day. In fact we removed the foam from my wife's Legacy to fit in a full size spare, which we replaced the donut with.

    -juice
  • danjaecksdanjaecks Member Posts: 54
    Wow, I am so happy. I have a '02 Forester with about 17k miles on it, and it has a clutch that chatters and grabs at times, usually when the weather is cool and damp, but at other times it seems fine. It can actually shake the whole car violently at its worst (and yes, I have been driving stick since before you were born, so don't even think about it.)

    Anyway, I have it in for the 15k mi service and I mentioned this clutch problem and the service writer said they would look at it. Since it's warm and dry today I figured they would say it was fine, but they just called and said they are going to replace the whole clutch with upgraded parts!!! I was so surprised and happy I almost cried. Congratulations Subaru, you've earned a customer for life. Keep it up!!
    Now, how much is that Turbo Forester again?
    Dan Jaecks
  • ateixeiraateixeira Member Posts: 72,587
    Sweet Dan. A spankin' new clutch with 14k fewer miles than the rest of your powertrain, too.

    -juice
  • rjweissrjweiss Member Posts: 20
    At 76k miles the 98L Forester was getting up there in miles and the time was right to trade it in. We managed to get an 03 XS Premium auto at a few hundred above invoice and the dealer allowed us $6,500 for the 98L manual. We were disappointed in the trade in value but not in the 03 !!

    Hands down a better vehicle...

    Steering much quicker.

    Brakes, much firmer than the 98's

    Manual vs auto, no contest. The 98 was on it's second clutch and still chattered. Auto has nice crisp shifts. I'm not thrilled about the gated shifter though.

    Handling is flatter and firmer on 03.

    Engine, much quieter, the DOHC always had mucho valve train noise and the start of piston slap also.

    Economy looks even so far.

    Ergonomics, about the same, except that auto climate control still has me confused...What does the "bright" switch do? and when do the outside mirror defrosters go on, when you hit the defroster, wiper blade heater or rear defroster?

    Headlights much better on 03 as well.

    I'm only at 450 miles so far, will come back with another report at 5,000.

    Regards

    Ron & Liv
  • russskirussski Member Posts: 47
    HI everyone,
    I have noticed by checking a dipstick of my brand new 2.5x, that oil level drops approx. 1mm every 1000Km. I have approx 3500Km on the Clock so far.
    I know that for some cars it is normal to consume oil while it is running in.
    The questions are: Is it normal for Forester at this rate ? Should it stop using oil and if so when ? And also, does anyone know, what is the actual volume of oil in the pan between LO and FULL on the dipstick?
    BTW I'm checking an oil level on the same spot in the morning - when engine is COLD.
    Thanks in advance......Vitaly
  • mckeownmckeown Member Posts: 165
    Dan, with 35,860 on mine, and armed with a TSB, I approached the Service Dept last week. I have complained about this clutch since day 1 only to be told, this is how they are. WELL I can no more. It's now replaced along with the flywheel and pressure plate. This is NOW how it should have felt since day 1. Much 'lighter' feel like my previous Subaru's, VERY SMOOTH in the morning, as well as all day.......NO SHUDDER. YES THANK YOU, and it's about time.
    PS, I still would have bought another SUBARU as they have always given me great service, this shudder may have made me consider my 1st automatic in over 30 yrs of driving.
  • forestergumpforestergump Member Posts: 119
    Did you mean the SOHC vs. the DOHC?

    Whatever. I'm glad to hear you like the new generation model. I'm planning on trading my 99' Forester for the new 04' XT this fall, and its good to hear that the upgrade will include more than just the new engine.
    -Bob
  • gmginsfogmginsfo Member Posts: 116
    Deepdrop, Thanks for the link to Crutchfield. After looking at it though, and having just installed - and being very happy with the sound from - the tweeter kit into the upper doors, why would I want 2-way speakers that duplicate the tweeters I just put in? If I could find a two way bass/midrange speaker for the lower door speaker grills, that would be great, but I've yet to see that combo anywhere - and I'm not interested in a subwoofer. Am I missing something here - besides decent midrange sound???
  • rjweissrjweiss Member Posts: 20
    Forestergump, Yes the 98L had the double overhead valve engine, I'm not sure when they changed to the SOHC but it sure seems quieter.
    When the 98L was cold there were a few valves that clacked and ticked for awhile till warm. Then at about 60K I started to hear some piston slap, which got quieter when hot but never completely abated and was getting much worse at 76k.

