Stang49

Lately I've noticed my car making a squeak squeak squeak sound. It is easier to hear at low speed and picks up with speed. I changed the brake pads and rotors but it didn't fix it. I jacked up the car and rotated the tires and listened. The sound was coming from the rear end. I disconnected the driveshaft and the noise remained. I put wd40 on the pinion flange where it connects to the differential and the sound went away. I decieded to grease it real good. I took it for a drive and the sound came back. What could cause this? I've isolated it to the diff but wouldn't it mean it was a problem on the outside of the diff it spraying it fixed it?

Stang49

Fixed it. I decided to try changing the diff fluid. No more squeak.

tx_zstang

did you put friction modifier in as well? that'll prevent low-speed turning groaning.

alkemist

Depends on the oil.. friction modifier may not be required.

157dB

GT - Modifer needed
Unless you can URL some diff fluid that
has the friction modifier in it already...
http://www.stangnet.com/mustang-foru...-modifier.html

wish the OP would really tell more instead of 'its fixed' and not
what type/brand of fluid fixed it....

I drained that 'good for 100,000 miles' synthetic OEM crap at
30K miles and went with the Royal Purple and Lucal Oil Stabilizer.
The synthetic had absorbed so much water from the atmosphere
that it was milky in appearance and as thin as water.

ps throw the WD-40 away
it is probably is going to cost you a pinion seal and a pinion
crush sleeve in the near future...

Whitehorse10

Had you never changed your diff fluid before this?

alkemist

http://www.americanmuscle.com/royalp...0-gearoil.html

My installer recommended friction modifier just for extra security, but it was not required.

157dB

http://www.motorz.tv/blog/2668/ford-f150-gear-swap/

They used RoyalPurple and added the friction modifier as well
(even though the diff didnt appear to have any T-Lok in it)...