whats causing this tranny/driveline noise?

I am new to this svx forum and am inquiring if anyone out there has experienced a similar problem with the one I'm currently having with my 93 svx (awd) SE with 129,000 miles on it. It sounds like a wheel bearing noise, that increases in both volume and frequency corresponding to the speed of tire rotation. (faster rotation equals higher noise and frequency). The volume of this noise is highest between 45 and 55 mph, and dissipates slightly in intensity after about 5 minutes of sustained cruising at highway speeds. However, within the past 15,000 miles, I have had all four wheel bearings professionally replaced, after having those new bearings first repacked with synthetic wheel bearing grease. A professional (master) mechanic who has solved/fixed just about every possible problem on this svx to date, is now unsure of the source of this noise. He has already taken this car out on the highway with 3 mechanic friends aboard in an attempt to pinpoint the direction/side of the car that this noise is coming from. All four mechanics agreed that the noise appeared to BE COMING FROM ALL FOUR CORNERS OF THE CAR EQUALLY! After putting the car up on a hydraulic lift and running the car with the wheels off the ground, much of the overall noise disappeared, so stethescopes were used to determine the location. These mechanics concluded that this noise appeared to be coming from loudest somewhere at the very rear of the transmission, and possibly rearward from there from the u-joint backward. The stethescope said the noise was loudest almost equally along this area, leading them to beleive that it was possibly a bad u-joint or some kind of rear output bearing on the transmission etc. Subaru does not sell just the u-joint itself, but rather a whole "propeller" assembly containing other shafts and bearings as well that I priced from Subaru for about $500.00 after substantial discount. However, I do not want to randomly kick in for this repair if it will not solve this problem. Does anyone have any ideas of what is causing this wheel bearing like noise here? Additionally, does anyone know of potential after-market parts available for these potential repairs for this problem? Thanks. Bernie. Concerning the tires as a potential source for this wheel-bearing sounding problem, they worked fine (smooth and quiet) for the past 15000 miles ever since the wheel bearings were replaced. This noise basically appeared "overnight" (within a 2 day period), and noise has not grown better or worse since then. The tires are Z-rated Generals (soft rubber). YES THERE IS A SLIGHT VIBRATION that sounds almost like a single out-of-round bearing or single tire that is out of balance/round at highway speeds. However the tires have recently all been balanced. Does this help? Thanks Earthworm -- Bernie.

[Earthworm]

Welcome to the site!

Now I bet tire noise is "part" of the problem. It could be the drive shaft but is there any vibration, almost a surging, when you're driving at those speeds?

[Beav]

Have them install a fuse in the 'FWD' slot, in the under-hood fuse box. Then raise it on the lift and see if the noise is still there. This will eliminate all power from the trans to the driveshaft.

Thanks BEAV for the info. I'll have them do it this weekend and let you know
Bernie.

[pavanbabut]

Originally Posted by bernard

I am new to this svx forum and am inquiring if anyone out there has experienced a similar problem with the one I'm currently having with my 93 svx (awd) SE with 129,000 miles on it. -- Bernie.

Wow!... is this one a new model for 93, 'SE' . I haven't heard about SVX-SE model till now

-Pavan.

[Merz]

Anyone ever figure out what was wrong? I seem to be having the same problem. Loud humming sound coming from center/rear of car. Im pretty sure it isnt the wheel bearings. Replacing the driveshaft didnt help. What could it be????

[SSSVX]

Originally Posted by bernard

BE COMING FROM ALL FOUR CORNERS OF THE CAR EQUALLY!

How could that be? If you have the "z" rated and soft compound tires, it shouldn't be noisy.

How do all the tranny/driveline fluids look like?

Keep us updated.

[SSSVX]

Originally Posted by evanmerz

Anyone ever figure out what was wrong? I seem to be having the same problem. Loud humming sound coming from center/rear of car. Im pretty sure it isnt the wheel bearings. Replacing the driveshaft didnt help. What could it be????

Why don't you try to put the fuse FWD to drive and see if the noise is there?

Did you check your rear differential fluid? How does it look like?

Mind telling, how much it cost you to replace the driveshaft? Thanks.

[Merz]

Ive changed the tranny and rear diff fluid and checked the front diff fluid.

Tried putting in the fwd fuse and it didnt make a difference.

Im sure its not the tires. I just got new ones. Same kind as my old ones. had alignment done also.

I jacked up the car and wiggled the wheels and they were tight. also spun them by hand with no noise.


i got a used driveshaft for $100 from someone on here. install was easy.

thanks for the reply.

[Merz]

If it were a wheel bearing, would i be able to tell which side of the car it was coming from? or would it just sound like it was coming from the rear. Ive ridden in the back of the car and it is louder, but not coming from a certain side.

[SSSVX]

Okay, thanks for the reply. Mine sometimes has a lil jerk I ain't sure if it's the driveshaft. But I was thinking and asked you how much . . .


After my lower gearing tranny/rear end swap, talking about rear-end center, I have some whining noise coming from the rear-center also. I am thinking about the rear-differential problem and it's getting louder and louder now. Well, I will go to the shop soon and let them check on the fluid and determine.

Why do I guess it's from the rear-differential/driveline? Because when I was driving 40-50mph downhill, when I put from "D" to "N", in 2 seconds, the noise will be totally gone. That's why I myself determined it's from the driveline.....
Will find out!! Did you try this before? If you push to "N", the noise is still there?

[SSSVX]

Originally Posted by evanmerz

If it were a wheel bearing, would i be able to tell which side of the car it was coming from? or would it just sound like it was coming from the rear. Ive ridden in the back of the car and it is louder, but not coming from a certain side.

I think you should be able to tell which side it is coming from. I have been in a friend's SVX who had a bad bearing....I remember the noise is not really from the center.

[Merz]

The noise doesnt change when i put it in neutral, or downshift, or whatever. It also doesnt change when the road surface changes, so it cant be the tires. the faster i go, the louder it is. by 100 mph it is screaming. When going slower, like around 30, i can hear sort of a whobbling sound in it. and there is a slight vibration in the car that matches the sound. but when going faster, the frequency increases and the whobble and vibration go away, or just gets too fast to notice.

[dannmarr]

Check for cracks or breaks in your exhaust.

[Merz]

i dont think it could be the exhaust, because the noise changes according to the speed that the car is going. If it was the exhaust, it would change according to the rpm and/or the throttle. So i am convinced it is coming from the drivetrain. Thanks for the reply though.

Is there a chance it could be one of the rear cv joints? Would they make this sort of sound if they were bad?

I was also thinking it could be the rear diff. How would i check it? Ive checked the fluid and it looks fine.

I cant handle this noise much longer. I drive 50 miles round trip to work everyday and have to listen to it. Its getting old fast. -Evan