2QtsLow Posted December 18, 2005 Share Posted December 18, 2005 I have a question, but first I'd like to say hello since this is my first post here. First off, I recently traded in my old reliable 95 Camry on my 96 Legacy since I need AWD here in the Colorado mountains. It is my daily driver and the 6th Subaru in my family's history. I checked it out closely before buying and serviced the auto trans, and rear diff myself once I got it home. Everything else checked out fine: new looking struts, CV boots all good, new filters, new brakes, tires fair but wearing evenly. Now to my question. When I test drove, I jumped onto a highway to run it up to speed (80 mph). It ran smooth as glass. I also ran it on city streets with the same result except for the classic minor motor rumble stopped in drive. Once home for a couple of days, I notice a slight vibration/audible rumble at 40 mph when cruising or decellerating. Under full power it is smooth and quiet. It is still there at higher speeds but barely noticeable. What could this be? I've checked the axles for play, the driveshaft, wheel bearings for play, ball joints for play, visual check of the motor and trans mounts, the front and rear bumper cowling for play, all heat shields, and replaced the tires with a set of new Pirelli's. Everything appears to be tight and in good shape. My local mechanic, Dr. Subaru, says to let it go to see if it gets worse. What do you Soob Junkies think? Quote Link to comment Share on other sites More sharing options...
nipper Posted December 18, 2005 Share Posted December 18, 2005 Did you check the center universal joint and carrier bearing for the driveshaft? If not check it then let us know.. i can give you advice on how to fix it. a raor at 40mph is usually tire realted or wind related. Also take a look at the electric cooling fans, are all the blades there. Turn on the ac and se if the fans come on, and do they look like they are in balance. Look for any loose body cladding or plastic wheelwell liners. Look under the hood and make sure the air intake system is all in one peice Is this a sedan ? Lets tell you what it is not Differentials, they would get louder with speed Tire wear since you said you replaced them (that was going to be my first guess) Transmission, same as differential. nipper Quote Link to comment Share on other sites More sharing options...
2QtsLow Posted December 18, 2005 Author Share Posted December 18, 2005 Thank you for the reply. Ok, this morning, I checked the following: -Jacked the engine. Mounts good. -Under the hood, everything is tight. Some play in the radiator mounts, but they have rubber inserts. Play about 1/8 inch. Looks right. Checked front strut tower mounts, tight. Fans in perfect shape. Pulleys running true. -Hood, trunk, body cladding tight. -Spare tire tight. -Window trim and cowling tight. -Wheel well liners tight. -Drive shaft has no detectable play when trying to jiggle it or turning it. The rumble occurs at any RPM, in any gear @ 40 MPH, and decreases significantly when coasting or under full power. The car doesn't shake or anything, it's just annoying. Oh, and yes, it is a sedan. Quote Link to comment Share on other sites More sharing options...
Lesbaru Posted December 18, 2005 Share Posted December 18, 2005 My 96 Legacy did that, and gradually the rumble spread to other speeds, too. It was the wheel bearings in my case. They were just starting to wear out when I bought it. Quote Link to comment Share on other sites More sharing options...
the_bard Posted December 18, 2005 Share Posted December 18, 2005 As stupid as this may sound, it happened to me once... check for snow/ice stuck in the inside of the wheel rims. I hit a snowbank a few years back with the right rear of my Old's Cutlass Calais. Pushed snow through the spokes on the rim, into the inside where it melted and refroze into ice. Messed up the balance on the wheel, and made it vibrate like crazy around 40 mph or so. I imagine a smaller amount of snow might have the same symptoms, only to a lesser degree... Quote Link to comment Share on other sites More sharing options...
2QtsLow Posted December 18, 2005 Author Share Posted December 18, 2005 Thank you for the many suggestions. The iced wheel is a great suggestion, but the car is is a heated garage. It could be a wheel bearing, but doesn't a wheel bearing squeal long before grinding and rumbling? Maybe not, and this is a good theory, but difficult to isolate when all wheels show no play. I'm baffled. Maybe the cold snap we're in right now is part of the problem. When I bought the car it was about 40 degrees warmer that it's been for the last few days. Quote Link to comment Share on other sites More sharing options...
nipper Posted December 18, 2005 Share Posted December 18, 2005 Thank you for the many suggestions. The iced wheel is a great suggestion, but the car is is a heated garage. It could be a wheel bearing, but doesn't a wheel bearing squeal long before grinding and rumbling? Maybe not, and this is a good theory, but difficult to isolate when all wheels show no play. I'm baffled. Maybe the cold snap we're in right now is part of the problem. When I bought the car it was about 40 degrees warmer that it's been for the last few days. Subaru wheel bearings are heavy duty, they rumble , if you hear squeeling, its time for a tow truck. nipper Quote Link to comment Share on other sites More sharing options...