    Ron
  • paisanpaisan Member Posts: 21,181
    Here are some pics from the install of my ATF Cooler

    http://isuzu-suvs.com/svx

    -mike
  • dcm61dcm61 Member Posts: 1,567
    Forester and Impreza 2.5RS went from DOHC to SOHC in '99; Legacy GT and Outback in '00. Legacy L went from 2.2 SOHC to 2.5 SOHC in '00.

    DaveM
  • lfdallfdal Member Posts: 679
    "...What does the "bright" switch do? "

    When the outside light on a bright day makes it tough to see where the indicator lights are on the climate control, pressing and holding the Bright button for a couple of seconds will actually brighten the green indicator lights around the climate control dials. If you don't hold it for a couple of seconds it turns the system off.

    "...and when do the outside mirror defrosters go on, when you hit the defroster, wiper blade heater or rear defroster?"

    Since you have the all weather package (AWP) - there is a separate button on the lower left next to the Cruise control and Foglamp switch that turns the mirrors on when the windshield wiper defroster is turned on. - You can double check that in the owners manual but I'm about 99% sure of that.

    I wasn't thrilled with the gated shifter at first, but now I really like it. - I found after the first few days shifting is just as routine as before - unless I stop to think about it.

    Hope your as happy with yours as I am with mine.

    Larry
  • forestergumpforestergump Member Posts: 119
    ...clouds part briefly and clarity momentarily appears before the fog descends again...

    Thanks for the info...
    -Bob
  • danjaecksdanjaecks Member Posts: 54
    mckeown - Thanks for the good word, I pick mine up today and I'm really hoping!

    russski - I never measured the rate, but both my 02 Forester w/ 17k miles and my 96 OBS need a little oil (less than a quart) between oil changes. I usually change oil ever 5k miles.

    rjweiss - May be different on the 03, but on my 02 the heated mirrors go on with the rear defroster. I remember it because I'm looking backwards in both cases.
  • boba6boba6 Member Posts: 18
    Late yesterday, I saw a nail sticking out of my tire, right at the corner of the tread and sidewall. I've got 18k on the originals (2002 Forester). Ran around trying to find someone to patch/plug it, but they said they didn't do that on sidewalls, "but (someone else, usually already closed) would." Finally got the spare put on, so I now have several questions for those with knowledge/experience:
    My first instinct it to try to find someone to fix it. Does anyone think it's unsafe to do so?
    If I can't get it fixed, how important is the admonition to make sure all tires are the same age/wear? Is there some way I can I deal with one tire with 18K less than the others? I take good care of them (except for nails) and there is a lot of tread left. Do I really have to say good-bye to three tires?
    If I do have to buy a new set, what's the best recommendation? I live in Atlanta, so there's not much snow or ice. I saw someone on this board once describe the Forester as an "any-road vehicle." If I'm lucky, I test that once or twice a month (forest service roads in the mountains of N. Ga. - graded every few years, maybe some Florida sand). Otherwise, normal in-town/highway driving.

    Thanks for any and all advice.

    Bob Anderson
  • lfdallfdal Member Posts: 679
    In some places its not even legal to repair a tire with a puncture a certain distance from the sidewall. I had the same happen to mine with 5k and my puncture was about an inch away from the sidewall.

    The tire shop I took it to agreed to fix it on the condition that they put my new spare on the damaged tire's rim and the damaged tire went on my steel spare rim. Since they only charged me $20.00 for the whole operation I have to believe they were on the level.

