mtbe Posted January 4, 2006 Share Posted January 4, 2006 Took the manual 99 Forester with 114K miles on it to the dealer due to an 'umph...umph....umph' sound coming from the front right wheel (or so it sounded like that area from inside the car) when turning slowly and sharply, like into a parking spot. I brought this up before and many thought it was the torque binding, broken axle or CV joint. At first, they could not duplicate it. The car had sat in their shop all night. I ran into the same issue: if it sat for a while, I would not hear the sound. But after driving a while, it would happen. So I asked them to drive a while and sure enough they could hear it also. The said it was the center differential. Does that make sense? They also said when sitting on an incline with clutch in (not many inclines in Columbus Ohio), that the car would not roll backwards and this is another indication it is the center differential (maybe I should keep it this way for the hill brake? ). Also, if it could be the differential, does $1000 sound like a decent price? Thanks in advance for your help..... Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted January 5, 2006 Share Posted January 5, 2006 I guess I can see that. The center diff is binding and causing the issues. Do they give a break down of costs, parts & labor? Quote Link to comment Share on other sites More sharing options...
mtbe Posted January 5, 2006 Author Share Posted January 5, 2006 I guess I can see that. The center diff is binding and causing the issues. Do they give a break down of costs, parts & labor? This was a verbal on the phone. Slightly over $1000. Quote Link to comment Share on other sites More sharing options...
RallyKeith Posted January 5, 2006 Share Posted January 5, 2006 If it happens only after driving for awhile it sounds like there is enough of a mis-match in drive from front to rear that is slowly heating up the viscous fluid in the center diff and causing the problem. Check for the following things. All four tires should be: The same size ie. 195/65R14 Should be the same manufacturer and model tire Should have the same tread depth within something like 1/16 of an inch. Should be inflated to the recommended pressure (listed on the little plate on the drivers door sill.) If all of these are in check, then it sure seems like it would be something wrong with the diff itself and not just a symptom. Keith Quote Link to comment Share on other sites More sharing options...
tunered Posted January 5, 2006 Share Posted January 5, 2006 just make sure they dont recomend changing front axles while your at it,that price sounds way cheap to me???????? Quote Link to comment Share on other sites More sharing options...
idosubaru Posted January 5, 2006 Share Posted January 5, 2006 $1,000 for a dealer to fix a center diff sounds cheap as well. that is no easy job. if it were me i'd find a used trans for 300-400 and have someone install it for 150-200 and be done for around 500 bucks. if it's still driving you have time to source a used trans. check your tires for matching. sounds like the center diff is binding, i agree. check the fluid level in the transmission and differentials. actually i have one. i have one from a 1997 impreza, if that would work it's yours for $300 (rear diff included). i drive to canton, OH about once a month (wife from there) and could deliver it. Quote Link to comment Share on other sites More sharing options...
mtbe Posted January 5, 2006 Author Share Posted January 5, 2006 If it happens only after driving for awhile it sounds like there is enough of a mis-match in drive from front to rear that is slowly heating up the viscous fluid in the center diff and causing the problem. Check for the following things. All four tires should be: The same size ie. 195/65R14 Should be the same manufacturer and model tire Should have the same tread depth within something like 1/16 of an inch. Should be inflated to the recommended pressure (listed on the little plate on the drivers door sill.) If all of these are in check, then it sure seems like it would be something wrong with the diff itself and not just a symptom. Keith Well, the tires are all the same manufactuer, size and wear....now. But for a little while (maybe 1-2000 miles, off and on), I was running low on one or two tires. Not sure if this is long enough to cause damage. Finally sealed the rims and that took care of that problem. Quote Link to comment Share on other sites More sharing options...
mtbe Posted January 5, 2006 Author Share Posted January 5, 2006 just make sure they dont recomend changing front axles while your at it,that price sounds way cheap to me???????? Are you suggesting I change the front axles also at this time? Or are you saying that they may try to snooker me into that as well? I'm no mechanic, so I've no idea..... Quote Link to comment Share on other sites More sharing options...
idosubaru Posted January 5, 2006 Share Posted January 5, 2006 i think he's saying they might try to get you to do the axles as well. highly doubtful running the tires low for that little time would cause any issues. Quote Link to comment Share on other sites More sharing options...
mtbe Posted January 5, 2006 Author Share Posted January 5, 2006 I guess I can see that. The center diff is binding and causing the issues. Do they give a break down of costs, parts & labor? Can the center differential on a manual bind? I've read elsewhere that this is a viscous coupling, and if it fails, it fails open (back wheels do not spin - no AWD).... Quote Link to comment Share on other sites More sharing options...
georgeinmd Posted January 5, 2006 Share Posted January 5, 2006 Just got through with this on my '99 Forester. Its definitely the center diff.; specifically the VCU, based on my experience. All my tires were matched, and it had the same symptoms -- binding only after warmup, not rolling when warm... I replaced the whole transmission with a used one, which worked fine, but of course, you're taking an increased risk of the same thing happening with a used one. $1000 sounds like a fair price for replacement -- my total for a used tranny replacement actually came to a bit more, in the DC area. -- George Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted January 5, 2006 Share Posted January 5, 2006 Can the center differential on a manual bind? I've read elsewhere that this is a viscous coupling, and if it fails, it fails open (back wheels do not spin - no AWD).... All depends on how the viscous coupling fails. If the plates inside lock together, you're going to be getting some serious binding. Quote Link to comment Share on other sites More sharing options...
