Differential noise Problem!!!

[mcfattyfatfat]

Hey Guys,

I just replaced my diff fluid, I put in 75w90 sythentic into my 378LSD. I drove it about 20 KM and one day later I hear some rear end noise, like chattering/grinding, and I can feel it in the body as well as outside the car. I can recreate it when I am turning in circles, forward and reverse. I filled it right to the top and I cannot see any signs of leaking in my garage.

This obviously has to come a day before I have a trip planned, and so I have not even checked the level.

I am hoping that it could be something else, but is my diff toast? If there was an air pocket or something then I may have not put enough fluid, would driving 20Km be enough to screw it?

If it is screwed is it worth to get it rebuilt or just get one from the scrap?

Thanks in advance

[timothy100]

Did the gear oil you put in have limited slip friction modifier in it? I had the exact same problem. I installed my diff, drove it for a day or two, and it started making chattering noises while turning at slower speeds. You can buy the limited slip additive by itself, or some gear oils have it in there already. Read the label on the bottle carefully and it should say if it has it. I flushed the gear oil and put in Redline 75w90 with the friction modifier and haven't had any noises at all from that diff.

[delatlanta1281]

you need a modifier. it will clean up the noise. It is by the diff fluid.

[mcfattyfatfat]

No, I have not put a modifier in, I didn't know I needed it. I will now though.

Thanks a lot