2QtsLow Posted December 26, 2005 Author Share Posted December 26, 2005 Update and question: Ok, a couple of days ago, I removed the driveshaft heat sheild to gain access to the carrier bearing. I found that it is surrounded by rubber in it's mount. This rubber has a lot of give to it, about 1/2 inch. I loosened the mount and placed a fairly stiff piece of dense foam rubber between the top of the mount and the floorboard before tightening it back down. I did this in hopes of altering the resonance of the carrier should this be the culprit. I left the heat sheild off. I then put equal pressure at 32 psi in all four tires. Test drove and found a pretty good reduction in the rumble, about 75%. Question: Should the rubber in the carrier housing be that sloppy? It will move with very gentle hand pressure. Thanks for listening. Quote Link to comment Share on other sites More sharing options...
nipper Posted December 27, 2005 Share Posted December 27, 2005 DO you mean the bearing that is under the middle of the car ther the universal joints are? nipper Quote Link to comment Share on other sites More sharing options...
mikkl Posted December 27, 2005 Share Posted December 27, 2005 Thank you for the many suggestions. The iced wheel is a great suggestion, but the car is is a heated garage. It could be a wheel bearing, but doesn't a wheel bearing squeal long before grinding and rumbling? Maybe not, and this is a good theory, but difficult to isolate when all wheels show no play. I'm baffled. Maybe the cold snap we're in right now is part of the problem. When I bought the car it was about 40 degrees warmer that it's been for the last few days. I have had similar problems with mud on the inside of a wheel after a good round of rally drivin. The temperature difference could well affect the mounting bushing that you mention in another post. Cold weather will make the rubber shrink and become more stiff, potentially highlighting a new problem. If you leave the car out in the cold and then drive it, is the noise worse than when you start out from your warm garage? If so, some piece of rubber somewhere may very well be a part of the problem. mikkl Quote Link to comment Share on other sites More sharing options...
2QtsLow Posted December 27, 2005 Author Share Posted December 27, 2005 Yes, that is the bearing I'm talking about, the one just ahead of the u-joints. It supports the driveshaft and is surrounded by the rubber as described earlier. Quote Link to comment Share on other sites More sharing options...
nipper Posted December 27, 2005 Share Posted December 27, 2005 this is the 96 legacy? how many miles on it ... sounds like the rubber mount for the bearing is tired, or the bearing is tired or both. nipper Quote Link to comment Share on other sites More sharing options...
2QtsLow Posted December 28, 2005 Author Share Posted December 28, 2005 nipper- Yes, 1996 Sedan 2.2 Auto. 110K miles. Thanks! Quote Link to comment Share on other sites More sharing options...
2QtsLow Posted December 29, 2005 Author Share Posted December 29, 2005 nipper? Quote Link to comment Share on other sites More sharing options...
nipper Posted December 30, 2005 Share Posted December 30, 2005 Sorry had a few bad days .. cant wait for surgery for my back. i would have that replaced, as there shouldnt be alot of movement in that bushing, and what you describe is literally what Haynes describes as the bushing/bearing assy failure. i dont know if this is a dealer item only (your not that attached to your first born male child anyway ). i know when my universal joint went bad i took it to a driveshaft shop and they fixed it far cheaper then the subaru part. You may give one a call and see if they have a fix for it, along with subaru. nipper Quote Link to comment Share on other sites More sharing options...
2QtsLow Posted January 7, 2006 Author Share Posted January 7, 2006 UPDATE Hope your back is feeling better nipper! Back pain is long and slow. The rumble is history. Pulled the driveshaft and found it to be notchy and the noise was concentrated at the tail end of the shaft determined by use of a stethescope. Aquired a new driveshaft, installed and the noise was still there. Took it to the dealer who determined it was a bad bearing in the rear diffy. One reman differential later the rumble is history and I have nearly a new rear drivetrain. Had the timing belt, water pump, oil pump service and cam seals done while it was in the shop. A little dough, but worth it. Thanks for all of the help and suggestions! Quote Link to comment Share on other sites More sharing options...
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