    The shop also measured my treadwear and said I was good to go with 5k of wear on the other 3 tires.

    I have heard of tire shops that can "trim" down a new tire to the same size as the older tires so you don't have to replace a whole set. I'm sure that it was someone on this board that mentioned that, although I don't remember if it was a chain store or a specialty shop. Anyone remember?

    HTH

    Larry
  • steverstever Guest Posts: 52,454
    I've seen that too - probably over in Tires, tires, tires.

    Here's one thread about tread:

    anonymous02 "Tires, tires, tires" Mar 14, 2002 4:26pm

    Steve, Host
  • eps105eps105 Member Posts: 216
    Being OCD and religiously reading instruction manuals, I was very surprised to read that the '03 Forester has a slot in the subfloor to accommodate the cargo area cover, as this would be an undocumented feature that I had not yet discovered!

    So I went out at lunch and checked and was initially pleased to confirm the existence of these slots! BUT... and this is a big but, it does not fit with the FULL SIZED spare tire.

    My guess is that this feature is to be used in countries where a compact limited use spare is standard, which explains why this feature is not mentioned anywhere in the U.S. instruction manual. Bummer.

    However, if you haven't already discovered, the cover DOES just barely fit across the floor of the rear seat on all '98 - '03 Foresters (basically from speaker grill to speaker grill), so there's still a place to put it in a pinch when you've got no rear seat passengers.

    --Elliot
  • p0926p0926 Member Posts: 4,423
    Bob A- Greetings to a fellow Atlantan! I had a very similar circumstance with my Forester (almost identical mileage and nail location). I got a service station to plug it and then had a tire store put an additional "insurance" patch on the inside the next day. Neither would guarantee that the fix would last but now 30k later, the tire hasn't leaked any air at all. So I certainly recommend that you at least try patching it first (it costs very little).

    If that doesn't work, my guess is that you're borderline for needing to replace all four tires. Subaru's rule is that all four need to be within 1/4" in diameter. If one is off it can cause friction in the differential.

    If you decide you need new "shoes", Tirerack.com is a good site for researching tires. The Dunlop SP Sport A2 is a popular choice for the Forester. However, with 50k on my OE tires, I'm in the market for replacements and I really can't complain about the stock Geolanders so I'm leaning towards getting another set.

    Hope this help.

    -Frank P.

    Edit- Local tire store has the Dunlop A2s on sale at a price that matches Tirerack's so I'm going to go ahead and get them.
  • ducktapeguyducktapeguy Member Posts: 115
    For some reason the site doesn't work right now, but I'll try checking from home. I'm pretty sure I've visited your site before, but probably didn't pay attention to the cooler until now. A few questions:

    1) How did you hook it up and why? Series or parallel? Is there a preferred method. From what I've heard, seems like the best way is to put the cooler in series BEHIND the stock cooler.

    2) Have you noticed any negative effects from the cooler? Is it possible to overcool your transmission so it never comes up to operating temp? And are you using synthetic fluid? Thanks

    And my heated mirrors come on with the rear defroster too, I know this because I've never used the front one before, but I still see the mirrors clearing up

    For the tire, I think you might be able to patch it yourself, if you think it's safe. I patched my own tire after the tire shop refused to work on it because it's "unsafe", I think they just wanted to sell me a new tire. I used one of those plug kits, and drove it for another 30k before changing tires. If it's on the sidewall, I wouldn't try it, but if it's more on the tread, you might as well try it. What about using one of those tire fillers that prevent leaks, the green goop? You have nothing to lose.
    If you do get a new tire, check the circumference to make sure it's close to the other three. If it's not, you can shave the tire or use the spare tire (should be the same size). If you're really worried about them being different sized, I'd put the new tire in the front, if you have a LSD, and disconnect the AWD. Then you could run two different sized tires without messing anything up.
  • rjweissrjweiss Member Posts: 20
    Larry,

    Thanks for the reply on my switch questions.

