Whats wrong with my rear end?

[Beast Of Burden]

I changed the gear oil, added the friction modifier, when accelerating while turning at low speed, like pulling out of a drive way onto the road I get for lack of a better description I get a womp womp womp, and I can feel a vibration. Is the limited slip going out or is the whole rear end going? Its got 152,000 miles on it. Any help is greatly appreciated

[wiyrs]

u add motorcraft lsd add?

[Beast Of Burden]

I used Valvoline synthetic gear oil, it said that you dont need to use an extra additive, so I ran it for a while and noticed the womp in the rearend so I went back to NAPA and picked up there friction modifier, put it in and it still does it

[Beast Of Burden]

Ill go to Ford tomorrow and pick up there additive, should I drain and refill the diff or can I add the Ford stuff along with the stuff thats already in there?

[Degnol]

I'd drain and refill with what FoMoCo recommends.

[Beast Of Burden]

I put the Ford additive in it and it still does it. I hope I didnt wreck anything by not running it for about 2,000 miles with the NAPA additive

[hdfattboy2001]

I have the same problem in an 01 with 159000 on it, Changed with valvoline syn, put additive in, same problem, Everything looked great when i pulled my diff. cover off...

[Bad Night]

Same here . Just did this a couple months ago . Added friction modifier to the valvoline and it still does it . I figure it trashed the clutches in the ls. pack .

[Galaxie]

Sounds like you guys did take out the clutches in your diff. I did this in an 88 Mustang. Same thing, It was fine until I changed the fluid.

[hdfattboy2001]

man, i figured this was the problem, but didn't want to hear anyone agree with my thoughts! ha, whats the cost usually to replace the limited slip setups in these? I have put detroit lockers in my muscle cars that i know are reliable, but they cost me upwards of $750 just for the parts!