Center differential dead ( '02 WRX Wagon )

I think I've read of one other distinctly early CD failure on a manual. probably just bad luck. The mechanic was asking the right questions. Other than that...?

Carl

What about prolonged high speed driving?

Just a hypothesis.

I frequently make long distance trips where I drive very fast for many many hours at a time. I always worry about high speeds heating up the relatively small Impreza differentials. I use synthetic gear lube because of this.

Have you (or previous owner if this applies) done any extensive, summer-time high speed driving? What about dirty or old/never changed differential fluid? Or worse, low fluid levels? This one can surely kill a differential long before 100k miles.

MN

Shouldve bought the extended warranty!!!!!

Agree...but every general is smart after the battle is over....

Hmm...on a daily basis I drive approx. 30 miles to work and another 30 back. That's about 2 x 45 minutes of constant drive on highway. Speed is between 60-80mph and even turbine is idle as I drive in 5th gear at around 2500-3000 rpm. That should produce minimal load on any car segment. If differential fluid caused a problem I have to thank service personell. Since I bought this car back in '01 I didn't miss a single oil change or any other scheduled service as suggested by manufacturer. I even keep service history on MySubaru website. Have to check if tranny fluid was ever changed.

Center diff replaced on 1999 Forester. $1600 you got off cheap :) Mechanic said tired were out of spec, but also have taken several long distance trips (12-hours driving at a time) that may have contributed to this. Mechanic also said gasket seal had welded itself to the mount and that there was rust inside the supposedly sealed unit.

well at least the ones that survive the battle

Engine rpm, in itself, has little bearing on differential wear, I think.

The faster you go, or in other words the faster the parts move in the differential, the more heat is produced. The cycle of wear looks something like this: heat weakens metal > forces pushing on metal cause microscopic chips to form > tiny metal flakes start circulating in the oil further damaging/chipping into already existing damage. It is important to change the oil to get rid of the microscopic floating metal debris.

I think 60 mph speed would cause only regular wear, but 80mph for prolong periods of time, and if done in hot weather, may cause some additional, or accelerated wear. How much in terms of longevity of differential? Who knows?

It may be just bad luck. Likely some initial large crack or chip, perhaps from stresses of very rapid acceleration initiated an accelerated 'metal wear cycle.' Was the WRX floored frequently or used for towing especially on rough surfaces which produce jerking motion? - this can put a lot of stress on gears and badly undermine both a differential and a transmission.

MN

Should have read:

Was the WRX floored frequently or _E VE R_ used for towing especially on rough surfaces which produce jerking motion? - this can put a lot of stress on gears and badly undermine both a differential and a transmission.

MN

No ideas here, you're the first I have heard of with center diff problems. If any WRX should have trouble it should be my '02 wagon. It has just under

80k and has been hit three times, heavily abused (high RPM launches, power slides, long distances at sustained high speeds and I am terrible at keeping on top of maintenance.) and so far no issues with the tranny or anything else for that matter. Only things replaced so far tires, brakes and the clutch. I do however go through allot of oil-- 2 quarts every 5k or so. I attribute it to the fact the car spends so much time at high RPMs, because it is not leaking and the car makes no visible smoke.

Seems like just bad luck for you.

Steve

Well, I wasn't granny behind the wheel but none of my driving was so crazy to ruin the car. No racetrack shenanigans, no drop-clutch...etc. After all I bought it new to last some time and always tried not to abuse it. My clutch is still in perfect shape after 65k. Only brake pads were changed once at about 35K (it's about time to change them again) and tires twice at 30K and again recently. Seems like I just had a bad luck...Since I started driving, some 15 years ago, all my cars were mid- level performance cars. I had Lancia Delta Integrale long ago and that baby was really abused (young&crazy) but never had such fatal problem....

Yep. Seems like a bad luck. Anyway, I had opinion that this car is a bit more robust than other Scoobies and some parts are meant to be less prone to wear and tear. After all they market this one as a 'performance car' (besides STI). AS manufacturer, you shouldn't expect that people buying this car will not try to step on a bit harder and turn wheel with more enthusiasm....

That's probably it, bad luck, whatever it was.

I can't think of anything else, besides perhaps a misdiagnosis. Whas the differential really broke? If replacing it cured the problem then probably yes. You haven't described the initial symptoms. The last step is just trust in ones mechanic, right. Was he telling the truth, is there really a new differential in my car, etc?

Well, I think I covered all the angles. In any case, bad luck can also be defined as when your pocketbook gets hit. So either, way you had bad luck.

MN

Sorry you did:

Originaly, I noticed a problem as 'grinding/pulsating' when having wheel turned to lock position and slowly moving (usually when coming to or leaving a parking spot). Problem is definitely resolved now... .

Might have been the differential, indeed.

MN

Typically, a tire issue would be involved in the premature failure of the CD. frequent heavy cargo without increasing rear tire pressure, mixing in 1 or 2 new tires with older, slick tires, running on a low or 'donut' tire, possibly some maintanece confusion about fluids - I've read of that happening. very odd.

I DO NOT feel extended highway driving with all other factors being positive could lead to this. I believe a Subaru Forester even holds the world 'endurance' record.

Carl

If its high-speed hours upon hours I think it can have a significant detrimental effect. Try touching the rear differential after driving for half an hour, or so, at 70mph. Its hot, very, very, hot, I might add. If you happen to go more than 70 mph then the effect is even worse. Same goes for the front diff, although I have never touched the front. No wonder Subaru put cooling fins on these two parts.

MN

Wouldn't the same be true of any car's diff? I dunno, it didn't seem to concern the aforementioned endurance run(averaging over 100mph for a

24hr period); Carl

FYI both the center and rear LSD differentials on the WRX are viscous-coupling type units and are sealed. They do not have any contact with the gear oil/fluid and any contaminants in the fluid will not reach the actual differential. About the only thing that will kill these prematurely, aside from a defect or abusive driving, is unequal rolling circumference between the wheels caused by uneven tire wear or different size/brand tires being mixed on the same vehicle.

If this statement is really truth, I shouldn't be even making longer highway trip with this car but only use it for frocery shopping. I'm not buying this. That would make a really bad spot on Subaru's marketing campaign. I find them really reliable and well made vehicles despite this problem I recently had. Let's call it plain bad luck issue. Maybe I should visit Vegas and find out if I'll do better in gambling..:)