Excessive Cabin Noise

[coco26]

Hi all, I'm hoping someone can help me identify the source of my road noise. I know Subaru's are notorious for having poor insulation, but I think this is something else. Its the first thing everyone notices when riding in my car. It sounds very similar to normal road noise, but you can hear the actual road noise separately when changing surfaces/etc. This is everything I know:

 

1. Volume is speed-dependant
   
2. No change between 3 sets of tires (A/S, Winter, and Summer)
   
3. No change between different road surfaces
   
4. No change after fairly significant camber change
   
5. No change when turning/swerving at high speeds
   
6. No change when braking/turning/accelerating
   
7. No wheel movement on the hub
   
8. No unusual axle movement
   

 

My dad insists its a cv joint. If I had to guess, I would say wheel bearing, but it was present when I got the car and hasn't changed over the almost 20k miles since. Its impossible to pinpoint which direction its coming from. I just accepted it as a characteristic of my specific car, but today I used a decibel meter app, and was a little surprised. It climbed with speed as I expected, and stabilized above 45+ mph. 91 dB average. The app suggests "Inside a car" tops out at 75 dB. I've never been in another 5th gen to know what a normal amount of noise is, and the fact that it doesn't respond like road noise should makes me think its something else. Hoping someone has an idea before I start throwing wheel bearings at it.

 

I measured the sound with my iPhone 7 and an app called Decibel X, sitting on the center console, speeds between 65-85mph. It measures with Z weighting.

[dgoodhue]

My Legacy has some howling on the highway, I think its the snow tires (I seem to notice shortly after installing them), but its in the back of my head it could bee something like a wheel bearing. When I put my summer tires on, I will see if the noise persists.

[FLlegacy]

I had two wheel bearings go on my forester with no other issue except the noise. They were in the rear. I wouldn't be surprised if that is your issue.

 

Also do you know if there have been any hardened mounts or bushings added to the car. I noticed a lot of NVH coming from the rear of my car with the subframe and diff inserts. And as simple as it seems my sunroof cover blocks a lot of wind noise from the roof.

[raider600]

Couple things.

You said it's speed dependent. Does it go away at a certain speed? says its worse from 40-60. If you go 80 does it go away?

 

If you take it to a shop they might be able to put it up on a lift put it in drive and get it up to 30mph, or faster if they remove the ABS fuse. Then use a mechanics stethoscope on the hubs, tranny, and diffs.

[coco26]

Also do you know if there have been any hardened mounts or bushings added to the car. I noticed a lot of NVH coming from the rear of my car with the subframe and diff inserts. And as simple as it seems my sunroof cover blocks a lot of wind noise from the roof.

 

Previous owner was an older man, and it was bone stock when I got it. I haven't changed any bushings since.

 

 

Couple things.

You said it's speed dependent. Does it go away at a certain speed? says its worse from 40-60. If you go 80 does it go away?

 

It doesn't go away at all. Its present at every speed, but it doesn't overpower the engine noise until about 20 mph. It seems to really resonate inside around 50mph, but the decibel meter confirmed that it continues to get louder after that. It even overpowers the wind noise at more extreme speeds (85+)

[FLlegacy]

I would put it on jackstands and roll the wheels I am sure you will find it if its a bearing.

[raider600]

Maybe not a wheel bearing, could be tranny, front diff, center diff rear diff. Bearing inside the tranny going bad. My old WRX has several random bearings replaced 3 different times. Made lots of road noise.

 

Sounds terrible whatever it is.

[rgeo13]

I would put it on jackstands and roll the wheels I am sure you will find it if its a bearing.

 

 

x2, Wheel bearing issues have been very common with early-mid 2000's Subies, I'd start there.

[coco26]

I spun the fronts by hand, and the only noise was a hint of brake drag. I'll try the rears to confirm tomorrow.

 

If its a more serious bearing, I'll probably give up and just continue to drive it since it hasn't gotten worse.

[coco26]

No movement or sounds from the rear either.

 

Anybody ever changed the wheel bearing themselves?

[FLlegacy]

I used the opportunity on my forester to upgrade to disc brakes, but that won't help you here. There are plenty of youtube videos showing how to do it with a slidehammer. If I had the time I wouldn't hesitate to change the hub myself. I don't know if I would try to do just the bearing.

[FLlegacy]

You might also look at the tail-shaft on the transmission case and the center support bearing on the driveshaft. I have heard most people who have front or rear diff noise compare it more to a whine than groan or drone.

[GTEASER]

Does the sound change in volume or pitch when you load up the suspension in a slight turn left or right?