johnceggleston Posted January 5, 2006 Share Posted January 5, 2006 All depends on how the viscous coupling fails. If the plates inside lock together, you're going to be getting some serious binding. i take it the viscous coupling on the manual trans is different from the clutch pack on the a/t. i just had my AWD clutch /cover asembly replaced and it fixed my 97 obw a/t. the dealer quoted me $1000.00 to reelpace the clutch pack. i had a used one off my old trans, (different 97 obw i used to drive) . trans shop charged me $280.00 labor, gasket and 2 qts fluid to install my used part. (3.5 hours labor) i think he padded the labor bill but what the hell, it didn't cost 1000 and it's done. in hind sight i should have priced a new duty c sol and installed that instead of used . i don't know what they cost, but for 280 labor i should have used new. so i'm not sure exactly what the viscous coupling consist of, but if it bolts on to the rump roast end of the trsans there is a good chance you could get a used one save some money and keep most of your existing transmission. on auto trans, (per nipper) the failed clutch pack can ruin a trans, but the trans failing should not damage the clutch pack. so any bad trans could have a good clutch pack / viscous coupling??? any body have any pictures of a manual trans with the viscous coupling open??? good lucjk, john Quote Link to comment Share on other sites More sharing options...
idosubaru Posted January 5, 2006 Share Posted January 5, 2006 his is a manual trans. the center diff is just about that...centrally located. nothing like the clutch packs in the rear extension housing of the AWD automatics. completely different animal. nice work swapping in the used set, that's the way to do it and you didn't get hosed with the "you need a new trans" line. Quote Link to comment Share on other sites More sharing options...
tunered Posted January 5, 2006 Share Posted January 5, 2006 here is my question t5o anybody that wants to answer,why would a center diff only act like this when the wheels are cranked all the way,this part dont make sense,why not going straight? yes i do think the stealership knows more than they are saying,the only thing that can bind with wheels cranked all the way is the axle,if not please enlighten me. Quote Link to comment Share on other sites More sharing options...
tunered Posted January 5, 2006 Share Posted January 5, 2006 to get back to the orignal problem lets pretend his car is fwd only,now if the cen diff is bad and skipping,binding? why only when wheels are cranked,if this is pitting a load on it why couldnt you do the same thing going straight ahead with a little bit of brake and load the cen diff? Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted January 5, 2006 Share Posted January 5, 2006 I can't recall where the pic was, but the center diff on the Imprezas (except most STIs with the dccd) is viscous locking. There are viscous plates, when the slippage heats them up, they lock the mechanical diff. I dunno how it unlocks. yeah - check the bottom of this page; http://www.autozine.org/technical_school/traction/tech_traction_4wd_2.htm (how does it unlock?) Quote Link to comment Share on other sites More sharing options...
RallyKeith Posted January 5, 2006 Share Posted January 5, 2006 I can't recall where the pic was, but the center diff on the Imprezas (except most STIs with the dccd) is viscous locking. There are viscous plates, when the slippage heats them up, they lock the mechanical diff. I dunno how it unlocks. yeah - check the bottom of this page; http://www.autozine.org/technical_school/traction/tech_traction_4wd_2.htm (how does it unlock?) The difference in speed from wheels slipping expands the fluid and pushed a series of alternatly splines plates together to lock the diff. Once the diff is locked the fluid cools and it will shrink and unlock. Something like that. Quote Link to comment Share on other sites More sharing options...
tunered Posted January 5, 2006 Share Posted January 5, 2006 thanks rallykeith,this is a new one for me. Quote Link to comment Share on other sites More sharing options...
zyewdall Posted January 5, 2006 Share Posted January 5, 2006 here is my question t5o anybody that wants to answer,why would a center diff only act like this when the wheels are cranked all the way,this part dont make sense,why not going straight? yes i do think the stealership knows more than they are saying,the only thing that can bind with wheels cranked all the way is the axle,if not please enlighten me. Because when you are making a turn, the front wheels have to travel farther than the back wheels (in addition to the wheels on one side traveling farther). Take a look at the tracks you leave in fresh snow or dirt when making a tight turn, and you'll see how the front wheels go farther than the back ones. If you are going straight, the front wheels and back wheels are each turning the same distance, so it doesn't matter if the center diff is locked. Quote Link to comment Share on other sites More sharing options...
Legacy777 Posted January 6, 2006 Share Posted January 6, 2006 Here's some info on the center diff/viscous coupling http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/MT_centerdiff1.jpg http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/MT_centerdiff2.jpg http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/MT_centerdiff3.jpg http://www.main.experiencetherave.com:8080/subaru_manual_scans/FSM_Scans/MT_center_differential.jpg Quote Link to comment Share on other sites More sharing options...
mtbe Posted January 13, 2006 Author Share Posted January 13, 2006 Great pics. Those helped alot. Well. Just came back from the dealer with a new Viscous Coupling Unit and it seems that that was it. No more noise!!! Quote Link to comment Share on other sites More sharing options...
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