Stevo F Posted December 21, 2019 Share Posted December 21, 2019 I'm trying to tackle the issues with this car one at a time. Since I bought it last summer, the car (automatic, 255K miles) has had a vibration in the body (not specifically felt through the steering wheel) that starts around 35 MPH and is most obvious at around 45 MPH. The tires were newly replaced as were both front axles with no change before and after. Some other observances- when I put in the fuse to put the car in front wheel drive (to diagnose a rear differential noise), the vibrations gets a little worse. If it were coming from the rear, or the driveshaft u- joints, I would expect it to diminish when taking the load off of the rear drivetrain (the rear differential noise virtually disappears in FWD). The other thing I noticed when I had the front end up on stands recently was there is a slight amount o fend play on the front axles. If I pull out against each axle there is maybe 1/8" play in the axle going into the front differential. Don't know how normal that is, given how many miles are on the vehicle. The car is pretty solid for the miles- only a small amount of rust on the rockers and the 142K mile engine in it runs well. Other than the vibration and the rear diff whine, it needs a catalytic converter. Quote Link to comment Share on other sites More sharing options...
1 Lucky Texan Posted December 21, 2019 Share Posted December 21, 2019 all 4 tires the same brand/model/size/wear? any clunking sounds? starting, stopping, turning etc.? does the vibration seem to be in sync with wheel rotation or, about 4 times faster than wheel rotation? Quote Link to comment Share on other sites More sharing options...
forester2002s Posted December 21, 2019 Share Posted December 21, 2019 It could be wheel-bearings. I have had body-vibrations on my 2002 Forester (worse at about 105 km/h = 65 mph), and twice this has been rear-wheel bearings. I found the source of these vibrations difficult to trouble-shoot. The wheels show no looseness; there no noticeable heat build-up on the hubs; and it's difficult to identify whether the vibration comes from front or rear, left or right. Eventually to noise and vibration worsened, and the source was obvious. A couple of ideas: - what happens if you slip the car into neutral, and apply the brakes very gently? Does the vibration feel different? - what happens if you drive at speed round a very gentle curve to the left or right? Does the vibration feel different? If the answer is 'yes' to either, it could be wheel-bearings. Quote Link to comment Share on other sites More sharing options...
Stevo F Posted December 23, 2019 Author Share Posted December 23, 2019 No other noises when stopping or turning that I can hear. Hard to tell the frequency of the vibration, but it feels like it's in the whole car, rather than originating from one point. I've have to try putting it in neutral and applying the brake sot see if anything changes. I have no service history on this car other than the engine replacement, so I'm guessing some or all of the wheel bearings are original. Since the vibration feels more pronounced when in front wheel drive, I wonder if the front wheel bearings would be a place to look. Quote Link to comment Share on other sites More sharing options...
Stevo F Posted February 4, 2020 Author Share Posted February 4, 2020 (edited) Took it on a long drive the other day. The vibration is most pronounce around 50- 55 MPH. I put it in FWD briefly but doesn't seem to change when I checked it this time. Doesn't seem to vary on turns. It's just there. I had been thinking driveshaft u-joints, but I would think that would have diminished some when in FWD and not under load (like my rear differential whine does).It also doesn't seem to be worse when under load or accelerating. U-joints is my main worry (in case it decides to randomly self- destruct going down the road) otherwise it's not really bad enough to really worry about when driving. Just hoping it doesn't result in some catastrophic failure if I can't diagnose it right away. Edited February 4, 2020 by Stevo F Quote Link to comment Share on other sites More sharing options...
Numbchux Posted February 4, 2020 Share Posted February 4, 2020 Ujoints are almost always worse under load. But I wouldn't hesitate to drop the shaft and feel them. Hardest part of the job is getting the car up high enough to get under there (I usually drive one end up on ramps, and then jack/stand the other end). Does it get worse the longer you drive it? I've had a sticking caliper slide cause a vibration at speed once that brake gets hot. Also check all suspension bushings. What axles were used? I've experienced many an aftermarket CV axle cause a vibration. Quote Link to comment Share on other sites More sharing options...
idosubaru Posted February 4, 2020 Share Posted February 4, 2020 Based on what you just said, Unoints would be most likely. sometimes with a keen eye you can pick it out insitu, but usually you have to pull the shaft which isn’t that hard, mostly annoying working under the car. Pull it and check each joint for play or stiffness/lumpy feeling. Quote Link to comment Share on other sites More sharing options...