    Anyone want a good quality tire try the Aquatread III, bought them for my 98L Forester and had exceptional dry traction, and of course in the wet they could not be beat. Even worked pretty well in snow, something I couldn't figure out...maybe the deep channels redirect the snow as well as water.

    Ron & Liv
  • dcm61dcm61 Member Posts: 1,567
    Note that the tire tolerance is based on CIRCUMFERENCE, not diameter.

    DaveM
  • boba6boba6 Member Posts: 18
    OK, it may be hard to get someone to agree to patch my tire. Frank, if you'd tell me who did yours, I'd appreciate it. And, I guess, if you'd tell me who has A2's on sale, I may need to know that too (I'm in Decatur). But there appears to be about 1/8 inch difference in the treads on the ones I've been running on vs. the spare. Shouldn't that be a total difference of 1/4 inch in diameter? Is that close enough to prevent any damage to the drivetrain? If I just have the spare mounted on the primary wheel, and see if I can find a OE tire for the spare, am I tempting fate? Thanks.

    Bob Anderson
  • p0926p0926 Member Posts: 4,423
    Whoa, that's right, it is circumference. In which case, the spare or a replacement tire would certainly exceed 1/4" difference. However, that tire shaving suggestion might be a good option (still a lot cheaper than four new tires).

    Bob A- I don't honestly remember where I got it plugged. I think it was a place on Scott Blvd. However, you can always go to Autozone and plug it yourself (it's not exactly rocket science). I got my tire patched at the Goodyear service center next to the North Dekalb Mall (as you can see, I'm also in Decatur). That same Goodyear shop also has the A2s on sale. $421 for 4 tires mounted, balanced and out the door (sale good thru Sat).

    As to whether you're tempting fate if you don't replace all four, I'm not qualified to answer that. It does seem a stretch that Subaru's AWD system is that sensitive.

    Good luck and keep us posted.

    -Frank P.
  • boba6boba6 Member Posts: 18
    Frank, thanks for the info. I'll see if I can get a fix tomorrow.
    Bob
  • lfdallfdal Member Posts: 679
    Here's a question for you very mechanically inclined people who know lots more than I do about AWD (okay, that's everyone, all I know is it works wonderful in awful weather).

    I did some simple math:
    Assume a new tire diameter of 26.2 inches - this from tirerack.com for the GEO 900's on my 03,
    so 26.2 * 3.14159 = 82.309658 inches for the circumference. I assume pi * diameter hasn't gone out of vogue for a circumference calculation....

    If we reduce the circumference by 0.25 inches, we have 82.309658 - 0.25 = 82.059658 inches.

    If we divide 82.309658 by 82.059658 we get 1.00304 or about 0.304% difference.

    If my math is correct then we're saying for a stock Geolander 0.30% is the limit. That's a mighty fine tolerence.

    I tried that with revolutions over a given mile and the difference is less than 3 revs/mile.

    So for the true gearheads out there - is this a for real tolerence? Is the (limited slip)differential so sensitive that 0.3% is a killer?

    BTW as a cavaet to the quality of my math, tirerack and I get different numbers for revs per mile.

    Sorry for the long winded post, but I bet I'm not the only one wondering about this.
    Any thoughts? Anyone?

    Larry
  • kullenbergkullenberg Member Posts: 283
    Here is a link to a tire size comparison calc. that also gives revs per mile; http://www.miata.net/garage/tirecalc.html
  • ducktapeguyducktapeguy Member Posts: 115
    Thanks for doing the math, I also wondered about this for a while. Somewhere, I thought I read that the Viscous diff starts to lockup at speed differences of 6 rpm or greater. It seems like Subaru is just playing it safe by recommending a close tolerance on the tires. Most car companies do that to prevent lawsuits I assume. I know I've exceeded a lot of their maximum weight specs and I haven't had a problem yet, so there's always a factor of safety in there.

