'04 Rubicon axle gear oil, Is friction modifier necessary?

B.04rubicon

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The rear axle tag on my '04 Rubicon says to add 4oz of friction modifier along with 60oz of gear oil. Are there friction clutches involved with the locking device or is it purely mechanical, as I thought? Is it necessary to add the friction modifier or is this just a default tag for axles with traction devices? However, the front and rear tags differ in specifications!
Thanks in advance!

Rear Axle tag
20231025_170054.jpg


Front Axle tag
Front Axle tag Right.jpg
 
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Despite what the tag says, the TJ Rubicon OEM rear diff does not require friction modifier, since the limited slip function is a helical gear type, not clutch based. They apparently just used the same axle tag that was used on D44s with clutch-based l/s diffs, and did not produce Rubicon specific axle tags.

As indicated on the tags, the front diff does in fact require less gear lube than the rear. The rear requires a high enough level of lube so that a little will run down the axle tubes and lubricate the bearings

Interesting that your tags do not indicate the OEM 4.10 gear ratios. My '03 did.
 
No not at all. The Rubicon's LSD is gear based, not clutch based, so it does not need or benefit from a friction modifier.

That said friction modifier won't hurt it either, which is a good thing, since the vast majority of gear lubes contain a friction modifier.
 
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Despite what the tag says, the TJ Rubicon OEM rear diff does not require friction modifier, since the limited slip function is a helical gear type, not clutch based. They apparently just used the same axle tag that was used on D44s with clutch-based l/s diffs, and did not produce Rubicon specific axle tags.

As indicated on the tags, the front diff does in fact require less gear lube than the rear. The rear requires a high enough level of lube so that a little will run down the axle tubes and lubricate the bearings

Interesting that your tags do not indicate the OEM 4.10 gear ratios. My '03 did
Rouxbicon, Thanks for your response, just wanted to confirm I wasn't missing something! Mine has a seperate tag on the opposite side of the dif cover indicating the 4:10 gear ratio, same with the front.
 
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No not at all. The Rubicon's LSD is gear based, not clutch based, so it does not need or benefit from a friction modifier.

That said friction modifier won't hurt it either, which is a good thing, since the vast majority of gear lubes contain a friction modifier.

(y) Yeah, I just went ahead and added the FM figuring that as well!

Cheers!
 
Next time don't add more friction modifier since it's not needed or of any benefit. There's nothing in either of your axles that uses, benefits from, or needs it. 😊