yamahagr Posted January 26, 2017 Author Share Posted January 26, 2017 1 CV axle per wheel, 2 CV joints per CV axle. Noise only on right turn = right front CV axle. Probably inner joint, that's the most common boot to fail due to the downpipe's heat. Did you replace the right axle? Yourself or shop? I changed the whole right CV axle and problem remained exactly the same. Today I threw in the old right CV onto the driver's side just to be sure and there absolutely no change is symptoms. Another thing to note is there usually a few pops during a corner which all but rules out bushings and such because I'd imagine they'd make just one solid clunk as metal hit metal Link to comment Share on other sites More sharing options...
MilesA Posted January 26, 2017 Share Posted January 26, 2017 I think he's asking about viscous couplings, not constant velocity joints. OP, with the 2.5i I believe you only have the viscous coupling in the center differential. That is located in the rear part of the transmission. You said you saw metal flakes on the transmission dipstick when you checked it? That would indicate a likely issue. The center differential costs roughly $500 and labor to replace it, I'm not sure exactly, probably add at least another $500. You may have some other parts that need to be replaced. I know that is bad news, sorry. The transmission does not have to removed from the car to replace the center differential. Link to comment Share on other sites More sharing options...
yamahagr Posted January 26, 2017 Author Share Posted January 26, 2017 I think he's asking about viscous couplings, not constant velocity joints. OP, with the 2.5i I believe you only have the viscous coupling in the center differential. That is located in the rear part of the transmission. You said you saw metal flakes on the transmission dipstick when you checked it? That would indicate a likely issue. The center differential costs roughly $500 and labor to replace it, I'm not sure exactly, probably add at least another $500. You may have some other parts that need to be replaced. I know that is bad news, sorry. The transmission does not have to removed from the car to replace the center differential. Well I didn't see flakes, just fine specs and I find it hard to swallow that any major components would fail on a car with only 35k on it but that very well may be the case :/ I also haven't noticed any binding or shuddering of the wheels Link to comment Share on other sites More sharing options...
MilesA Posted January 26, 2017 Share Posted January 26, 2017 Of course, it's hard to diagnose these things remotely from a computer, but you might want to have that checked out locally. Driving on the flat tire for several miles could cause issues such as that. Link to comment Share on other sites More sharing options...
apexi Posted January 26, 2017 Share Posted January 26, 2017 Well I didn't see flakes, just fine specs and I find it hard to swallow that any major components would fail on a car with only 35k on it but that very well may be the case :/ I also haven't noticed any binding or shuddering of the wheels Running tires with different tread depth, or different circumference could wreck the center diff regardless of how many miles a car has on it. How much does it take to ruin the center diff? I'm not sure, but driving on the flat for 5mi could have done it, even if the tire was in the rear. I think it's even bad to drive on the spare a lot, I'm pretty sure I calculated its circumference online, and it was quite different from the standard 205/50/17 circumference. Replacing the center diff isn't too hard, it's just annoying. It turned into a 2 day job for me to let the rtv fully cure for 24hrs before adding new gear oil. There are different rtvs out there, but all the ones that seemed a best fit for the job said wait 24hrs. Link to comment Share on other sites More sharing options...
yamahagr Posted January 26, 2017 Author Share Posted January 26, 2017 Running tires with different tread depth, or different circumference could wreck the center diff regardless of how many miles a car has on it. How much does it take to ruin the center diff? I'm not sure, but driving on the flat for 5mi could have done it, even if the tire was in the rear. I think it's even bad to drive on the spare a lot, I'm pretty sure I calculated its circumference online, and it was quite different from the standard 205/50/17 circumference. Replacing the center diff isn't too hard, it's just annoying. It turned into a 2 day job for me to let the rtv fully cure for 24hrs before adding new gear oil. There are different rtvs out there, but all the ones that seemed a best fit for the job said wait 24hrs. Thats another thing, how could different size tires damage a differential? It seems like if that were the case then the diff would blow up every time you took a corner, I mean the whole point is it allows the wheels to spin at different speeds right? How was your diff diagnosed? Link to comment Share on other sites More sharing options...
solidxsnake Posted January 27, 2017 Share Posted January 27, 2017 Thats another thing, how could different size tires damage a differential? It seems like if that were the case then the diff would blow up every time you took a corner, I mean the whole point is it allows the wheels to spin at different speeds right? How was your diff diagnosed? Yes, but you're not constantly taking corners. Under straight-line driving conditions, with properly-matched tires, the VC center diff will not be "working," if you will, as there won't be any torque differential between the front and rear driveshafts to equalize. However, if one of the tires is of a different diameter, it will throw off the loading on the differential, causing it to make up the difference constantly, even when driving straight. The fact that it's constantly being "worked" is what will cause it to fail prematurely. Link to comment Share on other sites More sharing options...
