Vibrations.

[Alf]

I have an explorer XL 1992 when i acelerate it start to vibrate. i checked the screws in the driveshaft and it had only 2 y put the other 2 screws but cotinue vibrating.

 

[Boman01]

If it is the same thing mine does then it is just the limited slip rear end. I have a '91 with 3:73 Traci-lock (limited slip) rear end and i feel it all the time, especially when i have been drivinig alot. I took it to someone i know that is a mechanic and he said there is a special lube oil for limited slip rear ends that has to be put in it , but for now there is no harm.

 

[RTStork]

The additive is Friction Modifier. You can get it at the Ford dealer. Its the stinkiest crap you'll ever smell.

 

[Jason_25]

I second that, it nearly made me nautious when I pulled my LS slip out to put the powertrax in.

 

[DB_1]

Sta-Lube also makes friction modifier, don't know if its
any cheaper than buying it at adealer though.
I bought mine at Pep-Boys auto parts.

 

[Explorer58V8]

I just changed my diff fluid in my mom's '98 Ex over the weekend and I put the Ford Motorsports Friction Modifer in there. The worst part was the smell... and man does it smell.... but now when you come out of a turn and mash the peddal the passenger side tire doesent spin... the truck just takes off.......

I'm still happy with my FMS Limit Slip Locker in my '97. Like it a lot better.