Rear end chatter...
 

Long story...

Short version...

Does this sound like the factory limited slip going out?

When ever my wife turns, or accels hard you get a bad shutter, its been getting worse over the last few months.

Took the rear end apart and everything looks fine, but while its up on jack stands its extreamly hard to turn the wheels and will chatter like it does when your driving (altho much slower). Its the only thing I can come up with that would cause this issue.

When I changed the fluid about 3 years ago, I did not add the friction modifier. Forgot, or what ever... Could this cause the clutches to wear out quicker to where the steels are just locking up?

Damn thing feels like it has a locker in it around corners.

You could try putting some friction modifier in and see if it helps.

I did... Didnt do much if anything. We are talking YEARS (about 60k) of driving without it. Looking into a rebuild kit for it right now...

Just looking to see if anyone else has ideas what it might be.

Sounds like limited slip to me.

My factory one sucked really bad, so when I changed the fluid I didn't add the modifier to make it more aggressive. Now it chatters sometimes on turns and such.

I've been looking into taking it down to Six States and getting a new locker put in, but I've done enough to stimulate the economy this year with truck mods.....:'(

Definitely sounds like the LSD to me. Give that ring gear a close inspection while it's down. They'll stress fracture when they overheat. Sometimes you can see it in the web between the teeth.

Oh the ring gear has some minor chips, but its had those for over 100k... Just looking to loose the chatter. Chelsea is afraid she is going to break something when she corners.

Sometimes, it takes 2 bottles of additive, and you're supposed to do several 'donuts' in each direction (after adding it) to get the additive where it belongs - inside the clutch packs.

I like my tight limited slip (I added only 1 bottle and it chatters a bit), as it helps me get up my driveway in 2WD without locking the hubs.

Tell her to go straight! :-X03

After changing my fluid I had to add 2 bottles of additive and I was told to do figure 8s and that stopped the chatter.

Florida Powertrain told me they rarely see the clutch packs go out. They said the cure 99 percent of the time is new fluid & 3 bottles of the additive.

Additive?
 

What additive is being referenced here? I'm getting ready to change out mine and I do have a little chatter. Bought. 2002 excursion 7.3 limited 4x4 and slowly working out little issues.

Friction Modifier...some of the 75w140 has it already (Mobil is one that does)

Thx for the info...

Most of the oils that already have the additive do not have enough to meet Ford/Dana's standard. I changed my rear end fluid with the Mobile 1 & added two tubes of TransX.

https://cimg2.ibsrv.net/gimg/www.for...f27c5ca6b6.jpg

Sometimes it can take a few hundred miles for the friction modifier to fully get in and work. I had a Navigator that I had to road test over 400 miles for it to go away. I bet the customer the $140 in fuel I would use that it would. It did. and it was bad.

There is only one type of friction modifier that is the best. No other FM works like the old Ford Racing friction modifier does. It is now sold by Dana Spicer.

Use 2 bottles.

Differential Friction Modifier Additive - Dana Spicer - 43161

This is the only kind I have used for the past 20 years. with success.

Don't waste your money on anything else.

Warning....it stinks....bigtime!!!