I Donated Too sigmafour Posted January 27, 2017 I Donated Too Share Posted January 27, 2017 The VLSD in the center differential is designed resist the 2 output shafts from spinning at different speeds. If you slip the wheels on mud in snow that will be very brief and nothing gets too hot. There is also differentials at the front and rear axles which handle the turns but when you drive is a straight line the center differential is more on game along with the affected axles differential. With different size tires, or a flat or any thing causing a difference in circumference then the speed difference is a constant drag which overheats and burns up the differential components - unless they were actually all viscous not semi viscous and then it would be a complicated set of torque converters like in an auto gearbox which would suck and Subaru AWD would be a joke and the fluid would just get trashed and hot but these are components that shear and wear and break up into the metal flakes you now see on your dipstick. Or something like this... because I don't honestly know for sure how it works but that's the gist of it. TLDR - turns are over quickly but driving the car with a wheel that's smaller/larger than the others creates a constant stream of abuse at the differentials. Link to comment Share on other sites More sharing options...
yamahagr Posted January 27, 2017 Author Share Posted January 27, 2017 I get that but when you have slightly different tire sizes your differential isn't working very hard, certainly not hard enough to overheat, think of driving down a twisty costal road compared to to a 1/2 inch difference in tire circumference that. It let's say it does overheat, would that just lead to bearing failure? Could bearing failure cause that popping noise without making a whining/droning noise? Seems unlikely to me Link to comment Share on other sites More sharing options...
yamahagr Posted January 27, 2017 Author Share Posted January 27, 2017 Another key piece of info, I dont have to turn sharp to get it to pop, if i hit a bump mid turn its gonna pop. If im going fast and I swerve left then right turning the steering wheel about 1/4 turn (it doesnt have to be a sharp turn), its gonna pop, usually at least two pops. Sometimes when Im going around a corner it sounds more like a creak but my point is that suspension loading is a big factor that can cause it to pop. To me this does not indicate transmission/differential/VC problems but I cant be sure. Im blanking pretty hard here, have you guys heard of hydraulic steering components popping like that? Link to comment Share on other sites More sharing options...
solidxsnake Posted January 27, 2017 Share Posted January 27, 2017 I get that but when you have slightly different tire sizes your differential isn't working very hard, certainly not hard enough to overheat, Yes, it is, and yes it does. Some more reading on the topic. From the video you posted, it sounds really like it's coming from right under the center console. I wonder if there's something wrong with the prop shaft? I don't see why that would only appear on right turns, though. From what I've seen of differential failures, and by the way you describe it feeling like "lots of tension is being released somewhere," it sounds like a diff might be intermittently locking. Link to comment Share on other sites More sharing options...
