'91' XJ, rear diff (trak-loc diff) noise on sharp turns

Is the noise a low groan, banging, or something else? Is it worse on left or right turns, backwards or forwards, tighter or straighter? Are you running synthetic diff oil? How about friction modifiers?

The trak-lok diff is just a wet-plate style LSD made by Dana with a fancy name attached by the marketing types. If it sounds and feels like one axle is winding up against the other and then letting go with a bang you can hear and feel, or it's a low moan/groan that increases with more steering lock then it's probably what we call diff-chatter. That's when the clutch plates stick and then slip - when one axle is trying to turn faster than the other - and don't run smoothly. Usually caused by glazing and/or synthetic or "dry" oils. If you are running a synthetic oil (never recommended with any cone or plate style LSD but sometimes specified by the OEMs due to temp issues) try adding a friction modifier such as Mobil 3022L or Sturaco 7098. Warning, do not use more than the recommended dosage (as a % of oil) as friction modifiers tend to be pretty aggressive on seals (especially at higher temps) and more does not generally improve performance. From memory the Mobil should be about 2-3% and the Sturaco about 6% of total fill. My advice - drain the oil fully (hot) and then replace it with a good brand LSD mineral oil (LSX90 or similar) and see how that goes.

Good luck.... Clax.

The noise happens intermittently on sharp left hand turns (like U-turns). I don't know what the stealership mechanics put in the differential, but they supposedly rebuilt it.

-Bill (remove "botizer" to reply via email)