Ford F-150 Differential Specs

[LatLong]

I have a 2002 F150 ext. cab 4x4 with a 5.4(112k miles). I went to do axle bearings last night and found out that the bearing went bad a while ago. It looks like metal powder got in to the differential bearing and spider gear. There is galling on the gear and some hot spots. So I need a new carrier and spider gears. My Chilton manual doesn't differential specs like the one for my older f-150. Does backlash need to be measured on the spider gears as well?

This is the 9.75" rear end(34 spline axles)

This will be my first diff rebuild so what should I watch for? I don't plan on pulling the pinion gear as the ring and pinion look ok. Or should I do pinion bearings as well?

Thanks

[Macgyver55]

I need a new carrier and spider gears.

There is no adjustment for the spider gears but they should be ok with a new carrier, pin and washers. You will absolutely need to adjust pinion depth and shim for proper backlash especially if you replace the carrier. It would be foolish to not do the pinion bearings when you are this far into it since they have had metal particles circulating in it.

Brace yourself when you get parts, they are not cheap and you may well find that a used diff out of a junkyard is a far better option dollar-wise.

[LatLong]

So I checked at the junk yard and they have a rear end with more miles on it than mine for $700. not going to go that route. i'll do the pinion bearings as well. i'll be ordering the tools to do the install. does anyone have pinion depth specs or can i measure the depth before disassembly and be ok?

[bwa]

To properly do this job you will need special tools to measure pinion depth after you install your new pinion bearing races. You could take a chance & use the same pinion bearing shim that is in there now, but I can't guaranty it will be correct. Even so, you will have to press (or cut) the large pinion bearing off the to get to the shim. Backlash spec is .008"-.012".

Seriously consider a used axle assemlby. The cost of parts & tools necessary may exceed $700. Overhauling a differential is a bit more complicated than just replacing axle bearings. By the way, how do the axles look. Are they pitted at the bearing surfaces?

[LatLong]

I just priced out all the parts and I'm right about $715. Plus the price of the tools. This is at full retail and I can get a deal on the bearings, races, seals and probably the tools too.

I'm kind of wary of used rear ends. I could end up buying the same thing I'm trying to fix. I had to go back to a scrap yard 3 times to get an axle that wasn't shot for a bronco I had. That being said I'm going to call more scrap yards tomorrow on the off chance they have a low mileage rear end. The problem is having 3.31 gears...most of these trucks came with 3.55's so that will limit my choices.

The axles look fine. They are polished where the bearing rides but no groove or pitting.

[LatLong]

well you talked me in to it. i found a used axle with 41k miles. even with getting parts at a discount and the price of tools i was within about $150 of the used axel. and installing the whole unit is far less work than rebuilding the old one. thanks for the input and help guys! i might have just avoided doing something that I would have regretted

[Macgyver55]

Good choice! Setting up a differential properly is a pretty involved process even with the necessary tools. To achieve the proper pinion depth, clearances, pre-loads and tooth contact pattern takes a good deal of patience and a clear understanding of what the shims will change when installed and changing one affects the other.

[Scott K]

and a few rear pinion bearings.