 

Spinning the wheels with them up in the air will not tell you if you hgave a bad wheel bearing, you wont even be able to get it spinning 10mph. With the wheel in the air, grab it on the top and the bottom and it will rock a little and make some noise if the bearings are going.

[bigboy292000]

 

Just turning the wheel MIGHT show the bad wheel bearing but there are other things you can check.

[coco26]

Does the sound change in volume or pitch when you load up the suspension in a slight turn left or right?

 

Spinning the wheels with them up in the air will not tell you if you hgave a bad wheel bearing, you wont even be able to get it spinning 10mph. With the wheel in the air, grab it on the top and the bottom and it will rock a little and make some noise if the bearings are going.

 

Nope. I have yet to find a single driving scenario in which the sound changes pitch or volume at a given speed. Gentle turns, aggressive turns, turns on cobbled roads, etc. The one thing I haven't tried is reverse. My only other idea for speed-related components is the rear driveshaft and related bearings, but I would've thought they would react to changes in engine load. Planning on inspecting those tonight.

 

No movement on any of the wheels. I looked up the inspection spec, and it says anything above .002" of movement is bad. I can't see or hear any movement at all.

[TwoTone]

I spun the fronts by hand, and the only noise was a hint of brake drag. I'll try the rears to confirm tomorrow.

 

If its a more serious bearing, I'll probably give up and just continue to drive it since it hasn't gotten worse.

 

When you spin the wheel, hold onto to the strut, you can normal 'feel' a bad bearing.

[coco26]

When you spin the wheel, hold onto to the strut, you can normal 'feel' a bad bearing.

 

This actually worked. I would've never noticed it just spinning and listening, but I could feel it when I held on to the strut or knuckle. Rears were buttery smooth. I could feel a little bit of a vibration on the right front. The left front was horrible compared to the rest. Definitely not bad, but definitely not right. Still no play in the wheel, no sound when spinning.

 

I don't have the tools with me to handle the axle and such, so it looks like it'll have to go to the dealer. I'm going to start with the left front hub only, just in case what I felt on the right side was translating through the axles. I can't imagine this is going to be cheap.

 

Thanks for all your help.

[FLlegacy]

You can always rent the tools from a local auto parts chain store. The only uncommon tool is the slide hammer set.

[coco26]

I was just planning on changing the entire hub - or is that not worth it?

 

Edit: It looks like you can only order the entire hub, guess that's my answer.

[FLlegacy]

I was just planning on changing the entire hub - or is that not worth it?

 

Edit: It looks like you can only order the entire hub, guess that's my answer.

That's the best way to get it done. Make sure to use a good brand, some people have had problems with the wheel speed sensors on replacement hubs.

 

Sent from my SAMSUNG-SM-G920A using Tapatalk

[coco26]

I was just going to add that question to my last post... Subaru's are $183, RockAuto has SKF (a brand I trust) for $111, and others for less. Any reason I should stick with Subaru parts?

[raider600]

I tried to do a front wheel bearing by myself. It was going well until i figured out the bearing was seized/rusted to the knuckle and the only way to get it off without a slide hammer was an air hammer. Neither of which I had. I took it to a shop on a flat bed. hah. I think I used an NTN bearing, OEM quality.

[02LGTSNJ]

Change out the entire hub assembly, you would be insane to try to do just the bearing. The hub assemblies were not available on my third gen and the bearings have to be pressed in, its a PITA, but they have since changed it and you get the entire hub assembly its easier. If you go aftermarket get Timken or Moog, they should be just over $100

[dwbaily]

Pretty sure you can't JUST change the bearing. It's all one piece. Just had to change front right bearing on my son's '11 Legacy 3.6 Limited. Wasn't noisy going straight. Slightest turn to the left loaded it up and had a growling/grinding type noise/feel. Changed hub assy and it's gone. Firestone got me for $300 for the Subaru OEM bearing plus labor. I know they mark up 20% their parts.

[FLlegacy]

Pretty sure you can't JUST change the bearing. It's all one piece. Just had to change front right bearing on my son's '11 Legacy 3.6 Limited. Wasn't noisy going straight. Slightest turn to the left loaded it up and had a growling/grinding type noise/feel. Changed hub assy and it's gone. Firestone got me for $300 for the Subaru OEM bearing plus labor. I know they mark up 20% their parts.

 

Technically you can, if you can find the right part number for the bearing. You would need to press it off the hub and then press the new bearing onto the hub. I am sure without a hydraulic shop press it is a big pita, but it is doable.