rear end noise???

[cashmoney37]

ok i just did my first gear change on my 99 ranger. it has the 7.5. ok i put a set of yukon 4.56's in it. i put new everything in it. bearings seals. i checked all my measurments with the crush sleeve, back lash, bearing preload, and the marking on the gears looked good. i got the axel back in the truck and started my break in period. for the first 200 miles i noticed no noise everything seemed good. the rear end i did notice got hot. not to the point of burning yourself but deffenetly a uncomfortable hot now they dont seem to get as hot. but now i am at about 300 miles into the break in process and i started to hear a very slight whining noise from the rear. and it is slowly geting more noticible through out speeds. and it makes it whengiving gas and when breaking. some one said it might be a pinion bearing, but i checked all my measurments so how could that be? anyone know how to check what it is?

 

[Evan]

Take the cover off the diff and inspect the wear on the gears. Turn everything and listen for noises. Look at the magnet for metal filings.

Sometimes as the gears break in the carrier shims might settle or something changes that throws the gears off spec. Did you make sure you had a decent amount of carrier bearing preload? Maybe you had some grit between the pinion shim and the gear, and that got washed away, changing your pinion depth. If the gears are out of spec you should see a funny wear pattern on the gear.

Diffs get hot when they run, especially during long drives, so that's not necessarily a problem. However, low backlash, improper gear setup, or high pinion bearing preload will make the diff run even hotter.

 

[cashmoney37]

i just looked at the magnet and there was some metal shavings on it

 

[MAKG]

If the pinion bearings are loose, the companion flange will be at least slightly floppy.

If it's a whine that shows up when accelerating AND braking, I'd look in that direction as well. Most gear problems will be one of the other (or at least they will be different). But you should have some hint of polish now, so you can look at it (or just recheck the contact pattern).

Though the sounds are usually more rumbles than whines, I'd take a GOOD look at the axle bearings. Those are presumably not new, and it's surprisingly common for them to die and cut grooves into the corresponding axleshaft.