Stevo F Posted February 6, 2020 Author Share Posted February 6, 2020 On 2/4/2020 at 10:20 AM, Numbchux said: Ujoints are almost always worse under load. But I wouldn't hesitate to drop the shaft and feel them. Hardest part of the job is getting the car up high enough to get under there (I usually drive one end up on ramps, and then jack/stand the other end). Does it get worse the longer you drive it? I've had a sticking caliper slide cause a vibration at speed once that brake gets hot. Also check all suspension bushings. What axles were used? I've experienced many an aftermarket CV axle cause a vibration. Aftermarket axles but there was more vibration before they were replaced so don’t think they’re the culprits what is involved with dropping the driveshaft. Looking underneath, it looks involved getting to it- it appeared the exhaust system may be in the way? Quote Link to comment Share on other sites More sharing options...
idosubaru Posted February 6, 2020 Share Posted February 6, 2020 7 hours ago, Stevo F said: Aftermarket axles but there was more vibration before they were replaced so don’t think they’re the culprits what is involved with dropping the driveshaft. Looking underneath, it looks involved getting to it- it appeared the exhaust system may be in the way? More vibration before they were replaced - so repacking then changes the vibration? Maybe the old ones vibrates and the new ones vibrate too, but a little less. Rear shaft: not sure about 05 Impreza but in general you can sometimes get them out without removing any exhaust bolts. unbolt it then try to squeeze it around the exhaust. You can remove a exhaust hanger or two so it moves more readily. Just ample warm dishwashing soap for the rubber hangers. Quote Link to comment Share on other sites More sharing options...
Numbchux Posted February 6, 2020 Share Posted February 6, 2020 There's probably a heat shield towards the front that can make it a little tough, I throw that in the scrap. 4 bolts (you'll need a decent 12mm box wrench, as there's not enough room for anything larger, and a fair bit of force) at the rear diff, and 2 bolts that hold the carrier bearing to the body. Then snake the whole thing out towards the rear (there isn't enough room to drop it straight down without removing the exhaust). 1 Quote Link to comment Share on other sites More sharing options...
Stevo F Posted February 6, 2020 Author Share Posted February 6, 2020 One question that pops into my head regarding u-joints- wouldn't I expect the vibration to be less when the driveshaft is not under load (just spinning with the rear differential) when i put the car in front wheel drive? In comparison, the whine from the rear differential goes away in front wheel drive. Quote Link to comment Share on other sites More sharing options...
Numbchux Posted February 6, 2020 Share Posted February 6, 2020 2 hours ago, Stevo F said: One question that pops into my head regarding u-joints- wouldn't I expect the vibration to be less when the driveshaft is not under load (just spinning with the rear differential) when i put the car in front wheel drive? In comparison, the whine from the rear differential goes away in front wheel drive. On 2/4/2020 at 9:20 AM, Numbchux said: Ujoints are almost always worse under load. But I wouldn't hesitate to drop the shaft and feel them. Hardest part of the job is getting the car up high enough to get under there (I usually drive one end up on ramps, and then jack/stand the other end). Quote Link to comment Share on other sites More sharing options...
idosubaru Posted February 7, 2020 Share Posted February 7, 2020 (edited) 17 hours ago, Stevo F said: One question that pops into my head regarding u-joints- wouldn't I expect the vibration to be less when the driveshaft is not under load (just spinning with the rear differential) when i put the car in front wheel drive? In comparison, the whine from the rear differential goes away in front wheel drive. Not all ujoints failure modes are the same. Some lock rigidly tight, some have play, some show externally visible damage and others do not. I assume symptoms can also vary. it’s been awhile but I’m fairly certain I’ve seen them vibrate while coasting. I seem to recall driving one where I was trying to keep it under load. Edited February 7, 2020 by idosubaru Quote Link to comment Share on other sites More sharing options...
Stevo F Posted February 8, 2020 Author Share Posted February 8, 2020 The vibration doesn’t seem to vary when letting go off the accelerator. It also is about the same in front wheel drive when the driveshaft is just spinning free with the rear differential. Quote Link to comment Share on other sites More sharing options...
Stevo F Posted February 10, 2020 Author Share Posted February 10, 2020 Update- Today decided to swap all wheels and tires with my '98 Legacy GT to see what would happen with the vibration. Both sets of wheels and tireds are the same size, both have about 3k miles on them. The vibration at around 45- 50MPH was still there a little bit, but just barely noticeable. I then drove the Legacy with the Impreza tires and felt a little bit of vibration or maybe just road feel, which may be the cheaper Sumitomo tires, or maybe one or two tires that weren't balanced well when installed. Also, while I had the Impreza up on stands, I examined the driveshaft and u- joints. The driveshaft turned smoothly by hand and I could not observe any play with any of the 3 u-joints when turning it back and forth, and changing direction. There was some play in the transmission and rear differential, however. Quote Link to comment Share on other sites More sharing options...
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