XKE S2 OTS Driveline Whine

[TRDejaVu]

The problem; the car has a driveline whine and strangely I can't decide if it is the gearbox or diff. I think that the sound is also being transmitted along the prop-shaft tunnel.

Symptoms:
Generally all is good and quiet until I slip the car into 4th then the whine develops as I go onto the gas. When I lift off all goes nice and silent again. If I take the car above about 50 the whine seems to disappear; I realize that I might just be leaving it behind along with the exhaust note. HOWEVER, at the lower speeds in 4th, if I change down to 3rd I think that I can still hear it, but not as pronounced.

When I first got the car I drove it about 30 miles up to Lippincott's for the structural work. I don't remember this whine being present. Since then I have:
- had Terry replace the diff pinion seal
- replaced the diff oil with Valvoline 80W-90 gear oil and Trans-X Posi Trac limited slip diff gear oil additive (recommended by Terry)
- replaced the gearbox oil with Gm synchromesh Trans Fluid (again recommended by Terry)

Predominantly only in 4th would suggest a gearbox issue, but then again maybe it is diff RPM related as the pinion nut was disturbed.

Any thoughts.

Thanks.

 

[LarryK]

Since nothing was bothered but the pinion nut. It's possible it could be a pinion bearing noise. Possibly related to what torque specs were used to retighten nut. Best way to find noise would be on a lift and use a stethescope. Because it is only on acceleration look towards the pinion.

 

[TRDejaVu]

Thanks Larry.