[craigr]

This is MY05 manual transmission Forester that I have owned since new. It now has 103,000 miles on it. I drive it long distances mostly on the highway for work travel.

About 2,500 miles ago the problem started. A very serious vibration, similar in sound and feel to driving over a rumble strip started (but not quite as harsh as a rumble strip). The entire vehicle shook like on a rumble strip and there was a loud rumble. The sound and vibration would change with the speed of the vehicle. I was going about 75 mph and slowed down to 45 as soon as it started and the rumble slowed down in time with the speed.

At first I thought it was a tire about to blow, or maybe something weird with the road surface. But I continued to drive and the road surface changed with no change to the vibration. Then after about three miles the noise and vibration suddenly stopped.

I went probably 500~800 miles with no more incidents. Then it happened again the same way. The vibration and noise came back, lasted 3~5 miles, and then vanished. Over the last 2,500 miles or so this has happened maybe another 8 or 10 times.

I know a lot about cars and I am stumped by this. A friend of mine is a master mechanic and he can’t think of what it would be either (though he has not looked at the car). I rotated the tires and tried to wiggle the wheels while they were off the ground to see if there was too much play in the bearings, but they seemed fine. I also inspected all the boots and they are all in good condition so the u-joints should be well protected still.

What do you folks think? The fact that a vibration this severe can be intermittent is the difficult part in my mind. I suspect wheel bearings, a universal joint, or a half shaft, but how on earth could any of those things be intermittent?

I want to fix this before I get stranded, but I’d like a better idea of what to replace before I start working. Thanks for any help.

craigr

 

[Woody '04]

i agree sounds quite bizarre.

have you checked the tires very carefully when you rotated them?

did you check the axle lock nuts to be sure tight and staked?

If you DIY I would probably just plan on replacing the wheel bearings whenever convenient, especially if you have "hubshark" tools to do it without removing the knuckle.

Not sure if a center diff problem could cause some intermittent vibration like that. It would seem to be something either loose or out of balance.

 

[craigr]

Thanks for your thoughts. Anyone else have any suggestions?

craigr

 

[Fischbeef]

drive shaft universals can do this if they shift around causing the driveshaft to be out of balance when they are going bad. i dont know how this affects subarus but there are two you can check.

Other than that, if everything is fine i would suspect trans error, either front or the center dif going bad, wheel bearings wouldnt cause this dramatic of a noise nor would they be intermitent, same thing with cv's. Have you chenged the fluids in the trans lately?

have you had snow when it happens? i know large amounts of snow on the inside of the wheels can cause imbalance and make horrible vibrations in the wheels

Just some thoughts, good luck sir

 

[flstffxe]

Carrier bearing on the drive shaft. The rubber isolator/dampener gets old and allows the drive shaft to spin out of balance. Would be a good item to take a close look at.

 

[Surftaco]

Thats crazy! I had something very similar happen to me yesterday driving from Florida to Michigan. While I was in Alabama I had it on cruise control at about 75mph the whole donkey end started to shake. It lasted for a few seconds like you described and then stopped. It also swayed back and forth slightly like it was trying to go faster. Toyota has nothing on my forester lol

It did it again 30 minutes later. No codes popped. It didnt do it again the rest of the way up! I know if I took it to Subaru they would not be able to recreate it. I tried doing it the whole way to Michigan. Its like a weird demon.

Its almost as if the computer in the car had a glitch
I only have 32K on mine.

 

[Fischbeef]

^^earthquake and aftershock? haha

 

[funkymonkey1002]

Get all the wheel bearings checked, especially the fronts. One of my fronts failed badly enough to move the wheel about an inch or two in any direction. Before this happened I would get an intermittent shake on the highway, which for the last 300 or so miles before it got -really- bad, became a vibration like you mentioned. There was no typical wheel bearing noise, the only noise I got before it got that bad was the sound of the brake pad sometimes scraping the rotor (i guess because there was enough play with the full weight of the car on it for it to make contact).

I'd also make sure you don't have a broken wheel stud or something of that sort. I had 1 lugnut come loose a few years ago and the wheel would vibrate at random.

 

[craigr]

Carrier bearing on the drive shaft. The rubber isolator/dampener gets old and allows the drive shaft to spin out of balance. Would be a good item to take a close look at.

Thanks for all the suggestions guys.

Specifically regarding drive shafts. Are you talking about the mini-shafts (front and rear wheel drive shafts), or are you talking about the propeller shaft (transmission to rear diff)?

Thanks
craigr

 

[craigr]

Carrier bearing on the drive shaft. The rubber isolator/dampener gets old and allows the drive shaft to spin out of balance. Would be a good item to take a close look at.

I just did a pdf search of the service manual for "carrier bearing" and found nothing. Could you be referring to the "center bearing?" Below is a drawing from the service manual.

Thanks again
craigr

 

[flstffxe]

I just did a pdf search of the service manual for "carrier bearing" and found nothing. Could you be referring to the "center bearing?".....

one and the same. carrier bearing/hanger bearing/center bearing all depends on what the manufacture wants to call it.

They tend to vibrate more at highway speeds and under heavy loads, hard acceleration and deceleration.

If the bearing goes bad they can also throw the driveshaft out of balance. If it is the rubber isolator that has gone bad, they can get to the point that the driveshaft actually bounces around in the bearing mount.

