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#Another driveline vibration thread (long)

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 Post subject: Another driveline vibration thread (long)
PostPosted: Sat Aug 13, 2016 5:37 am 
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Joined: Sat Mar 29, 2003 5:57 am
Posts: 60
Location: Omaha, NE
I'm starting this thread as mostly an informational post regarding a vibration starting around 60mph and peaking at 65, then tapering a bit the faster it goes. And hopefully a good outcome without throwing a bunch of unnecessary parts at it. Here's my history with the car-

I was working for a transmission shop at the time, about 3-4 years ago, and a customer brought in is 93 legacy turbo wagon that wouldn't move. Turns out the front diff had grenaded itself. The ring and pinion gears were destroyed, and the diff case itself had cracked around the side bearings. I ended up purchasing the car and fixing it to be my daily driver. It sat for a year and a half or so till I ended up having the time to fix it. It had 3 different size tires on it so they got replaced immediately.

I don't really know for sure if the vibration was there all along, but I started to notice it getting outside the range I would call normal a year ago. Now it is so bad the whole car shakes violently above 60 and it buffetts, almost like a back window is rolled down a few inches.

The pads and rotors were shot so they had to replaced anyways. The tires have been balanced 3 times since 2014 with no change. I was able to borrow an electronic vibration analyzer (EVA2) from another shop. Got it all set up with the sensor on the seat rail and it picked up a pretty intense first order driveshaft vibration. (50 Hz, .14 g's at 65mph). On the hoist, I removed the wheels and secured the rotors to the hubs with a full set of extended lug nuts. Run it up and the same vibration is being picked up. I checked the runout on both sections of the shaft while mounted in the car in two separate places for each shaft. The front is .010" and the rear is .028" which seems a bit high but the Astro vans (which are horribly notorious for vibrations) allow up to .040. Naturally Subaru doesn't publish their specs. The next step was checking the frequency closer to the shaft so I could attempt to balance it with the EVA2's strobe function and hose clamps. I placed the sensor on the rear diff carrier but this time the frequency is 22 Hz at 65mph, totally different. I think the gears meshing in the diff was throwing off the readings. I was running out of time for the day so I just took the rear section off to eliminate everything behind the carrier bearing. Same vibration. At this point I had to start putting things back together so I could drive the car home.

Hopefully in the next week or so I'll be able to pick at it some more and get this narrowed down. The whole point of all this is I don't want to waste hundreds of dollars in parts that will not fix the problem (like I've read a ton of other people do). I'll share more info when I get it pinpointed. In the meantime if anyone else has any suggestions by all means speak up!

Jim


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 Post subject: Re: Another driveline vibration thread (long)
PostPosted: Sun Aug 21, 2016 8:28 pm 
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Jim,

Thanks for sharing this information. Are you positive the vibration is coming from the driveline? I had an intermittent vibration that sometimes was pretty nasty when my car was FWD. It went away after my AWD swap and the only thing I could hypothesize as the culprit was the CV axles. The boots had ripped, were cleaned, and repacked with grease. However I think I had run on them long enough to possibly cause irreparable damage.

Anyway, keep us posted of your findings but I did want to share my experience.

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Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
1997 Impreza OBS

If you need to get a hold of me please email me rather then pm


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 Post subject: Re: Another driveline vibration thread (long)
PostPosted: Wed Aug 31, 2016 6:08 am 
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Joined: Sat Mar 29, 2003 5:57 am
Posts: 60
Location: Omaha, NE
I'm not totally sure yet. I did take off the rear stabilizer bar during all this due to a different issue and the intensity of the vibration has dropped significantly. The next step I think is to swap the wheels and tires off my Impreza since it drives so damn smoothly. The tires on the legacy are year old goodyears but I've read people having issues with them being out of round. If it goes away when swapping, the next step will be to have them match mounted and road force balanced. We've been super busy lately I haven't had a chance to mess with it. The ej255/7's around here are dropping like flies and we can't keep up.


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 Post subject: Re: Another driveline vibration thread (long)
PostPosted: Mon Sep 26, 2016 6:05 pm 
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Just checking in to see if you were able to figure out the source of the problem or not.

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Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
1997 Impreza OBS

If you need to get a hold of me please email me rather then pm


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 Post subject: Re: Another driveline vibration thread (long)
PostPosted: Mon Sep 26, 2016 6:31 pm 
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Joined: Sat Mar 29, 2003 5:57 am
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Location: Omaha, NE
I haven't. We've got 6 ej205/255s in line that need engine rebuilds on top of our normal work. Our own cars are always the last ones to get worked on it seems!


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 Post subject: Re: Another driveline vibration thread (long)
PostPosted: Mon Sep 26, 2016 6:36 pm 
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Yeah, I can understand that.

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Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
1997 Impreza OBS

If you need to get a hold of me please email me rather then pm


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 Post subject: Re: Another driveline vibration thread (long)
PostPosted: Mon Oct 10, 2016 3:22 pm 
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Joined: Sat Mar 29, 2003 5:57 am
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Location: Omaha, NE
Well, I feel kind of stupid. Ever since I bought the car 20k miles ago, its also had a shudder and rattle from take off when making a sharp turn. Over the last week it seemed to get a lot more pronounced. I raised it up and grabbed the carrier bearing and it was flopping up and down. The bottom half of both carrier bearing bushings were installed upside down. I had checked this before but I wasn't able to move them. They finally wore to the point where I could move them by hand. Flipped them around and no more shudder. I have yet to get it above 60 to see if it fixes my vibration.


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 Post subject: Re: Another driveline vibration thread (long)
PostPosted: Mon Oct 10, 2016 6:00 pm 
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Well hopefully that fixes it.

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Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
1997 Impreza OBS

If you need to get a hold of me please email me rather then pm


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 Post subject: Re: Another driveline vibration thread (long)
PostPosted: Sat Jun 10, 2017 4:03 am 
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Joined: Sat Mar 29, 2003 5:57 am
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Location: Omaha, NE
Well, I feel embarrassed. It was the nearly new Goodyear tires. I recently picked up an almost identical car as mine, except it's a sedan, with decent bridgestone tires on it. I figured 'What the hell, what have I got to lose' so i switched sets, and the vibration is completely gone. Despite having the Goodyears balanced three times in less than 10k miles and it didn't matter how I rotated them


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 Post subject: Re: Another driveline vibration thread (long)
PostPosted: Thu Jun 15, 2017 6:11 pm 
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Well at least you know what it is now. You could try and take them back or get a credit for new tires.

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Josh

surrealmirage.com/subaru
1990 Legacy (AWD, 6MT, & EJ22T Swap)
1997 Impreza OBS

If you need to get a hold of me please email me rather then pm


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