Welcome to the North American Subaru Impreza Owners Club Monday July 28, 2014
Home Forums WikiNASIOC Products Store Modifications Upgrade Garage
NASIOC
Here you can view your subscribed threads, work with private messages and edit your profile and preferences Home Registration is free! Visit the NASIOC Store NASIOC Rules Search Find other members Frequently Asked Questions Calendar Archive NASIOC Upgrade Garage Logout
Go Back   NASIOC > NASIOC Technical > Transmission (AT/MT) & Driveline

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 04-14-2013, 11:25 PM   #1
gsla72
Scooby Newbie
 
Member#: 224573
Join Date: Sep 2009
Chapter/Region: TXIC
Vehicle:
2002 Wrx Wagon
Midnight Black Pearl

Default Drivetrain Knocking Sound

Lately my 02 wagon has started making a horrible knocking banging sound when decellerating from about 50-30 mph. The noise definitely feels like it's coming from the rear of the car, and it goes away if the clutch pedal is pressed in. It also occasionally clunks when shifting gears normally. I've taken it into a shop after making sure everything was tight, and they guessed it might be the rear dif but weren't sure. Any ideas before I start throwing parts at it?

Relevant mods/info:
Kb outrigger bushings (comfort)
Tic rear diff bushings (comfort)
Gear oil changed in dif 6 months ago (extra-s)
Stock driveshaft/rear end
Cv joints had no torn/damaged boots


Update: Noise was coming from the transmission or the clutch/flywheel assembly. All three were replaced and the decel noise is gone.
* Registered users of the site do not see these ads.

Last edited by gsla72; 07-16-2014 at 10:30 PM.
gsla72 is offline   Reply With Quote
Old 04-15-2013, 07:40 PM   #2
dkmImpreza
Scooby Newbie
 
Member#: 318115
Join Date: Apr 2012
Chapter/Region: E. Canada
Location: Montreal
Vehicle:
2007 Impreza 2.5i
Pearl Blue

Default

I'm having the same problem, especially when it's cold. When I down shift and go through a bit of a bumpy road. I hear a knocking sound somewhere in the hand-break and glove box area.

I wonder what is causing this sound?
dkmImpreza is offline   Reply With Quote
Old 04-15-2013, 08:29 PM   #3
Umadbroej26
Scooby Newbie
 
Member#: 352405
Join Date: Apr 2013
Location: Oddville kentucky
Vehicle:
1996 Mutt
Exotic sea

Default

Check drive shaft joints
Umadbroej26 is offline   Reply With Quote
Old 04-15-2013, 08:30 PM   #4
Umadbroej26
Scooby Newbie
 
Member#: 352405
Join Date: Apr 2013
Location: Oddville kentucky
Vehicle:
1996 Mutt
Exotic sea

Default

Quote:
Originally Posted by gsla72 View Post
Lately my 02 wagon has started making a horrible knocking banging sound when decellerating from about 50-30 mph. The noise definitely feels like it's coming from the rear of the car, and it goes away if the clutch pedal is pressed in. It also occasionally clunks when shifting gears normally. I've taken it into a shop after making sure everything was tight, and they guessed it might be the rear dif but weren't sure. Any ideas before I start throwing parts at it?

Relevant mods/info:
Kb outrigger bushings (comfort)
Tic rear diff bushings (comfort)
Gear oil changed in dif 6 months ago (extra-s)
Stock driveshaft/rear end
Cv joints had no torn/damaged boots
So the diff is tight? Check trans mount and drive shaft joints
Umadbroej26 is offline   Reply With Quote
Old 04-15-2013, 08:43 PM   #5
gsla72
Scooby Newbie
 
Member#: 224573
Join Date: Sep 2009
Chapter/Region: TXIC
Vehicle:
2002 Wrx Wagon
Midnight Black Pearl

Default

The rear end seemed ok when I popped the inspection cover, and the fluid was in decent shape with no metal flakes. Is there any other check I could do? Is there any procedure for checking the driveshaft out?
gsla72 is offline   Reply With Quote
Old 04-15-2013, 09:56 PM   #6
Umadbroej26
Scooby Newbie
 
Member#: 352405
Join Date: Apr 2013
Location: Oddville kentucky
Vehicle:
1996 Mutt
Exotic sea

Default

Just check to see if the joints have any play
Umadbroej26 is offline   Reply With Quote
Old 04-15-2013, 10:02 PM   #7
Umadbroej26
Scooby Newbie
 
Member#: 352405
Join Date: Apr 2013
Location: Oddville kentucky
Vehicle:
1996 Mutt
Exotic sea

