Humming noise from chase + sweating "T" gear box

[plopband]

2001 gold baby, with 11500 miles, runs super.

Recently replaced 4 tires. Before and after new tires on, I can hear a humming (actually supper fast rhythm drumming) noise from the chase when it goes above 50 mph on a CURVED (only on a curved road) road. No viberation is detected when the noise is on. Need diagnosis form experts!

I checked the "T" gear box. Found oil "sweating" outside the box and dropped on the plastic pan, but not on the ground. It seems that the leaking is from the seal on the passenger side drive shaft. The gear fluid was changed 6 months ago, with half transmission fluid and half regular gear oil mixed. Currently the oil level is right on the plug hole.

Do I need to do anything with the gear box?
Is the noise related to type of gear box fluid?

[plopband]

Anybody had this kind of experience? Need recommandation! Thanks.

[BillAileo]

I'm not really sure I'm following what you are talking about as the "T" gear box. Do you mean the bevel gear which is also sometimes called the angle gear? If you replaced the fluid in that with half transmission fluid and half regular gear oil mixed I think you made a mistake. The bevel gear should have nothing but a full synthetic gear oil in it. The Volvo part number is 1161648 but any full synthetic 75W90 gear oil should do fine. Using a full synthetic is very important in the bevel gear because of the high temperatures it reaches. Of course, if the bevel gear has been damaged, adding the corerct lubricant now isn't going to fix it.

Bill

[plopband]

It is bevel gear box. I will have it checked.