Welcome to the North American Subaru Impreza Owners Club Friday December 14, 2018
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Go Back   NASIOC > NASIOC Technical > Service & Maintenance

Welcome to NASIOC - The world's largest online community for Subaru enthusiasts!
Welcome to the NASIOC.com Subaru forum.

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, free of charge, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!

If you have any problems with the registration process or your account login, please contact us.
* Registered users of the site do not see these ads. 
Reply
 
Thread Tools Display Modes
Old 09-18-2018, 09:24 AM   #1
fly_25
Scooby Newbie
 
Member#: 467978
Join Date: May 2017
Default Deep/low aggressive vibration at certain speeds

Good morning all, my 2004 outback has a very aggressive vibration that can be felt in the seat at 80-90 km/h, not faster and not slower. It seems to get worse when I let off the gas within these speeds as the vehicle coasts. It's not engine related and I can't really feel anything in the gear shifter either (manual trans). Any ideas as to what could cause this? Also I swapped the wheels for a different set and still same problem
* Registered users of the site do not see these ads.
fly_25 is offline   Reply With Quote
Sponsored Links
* Registered users of the site do not see these ads.
Old 09-18-2018, 02:30 PM   #2
yarrgh
Scooby Specialist
 
Member#: 80465
Join Date: Jan 2005
Chapter/Region: RMIC
Location: Bailey, CO
Vehicle:
2001 2.5RS
Black Diamond Pearl

Default

Isolate the engine from the transmission. Get faster than the vibration speed, clutch in, and coast down through the vibration speed. See if anything changes. If not, it's definitely in the drivetrain. Given the observations, it's likely not the engine, this will confirm that.

One thing aside from wheel imbalance could be a driveshaft imbalance. You may have to get underneath, slowly rotate the driveshaft by hand (in neutral, rear wheels off the ground) and look for any sort of external balancing weight that's missing.

Look for any bushings in the drivetrain that are worn/missing. Rear diff, trans, and engine mounts are all I can think of at the moment.
yarrgh is offline   Reply With Quote
Old 09-19-2018, 01:27 PM   #3
fly_25
Scooby Newbie
 
Member#: 467978
Join Date: May 2017
Default

It's definitely not engine related, I've had clutch in, out, coasting, nothing the engine does helps the vibration. Although the vibration is considerably worse when let off the gas and put the car under no load. I didn't notice any missing weights or anything unusual about the driveshaft, but what I did notice is that the driveshaft does not look like the stock driveshaft for this car. It's still a 2 piece with the carrier bearing but it just has a different design, maybe from another type of Subaru? Could the different driveshaft design cause the vibration?
fly_25 is offline   Reply With Quote
Old 09-19-2018, 03:44 PM   #4
Charlie-III
NASIOC Supporter
 
Member#: 30669
Join Date: Dec 2002
Chapter/Region: Tri-State
Location: USA, North NJ, 07456
Vehicle:
1998 Legacy 2.5GT
Silver Sleeper BK, 5MT

Default

Quote:
Originally Posted by fly_25 View Post
It's definitely not engine related, I've had clutch in, out, coasting, nothing the engine does helps the vibration. Although the vibration is considerably worse when let off the gas and put the car under no load. I didn't notice any missing weights or anything unusual about the driveshaft, but what I did notice is that the driveshaft does not look like the stock driveshaft for this car. It's still a 2 piece with the carrier bearing but it just has a different design, maybe from another type of Subaru? Could the different driveshaft design cause the vibration?
Could it be?
Sure.

If it was fine before but sucks now, I will assume it was fine.
Maybe center carrier failed. In general, no decent way to fix that other than replace DS.

Stupid check, make sure DS hardware is snugged up.
Minimal play in DS (hard reach around exhaust, etc......).
Decide or check back.

A Subaru center bearing support is hard to do on your own. Really need to replace.
Yes, penny pincher hardcore may find a way, but........forget about it.
Charlie-III is offline   Reply With Quote
Old 11-11-2018, 09:49 PM   #5
fly_25
Scooby Newbie
 
Member#: 467978
Join Date: May 2017
Default

Bring this back, I was spending my time looking for a driveshaft and finally swapped out the driveshaft but the problem remains, same speeds, and vibration. So it was not the driveshaft that was the issue. Anyone ever experienced something like this?
fly_25 is offline   Reply With Quote
Old 11-12-2018, 12:12 PM   #6
Broxh
Scooby Newbie
 
Member#: 415302
Join Date: Mar 2015
Vehicle:
2016 WRX
DMG

Default

Have you changed your tires? Sounds like one could be slightly out of balance
Broxh is offline   Reply With Quote
Old 11-12-2018, 12:17 PM   #7
fly_25
Scooby Newbie
 
Member#: 467978
Join Date: May 2017
Default

Changed them out and still no change. I'm thinking maybe a rear CV joint? I don't feel any vibration in the steering wheel at all, only the seat and a low vibration sound
fly_25 is offline   Reply With Quote
Old 11-12-2018, 11:39 PM   #8
jasonwrx86
Scooby Newbie
 
Member#: 472037
Join Date: Jul 2017
Chapter/Region: MWSOC
Vehicle:
2018 WRX Limited
CWP

Default

Could it be bad shocks?
I have seen cars with bad shocks the tires would bounce violently at highway speeds.
jasonwrx86 is offline   Reply With Quote
Old 11-13-2018, 12:20 AM   #9
fly_25
Scooby Newbie
 
Member#: 467978
Join Date: May 2017
Default

Could have been that if the vibration was at 100km/h and higher but it's only within 80-100 the car vibrates only when I let off the gas
fly_25 is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

All times are GMT -4. The time now is 11:12 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2018 Axivo Inc.
Copyright ©1999 - 2017, North American Subaru Impreza Owners Club, Inc.