Default

Also check to see if the diff is loose in the mounts
Umadbroej26 is offline   Reply With Quote
Old 04-19-2013, 12:03 AM   #8
gsla72
Scooby Newbie
 
Member#: 224573
Join Date: Sep 2009
Chapter/Region: TXIC
Vehicle:
2002 Wrx Wagon
Midnight Black Pearl

Default

Just an update. Replaced the rear diff with a used unit and I'm still getting the noise. Either the used differential I bought is also bad, or the driveshaft is out. I'm going to find a used driveshaft and see if that fixes it.
gsla72 is offline   Reply With Quote
Old 04-19-2013, 10:03 AM   #9
Umadbroej26
Scooby Newbie
 
Member#: 352405
Join Date: Apr 2013
Location: Oddville kentucky
Vehicle:
1996 Mutt
Exotic sea

Default

It's the last thing left
Umadbroej26 is offline   Reply With Quote
Old 04-22-2013, 02:05 PM   #10
Zefy
Scooby Specialist
 
Member#: 105104
Join Date: Jan 2006
Chapter/Region: VIC
Location: Coquitlam, BC, Canada
Vehicle:
1979 BRAT / 01 RSTI
99 2.5TS (DEAD) / 87 GL

Default

Quote:
Originally Posted by gsla72 View Post
Just an update. Replaced the rear diff with a used unit and I'm still getting the noise. Either the used differential I bought is also bad, or the driveshaft is out. I'm going to find a used driveshaft and see if that fixes it.
it sounds like you're on the right track but also check your outrigger bushings. If a rock or something gets jammed in there it can make one hell of a racket while decelerating and shifting... Also the metal plates that bolt the outriggers to the chassis can bend if you put jackstands under them. It can really sounds like your diff is exploding.
Zefy is online now   Reply With Quote
Old 05-22-2013, 02:13 PM   #11
gsla72
Scooby Newbie
 
Member#: 224573
Join Date: Sep 2009
Chapter/Region: TXIC
Vehicle:
2002 Wrx Wagon
Midnight Black Pearl

Default

Driveshaft just replaced, still making noise. It seems to get worse the hotter it gets. I geuss I'll try replacing the outrigger mounting plates next.... Either that or the replacement rear diff is bad.
gsla72 is offline   Reply With Quote
Old 05-23-2013, 10:23 AM   #12
South Bend Clutch
Former Vendor
 
Member#: 269525
Join Date: Jan 2011
Location: South Bend, In
Vehicle:
2005 350z
black

Default

get the car up on a lift and have someone inside with the car running. Have them shift through gears. You should be able to see trans, engine, diff movement if it's a mount.
South Bend Clutch is offline   Reply With Quote
Old 12-29-2013, 10:47 AM   #13
gsla72
Scooby Newbie
 
Member#: 224573
Join Date: Sep 2009
Chapter/Region: TXIC
Vehicle:
2002 Wrx Wagon
Midnight Black Pearl

Default

Update on this. I replaced the rear end with a low mileage R180 and hybrid rear cv joints (I had wanted to do this with plans of upgrading to a six speed later on). The noise is still there but dosent seem as bad. It's still definitely located in the rear of the car. I'm guessing outrigger bushings or something along those lines. I'm slowly running out of parts to change out, and no one seems to know what it could be.
gsla72 is offline   Reply With Quote
Old 06-27-2014, 04:53 PM   #14
gsla72
Scooby Newbie
 
Member#: 224573
Join Date: Sep 2009
Chapter/Region: TXIC
Vehicle:
2002 Wrx Wagon
Midnight Black Pearl

Default

Update for anyone interested. I'm beginning to think this is a failed/failing center diff or center diff bearing. Since my 4th gear grinds a little when it's warm anyway, I've decided to go six speed. I've wanted to do a 6mt since I bought the car, so it will all work out.

I have a low mileage 06 sti transmission, brand new clutch, flywheel, etc all waiting to go in. I'll update this once it's up and running with the new equipment. Hopefully this takes care of the noise.
gsla72 is offline   Reply With Quote
Old 07-16-2014, 10:30 PM   #15
gsla72
Scooby Newbie
 
Member#: 224573
Join Date: Sep 2009
Chapter/Region: TXIC
Vehicle:
2002 Wrx Wagon
Midnight Black Pearl

Default

Update: It seems the noise was in the transmission or in the clutch for anyone having the same issue. No longer have a knocking sound when decelerating. However, I'm worried my 6 speed has a different issue, but I'll address that in a new thread.
gsla72 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 06:59 PM.


Powered by vBulletin® Version 3.7.0
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Powered by Searchlight © 2014 Axivo Inc.
Copyright ©1999 - 2014, North American Subaru Impreza Owners Club, Inc.