1991 4WD Cherokee (noisy rear-end)

[evails]

What is the cause of the hum in jeep rear-ends? And how can I fix it?
My '91 has 120k miles and has since developed a vibrating hum comimg from the rear-end/ differintla area.

when was the last time you had the fluids changed....i do mine every 30,000 miles or right after i play like mad in the mud trust me if you get the fluid dirty youll know it...try that then repost...
themud

[CALIFORNIA JEEPER]

It sounds like the rear diff is going out like mine did, my spider gears gernaded on me and it was not a fun ride [img]images/smiles/icon_eek.gif[/img] at all

[CALIFORNIA JEEPER]

It sounds like the rear diff is going out like mine did, my spider gears gernaded on me and it was not a fun ride [img]images/smiles/icon_eek.gif[/img] at all

[ohms]

Any time you hear a hum or a grind comming from your rear or front diffs....PUL THE COVER ASAP...the longer you drive on a axle with some internal problem the more money you are going to be shelling out. These components work as one unit...if one parts is failing then your components start to 'domino effect' or one thing after another goes. On a lighter side...take your jeep over to a mechanic and have him check your carrier bearing... that is usually the source of most humming or whinning. [img]images/smiles/icon_smile.gif[/img]

[gkatzens]

I agree with the above. My 89 tossed its carrier bearings at a similar mileage. I blame myself really for never changing the oil in the rear end. If it is a wump wump wump sound that varies with rear wheel speed, there is a really good chance that this is the problem.



Cheers,

Garrett[addsig]

[Chuck]

My 87 had a noisey rear end, the spider gears were worn (rounded). It´s often hard to isolate the problem,, sound travels through the whole drive train. But a visual inspection and a little prying and shaking can tell you alot. Grab the pinion yoke, that piece sticking out of the differential and give it a good shake up ahd down any play and the shims are worn,the bearings are worn or the suicide nut is loose. Do the same thing with the axles, with the tires and drums removed, a little play up and down is OK (about a Millimeter) any more is a sign of worn wheel bearings (also if the seals are leaking). If you take the cover off of the differntial and stick a screw driver by the inside (carrier bearings) and there is any play up and down, it is a sign of worn bearings. Lastly grab the yoke and twist it left and right to see how much play there is between the pinion gear and the ring gear. There is always a little play, some of the Chiltons manuals give the allowable play which can be checked with a feeler gauge. I´ve done it enough times I can tell by the feel wether it´s right or wrong.

Other than worn spider gears, a loose pinion gear or wheel bearings I don´t worry about it to much. I just add a good bit of Moly gear additive to quiet it down a bit and drive it for another 40-60 thousand miles. Rear ends are pretty easy to find in a junk yard, and not that hard to change. Buy a new set of U-bolts and away you go.[addsig]