I would also be giving the u-joints a good once over on the drive shaft.

 

[craigr]

one and the same. carrier bearing/hanger bearing/center bearing all depends on what the manufacture wants to call it.

They tend to vibrate more at highway speeds and under heavy loads, hard acceleration and deceleration.

If the bearing goes bad they can also throw the driveshaft out of balance. If it is the rubber isolator that has gone bad, they can get to the point that the driveshaft actually bounces around in the bearing mount.

I would also be giving the u-joints a good once over on the drive shaft.

THANKS.

It's always happened on the highway. I am also starting to feel that it happens usually after braking on the highway.

The sensation seems like what I would imagine a driveshaft slapping around in there would be. I've also not been able to tell if it's coming from the front or rear of the car, and the CB is right near the middle of the vehicle.

I will check this out when I get back home in a few days. It seems like a solid theory to me though, so here's hoping I find the problem. I need to order parts for the timing belt anyway.

craigr

 

[craigr]

one and the same. carrier bearing/hanger bearing/center bearing all depends on what the manufacture wants to call it.

They tend to vibrate more at highway speeds and under heavy loads, hard acceleration and deceleration.

If the bearing goes bad they can also throw the driveshaft out of balance. If it is the rubber isolator that has gone bad, they can get to the point that the driveshaft actually bounces around in the bearing mount.

I would also be giving the u-joints a good once over on the drive shaft.

I've been traveling by plane all over the country for work and hadn't had time to look into the car until yesterday.

I removed the heat shield to get to the center bearing and the bearing looked fine upon inspection. I removed the two bolts holding the bearing and lowered the drive shaft. The bearing rotates smoothly and the rubber is all intact. I don't know for sure what the center bearing rubber should be like in terms of stiffness, but it is solid and not at all torn up.

Could this issue still be the center bearing, or should I look into other options?

Thanks everyone again.

craigr

 

[SubieHo]

An intermittently stuck brake caliper can cause the symptoms you describe.

 

[craigr]

An intermittently stuck brake caliper can cause the symptoms you describe.

I think you may be the winner :icon_biggrin: but time will tell.

I have 103K on the car now and it is 90% highway. Because of this, I have never worn down the brakes and have never changed them. I decided it was time two days ago and installed new front pads.

When I went to remove the pads from the drivers side, the pads were absolutely stuck in there. It took a lot of work to get them free and I am pretty sure that they had been binding. I think I had binding brakes on the driver side. Passenger side came right out as is normal.

I sure hope that's it and I'll report back either way after I do some highway driving.

Thanks for the help again guys!

craigr

 

[craigr]

...incidentally, the front pads still had more than 1/3 of their life left. I really drive this car easy. I also got 65,000 miles on the factory Geolanders, and I think most folks here get only 1/10 of that usually. There was still ok tread on the tires when I replaced them.

craigr

 

[craigr]

800 miles and no trouble with the vibration after changing the front pads.

I did the timing belt today so the car is pretty happy.

craigr

 

[uk89camaro]

I think you may be the winner :icon_biggrin: but time will tell.

I have 103K on the car now and it is 90% highway. Because of this, I have never worn down the brakes and have never changed them. I decided it was time two days ago and installed new front pads.

When I went to remove the pads from the drivers side, the pads were absolutely stuck in there. It took a lot of work to get them free and I am pretty sure that they had been binding. I think I had binding brakes on the driver side. Passenger side came right out as is normal.

I sure hope that's it and I'll report back either way after I do some highway driving.

Thanks for the help again guys!

craigr

I glad the search button exists, I've had the same thing over the last week. Looks like I'll try the pads first, then a wheel balance, then the drivetrain..(really, really don't want anything going bad in there!!)

Thanks folks.

 

[JFC]

Final Outcome ?

Hi,

I would like to know if your brake pad fix was still successful since your last post.

I have been experiencing for 6 months what seems to be the vibration you described. Your post is probably the most relevant I have seen in all my research - there are not that many. I own a Forester 2008 manual with almost 30000 miles.

What I would add to your description is that the vibration would slowly build up before getting disturbing, then last for a few too many miles and disappear. My feeling is that I would not like to experience this on icy conditions and I would very much like to clear it before winter.

It would only occur on highways, around 60-70 mph, possibly triggered by a slight rocking motion on the steering wheel on some uneven surface (that's how I managed once to reproduce it). A strong cross wind might also help. The vibration would disappear after steering sharply in a way that cannot be done on the highway at highway speed (backing up a few feet on the highway shoulder seems to do fine). This may explain why it would never appear on long trips along secondary, thus winding, roads.

I have seen the dealer twice with no avail.

Lately, I have been wondering if it could be a wheel balance, natural resonance, problem caused by locking lug nuts getting in sync. The last time it occurred, I stopped as soon as I got off the highway, steering as little as possible. I found that both front locking lug nuts were aligned at exactly the same position. Problem is, why would it occur now and not last year ? I estimate that the vibration frequency is around 10 Hz.

Thanks for helping,

 

[smilingjack]

Ive had the same problem with my car. Subaru dont sell the bearing seperate - $1900 aus for a complete new tail shaft only. when all it needs is a flimsy piece of rubber replaced. eek!