Grinding sound from rear

[Osiris]

I hear a grinding sound from the rear when doing a sharp right turn. Went to the dealer; they said it's the differential and added / changed the oil in it. They said if the sound doesn't go away after 1000miles they would replace it. Any one got this, any thoughts?

[Dackelone]

Did you dealer use the Castrol SAF-XJ+FM oil? The +FM(friction modifier) oil has an additive that gets rid of this noise. There is nothing wrong with your diff... its just on tight(full lock) turns the diff's clutch plates will "chatter" and make this noise.

The cars come with the plain SAF-XJ oil from the factory.

IF you have the +FM oil in your diff... go to a empty parking lot and do 20 full lock turns to the LEFT and then to the RIGHT. That will coat the clutch disc in your LSD and the noise will be gone. In normal driving it will take a few thousand miles for the noise to go away. You should do some tight turns in a parking lot.

Castrol SAF-XJ+FM

[Osiris]

Thank you. That is very helpful. Will check what oil they put in and get in some turns.

[Dackelone]

Originally Posted by Osiris

Thank you. That is very helpful. Will check what oil they put in and get in some turns.

You could also look at this thread...

CORRECT 1M Fluids List [Engine, Transmission, Differential]...
http://www.1addicts.com/forums/showthread.php?t=620282

[Osiris]

I did see that thread. Just didn't know about the 1000 miles thing. I am not so worried about replacement since it's on extended warranty. I would rather not replace anything and keep it all factory original. But as usual your input was very insightful.

[Osiris]

Getting better after the miles and 20 turns. But still occasional can hear it once in a while. But once heard doesn't come back until the next ride. Any advice?

[Osiris]

Originally Posted by Dackelone

You could also look at this thread...

CORRECT 1M Fluids List [Engine, Transmission, Differential]...
http://www.1addicts.com/forums/showthread.php?t=620282

So I did change the fluid. Took a while but the diff grinding on slow right turn went. After diff schedule maintains it came back but fading away. Still there on occasionally with slow right turn. Any thoughts. Trying to decide before extended warranty expires. I prefer not to change diff.

[Dackelone]

Originally Posted by Osiris

So I did change the fluid. Took a while but the diff grinding on slow right turn went. After diff schedule maintains it came back but fading away. Still there on occasionally with slow right turn. Any thoughts. Trying to decide before extended warranty expires. I prefer not to change diff.

You never know what fluid a tech ends up using in your car. I would try the SAF-XJ +FM diff fluid and do some tight, full lock turns in each direction. Say 30 full lock turns in a empty parking lot in 1st or 2nd gear. Then after driving the car for another 400 miles... that diff clatter/chattering noise should go away.

But note that even IF your diff still makes some noises when parking or doing some tight turns at low speeds... that sort of noise is normal. It does not indicate that your diff is bad. It only indicates that the clutches inside the diff are working!


Liqui Moly and Lubegard both make FM(friction modifier additives)for use in clutch type diffs... You simply add it to your diff fluid.









http://www.amazon.com/Liqui-Moly-201...fferential+oil


http://www.amazon.com/Lubegard-31904...r+differential



Dackel