JustCallMeNick Posted January 27, 2017 Share Posted January 27, 2017 1 CV axle per wheel, 2 CV joints per CV axle. Noise only on right turn = right front CV axle. Probably inner joint, that's the most common boot to fail due to the downpipe's heat. I feel like I remember hearing that the right one fails more often on cars in general that are driven on the right side of the road because right turns are a little bit tighter and the wear adds up over many thousands of miles. Maybe? (unrelated to the diagnosis....) I took the car to a mechanic friend who immediately diagnosed it as a bad CV axle. I went and changed it but the noise is still there and now I'm really bummed out because I'm just a broke college kid that should have spent the evening studying for two exams that I have tomorrow morning instead of throwing away $$$ on perfectly good parts... Anyways I checked the trans dipstick and it has a bit of fine metallic specks in it, okay now someone deliver the death blow... You should get that money back from your mechanic friend or else go to an accountable mechanic. I would find a very experienced transmission shop or a very experienced Euro/Import shop that you KNOW works on Subarus (NOT the dealership - they are usually mechanically inept). and I find it hard to swallow that any major components would fail on a car with only 35k on it but that very well may be the case :/ Any car that is badly abused (a Subaru driven 5 miles with one flat tire) can potentially have a failure - mileage doesn't really come into the picture because that's not really normal wear and tare for a car. :/ Another key piece of info, I dont have to turn sharp to get it to pop, if i hit a bump mid turn its gonna pop. If im going fast and I swerve left then right turning the steering wheel about 1/4 turn (it doesnt have to be a sharp turn), its gonna pop, usually at least two pops. Sometimes when Im going around a corner it sounds more like a creak but my point is that suspension loading is a big factor that can cause it to pop. To me this does not indicate transmission/differential/VC problems but I cant be sure. Im blanking pretty hard here, have you guys heard of hydraulic steering components popping like that? Did we rule out front swaybar end links? I replaced mine over the summer and didn't tighten them down enough. I was terribly concerned about the noise but it was just loose end links hehe. Although that won't cause metal in the trans fluid... Link to comment Share on other sites More sharing options...
apexi Posted January 27, 2017 Share Posted January 27, 2017 Thats another thing, how could different size tires damage a differential? It seems like if that were the case then the diff would blow up every time you took a corner, I mean the whole point is it allows the wheels to spin at different speeds right? How was your diff diagnosed? I'm feelin super lazy right now, so here's a link to where I briefly talk about the symptoms my car had. I figure it might be a good idea to link to that thread anyways in case you try to DIY the center diff. http://legacygt.com/forums/showpost.php?p=5425477&postcount=70 I replaced my center diff at 196k. I had replaced both from cv axles at about 155k, so I basically just rolled the dice and assumed they were still good, and that it was the center diff that had gone bad. Plus, after reading a bunch of other threads online, the fact that the metallic clicking sound happened more frequently once the transmission was warmed up pointed to the center diff as well. But I just want to reiterate, my metallic clicking sound I was hearing from my center diff sounded nothing at all like the sounds i hear in your video. The sound my car made was like a baseball card in bicycle spokes type sound I think. I tried to record some videos, but recording sounds can be really hard sometimes. However like I said earlier, if your center diff really exploded or something, then maybe that's why yours sounds a lot harsher than mine did. Link to comment Share on other sites More sharing options...
apexi Posted January 27, 2017 Share Posted January 27, 2017 Just gonna throw this out there as well.. A few years ago when I replaced my front struts, I incorrectly installed the conical shaped washer on the passenger side of the car, and I would get a loud banging sound when turning the wheel. The loud bang was the spring basically winding up, and then releasing tension. Have you had any type of suspension work done on the car at all recently? I mean, it's probably not this, but hey, you never know. You can hear the sound at 17 seconds. https://youtu.be/tGuJMVwxDxw **Just watched your video again, I think your popping sounds are too close together to be this. But I'll leave this post up anyways just to show you can get crazy popping sounds from a lot of different places. Link to comment Share on other sites More sharing options...
yamahagr Posted January 27, 2017 Author Share Posted January 27, 2017 I had my brother watch the front wheels for binding and shuddering as I made a few tight turns on loose gravel and he didnt notice any problems, even when it was popping. I was thinking about struts too but they seem unlikely because the noise seemed to be coming from the center not the sides. I doubt the propshaft as well but I'll get under the car and have another look. And as I mentioned earlier, loose links or bad bushings would only make one noise while under pressure right? they arent bouncing around mid corner while theyre being pressed together. Link to comment Share on other sites More sharing options...
yamahagr Posted January 27, 2017 Author Share Posted January 27, 2017 By the way, huge thanks to everyone who's replied so far. This is looking to be a pretty complicated issue and I'm grateful for the support. Keep it up guys! Link to comment Share on other sites More sharing options...
apexi Posted January 27, 2017 Share Posted January 27, 2017 My money would be on the center diff, but I'm no expert. I paid around $465 for my center diff from chaplains subaru on ebay. Then when you factor in replacement gaskets, nuts, bolts, transmission fluid, you're looking at probably low to mid $500's depending on what type of gear oil you buy. Taking my sweet ocd time, being meticulous, I think I had the old center diff out in around 4 hours. So just trying to give you an idea what you're in for if you do try it, I have no idea how much labor shops would charge, what book time for something like that would be. So it'd be an expensive gamble if you do try it. If you decide to replace your center diff, before you do anything, make sure all 4 tires are within .25" of each other, total circumference. Link to comment Share on other sites More sharing options...