    Don't forget the tire pressure and velocity, that would also affect the rotational speeds of each tire. I bet the AWD system can handle a greater difference than .25 in circumference in most cases, but in certain extreme cases, something bad might happen, so they just rate it under worst case conditions.
  • p0926p0926 Member Posts: 4,423
    Larry- I was wondering the same thing. Ducktapeguy's explanation makes sense to me.

    So Bob, if the plug/patch doesn't hold, are you willing to be our guinea pig in this matter? :-)

    -Frank P.
  • deepdropdeepdrop Member Posts: 89
    gmginsfo, if you're happy with the sound with just the tweeters, then I'd stick with it. I put in the pioneers (TSA1670R) which are two way. The result is interesting. I compared the two sides once I had installed one of the Pioneers. The OEM spkrs actually have a better base response than the new pioneers. This was disappointing to me at first. Then I realized that the midrange is much cleaner with the new speakers. There is not too much high end even with the tweeters. I did bump up the bass one notch to compensate for the loss of base. Overall, I like the sound better with the new spkrs but it's not a huge difference. Many people have gone with the Sony's. Maybe they can share their impressions.
  • rsay777rsay777 Member Posts: 100
    I would like to add my tire(s) story.

    I did report 10k and 7 months ago that I had a puncture in the G-900's that was too close to the side wall and was not repairable. There were none in town (Portland, OR) and one had to be ordered from CA and it took 5 days. Needless to say I was pixxed!

    Now 10k later another puncture unfixable, no tires in town did I order a new one? no.

    Without thinking about shaving tires and switching rims/spare etc etc. I went back to my old stand by the Z-800 100k Toyo Ultra. I had these on the 91 Legacy and traded it in with 75k on the tires 130k on the car. These tires are smooth runners, agile, good in rain and snow. I can't say enough about Mr Schwab and his tire dynasty in USA NW.

    I have now purchased all 5 tires new.
  • subiemansubieman Member Posts: 10
    Since diameter and circumference are inter-related, saying tire tolerance is based on circumference rather than diameter is kinda confusing isn't it....

    SInce we can measure diameter and get the same thing.
  • c_hunterc_hunter Member Posts: 4,487
    speakers: If you add good aftermarket speakers, you may notice that you have to turn the volume up a bit more than before. Most aftermarket speakers require more driving power than the OEM speakers. The 6-CD radio in the Forester/Impreza has an auto-loudness feature that will keep the radio from distorting as you crank it up. So, if you put in OEM speakers that want more power, you'll definitely notice less bass.

    Vitaly: you speak of 1mm differences in the oil level. I would be surprised if you could read the dipstick with that much accuracy. The level will vary from reading to reading based on numerous factors (slope of the ground, ambient temp, temp of the engine, how long it has been off, phase of the moon, etc...). Don't worry about minor changes in level, especially during break-in. When you start losing quarts (usually the difference between the full and low lines on the dipstick) then it's time to worry!

    deepdrop: are you sure the tires were cold? If you drove any significant distance or at a high speed (highway), the tires would heat up quite a bit and you could easily get another 4-5 psi just based on the temp increase. I would not be surprised if the dealer left too much air in the tires, but definitely check the pressure cold (not in the sun either) to be sure.

    Frank: you discovered the reason why it's better to tow with an auto trans than a manual. Towing is really tough on a clutch, unless it's a heavy duty unit designed for this kind of thing (say, truck clutches). My neighbor, a landscaper, switched from manual transmission to auto in his new truck for this very reason.

    I can remember some exciting moments on the boat ramp when I was a kid. Whenever we towed our boats with a manual transmission vehicle, there would always be some wheel slippage and clutch stink unless my dad finessed it just right. The autos made it a non-event to get the boat out of the water -- just put it in 1 and press on the gas.

    Going in reverse may actually be tougher on the clutch, as reverse is sometimes a taller ratio than first gear (depends on the car, I suppose). If so, it would require more slippage to get going. Anybody know the ratios on the Forester?

