paulsiljama Posted August 14, 2012 Share Posted August 14, 2012 Hi, I would have a question regarding the center differential of my Subaru Legacy (BH5, 2.0 l petrol manual) I've been hearing a klunking sound when turning my wheels (both directions). It's mostly at slow speeds when parking or something, when the wheels are turned all the way to one side. It get worse when the engine is warm, and I guess it's the grease in the bearings heats up and doesn't do it's job that well anymore. I figured this could be a drive shaft output bearing problem (feels like the bearings where the driveshaft comes out from the gearbox/front differential are quite worn.) My concern is that there could be a problem as well with the center differential. And my question is how does the center differential in my 2000 Legacy work? Because in mine it seems to be locked. So that turning the front wheel turns the back wheel. (When I lifted up one side of the car, can't remember now which one we tested gearbox in neutral or 1st gear since it was done by a friend whos knows a lot more about this stuff than me). My second question is that I guess I need to replace the output front driveshaft bearings (gearbox/front diff side). Is this possible or do I need to replace the whole gearbox. Which one is cheaper if I find a used gearbox, and how much are they usually (so I don't get screwed ). Thanks for your help Paul Quote Link to comment Share on other sites More sharing options...
torxxx Posted August 14, 2012 Share Posted August 14, 2012 I'm pretty sure its a viscous coupler in a 5 speed. How mechanically inclined are you? I actually like taking apart the EJ 5 speeds. I'd rather do them than do head gaskets on a EJ25D. If you can read a factory diagram and have a decent memory they arent too bad to do. I would suggest rebuilding it. That way you can replace the input shaft seal and the 2 bearings that like to wear out. And you'll be able to check your gears for abnormal wear http://www.mrtrally.com.au/performance/viscous_coupling.htm that kinda explains how it works Quote Link to comment Share on other sites More sharing options...
paulsiljama Posted August 17, 2012 Author Share Posted August 17, 2012 Thanks for your reply, No I'm not very good at taking apart this kind of stuff, or well the space/workshop is more of a problem, but it seems like it can be done without changing the whole gearbox. Paul Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted August 17, 2012 Share Posted August 17, 2012 Is it a one-time sound or does it clunk repeatedly? Can you feel the car jerking as you turn or only hear a noise? Are all your tires the exact same model and have the same amount of wear? Quote Link to comment Share on other sites More sharing options...
WoodsWagon Posted August 20, 2012 Share Posted August 20, 2012 (feels like the bearings where the driveshaft comes out from the gearbox/front differential are quite worn.)I guess I need to replace the output front driveshaft bearings (gearbox/front diff side). Is this possible or do I need to replace the whole gearbox. The axles are often wobbly where they plug into the side of the transmission. There isn't actually a bearing there, it's just the inside of the differential carrier and the side gears. As long as you can't pull the axle out by hand (they're held in with a spring clip) it's fine. The clunking could be a couple things. If the front outer CV boots are torn, the joints will start to click and make noise on tight turns. They should be the same warm/cold though. The center diff has a viscous coupling that limits the amount of slip between the front and rear outputs of the transmission. As they start to fail they will cause "torque bind". It gets worse as the transmission heats up. If you drive in a tight circle on pavement, it will take more throttle to keep it going around and you will feel a shuddering and thumping in the middle of the car. As it gets worse it will start chirping the tires to relive the binding. It's essentially turning into a 4x4 truck instead of an AWD car. The center diff can be replaced without removing the transmission from the car. The tailhousing unbolts from the back of the trans and the center diff slides right out. Hardest part is getting the double roll pin out of the shift yoke. Your transmission is a Phase 2, so you'd need to get a replacement from a 2000 or newer trans. Or buy a new/rebuilt one. The center diff isn't serviceable, so you have to get the whole chunk. Quote Link to comment Share on other sites More sharing options...
GeneralDisorder Posted August 20, 2012 Share Posted August 20, 2012 You need new front axles. You DO NOT need diff carrier bearings. You *might* need a new center diff. But that would have to be checked by a knowledgable mechanic. GD Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted August 20, 2012 Share Posted August 20, 2012 Play at the output stubs from the front differential is normal. They are high clearance and offer quite a bit of wiggle room between the stubs and the diff carrier. A bad center diff can make clunking sounds, but usually causes binding when turning tight circles. The car will not roll easily, you will have to give a LOT of extra throttle in order to make tight circles. The car will jerk/jump and the tires will squeal on asphalt. There was a year or two that the center diffs had problems, but their failure mode results in the diff basically exploding and usually taking out the transfer gears with it, which eventually leaves you with NO drive at all. Warning signs of this are slight, usually a constant grinding or squealing sound from the transmission. Clunking/ clicking when turning is usually an axle. Quote Link to comment Share on other sites More sharing options...
paulsiljama Posted August 20, 2012 Author Share Posted August 20, 2012 Hi thanks again for the info. Seems like the symptoms align with a worn/failed center differential. It got worse now in the summer with warm temperatures, and after say driving on the highway for a couple of hours and then parking (when turning the wheels). I can really feel the clunking then, which is starting to feel/sound quite bad (Not only can I hear it but feel it too). Going straight is no problem though. And yes it seems like I have to apply a bit more gas when accelerating while turning. How about if I find a rebuilt whole gearbox and replace the whole thing? Quote Link to comment Share on other sites More sharing options...
WoodsWagon Posted August 20, 2012 Share Posted August 20, 2012 You could but that's a lot more work and money than just swapping the center diff. Quote Link to comment Share on other sites More sharing options...
Fairtax4me Posted August 20, 2012 Share Posted August 20, 2012 (edited) Rebuilt? Nobody PROPERLY rebuilds Subaru manual transmissions. There are too many components that SHOULD be replaced, too many clearances to set, and not enough demand for them. The center diff is cheaper than a whole transmission and is very easy to replace. Even a brand new part from the dealer is cheaper than a used trans from that era. Before you go buying differentials and transmissions check two things. Tire size. Are ALL 4 TIRES the EXACT SAME Brand, Model, and Size? Different brands of the same size are often different sizes when actually measured. On these cars, all 4 tires must be within 1/4" (7mm) circumference. Tire wear. Tire wear can not be more than 1/4" difference in circumference between the tire with the most amount of wear, and the tire with the least amount of wear. Make sure they all have the correct air pressure as well. If the tires are mismatched, or are worn more on the front than on the rear (or vice versa), a new differential will be a waste of money and will be damaged in the same manner in a short time. A new set of matching tires may cure the binding problem, or at least lessen the severity of it. Edited August 20, 2012 by Fairtax4me Forgot to finish a sentence Quote Link to comment Share on other sites More sharing options...
paulsiljama Posted August 21, 2012 Author Share Posted August 21, 2012 I change tires every six months (summer and winter tires), so not sure about the wear. And the winter tyres are relatively new, and the clunking sound is independent of which set of tyres I use, so I don't think it's that. The front axels also seem fine, (one side CV joint is changed but it didn't do anything for the clunking, could ofcourse be the other one, but then the problem doesn't look at which way the wheels are turning.) Quote Link to comment Share on other sites More sharing options...
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