rear differential grinding

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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Limited slip carriers definitely require the friction modifier additive.

This ^^^^ Of course, pretty much all synth gear oil has it in it.

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

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.
 
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.

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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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.

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
 
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

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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