yamahagr Posted January 27, 2017 Author Share Posted January 27, 2017 I've already measured each tire and modulated the air pressure to get them as close as possible in terms of circumference and yes I'm within 1/4". Link to comment Share on other sites More sharing options...
yamahagr Posted January 27, 2017 Author Share Posted January 27, 2017 Okay so I've already posted some valuable belongings on craigslist and I'm bracing for that $600 repair pricetag. I just left my job to focus on school so its gonna be a challenge but hey stuff happens. So at this point It seems that the center diff and viscous coupling(s) are the primary suspects so of the two, which one seems the more likely culprit based off the symptoms I've described? Link to comment Share on other sites More sharing options...
apexi Posted January 27, 2017 Share Posted January 27, 2017 Again I'm no expert.. but isn't the vicious coupling inside the center diff, which is a sealed unit? I think the center diff in the link below is a different part number, but the assembly is probably the same? http://subaruidiots.com/subaru-wrx-five-speed-manual-tips-and-tricks/2/ The picture below is from the 2005 factory service manual Link to comment Share on other sites More sharing options...
I Donated Too sigmafour Posted January 27, 2017 I Donated Too Share Posted January 27, 2017 It is a sealed unit but I have been scouring for pictures to see if someone has taken one to bits to see what's in there. Lots of pictures of people taking it out along with shrapnel though! I have one in an old wornout gearbox sitting outside which I am inclined to go and pull apart and take one to bits myself but time? I have none. Link to comment Share on other sites More sharing options...
MilesA Posted January 27, 2017 Share Posted January 27, 2017 Older Subaru 5-speeds have a different design center diff that can be taken apart, so it's possible to replace just the viscous coupling in those. Newer 5-speeds use a sealed center diff that has to be replaced as a unit. Here's a few pictures of the center diff internals (from another website). The steel plates are interleaved, half are keyed to the front drive and half to the rear drive. Between the plates is a special silicone fluid. When the plates rotate together, this fluid stays liquid. When the plates move at different speeds, the fluid becomes firm and locks the plates together. This normally happens very smoothly and quickly so you don't notice it. However, if the diff gets overheated the fluid stops working as it should. The steel plates grab and release suddenly, not smoothly as before. The diff has to be replaced. Link to comment Share on other sites More sharing options...
yamahagr Posted January 27, 2017 Author Share Posted January 27, 2017 So overheating should cause the differential to lock up and bind then? None of that was observed on my car... Whenever I go on those parts diagram pages I select my model/year but when I come to powertrain it doesnt show an option for a 2009 Legacy with a manual transmission, how can I get the exact part number for the center diff/VC? Link to comment Share on other sites More sharing options...
MilesA Posted January 27, 2017 Share Posted January 27, 2017 Subaru OEM P/N 38913AA102 runs about $500 online. Just going by the info presented so far. You posted a few seconds of video online. You don't like to hear bad news, I get it. Your car does seem to have a grab-and-release issue somewhere in the driveline. In the video, it happened when turning. People see a variety of symptoms when these start going out. You did drive for five miles or so on a flat tire, that has been seen by others to cause potential overheating. This leads me to suspect the center diff. It is not the only possibility. Is there another, more likely explanation? Link to comment Share on other sites More sharing options...
MilesA Posted January 27, 2017 Share Posted January 27, 2017 The goal is diagnosis, not guessing what is wrong. Why not do a few diagnostic tests when you get time. First, get the transmission warm by driving normally for 10 or 15 minutes. Go find an empty, smooth road. Accelerate to 50 mph or so. Do you hear or feel any noise in the driveline? Now, turn sharply left and right at moderate speed. Do you hear or feel any noise now? While driving straight at moderate speed, brake hard. Notice anything unusual? Now, repeat the tests on a bumpy road. Any difference? You get the idea... If you get more info, maybe that will shed some light. Link to comment Share on other sites More sharing options...
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