georgeinmd Posted April 13, 2004 Share Posted April 13, 2004 Howdy -- My first post here. I'm impressed with the useable technical information I've seen here; hope someone can address this... '99 Forester L, (mt, regular front and rear differentials) -- feels like the viscous coupling unit in the center diff. is going south -- drive train binding in sharp turns after warm-up. I've read all the threads on torque bind, etc. Has anyone replaced this unit themselves? Is it something an experienced shade tree mechanic can do? Is the unit available anywhere except a dealer? Any advice, experiences, portents of doom, etc. welcome. Thanks very much -- George Link to comment Share on other sites More sharing options...
CardinaA Posted April 15, 2004 Share Posted April 15, 2004 hey, had my VC replaced- current thread running from Hawksoob about this topic. I had a mechanic do the job for just under 500 because he had a good source on the VC (only about 250 bucks for the unit). he claimed it was a pretty easy job, but i, being a medical student, had very little time and or inclination to fix the sub myself (i used to be a volvo nut, and by virtue, a shade tree mechanic). i think there are suppliers out there- i will try to get this guy's number and get a line on his supplier. Link to comment Share on other sites More sharing options...
georgeinmd Posted April 15, 2004 Author Share Posted April 15, 2004 Thanks, CardinaA! That would be great if you can find the supplier. That's about half the costs I've been quoted. -- George Link to comment Share on other sites More sharing options...
The Dude Posted April 16, 2004 Share Posted April 16, 2004 George , I have a 99 Forester AT. However, I have been reading the various Subaru boards for a number of years. First, viscous coupling units do fail, but it does not appear to be a very common problem. Second, when the viscous unit fails the typical symptom is a loss of AWD. Usually the driver is unaware that the viscous unit has failed until he gets stuck in snow and then notices that the rear wheels aren't turning. I guess that it could happen, but I have never read of a viscous unit failure causing binding during sharp turns. When the multi-pack in the AT goes, that almost always causes binding. I wouldn't be so certain that the viscous diff is the problem. I would check the front end and steering just to make sure. You don't want to replace a fairly expensive part, and then find out it was the wrong one. Perhaps one of the more experienced mechanics on this board could provide some additional advise on this problem. Link to comment Share on other sites More sharing options...
scubaroo Posted April 16, 2004 Share Posted April 16, 2004 I own a 90 Lagacy AWD 5/m with 210k I don't think the viscous coupling has ever been changed. When making slow tight turns (ie, turning in to a parking space) my car shudders a little, this is normal. If the viscous coupling unit went out you would have either no drive (unit is not coupling) or vary notisable binding (unit is locked up). A quick way to tell if the unit is locked up is to jack up one tire and try to turn it . If it turns with some resistance your OK if not The unit is locked up. Good luck Link to comment Share on other sites More sharing options...
hklaine Posted April 16, 2004 Share Posted April 16, 2004 I haven't had experience with this, but based on the way a VC works I would think that a loss of AWD would be a much more likely symptom as The Dude stated. -Heikki Link to comment Share on other sites More sharing options...
camosuba Posted April 16, 2004 Share Posted April 16, 2004 my understanding of the VC is it works like an lsd in a rear axle, you only lose drive (assuming its failed ) if one wheel has lost traction and same with awd if the vc is not working you only lose drive if any of the 4 wheels has lost traction? Link to comment Share on other sites More sharing options...
georgeinmd Posted May 11, 2004 Author Share Posted May 11, 2004 Sorry for the long lapse; thanks for the replies. Scubaroo, good suggestion on turning a rear wheel -- it doesn't; compared it with another Forester MT -- it does, so I'm concluding the unit is bad. A local shop corroborates this diagnosis. CardinaA -- any info on where your mechanic procured a new one? Thanx! -- George Link to comment Share on other sites More sharing options...
CardinaA Posted May 11, 2004 Share Posted May 11, 2004 hey george, i can't seem to find his # (or the receipt for the job, for that matter). also, is your car a manual or auto? mine is manual, so i don't know details on the automatic pathology of viscous coupler (clutch pack) death. Link to comment Share on other sites More sharing options...
georgeinmd Posted May 12, 2004 Author Share Posted May 12, 2004 CardinaA -- mine's manual; I'm speaking of the unit that bolts to the tailpiece of the transaxle. Thanx, George Link to comment Share on other sites More sharing options...
cookie Posted May 12, 2004 Share Posted May 12, 2004 And I am not sure if you can turn my rear wheels freely. If you don't get an answer I can check mine this weekend. I would not be in a hurry to change an expensive part like that unless I was very sure it was bad. Link to comment Share on other sites More sharing options...
georgeinmd Posted May 13, 2004 Author Share Posted May 13, 2004 cookie -- agreed; I'm not jumping on this right away. George Link to comment Share on other sites More sharing options...
cookie Posted May 16, 2004 Share Posted May 16, 2004 manual L series with 100,000 miles. If both wheels are off the diff just lets one wheel be spun. The driveshaft stays in place. This is with the five speed in reverse and emergency brake off. If I jack up the right rear wheel and leave the left down the tire cannot be spun. It just takes up driveline play. This makes me think the VC stays engaged all the time. Link to comment Share on other sites More sharing options...
timn29 Posted May 17, 2004 Share Posted May 17, 2004 FYI, I tried the "jack-up one wheel at a time" trick and found that, independently, each one of my rear wheels spins completely free of any resistance. So, what does this mean? My wheels turn. Link to comment Share on other sites More sharing options...
cookie Posted May 17, 2004 Share Posted May 17, 2004 and one wheel is on the ground I think they might be right about the coupling. Link to comment Share on other sites More sharing options...
georgeinmd Posted May 17, 2004 Author Share Posted May 17, 2004 Its the only explanation I can see. My understanding (based on theory and research, not experience) is that the unit should permit differential rotation between front and back when there's a small difference in rotational speed, but begin to lock as rotation differential increases (as when front wheels start to slip under power). Thanks for the input -- George Link to comment Share on other sites More sharing options...
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