sixtyninestang

Hi, I just installed a used rear end with 3:55s in my 90 7up. I pulled the cover when I bought it, inspected the gears, and everything seemed okay. I followed everyone's suggestion on how much differential fluid to use, what weight, posi additive, etc. Took it for a ride, and driving straight down the road it was great. Everything nice and smooth and tight. Then I took a U turn, and heard this groaning sound. We thought something was rubbing, maybe the brakes, but it wasn't. I did both left circles and right circles in a parking lot, and the groaning persisted. Since there's no noise at all driving straight ahead, anyone have any suspicions about what's going on with it? Thanks for any help you can provide.

Bubba 95SN

Ford friction modifier?

sixtyninestang

I just saw a TSB (06-19-2) that describes my problem. Looks like I'm doing clutch packs. Any additional comments really help a lot. Especially things like, "Don't forget to put this in first..," "Get this thing out of the way or it will break" etc. Thanks guys

mjr46

if the rear has been sitting a while drive it around alot and give the clutch pack time to reabsorb the fluid/ modifier

sixtyninestang

I got that suggestion from the guy I got the rear from. It's not horrific, there's no shudder or anything, just that groan. Lovin the 3:55s with the AOD, it's a whole different car. Top end is great. Now I have to do something about the drag strip tranny with the shift kit that's in it. I'm looking at replacing it with a 5 speed because I can't get the clunk out of it when it shifts into OD (unless I have my foot in it in which case it shifts smoothly). Although I have noticed that with the gear change I don't need to get into OD unless I'm on the highway.