    Craig
  • dcm61dcm61 Member Posts: 1,567
    My post was implying that the "1/4 inch" tolerance that Frank P. posted is based on circumference.

    Subaru specially states (noted at http://www.endwrench.com) to measure the circumference of an unloaded tire around the center of the tread. To me, this would be much easier and probably more accurate than measuring the diameter of an unloaded tire. Of course, those with 30" calipers would have no problem measuring diameter. ;-)

    DaveM
  • kajkokajko Member Posts: 70
    Craig,

    according to the PDF from the Australian website, Forester's gear ratios are:
    Type Automatic Manual
    Gear ratio 1st 2.785 3.454
    Gear ratio 2nd 1.545 2.062
    Gear ratio 3rd 1.000 1.448
    Gear ratio 4th 0.694 1.088
    Gear ratio 5th 0.78
    Gear ratio Rev 2.272 3.333

    I don't think they would be different in NA models (why would Subaru build a different transmission?), but Australians do get High/Low transfer case (1.196).
  • paisanpaisan Member Posts: 21,181
    Yeah the site was down earlier for a few hrs.

    I connected mine in series with the in-radiator cooler. I have the hot line going into the stock cooler then into the aftermarket cooler then back to the AT. This cooler is between the condensor and the radiator. It is possible to overcool or not heat up your ATF quickly enough with such a cooler, but I haven't experienced that at all on the SVX. For the summer I'm thinking of actually disconnecting the stock one because I think it's actually heating up the ATF more than it needs to be in race situations. The reason for the cooler is that on the SVX heat is known to cook the ATs so no reason to risk it especially with running it on the track about 2 track days a month. I'm planning on going to Redline Synthetic High Temp ATF which will hold it's properties ~70 degrees higher than std ATF fluid.

    For racing I also disconnect the AC Compressor wires and run the AC, this will keep my fans turning and pulling cool air over the radiator. In addition I put in Water Wetter for the coolant to help keep the engine side extra cool.

    -mike
  • p0926p0926 Member Posts: 4,423
    A difference of 1/4" in circumference is the equivalent of approx 5/64" in diameter (assuming my rusty math is correct). I would think it would be hard to measure the diameter that accurately. Which again begs the question, is the AWD system really that sensitive?

    -Frank P.
  • c_hunterc_hunter Member Posts: 4,487
    I agree it would be hard to measure the absolute diameter or circumference easily and accurately. But that doesn't matter, since Subaru's specs seem to key in on the differences and not absolute measurements.

    So, a good way to look at it is incrementally: any change in circumference is proportional to the change in radius. The constant of proportionality is 2*pi (2*3.141592654...). Assuming all your tires are otherwise equal, you can get a measure of the difference in circumference due to wear just by measuring the tread depth. If one of the tires, say a new one, had 0.1" more tread depth, the difference in circumference would be:

    deltaC = 2*pi*deltaR = 2*pi*(0.10) = 0.628"

    and clearly the tire would be way out of spec. Anyway, the main point it that we should be able to do this by measuring the difference in radius, not the radius (or diameter) itself.

    Craig
  • ducktapeguyducktapeguy Member Posts: 115
    I'm ordering an AT cooler today, probably the B&M. I'm probably going to go with the smallest one since I don't tow with my vehicle. i just wanted a little added protection while driving hard.

    You could measure diameter, circumference, radius, whatever, but what really matters is the circumference of the tire, and that's the easiest to measure, so you might as well do it that way. Measuring the diameter or radius of a tire is pretty difficult. I suppose you could use tread depth as an indication, but I do not know how accurate that would be. You would have to assume the bottom of the tread on all 4 of the tires is are the same diameter, and I seriously doubt that's true. Even with the exact same size and brand of tire, there's always some tolerance. I've compared two new "identical" tires and noticed a slight difference between them.

