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2008 Subaru Legacy Vibration at wits end!

Posted By: racin4ds

2008 Subaru Legacy Vibration at wits end! - 06/13/18 12:23 PM

Hi guys, I'm looking for some advice. I consider myself a pretty decent mechanic, been turning wrenches for around 20 years and have many certs to go with it but I don't do it as a trade anymore.

Anyway, my wife's 2008 Legacy GT has had a vibration or "shimmy" that has been there since we acquired the car. I thought new tires and good balance would fix it but I was wrong. It occurs exactly at 62-65mph and seems to come and go... I've rotated the tires, checked for bent wheels etc. I've went up with air pressure and down. I've checked for wheel bearing play and tie rod play. Nothing in the front end seems loose. I'm convinced it is NOT the wheel/tire as it is still occurs exactly the same speed no matter which tire it where and done it with the old tires.

The only fault thats visible that I haven't addressed yet is a torn CV boot on the passenger side. I have a new axle and plan to do that this weekend.

Brakes and rotors were replaced with new powerslot kit about 10k miles ago. I'm getting ready to just rip the entire front end apart and replace everything but I'd like to avoid that if necessary...
Posted By: Chris142

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 12:38 PM

Bent or worn axle
Posted By: racin4ds

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 12:44 PM

But in my years of experience, a bad CV axle usually only rears its head on hard acceleration or sharp turns, neither of which mine does.
Posted By: Trav

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 12:59 PM

Inner CV joint problems can cause this on some Subaru, the boot looks perfect but the grease has turned to oil and the joint worn out. Did you check for rack play, internal movement and the mounting bushings?
Posted By: Oily_Thing

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 01:15 PM

Bad engine mount.
Posted By: krismoriah72

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 01:27 PM

Could be a few things..im a subaru guy..or was.

If its an aftermarket CV shaft there were issues with them not being balanced properly that was yrs ago.

Sticky or frozen caliper/piston

Bad hub or wheel bearing

Ball Joints

Bent Rim
Posted By: Danno

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 01:36 PM

I would listen to the 2 answers from the seasoned mechanics - and they point to an axle related issue.
Chris142 and Trav
Posted By: JohnnyJohnson

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 03:46 PM

This problem has been on going since the car was new and the Stealership never fixed it? I guess that's just one more reason not to buy a Subaru they ignore to many warranty issues.
Posted By: SubieRubyRoo

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 04:43 PM

Originally Posted By: JohnnyJohnson
This problem has been on going since the car was new and the Stealership never fixed it? I guess that's just one more reason not to buy a Subaru they ignore to many warranty issues.


Johnny, way to jump off the cliff without reading the details... he said it was present "since we acquired the car". Nothing mentioned at all about buying it new. And Subaru obviously isn't as horrible as you make them out to be, they've been awarded the vehicles with highest resale value like 3 times out of the past 5 years... people aren't willing to pay top dollar for used pieces of junk. Not like a new Dodge minivan, which loses something stupid like 83% of its value in the first 5 years...

OP, I had the same issue on my Odyssey two years ago, which showed up when I had snow tires on. At first, I thought it was the tires, so I rotated and rebalanced them to no avail. I called my brother who is also a mechanic, and said essentially the same thing as Trav; inner CVs. I checked and none of the boots were torn, but the vibration was getting pretty bad. I had both axles replaced, and voila, no more vibration at any speed.
Posted By: SatinSilver

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 05:12 PM

Looks like car was purchased 1/15/17:

Originally Posted By: racin4ds
Hi All,

Just picked up a nice little 08 Subaru Legacy GT 2.5 Turbocharged. Very nice little ride! I have no previous experience with a turbocharged gasoline car. It calls for 5W30 but I'm wondering since it is likely to abuse the oil more than a standard engine if I shouldn't run a 5W40 or 0W40 syn? In the diesel world most cars/trucks are running a 40W I guess due to viscosity breakdown from the extra heat.

Looking for thoughts and opinions from others with small, turbocharged vehicles. I could care less about CAFE/MPG. I want PROTECTION!

Also Subaru experts, anything I should be on the lookout for? Are these things reliable?
Posted By: Oldmoparguy1

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 05:34 PM

I had a similar issue on my 2000 Dodge GC some years ago. Was the original axle with 120k on the van. It looked fine. Finally, the boot cracked and it started slinging grease. Replaced with a new shaft and there was no more weird stuff. In my case it was the right shaft.

YMMV

Wayne
Posted By: racin4ds

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 08:36 PM

Yes car was purchased used- not new so no dealers involved.

I'm going after the axles this weekend so we'll see what that brings, thanks for the tips/advice gents!!

