Well, some of us have all the luck ! I have a 2002 Explorer that had the rear axle whine since about 30K miles. Always thought it was the gear mesh. Now it has 170K miles and about 10K miles ago it started having much higher noise. I removed the drive shaft and the pinon moves up and down almost 1/8 inch.... so i decided to pull the rear end this week and overhaul.
Things went great tonight. Rear up on jacks, tires and wheels off, pulled brake calipers and tie rod ball joint and hung to the side. Popped off the upper ball joint and swung the knuckle and wheel hub outward while pushing the axle half shaft inward. Layed the knuckle and hub down hanging on the lower bolt mount.
Removed the drive shaft bolts and set rear Ujoint on the ground. Drained the pumpkin. Took a 12 inch 2 x 2 and whacked each axle half 2-3 times and they both popped out of the pumpkin. Set both axle halfs in the garage...
Hour and 20 minutes and im ready to pull the differential bolts tomorrow night ! I thought this was going to be a really bad job, but so far so good. All ball joints and both axle shafts popped loose with a couple smacks. Bought a TIMKEN bearing set on e-bay for $85. and a pair of shaft seals for the axles for $15. ... thinking of buying rebuilt CV axles since i have everything apart.

 

Keep us up to date and post pictures if you can. I thought about doing this for my Explorer (mine's not IRS) but the parts alone cost more than what I paid for a rear axle assembly from the junkyard.

Is the housing aluminum on yours? Does the manual call for using a housing spreader? Some people say it's not needed so I'm curious what you find once you start taking things apart. Also, I've heard that you usually don't need to reset backlash and pinion depth if you just change the bearings since the bearings are held to tight tolerances.

Good luck and let us know what you find.

 

Im hoping to rebuild with $100. for bearings and seals. . and another $100 for two rebuilt CV joint axles. Book says to use a spreader on the aluminum case, but i have read several places that say its not necessary. I dont plan on using one.. Dont see why it would be needed. I think your right about the backlash and tooth pattern. I plan to set the pinion depth the the factory spec, new bearings, then shim the sides with the original shims and check the backlash. Might have to shim a little from side to side to keep backlash into spec, will see. Hope to reuse the original gear set.

 

Do you have the tools to set pinion depth? If not then just reuse the original pinion shim. Also do not mix up the carrier caps or flip them. Make sure you install a new crush collar and set the pinion preload. You can't reuse the old collar. You will need a dial in-lb torque wrench to set the preload. You can get by without the housing spreader just be careful driving the carrier shims in they will break pretty easily. Good luck

 

here is a good demo for anyone trying to picture what longbed is saying.

 

Differential mounted on angle iron to hold steady for work. Clamps to hold pinion from rotating while i check backlash, end shake, and pry out bevel gear and shaft.

 

Had to press pinion out of housing. About 1000 pounds effort. Outer bearing froze to pinion. Outer bearing and washer show excessive heat . Blue color.

 

Pinion bearing discolored and some minor spalling on outer race. Spalling also noted on cross shaft bearing races.
---backlash on bevel gear .020 inch
---endshake on bevel gear shaft .005 inch
---end shake on pinion shaft .015 inch

 

There is an outboard roller bearing on each side that supports the axle half shaft in the housing. The shaft seal sets just outboard of this. I dont remember this bearing being part of the overhaul kit...

 

It would be a good idea to replace those bearings since you are installing new axles.

 

There is six bearings total in the rear end I would suggest replacing all of them the little roller bearings tend to go first causing the seal on the shaft to fail. By the way the unit should have come with a one piece seal on the shafts they should be replaced with a TWO piece seal. Most parts houses only stock TWO piece seals as a rule but the singles are around and that would be a mistake.

 

i bought a bearing/ seal kit , then both CV axles (rebuilds) just to get "better" parts, then bought both needle/ roller bearings that hold the CV shafts at the differential. Installing the pinion tonight. Gone for the weekend. Finish assembly next week and install in truck by friday.. I HOPE !

 

If you want to get rid of the rear end roaring change the two main rear end gears they're not cut correctly. Problem was corrected in 06 I have two 05's.

 

Well i just got everything back together an hour ago. Drove 5 miles to town and 5 miles back. EVERYTHING is 100% QUIET !!!

I bought a bearing kit for the differential, then two additional needle bearings that go in the housing and support the end of each axle half shaft, and the seal that sets outside the housing and seals the axle shaft.
I put the pinion into the case and tightened up the flange nut as shown in the movie above. I got it about 24 inch pounds preload. You can turn it easy by hand, but no endshake. I then set the bevel gear and shaft into the housing and put the original shims in place. I had .020 backlash so i reversed the two shims ( one was .250 and one was .260 inch). That got the backlash at .011 inch so i left it there.
The first shim just drops in (end of bevel shaft). The second shim normally you have to tap it into position. Mine was right at ZERO, no tapping to get it in, i pushed it in with my thumb. I tightened the bearing caps and checked endshake on the bevel gear shaft to be .000 inch (no preload).
As i mentioned earlier my pinion bearing was overheated and had .020 endshake when disassembled. My opinion is the bearing preload may have been too tight from the factory. Quiet for 30K miles, then started making noise and noise was constant level for 100,000 miles. I was blaming gear mesh for 10 years, but now i think it was the pinion bearing.
I did check the gear pattern and it was acceptable but far from what i would call "good". WIth proper bearing clearances and backlash, i decided to leave it that way.
During reassembly in noted the drivers side wheel bearing was a little "tight" so i bought a new bearing and replace that, using the original hub. You have to remove the spindle and press everything apart and then back together.
I bought two rebuilt axle shafts so i would get new grease and boots. Figured the axle steel condition would be about the same as mine. Took me an extra evening because of the axle shaft install. Passenger side is 1 inch longer than drivers side... YEP, i measured it twice, then picked up the wrong one and installed on passenger side. When i got to the drives side, i noted the hub turned a little hard after assembly. The LONG axle will not give enough wiggle room for proper rotating clearance. Had to pull both axles a second time !.
All is back together, installed the oil. Got almost 2 quarts in the case. Drove 10 miles at 55 MPH. Checked seals when i got home and all 3 are dry. Put my hand on the aluminum case and it might be 85 degrees in a 70 degree ambient. Sets close to the muffler and tail pipe so who knows where the heat comes from.
This truck is the spare since we got the EDGE. I drive it about 40 miles per week to keep the battery charged so i only gets 2000 miles per year. If i note anything happening, i will get back and post.

 

The Ford 8.8 differential is commonly called an "integral" design: the pinion gear and it's bearings are not mounted in a separate part which is removable from the differential case proper. The old Ford 9-inch system had a removable pinion carrier.

The 8.8 relies on shims placed behind the differential carrier bearings to both accurately locate the ring gear in relation to the pinion gear, AND also to establish correct carrier bearing preload. The 9" had threaded "nuts" which were adjustable to achieve the same result as the shims mentioned.

Ford Shop Manuals always called out the use of a "case spreader" when inserting or removing a diff. carrier from the "integral" type case. Generally, the old "Mechanics'" method used a crowbar to pry the carrier out of the case, and heavy hammer to get it back in. Since the bearing preload involves only a few thousandths of an inch of case spread preload, the "back-alley" method worked, so long as the guy didn't damage bearings when hammering the thing back in.

The "integral" design dates 'way back to the original Dana Corporation's models used in many different makers' vehicles. G.M. also used it in most of their vehicles. In my book, the 9-inch is superior in concept, easier to work on, very strong, but last-used only in light trucks by Ford up into the 1980s sometime.

Thanks for reading! impish