I've read the other posts and it looks as though the rear diff problem is not uncommon. I would appreciate some help with a couple things

2000 F150, 4X4, 50k. Most on highway, occasional heavy tow of jet sled.

From the beggining I have had a chirp on turns from a stop. Changed rearend LS fluid on time with Amsoil full syn as dictated. Still chirped. I assumed this was due to the original poor tires I got since they always spun with the hint of wet road, but got new tires 5k ago and still happens even though these stick well. Is there an adjustment? Sound like diff may be too tight. Correct or not?

On this last road trip the truck started to develop a "gear whine" in the rearend. I am not sure where it is coming from, but it sounds like it must be the diff. After reading posts, I assume it is.

Here are my questions.. Those that have had similar problems, what all needed to be done? Pinion bearings and seal? When I changed gear lube, there was a light amount of metal shavings on the plug, but I assumed this was normal as the plug is magnatized. Is it? How much is normal? Do you typically have to replace the gears?

Also, is this something that should be done at a dealer, or can a mechanic I trust do the job correctly? And finally, anybody have an idea what is an "average" cost for this to get fixed?

I don't see any transfer case issues coming up on the board, so I can probably rule that out as the noise, or not?

Thanks for the help!!!

 

Is the whine on acceleration, de-acceleration, or all the time?

Whine all the time--look for bad axle brg's. or bad brg's on differential ring gear carrier.

Whine on acceleration, look for bad diff. carrier side brg's or bad inner pinion cup and cone.

Whine on de-acceleration, look for bad outer pinion cup & cone.

These are not always fool proof tests; however, they are good indicators to judge where the problem may be at.

If any bearing in diff. is found bad, I would advise replacement of all brg's. and seals in diff. Contamination from a failing bearing will damage other bearings in the diff.

 

whine is all the time. Speed sensetive, i.e: High pitched at high speeds, lower pitched at slower speeds. Does not change on power input, just on speed. Does not change if tranny is engaged or in nuetral/coasting. Whine sounds like gears to me, somewhat like you would hear from a manual tranny when going in reverse quickly. (but I know it is not coming from tranny) I just came back over mountain passes, and coasting downhill in neutral at 60 mph sounded exactly the same as on the flats at 60. Quick test at slow speed on a slight incline in nuetral with engine off I could hear whine, but being alone could not directly identify exact location.

Thanks...

 

Problems sounds more like bad axle brg., bad diff. side brg., or completely toasted (burnt-up) rear end.

Did you refill diff. with lube, when you drained the old lube?

Another thing many people forget when they do a complete drain & refill of diff., refill diff. with axle assembly level. Then jack-up one side (to let some lube run down axle tube) and wait about 4 minutes. Then level axle assembly & refill diff. to full. Then, repeat procedure to enable lube to travel down the opposite side axle tube.

Last, refill diff. to full level.

A Friend of mine recently changed wheel bearings and did not do this procedure on his 87 Bronco with a 8.8 Ford diff. About 100 miles later, left side wheel brg. gaulded to the axle. This cost him a big tow bill and new axle shafts, axle bearings & seals.