rear differential grinding

Unlimited4x4

Unlimited4x4

New member
I have a 2005 LJ with a Dana 44. I did a fluid change on it and drove to work today and there's a grinding noise coming from the rear end while turning. It has 141,000 miles on it. I do the fluid changes every 20,000 miles +/-. I did not put the friction modifier in because it is my understanding the limited slip fluid should not need it. Could this be the cause?
 
I thought they only made rubicon LJs with air lockers.. do those still require the modifier? I could be wrong but arent they worm gears not clutches? And theoretically not need the LSD additive

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WJCO said:
Limited slip carriers definitely require the friction modifier additive.
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This ^^^^ Of course, pretty much all synth gear oil has it in it.

Wethy said:
I thought they only made rubicon LJs with air lockers.. do those still require the modifier? I could be wrong but arent they worm gears not clutches? And theoretically not need the LSD additive
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Not all LJ's were Rubicons.
 
It’s starting to make sense why I have the grinding this time and not previously. I usually use synthetic, but this go around I used traditional gear oil. I guess the non synthetic, even though it’s LSD, does not include the modifier. I’ll add the friction modifier when I get home. I have a tube of it.
 
Unlimited4x4 said:
It’s starting to make sense why I have the grinding this time and not previously. I usually use synthetic, but this go around I used traditional gear oil. I guess the non synthetic, even though it’s LSD, does not include the modifier. I’ll add the friction modifier when I get home. I have a tube of it.
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Hopefully there isn't damage already done to the clutches. Good luck.

However, if the traditional oil SAID that the modifier was in it, it should be in there.
 
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Unlimited4x4 said:
It’s starting to make sense why I have the grinding this time and not previously. I usually use synthetic, but this go around I used traditional gear oil. I guess the non synthetic, even though it’s LSD, does not include the modifier. I’ll add the friction modifier when I get home. I have a tube of it.
Click to expand...

I’ll add that LSD’s usually have some chipped teeth on the spider gears, at least on the ones we’ve re-geared. Sometimes that shit gets out of hand and starts tearing things up. Next time you have it open take a good look at them.


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Looking at the teeth was one of the reasons I did this. No chips or chunks in the bottom of the casing and no observable damage to the teeth.

Just took it around the parking lot for a while, lots of turns. No grinding. Didn’t grind on the test drive yesterday either, but it was all local. The difference is I drove interstate for about 20 minutes this morning then some local. It was after the interstate driving I noticed the grinding while turning on the local side street
 
Unlimited4x4 said:
Looking at the teeth was one of the reasons I did this. No chips or chunks in the bottom of the casing and no observable damage to the teeth.

Just took it around the parking lot for a while, lots of turns. No grinding. Didn’t grind on the test drive yesterday either, but it was all local. The difference is I drove interstate for about 20 minutes this morning then some local. It was after the interstate driving I noticed the grinding while turning on the local side street
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Are you sure the sound is coming from your gears and not something like your u-joints?
 
99% positive. Didn’t start until after I did the fluid change yesterday. I’ve been reading and found a few threads that make reference to the chattering/grinding not occurring until the rear gets to it operating temp. Is this true? If so, makes sense why I didn’t hear anything. I would not have hit that temp doing the short local test drive I did.
 
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