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'94 legacy wagon: front end humming/vibration


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hello all,

 

i'm getting a low volume humming in the front end while driving whether in gear or not. it changes in frequency depending on the speed of the vehicle. as well, you can feel it somewhat through the shifter. it has no relation to rpm of the engine, either, which leads me to suspect it's in the drivetrain. perhaps cv's or transmission. also, the vibration/humming seems to be slowly getting louder/worse

 

the cv's aren't that old. i replaced them not long after i acquired the vehicle...maybe 5-6 years ago. the transmission i replaced a couple of years ago with a used unit. over 100k on it, but not much. it shifts great (considering a gl4 in it, though) and, to cover some other bases, i have new wheel bearings, new struts, control arm bushings, and ball joints. basically new front end.

 

anyhow, when i get under the vehicle and shake the cv shafts where they mate with the tranny...at the splined stubs...it seems like an awful lot of play. i don't really know what's acceptable and not, though. is there a standard and a way to gauge tolerance? also, are there some bearing/s within the tranny behind that little plate with the single bolt that the splined stub protrudes through that could possibly need replacing? also, i can't really tell if the play is from the axles meeting at the stubs or if it's the stubs themselves moving around in the tranny. not without removing the axles, anyway.

 

would anyone have some experience with the given symptoms? or perhaps be able to guide me in what and where to start focusing my attention with this?

 

thank you kindly!

 

ps. the drift pins are still in the axles...ie, they haven't fallen out. as well, plenty of clean fluid in the tranny. 

Edited by thook44
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Questions- You said clean trans fluid, are you sure u checked trans and not front diff?, Said there is play/slop in diff end of cv, up down side to side or in and out? I have a very similar noise, slight feel of vibration that is relative speed and not rpm, no cv slop. I know my issue is a front left wheel bearing.

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tranny dipstick.....pass side of the tranny right behind the motor, correct? yellow handle

 

i didn't see any in and out play on the stubs coming out of the sides of the tranny (not sure what they're technically called) like i'd seen on the youtube vid, but there's up/down side/side play at the cv as it mates to those stubs. i still have to drop the cv's to get a better look, though. i mean, the cv's are kinda in the way to really see what's going on with them stubs. has to wait until next week. i work all weekend

 

edit: I should've noted it's a 5spd mt and just learned it shares fluid with the diff. elementary, of course, to you guys more educated on subys. admittedly, I've not learned a lot about my car, yet. some essentials, though

Edited by thook44
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well, now i'm wondering if isn't a bad bearing install. I noticed driving into work this morning that the noise became louder as the car leaned into left turns on the highway.

 

I managed to find some adequate search terms and dug some info on what's apparently a common issue. I hope, in a way, it's a bearing and not the differential. still a PITA to do the bearing, again, if that's the problem. but, even more so if it's the diff. mating the tranny up to the motor was a royal beetch

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I've only visually check the u-joints and that was a few months ago. I went to see about greasing them and found they were sealed/no lube points. I even grabbed the shaft and shook it real hard, but there wasn't any play. having said that, I didn't have all 4 wheels off the ground and so haven't checked for any binding.

 

i'll check all that this week. again, though, the vibration gets worse into those left hand curves. i'll post what I find

 

thanks!

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I believe you checked the front diff fluid, the trans dip stick is on the driver side hidden under some black hoses very near the same spot as the diff stick just on the driver side of the car. Don't feel bad at all I did the same thing awhile back. If the noise/grinding feel changes depending on turning left or right verses driving straight it is the wheel bearing. A bad CV will make a noticeable click click click noise then turning. I have had 2 subies now and both had all 4 wheel bearings go bad. As far as I understand it is a common Subaru problem. Millage seems to very when they go bad. It is a pressed In bearing only you cannot buy a hub assembly. Buy or have a shop install a QUALITY wheel bearing like a National or Timekin brand anything else will not last long 6mo-1yr. 

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I believe you checked the front diff fluid, the trans dip stick is on the driver side hidden under some black hoses very near the same spot as the diff stick just on the driver side of the car. Don't feel bad at all I did the same thing awhile back. If the noise/grinding feel changes depending on turning left or right verses driving straight it is the wheel bearing. A bad CV will make a noticeable click click click noise then turning. I have had 2 subies now and both had all 4 wheel bearings go bad. As far as I understand it is a common Subaru problem. Millage seems to very when they go bad. It is a pressed In bearing only you cannot buy a hub assembly. Buy or have a shop install a QUALITY wheel bearing like a National or Timekin brand anything else will not last long 6mo-1yr. 

it's a 5spd MT. only the one stick

 

GL-5 but, some folks have problems if they run full synthetic. so, stay with dino oil. Or, some folks like the synth BLEND from walmart.

 

any change in the sound with clutch out vs in?

 

could have been a bad bearing install. a good press should have been OK, but if someone 'rigged' the bearing install, could be some misalignment that compromised the longevity of the bearing ????

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it's a 5spd MT. only the one stick

 

GL-5 but, some folks have problems if they run full synthetic. so, stay with dino oil. Or, some folks like the synth BLEND from walmart.

 

any change in the sound with clutch out vs in?

 

could have been a bad bearing install. a good press should have been OK, but if someone 'rigged' the bearing install, could be some misalignment that compromised the longevity of the bearing ????

