I finally had enough and set about rebuilding mine. I'm glad I did the job when I did. The bearings (all of them) were pitted and worn. There were signs of overheating, the pinion bearings and side bearings were seized on. The updated kit from Ford does not include the inner axle bearings. The dealer told me they don't usually replace them because the TSBs don't say to. No way I am going to trust them when they were swimming in the pieces of the other bearings! Either way, putting everything in new only cost me half what the dealer wanted to do the job. I have done other 8.8 axles in the past and these work the same way. A note that may save someone else some frustration: The factory replacement gears will not pattern in the center like most gears. Look at a good driveline manual under alternative acceptable patterns- these gears are cut different for noise reduction. Also, I noticed the oil fill hole on these axles are much lower than a straight axle would be, meaning they hold less lube. I'll bet a little fluid capacity would have helped these axles out.

 

[quote=bigbluetruck;9685605]I finally had enough and set about rebuilding mine. The updated kit from Ford does not include the inner axle bearings.
Do you mean by this, the differential side bearings? Or the inner C-V joints? Forgive my dumb, please.
The dealer told me they don't usually replace them because the TSBs don't say to. Sounds ridiculous, maybe dealer wanted your own job to fail?
The factory replacement gears will not pattern in the center like most gears. Look at a good driveline manual under alternative acceptable patterns- these gears are cut different for noise reduction. May be so. Most Ford Shop Manuals I have show acceptable alternate patterns. Generally, the coast side is not as critical as drive side. I have always set up such that when I rotate by hand grasping ring gear, I feel the most smooth movement. Any harshness felt is bound to produce noise.
Also, I noticed the oil fill hole on these axles are much lower than a straight axle would be, meaning they hold less lube. I'll bet a little fluid capacity would have helped these axles out. Could this possibly be due to the fact the gear carrier is "fixed" to the frame, and consequently, movement of housing ends up & down with suspension does not occur, which "spreads" the lube around to the ends, thereby lowering the level in center, until it drains back?..../Quote]

 

To answer your questions in order;
1. There are additional bearings outboard of the carrier side bearings, but inside the seals that further support the CV axles.
2. The update kit from Ford does not include, nor does the TSB mention the replacement of these bearings. I think they just take the attitude that if they wanted them replaced they would put them in the kit, or state that they need to be purchased seperatly. The axle seals are the same story, got to buy them separate. Look at it this way, if they fail later the shop gets repeat business, and a reason to fall back on if they do.
3. I imagine the fluid level was lowered because of the axle seal location. If they made it hold as much as a conventional 8.8 the level would be too high on the seal and leak. Like I stated above the independent axles don't need to provide lube to an outer wheel bearing at the end of the axle tube. The problem is the fluids job is also to carry away heat in addition to lubrication. Instead of making the cover in the same shape as a conventional 8.8, Ford should have put a potbelly in it to give it more fluid capacity without making the fluid rise up to the seals too much. An improved cover like this should be part of the update in my opinion. Notice the bigger axles in the expeditions don't have this problem? They hold alot more fluid just because the bigger ring gear means a bigger housing. The explorers really only take a small amount of fluid compared anything else. Also, any extra heat compounds the amount of expansion of the aluminum housing, therefore increasing any deflection effects to the bearings.

 

What was the cost to complete this. I recently bought an '04 and seince purchase i have replaced throttle body, replaced ABS wheel speed sensor, rebuilt transmissiona and know i am hearing whine from rear at 55+ mph. Tired of spending money. My dad thinks it sound like differential might need to be worked on.

 

I think I had around $700 in mine. That is including some tools like a pinion flange wrench and a big two jaw puller (I broke mine, had to get another to finish the job) and a set of pinion bearings I honed out for setup bearings. That's including some misc shop supplies I needed also. I will say I did not skimp on anything- not the kind of job you want to do twice.
Another point worth mentioning is the update kit does not include shims for the side bearings. I bought a mini install kit seperate just to get those. The original axle seals had a high failure rate in the explorers be sure to get the updated seals.
You'll need in addition to the tools listed above, an inch lb torque wrench and a big breaker bar to set the pinion preload. One thing that made the work easier on me was to strap the differential down on blocks to a sturdy work bench using a ratchet strap. Hope this helps.

 

Wish i had enough knowledge to attempt myslef. But i only know very basics and have very limited tools. I have co-worker who been doing much of the difficult work for me.

 

bearings will whine at all speeds. If you noise comes only at 55 MPH and then fades out above 70 MPH, you have gear maesh whine. Not a real problem, just anoying.

 

That's mostly true, but my diff had pinion bearing wear so bad that I had end shake on my pinion. I had a gear noise and a bearing noise. It was so bad that it covered up the noise from a bad wheel bearing that was also going bad. Mine made less noise under part throttle and got loader as speed leveled off no matter what speed I was going.
The differentials in these explorers needed alot more attention paid to factors that weren't present on conventional axles. The updated kit is supposed to take care of several known issues. The parts in the update kit are supposed to be heat treated to help with the problems caused by the fit changing on the parts as the housing expands from various operating temps.

 

Here' a thread from explorerforums that has a few pics from an '02 diff rebuild. How did your old bearings and parts compare to these? Can you still post any pics here?

Whine in Rear End? - Ford Explorer Ranger Enthusiasts "Serious Explorations"®

 

I have already thrown all the old bearings away, but mine were pretty similar to the post you linked to. I know mine had a track worn into the outer pinion bearing to the point that there was major play in the pinion.