On my 1986 F250 with a 10.25" Sterling Rear End. Twice now I have had the pinion nut come loose. Has anyone else had this happen? Just curious. If so have you found a fix? I have torqued the nut to around 200#. I didn't want to tighten it TOO TIGHT. and damage the crush sleeve.

 

390313S100 .. Flange to Pinion Locknut ~ 7/8" -20.

My guess is...you need a new one.

FTE sponsor Direct Ford Parts (Gaudin Ford-Las Vegas) shows a list price of $8.12 / FTE member price $4.28.

 

As Bill stated, you need a new locknut. At this point, you might as well get a new crush sleeve while your at it and change the pinion seal.
Also, there is no torque spec for the locknut on a 10.25. You have to continue tightening the locknut until you reach the required rolling torque. I cant remember the values off the top of my head, but when I replaced mine, I was using a breaker bar with a 4 foot piece of pipe to tighten the nut. I want to say 8-12 in-lbs for used bearings. Check a repair manual for sure or seach the net. Remember this the rolling torque, not the torque require to get the pinion turning. You will need a beam style or dial face torque wrench. The clicker style wrenches are useless because it will click before you even get the pinion turning. Tighten the nut in small increments, then recheck the rolling torque. If you go too far, you have to start all over again with a new crush sleeve. So take your time.

 

B7A4662A .. Crush Sleeve ~ List $7.39 / Net $5.22 (same as a Ford 9 inch!)

E5TZ4676B >> replaced by >> E8TZ4676B .. Pinion Seal ~ List $13.07 / Net $9.24

 

Thanks guys for the info. I changed the seal about 3 years ago, the other day I noticed spots of oil under the truck and saw oil on the pinion nut. So I dropped the rear of the driveline to find the nut loose. I noticed this right after I bought the truck in 1998 & tightened it up. It was good for 5 years now 4 years and the same thing. The spec you gave sounds about right. That is close to what the Dana 60 in wife's Dodge is. I removed 4:10s & put 3:54 gears in it a year ago. I need to go through this rear end one day. Right now we are in Arizona my wife has a 1 year contract with the school here then we are going home to Western Nevada to stay. We haven't been home except to visit in 10 years. My wife & I want to head home.
I'll go buy a new lock nut. I never gave a thought to the nut being wore.

Again Thanks

 

I have read that there's 2 different pinions for your rear end the old one which you have and the newer models I think 2000 and up.

Only the older models had this problem due to the fact it is about 1/2 an inch or so shorter. Thats the on going problem.

Sorry I don't know anymore I just remember reading about them.