 

i'm running a gl-5 M1 synth now, but since the redline mt90 works so great in my '86 4rnr 5spd i thought i'd switch to it. however, i've done a little reading. mixed reviews on what to use, but many suggest 75w-90 redline vs the mt90 because of the diff. i'm not really liking the M1 in there. didn't like in the 4rnr, either. not sure why i thought it would be any different in the suby. i mean, the shifting is okay...just not "butta" how i'd like. kinda sticky downshifting into 4th at 45-50pmh, actually. bugs me out. maybe i'll go to the castrol someone mentioned in another thread i found.

 

i did the bearing install myself a few months ago (plenty of experience with those things). everything seated well in the knuckle using a press, but i'm afraid perhaps i didn't torque well on the spindle. or maybe i got it too tight. don't know. i'll just have to look at it tomorrow. otoh, it's an o'reilly bearing. i wanna say national. don't remember offhand.

 

and, no change with the clutch in or out. and, again, no change with engine rpm.

Edited by thook44
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I believe you checked the front diff fluid, the trans dip stick is on the driver side hidden under some black hoses very near the same spot as the diff stick just on the driver side of the car. Don't feel bad at all I did the same thing awhile back. If the noise/grinding feel changes depending on turning left or right verses driving straight it is the wheel bearing. A bad CV will make a noticeable click click click noise then turning. I have had 2 subies now and both had all 4 wheel bearings go bad. As far as I understand it is a common Subaru problem. Millage seems to very when they go bad. It is a pressed In bearing only you cannot buy a hub assembly. Buy or have a shop install a QUALITY wheel bearing like a National or Timekin brand anything else will not last long 6mo-1yr. 

 

yep...it's a 5spd :) not a big fan of auto's in general. i do like them towing a trailer around the hills, though....ironically, i guess.

 

i could have clarified better earlier, but i'm not concerned with the cv's themselves. just the diff where the cv's connect. well, more the wheel bearings, now. but, still...the diff was my original concern because of the slop i mentioned. and, i'm still gonna look at it just to know

 

right. i used a bearing press a few months ago to do the change out at my friend's shop. i discovered the originals were bad when i was doing the ball joints, steering rack, tie rods, control arm bushings, and struts. again, they're o'reilly bearings. i've used o'reilly bearings before without issue, but that's not to say i got some iffy parts. that's happened before, too, with other things. a few years ago i went through two freakin' fuel pumps within a short time on the '92 4rnr before o'reilly finally went to a better brand after repeated warranty replacements with their customer base. sucked because i'd had to drop the tank far from home both times...in the middle of the night.....in 3ft of snow...both ways... :D

Edited by thook44
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btw, gentlemen....thanks so much for some input. this is the first suby...or even awd vehicle...i've had. not too far removed from 4wd's, i suppose. nevertheless, the suby is still kinda foreign land to me. you guys have any early efi yotas...feel free to ask me any questions about'em. :)

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I'd suspect the o'reilly bearing having an early failure. I know it's usually a good idea to consider something else, but symptoms do kinda point to it. many of us would probably have gone with OEM or Timken or similar - still, there are so many early bearing failures, I don't think OEM is all that great.

 

in AZ, I think you might be wise to consider Redline Lightweight Shockproof. In my WRX, it was the best 'feeling' fluid . Second best is the Amsoil Severe gear that's in it now.   But, I haven;t been trhu a full summer with it yet. The Subaru fluid was kinda scrape-y/notchy.

 

I have the RL LW SP in the diffs in our Outback. It seemed to quiet the front diff slightly.

Edited by 1 Lucky Texan
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it was national bearings i got. they only offer two brands for the '94, and i know i didn't get the masterpro with only a 1yr warranty. anyhow, does still sound like a bearing with the symptoms.

 

i'm in arkansas. yes...there's also a winslow here. though, without the tumbleweeds and cactus. ;)

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on my way into town tonight, i found a stretch of road in which there were some hard, uphill, lengthy'ish right turning curves. i purposely took them at a good clip and leaned hard into them thereby unloading the passenger side.....where the suspect bearing is. sure enough, the noise stopped. so, i'm more sure now it is the front wheel bearing pass side. i'm just going to try another national, though. it's under warranty still and i can have it by wednesday rather than later ordering a timken or whatever online.

 

i'll update once it's done

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  • 2 weeks later...

finally mustered the motivation to pull the knuckle off and inspect the bearing. yep...bad. just enough play to cause a vibration, although it's very little. not sure why there's play, yet. gotta get to the friend's shop tomorrow and press it apart. but, gotta order another bearing, first.

 

anyhow, figured i'd update thus far

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turns out the bearings i put in were actually the master pro. oopps! a tad embarrassing given what i already said. hmmm....i suppose i thought the saved $20 over the national was worth it and MP bearings were sufficient. still can't say why the bearing failed. nothing was apparent. nevertheless, i'm putting in a national/kyo bearing, now! didn't finish today. ran into a few challenges getting things apart and using the right tools, etc. tomorrow i plan to be finished, though

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i finished everything up friday and was driving her by today. all is well, again. those kyo bearings are nice. needle bearings! (vs the MP ball bearings) so, ought'a last a good long time

 

well, that concludes this thread i do believe. :) thanks to all who contributed!

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