After backing out of my driveway,I put my car in drive and as I start to pull forward I hear a noise coming from the rear of the car that sounds just like when an automatic equipped car is put in 'park' while the car is moving. It only lasts about two seconds and it doesn't happen everytime I pull forward...only when I have previously moved the car in reverse. It also does not always happen after using reverse. Any ideas? Thanks.

That sounds like the posi clutches are chattering. You can try changing the fluid in the rear. Make sure it's name brand and made for lockup diffs. I run Red Line but Royal Purple or others will work. Also check with your local parts store, there are some additives that may also do a quick fix.

Thanks 396c4,the car has 66,000 miles on it..(I bought it last May) so I'm not sure how old the fluid is. I'm getting ready to change out all the u-joints so I might as well change the fluid while I'm down there. Thanks

Try driving in figure 8s, both directions before you do anything else.

Thanks blacksharkL-82. I need to buy an owners manual for it also. I'll give the figure -eight a try. I'm in North Dakota so it will be a while before I can get it out of the garage...we just had about a foot of snow yesterday and today it's -5 outside. Are you thinking that the posi  parts are sticking? Is this a common positraction problem? Thanks

Posi clutches usually don't "chatter" like that unless you're turning. If you are backing straight back, and pulling straight forward, the problem may be something else...perhaps something in the park brake, or u-joints. Could also be a problem with the ABS system, or one of the wheel speed sensors. However, I have to assume you are backing up, then turning to go forward...or else you are just going in/out of the garage!
Try the posi additive first, and see how that works.Chatter in the clutches is usually more common after driving forward for a while, then stopping, and turning.

|UPDATED|2/27/2012 3:14:14 PM (AZT)|/UPDATED|

Thanks adams apple. I'm agreeing with you on this noise since I'm backing out of the driveway and turning,then turning as I move forward. Thanks