Overall, I love the car, it has 150k on the clock now and nothing has been done other than the turbo replacement when I bought it. (why I got it so cheap) It handles great, runs very well and is a blast to drive with the 5 speed.
Posted By: Trav

Re: 2008 Subaru Legacy Vibration at wits end! - 06/13/18 09:04 PM

I have 3 of those OE axles sitting right in the garage waiting for new inner joints (outer are perfect just reboot job with poly) I ordered from Europe. Every one of them a lube fail on the inner, perfect boots.
Posted By: sxg6

Re: 2008 Subaru Legacy Vibration at wits end! - 06/14/18 06:41 AM

Just a heads up.. If it's an AT legacy, I've heard that people have vibrations at idle with aftermarket cv axles. I understand that's not your current issue, but if you're putting an aftermarket in this weekend, that could happen. The vibration occurs when stopped in drive, but goes away if you shift into neutral.

Not sure what the culprit might be for your current vibration issue.
Posted By: ccs368

Re: 2008 Subaru Legacy Vibration at wits end! - 06/14/18 10:37 AM

I replaced both left and right side torn inner boots with Dorman universal silicone CV boots as they claim silicone is more heat resilient to poly boots. So far it has not torn after 1 year or 12K miles. It was for a 06 Outback with 95K at the time. The reason for boot replacement and not entire axle replacement was for the reasons posters mentioned above with aftermarket axles creating vibration or fitment issues plus cost. Allwheeldriveauto.com has an excellent write up just for this repair. Also, two well respected youtubers, south main auto and pine hollow diagnostics have videos depicting using OEM and not aftermarket axle replacements too. I followed pine hollow diagnostics video to separate the joint but keeping the green cup coupled to the transmission case. Maybe investigate if your axles were replacements with aftermarket too before you purchased car and systematically eliminate potential causes of your vibration issues.
Posted By: racin4ds

Re: 2008 Subaru Legacy Vibration at wits end! - 06/19/18 02:49 PM

UPDATE for those that care-

I pulled the pass. side apart over the weekend and replaced the OEM axle (denoted by the green cups and Subaru markings). I used a brand new Carquest brand axle which seemed of very good quality.

The car is still doing the exact same thing at the exact same highway speeds! I checked ball joints, tie rods, wheel bearings and everything while I was there and see nothing standing out at me. However I have began noticing a shimmy under braking, any chance I could have a bad rotor causing this? The rotors are slotted powerstop brand with less than 10k miles on them...
Posted By: Trav

Re: 2008 Subaru Legacy Vibration at wits end! - 06/19/18 05:13 PM

What about the other axle? Either side can cause this. If you suspect rotors throw a cheap set on the front and test it, all that drilling on the power stop may have caused an out of balance condition. shrug
Posted By: racin4ds

Re: 2008 Subaru Legacy Vibration at wits end! - 06/19/18 07:53 PM

Originally Posted By: Trav
What about the other axle? Either side can cause this. If you suspect rotors throw a cheap set on the front and test it, all that drilling on the power stop may have caused an out of balance condition. shrug


Trav- I haven't replaced the drivers side axle yet since it still seems to be in perfect condition and its OEM Subaru. I think I'll try the rotors next since thats a cheap and much less labor intensive thing to try out. If that doesn't do it, I guess I'll go ahead and swap out the drivers side axle...
Posted By: Trav

Re: 2008 Subaru Legacy Vibration at wits end! - 06/19/18 08:29 PM

They look perfect but if you move the inner joint around you can feel if it isn't smooth operating before swapping it. If its nice and smooth its fine, any sort of roughness and its toast.
Who knows, it could be something funky with the rotors.
Posted By: 2002 Maxima SE

Re: 2008 Subaru Legacy Vibration at wits end! - 06/20/18 02:05 AM

Alignment? I had a slight vibration above 60 mph after I replaced the outer tie rod ends on my Taurus. The shop found it was out of alignment.
Posted By: chrome

Re: 2008 Subaru Legacy Vibration at wits end! - 06/20/18 03:47 AM

Have you checked the central drive shaft, or prop shaft? They are balanced with thin pieces of steel tack welded to the shaft, and rust can sometimes dislodge these causing the shaft to be out of balance.
Posted By: racin4ds

Re: 2008 Subaru Legacy Vibration at wits end! - 06/20/18 01:11 PM

Originally Posted By: chrome
Have you checked the central drive shaft, or prop shaft? They are balanced with thin pieces of steel tack welded to the shaft, and rust can sometimes dislodge these causing the shaft to be out of balance.


This I haven't looked at! I wouldn't think it would cause the shimmy I'm experiencing so heavily in the steering wheel though?

Thanks, something else to look into though!
Posted By: chrome

Re: 2008 Subaru Legacy Vibration at wits end! - 06/20/18 11:25 PM

If you still experience vibrations after going through everything, you can dive deeper into the diagnostic using a vibration meter. It may be something you can rent affordably from a specialty instrumentation shop.

The meter can measure the vibration frequency of the shimmy when you drive at the speed where it is felt the most. Working backwards, you can then identify the rotational speed which a first order or second order harmonic is occurring. You can then correspond this rotation speed with various components on the drive train. Engine, prop shaft and drive axles all turn at different rpms at the same road speed due to gearing, so you can identify which is the main culprit using this method.
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