    Anyway, now I'm curious as about this. I wonder, maybe if I jack up one side of my car with the wheel in the air, I can start spinning it until I can see the LSD start to take affect. I've done it before, and I'm pretty sure i can spin it about 60 rpm without noticing anything (I'm too lazy to calculate how that translates to diameter differences). So if it can take that much speed difference, i dont' think 1/4 inch or more would make a difference. I don't know about the center diff though, maybe that's more sensitive. hmm..now that i think about it, it's probably less sensitive since it's averaging the speeds of the two wheels. Either way, I would almost be willing to bet that the 1/4 tolerance subaru specifies is on the very conservative side of things. Because if they don't specify it, someone's going to try and use a doughnut spare to drive across country, and wonder why their diff is smoking.
  • boba6boba6 Member Posts: 18
    Well, I see from the discussion that I'm not the only one who has had this problem, or at least wondered about it. Craig, that's the way I was figuring it, but without using Delta; never did like seeing those Greek letters. Larry, that's essentially what I was wondering; is the difference so great as to make a real-world difference? I can see that the system is designed to respond to and switch between a variety of changes, not roll for 10k with one wheel needing adjustment until it "shaves" that tire down, so maybe it's reasonable. But still, 1/4" difference in diameter? I suspect Ducktapeguy's got it right, it's got to do with being super cautious. And yes, Frank, I'd be willing to be a guinea pig (and keep a constant watch on my differential tire pressure) except for the fact that I shouldn't have to. Found a garage with an older "tire guy" who looked at it and actually thought about the problem instead of just saying "can't do sidewalls" like in all the corporate places. When he said "if it was mine, I'd fix it," that was enough for me. Had to leave the tire, so I guess it could still not work, but as of now, I'm considering it solved. Thanks for all the advice and discussion.
    Bob
  • lfdallfdal Member Posts: 679
    Okay - so lets try it from this direction as a cross check - assume tirerack's number of 26.2 for the diameter of the GEO 900's.

    Then assume an extra 0.1 inch of depth would bring the diameter out to 26.4 (radius = 13.1 + 0.1 = 13.2*2 = 26.4).

    I know I'm using an increasing diameter vs. a decreasing one, but it really shouldn't matter since we're after a relative change.

    So going back to circumference, which is what started this, 26.2 * pi = 82.3097 & 26.4 * pi = 82.938 which gives us back Craig's delta of .628 - ain't math grand when it works?

    So percentage wise we're at 0.76% delta - still a really tight number. But - on a straight inches/inches number (63360 / 82.3097 = 769.77 rev/mile and 63360 / 82.938 = 763.94 rev/mile) we start to hit ducktapeguy's number of 6 rpm (assuming he meant 6 revs/mile ?).

    So maybe 0.1 inch delta in treadwear is a good rule of thumb to think about going out of spec as 0.1 inch is only a little more than 3/32's of treadwear.

    I'm sorry to be hammering this into the ground, but like most of you I've got a lot of bucks tied up in my Forester (and my Outback) so I'd like to come up with a good rule of thumb for ditching the tires when I lose one.

    BTW re: revs/mile - Tirerack's published revs/mile is 792. The Miata's site link above yields 771 revs/mile & a straight inches/inches calculation yields 769 revs/min. So Tirerack appears to be much higher than either my number or the miata.net site.

    Thanks for all the feedback

    Larry
  • danjaecksdanjaecks Member Posts: 54
    lfdal - your math seems correct
    c_hunter - that is a good way to look at it.

    Most tread depths are measured in 32nds. A new tire has 10 - 12 (I think the Geos have 10). Subaru's tolerances of .25 inch in circumference = 0.25 / (2*pi) = 0.04 inch in radius, which is just a little more than 1/32 inch!
    I believe a tire is legally bald with 2/32 of tread left, which is when the wear bars show, so there are about 8/32 inch of usuable tread, so to stay within Subaru's tolerance (assuming perfect tires and inflation, etc.) one tire can't have much more than 1/8 more wear than another.
    If we assume a life span of 40000 miles for the tires (generous for the Geos), then the tires have to be within about 5000 miles of each other in age.
    This is absolutely nuts. Subaru is effectively saying that you can't use your spare tire once your car is much more than 5000 miles old!!!

