Hi,

ever since I had the grease changed in the rear differential it is made some funny noises. Sounds very much like similar noise I heard on a 10 bolt positraction rear end I had on a car many decades ago. Kind of sounds like stretching the cable on pulleys like the old-fashioned parking brakes were. Any suggestions? Any idea why this would happen right after changing the oil?

thanks!!

 

This Torsen diff needs the proper gear oil, a 90-weight (or 75W-90 if you encounter colder weather), preferably API GL-5 rated. What did you use?

 

I took it to a local Speed shop and I think they know what they’re doing. Not really sure what they used.

 

I thought they had closed for Covid but they were just extremely busy. Yes they used the right stuff and it’s still making a bit of noise. I took one of their technicians for a drive and he said he thought it was just normal wear and tear. Anyone else know anything different?

thanks!

 

"Not really sure what they used"? I'd drain whatever in in there and put in something you know is correct. Takes less than a quart of SAE90 GL5 Hypoid Gear oil. Plenty of recommendations here.

-- Chuck

 

Any information about the noise?

 

It might not be the diff; the transmission output shaft bearings are notorious for galling and creating a loud whine.

With the car securely on jackstands, have a helper "drive" it gently in 3rd or 4th gear while you listen from underneath. You'll be able to tell very quickly whether it's the trans or the diff.

 

...and with unknown "grease" in the differential there's no telling what the noise might be. These are Torsen differentials will have different sounds based on how they work. Gotta admit I still don't understand how they work despite printing a 3D model of one and having it on my desk. But work they do.

-- Chuck

 

My assumption is that the noise is caused by something grinding together to create that specific resonance.

In seriousness...take a look and check. Its not plausible to do this online. Maybe a rotor dust shield? Maybe you're grinding your teeth? A million possibilities.

 

The grease was correct. I didn’t think it was really pertinent so we don’t have to worry about that now. The noise only comes on when I engage the clutch, usually in first gear or reverse. Here a little bit of clicking when turning but not always. I don’t think it’s anything constant.

thanks for the help.