Thumping Noise When Turning

[mnredfox]

Hi folks, newbie here need some help.  I have a 2001 Legacy Subaru GT Wagon.  It has MT and 124K miles.  I've keep up on all required maintenance and all major service/repair done at dealer.

 

Recently an intermittent problem has developed.  After driving for awhile (~15-20 min or longer) when I turn left or right the car makes a thumping/whumping or clunking noise that causes the car to judder/jerk slightly.  This is repeated for what appears to be every rotation of the wheels.  The noise/vibration feels in the middle (not isolated to left or right) and is related to the wheel speed (faster the car moves faster the noise).  It happens left turn and right turn, and happens when my car is in gear or not (whether I step on the clutch in the turn or not is irrelevant).

 

I've called a few folks and read a bunch online and the guesses are all over the board from suspension related (sway bar, CV joint, ball joints, tie rod, strut, control arm) to mounts (engine) to axle to differential.  I called a few folks in town and they all say things all over the board (some swear it's CV/ball joints another thinks it's diff).

 

My guess is it's transmission/diff related since it cause the car to shake and only happens after warm up (fluid or metal related after expansion due to heat).  There is no diff leak and the fluid seems fine.

 

Any thoughts?

 

 

[MilesFox]

Search for "torque bind" or "Duty C solenoid"

 

Perhaps changing the trans fluid may help.

 

Make sure all the wheels are the same size and type, and all of them are within 1/4" in circumfrence from eachother.

[chaz345]

If it's  during relatively sharp turning then I'd agree that it's probably torque bind.

 

Does the AT Temp light ever flash several times on startup? If so then it's almost definitly torque bind and is most probably the duty C solenoid.

Edited June 10, 2013 by chaz345

[mnredfox]

Thanks for your replies.  I drove it around the city (live in San Fran) for 45 minutes and it didn't appear.  Had to drive another 20 min at high speed on highway to get it to return.

 

Brought to dealer and had a service manager and tech drive the car around the block, both think it is the center differential.  They said they'd call with a prelim estimate and shop around.  They said it's something they've seen but not often.

 

Trans fluid was changed at 118K (1 year ago) and has been changed religiously per Subaru's recommended intervals (every 30K).  Fluid is not low (just checked few days ago) and tires are all the same and rotated every 7500 miles.  Treads are all even within 1/32" (per last check).

 

I don't think I have any AT light.  When you say Torque bind do you think that's differential?

 

Thanks.