question for the pros. I noticed the yoke wiggled some today while checking it out. So i pulled the drive shaft and put a socket and bar on the nut. It turned just a little fairly easily then stopped moving. I put a little force on it and saw it wasnt gonna turn more so i stopped and put the drive shaft back on. The yoke no longer wiggled and seemed to turn with the same force. Took it for a drive and came back and everything was still cool and no noises. So is any harm done just snuggin the nut back up? It seems to have gotten rid of my highway vibe too.. So satisfy my curiosity, is snugging up that nut gonna affect the bearing or gears in any way?

Later!! chris

 

The 8.8" pinion nut should be torqued to 160 ft/lbs. A somewhat common problem with the 8.8 rears is that the pinion nut will loosen up. I'd keep an eye on it.

 

Thats interesting to know. My brothers 1991 F150 had a nasty/ noise vibration, and upon looking into it we found the pinion bearings real sloppy, but no abnormal metal in the diff oil. I'm curious as to if the nut backed off? We're probably just going to do the bearings anyway.

 

I just found this thread dping a search and it addresses my question perfectly. After doing some reading about the pinion nut torque in a CD version of a Ford manual I too ran into the 160 ft-lb number but alsofound a referance to 8-14 in-lbs for a used bearing and 16-29 in-lbs for a new bearing. They also mentioned something about exceeding the preload meant that you would have to back off the pinion nut and that would require installing a new collapisble spacer.

The torque dicrepancy has me confused and I guess I would like to be reassured that tightening that pinion nut is a safe thing to do. The manual also says to use loctight on it.

 

It's a bit complicated.
Not so sure about the 160 ft lbs part, I do that part by eye and feel.

The inch pound part is the force needed to rotate the pinion, not tighten the nut.
Checking it this way is a measurement of bearing preload, and you will find a different spec for new and used.
.

 

That explains the discrepancy. I'll read the manual again with this insight but it seems to me that 160 ft-lbs is running a wild risk of crushing anything that they refer to as collapsible. My pinion nut is loose and has been that way for some time. I drive the truck around 90 miles a day and would like to keep doing so. Right off the bat I'm inclined to at least snug it up.

If you would elaborate a little about doing it by eye and feel, I would really appreciate it. Thanks.

 

In your case you are pretty well limited to doing it by feel unless you want to take it apart and start from scratch. The inch pound deal is without the ring gear in.

First, being it got loose you probably should buy a new nut while you are doing it, this way there is less of a chance of having to do it again.

It's hard to explain in words but here goes.
I would get the nuts changed over.
You want to tighten it while checking it to see if it's still loose and at just before it has no play hand check the feel of how it turns back and forth.
You won't be able to get it to move much before it engages the ring gear so turning it alot won't tell you much, just wiggle.
At this point you want to tighten it until just the point there is no play, you might note a little difference in feel, then give it a tad more, probably 1/8 turn or less. It should now turn a little harder (think of that inch pound rating, it's not alot). My rule is you are better off a tad loose than too tight.

I would try to do this right the first time so you don't have to back the nut off.

Keep in mind that many a garage mechanic would do this with an impact in a heartbeat and not blink, right or wrong. It has been loose without giving you problems so snuging it up without over doing it shouldn't cause problems either.

 

That is a fantastic explaination. I'm glad I took the time to ask and appreciate you taking the time to respond. I do understand that overtightening it and then backing it off would require a new collapisble spacer and I don't want to go there.


Alex