I just picked up an 03 explorer, the rear end makes a humming almost grinding noise. Was told it's no big deal but I still want it gone! Would the crush sleave be the problem?
If it hums during a load, quiet during coast, then most likely the carrier bearing are worn.
The ring-pinion backlash gets large, which is usually the source of the sound.Mine has been doing that for 100,000 miles. I changed the fluid out for the synthetic that the TSB prescribed, and it helped a little. It doesn't seem to be getting any worse, so I'm driving it.
The ring-pinion backlash gets large, which is usually the source of the sound.
Can one get away with just re-shimming the carrier to bring the backlash into spec or is a rebuild a must?
Surprised by your question. Gear teeth rarely wear enough to increase clearance. Same for bearings properly preloaded. UNLESS foreign material becomes present, metal particles, OR the axle is run low on lubricant. That causes much higher temperatures, which alone can kill gears.
Re-shimming: Condition of the gear teeth faces would determine suitability for readjustment. If they are scored the least bit, chipped anywhere, or not generally shiny in appearance (satin-like surface), or burned, indicated by brown or even bluish-brown discoloration, they will make noise forever after.
As a general rule, when setting up a ring and pinion set, I like to go towards the high-end of backlash allowed, so long as contact pattern, especially on the drive side of the teeth, is acceptable. Unacceptable contact pattern would be if way off-center, especially out towards the outside diameter of the ring gear. FWIW, contact pattern is always observed on the teeth of the ring gear; pattern on the pinion teeth is largely meaningless. It should be understood that the contact pattern observed while manually turning the ring gear, while applying constraining force against rotation on the pinion (I use a rag wrapped around the yoke), covers only a small portion of the entire ring gear tooth, perhaps 30% of the entire area. Under load, due to deflection of the parts involved, as well as elastic compression of the tooth surfaces themselves, the entire tooth is under contact with the mating pinion teeth. imp
I'm just getting desperate thus dumb, lol. It was quiet when I got it then it got loud suddenly after flooring it from a stop one time if that means anything... (squeezed the shims?) no idea.
I can't begin to consider a rebuild until late fall/winter. It's 100 outside and 120+ in the garage.
Ah! Sudden high load from a stop, if anything had gotten slightly out of whack, due to any one of a number of things, the critical alignment of the two gears was lost, resulting in gear hum. Squeezing shims won't make it. Cracked outer race of Differential Carrier bearing, either one, or pinion bearing, though that's much less likely. The torque applied to the diff carrier is driveshaft torque times
the gear ratio, can be several thousand foot-lbs, when transmission is in lower gears. If the hum is tolerable, not getting worse, and just a "singing" hum, no radical grinding-like sounds, you just might get by driving it with care for quite awhile. After all, some of the guys here say they have tolerated and driven with it for thousands of miles. OTOH, hum which develops gradually is the more likely type to allow use much longer than your type of problem, sudden gear noise.
Keep in mind that, if any gear teeth are chipped, or other hunks of metal debris is present, a corn-kernel sized one suddenly lodged between teeth can break off the ring gear tooth, which then lodges between the next two, which breaks another: like shucking corn off a cob. I've seen ring gears with half their teeth broken off, and one can only imagine the noise it made, and the stress it put on the center-section. Matter of fact, my buddy who raced a brand-new 1963-1/2 427 Galaxie, broke his center section clean in two! 9-inch Ford. imp
Mine is a loud gear noise like when you reverse with a manual transmission, louder under acceleration or up hills, quiet somewhat if let off the gas.
I have changed the oil and inspected the ring though the drain hole as much as I could. May have had some fine metal particles in the old oil, I cleaned the magnet on the fill plug which had a bit of build up on it. Gone about 9000 miles on it now I think (or 6000 I'd have to check) has not gotten any worse as far as I can tell.