I'm posting here since there are numerous owners here who do the work themselves. I'm pretty confused on how the pinion flange and nut provides preload on the pinion bearings with a 9.75 rear end. The nut pulls on the shaft and presses down on the pinion flange which presses on the bearings and provides the preload. If the pinion flange is pressed onto the shaft, then how does the nut provide preload? Shouldn't the pinion flange be floating on the shaft instead of pressed on to allow the nut to work? Please help as I'm feeling pretty stupid and frustrated right now.


The pinion flange has to be pressed onto splined pinion shaft using a special tool. I used the old pinion nut to do this as I do not have this special Ford tool. Did I screw up? How do you know how far to seat the pinion flange?

 

Anybody? I'm trying to finish the truck today.

Thanks,
Chris

 

The pinion flange is not always a "press" fit, it varies. I have had them be a slide (hand) fit on and off. Spline fits are very difficult to control due to the multiple tolerances involved.

Regardless, if the flange is a tight fit, it doesn't matter. When you tighten the pinion nut to crush the new sleeve, you are looking at in excess of 150 ft/lbs of nut tightening torque to make it go. It will overcome the press fit, I can ssure you.

 

So now that it is pressed on, I should just put the new nut on and tighten it up until the torque reading for rotating the diff is back to 8-14 in-lbs per the Ford spec for used bearings?

 

I think I'm talking about the same thing
The guy who did mine, put it in the freezer to "shrink it" and it slid right on. I didn't believe him when he said that, but I watched and it worked. Okay, it didn't slide right on, but it went on with little effort.

just a thought.

 

Just a note to make sure you know that you will be turning only the pinion, not the differential. A small beam torque wrench is needed since the torque reading needs to be taken while the pinion is moving, not the amount need to get it moving. You will likely need a set of adapters since the torque wrench will likely be 1/4" drive and the pinion nut socket a 1/2" drive. Remember if you tighten too far you much replace crush sleeve and start over. You are not supposed to re-use pinion nuts, but I have re-used before with libral use of red Locktite.

 

The Ford procedure says to make sure the wheels and the brakes are off so that you don't influence the torque reading. This has to mean that the diff is still installed. The only small torque wrench I have is a split beam (click type) which probably won't work well for this application.

Before I took it apart it felt like there was a lot of backlash so I'm wondering when the shop rebuilt it before they didn't know what the hell they were doing. I'm leaning towards finding a good shop in the Houston area that knows these rear ends and towing it to them to check it all out. Assuming all of the parts are still good, what is a far price to take it apart and put it back together correctly?

 

Pyle Brothers in Baytown (east of Houston) does nothing but rear gear work and they are excellent.