    Another way to look at this is the 0.3% difference in circumference yields about 2 extra rotations per mile on the smaller tire. At 60 miles per hour, this is a difference of 2 RPM (e.g. 772 RPM vs 770). Seems like a pretty small difference.

    Has anyone actually seen any problem with using a spare tire or new tire on these cars to replace a fairly well worn tire??? (Say a tire with 15000 or more on it.)

    Another thing is that 0.04 inches in radius is tiny compared with how much your sidewalls flex if one tire is low on air. 10 PSI difference in inflation would probably give you 10 times that much difference in radius (I'm guessing here).

    This just doesn't seem reasonable, does anyone have an actual reference to a Subaru document that gives this tolerance?
  • ateixeiraateixeira Member Posts: 72,587
    Though the tolerance does seem tight, I noticed my tires tend to wear very evenly, even when I waited longer than normal to rotate them.

    It's not like FWD, which tends to carry 62% of the weight, 100% of the steering, 90% braking, and 100% of the acceleration duties.

    AWD splits the accelerating duties, plus the weight is distributed more evenly. So it's not like you have a bald front tire with hardly worn rears, which happens with FWD when you forget to rotate.

    Ron: I have to say, you're very perceptive. Few have mentioned the quicker steering ratio, you might be the first (OK, maybe second). It went from something like 19:1 to 16:1.

    Also, the stock rear sway bar is thicker, plus the tuning is revised slightly.

    -juice
  • dcm61dcm61 Member Posts: 1,567
    http://www.endwrench.com/pdf/drivetrain/MeasuringDeviceInfoS000.p- - df

    Another link stating that as little as 1/4" difference in circumference can cause binding in turns:
    http://www.endwrench.com/pdf/drivetrain/RearAxleBindingInfoF99.pd- f

    DaveM
  • lfdallfdal Member Posts: 679
    Thnaks for the links. There's no ambiguity there at all.

    So basically, after you've put a few thousand miles on your tires, your full size spare makes a nice piece of ballast in the rear end of the car. Ouch.

    My wife's Outback has the fuse for disabling AWD when you put on the donut. Does anyone know if the 03 Forester's do as well? I've seen a spot for it in the fuse box, I think, but is it still capable of being activated?

    Larry
  • ateixeiraateixeira Member Posts: 72,587
    I believe it exists. I don't have an auto to verify that. Anyone?

    -juice
  • rsay777rsay777 Member Posts: 100
    I suppose one way would be to use the 5th tire (spare) in the rotation process. Each tire would then live in the cargo area for a period of time. Since the recommended rotation is (LR to LF) and (RR to RF) I'm not sure how the spare would enter the mix or how many miles should be driven in this case. Just my .02 Bob L.
  • ducktapeguyducktapeguy Member Posts: 115
    danjaecks,
    http://www.subaru.com/owners/care/carcaretips/middle.jsp?pageID=2

    If subaru says 1/4 inch, and in the rotation they don't say to rotate the spare tire, I wonder what would happen if you put the followed all the maintenence and put the spare tire on and destroyed the transmission? Seems like they couldn't blame you since you followed the rotation specs. Anyway, I have put my spare on after about 25k on the original tires, drove it like that for a while, and I didn't notice any problems.

    I wish there was someone from subaru that could give us a definitive answer on this.
  • p0926p0926 Member Posts: 4,423
    I wish there was someone from subaru that could give us a definitive answer on this.

    Hmmm... just the type question that Patti use to be so good about getting answered.

    -Frank P.
  • kullenbergkullenberg Member Posts: 283
    WHEN ARE WE GOING TO GET PRICES ON THE XT - yes, I know I'm shouting - yes,I know it's bad form, but the bloody thing is going to be in the stores next month!!
    Cheers
    Pat
This discussion has been closed.

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