Rear end noise (on the Jeep!)

[UnkleMunky]

http://www.ifsja.org/ubb/smile.gif Well, I got a noise in the read end of the Jeep and I don't think it's a good sound! Had to patch an exhaust leak last weekend and she's pretty quiet for exhaust now, so am hearing more things than I'd like! I checked the 78 TSM(this is the '78 J10), and I'm narrowing this down to the differential right now, but not sure.

I get a revolution sound, sort of a grating/whirring.....fairly low pitched....almost like if brakes were dragging some, but the sound makes NO change when braking or not....stays the same. Also stays the same whether going straight or around corners, so am leaning a bit away from bearings right now. Sound is present whether accelerating OR coasting. It is most noticeable(and VERY persistent...doesn't miss a revolution!) at about 30-55mph, and sounds like the revolution is consistent with the tire revolution, but I can't say as I'm usually inside the truck when it's moving that fast! http://www.ifsja.org/ubb/smile.gif

In the '78 TSM, it pretty much narrows that type of noise to the differential. I checked fluid yesterday and added just a squirt, and it overflowed, so it's full(and still makes the sound as I had to drive a good distance yesterday with it after that!). However, it doesn't look all that fresh and could well enough use a change. I'm figuring I'll have to dig and look at the diff, but just wondering if this is sounding likely to anyone, and, if so, what kind of trouble might I be looking at inside?

I'm assuming I'll need to get a gasket to put back on the diff cover when I put it back....is that so? Also....I've been thinking of going synthetics in the gears. The diffs call for 80W90, but I've only seen like 70W90 and/or 75W90 in synthetics. Anybody know what kind of syntethics should go in there....brand, weight, etc.? Just thinking ahead here as to when I refill things. I might do the front diff at the same time if it works out too!

As for the gears inside....what kind of nasty job am I in for if I have to repair/replace anything in there? Could it possibly be wheel bearings? Just trying to narrow this down more, and understand better too!

Thanks.....

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Michael(UnkleMunky)
'78 J10: 258, 4 speed, longbed, topper
'76 J10: Honcho, 360, TH400/QT
'89 Plymouth Reliant(PluggerMobile)
J-Pages(some of my auto pages) (http://www.eskie.net/superior/j-pages/index.htm)
unklemunky@eskie.net

[River Beast]

first... jack it up and feel for play in the up and down in the wheel... could be the outer wheel baearings going out. I had a constant vibe/whirring in the front of mine for a LONG time (before the gear change)... the carrier bearings were shot. You can't feel carrier bearing play...sorry. the only eay to check those that I know of is to remove the diff carrier.

Excessively worn spider gears can contribute to the whirring noise as well. they should not looked 'polished' or shiney... more of a machined finish.

what did your diff fluid look like? black and particulate metal could be a sign of excessive wear. Remove the diff cover and inspect the ring and pinion gears for grooving,... deep in the pocket. As the R&P wear together, they will have a wear pattern visible to the naked eye. The pattern should be somewhat centered on the ring gear( you should see some discoloration between the outside edges of the teeth and lighter towards the center of each tooth). You can also see the spiders, too.

It oculd run into some $$$ for a rebuild depending on what's needed. Carrier bearings are about $20-$30 each. plus the inner and outer axle seals are about $30 and might as well do the axle bearings if your this far into it.... about $20... USE THE OUTER BEARINGS WITH THE RACES, NOT THE SEALED BEARING alternates.

now you have to look at labor to get it done...depending what needs to be done. A large press is needed for axle/carrier bearings... not something the home mech usually has... I got my axle bearings removed/replaced for $25 not including the price of the beaings. I alos got a hook up for the rebuild on my axle for $150 each... all new parts of course supplied by me... took a while to save the $$$$ up to do it though...

I don't want you to think the worst of the situation, but sometimes you have to for monetary reasons. I hope it will be an inexpensive fix for you.... http://www.ifsja.org/ubb/wink.gif

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Todd
"River Beast" (http://home.earthlink.net/~tjnkk)
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14" of total Lift on 39.5" Swampers
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...and other stuff...
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"When approaching an intersection, remember...
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'93 3/4 ton 4x4 Suburban...a.k.a. "FSJ Hauler"

[SpruceMoose]

I'm using Amzoil synthetics all around. I think the gear lube is 85W90, but close is good enough. i check the level twice a year, or right away if i see anything on the driveway. The xfer case is leaking just a little bit, so i try to check it every few months. running 20w50 in the engine, change it once a year, and the filter twice. doing about 15000 miles per year.

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88 Grand Wagoneer
"Spruce Moose"
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