Limited slip diff

[Ken M]

What happens if friction modifier is not added to a limited slip diff? My '76 Dodge van developed a clunk from the rear end when the shop that serviced it failed to add the friction modifier. I added the friction modifier after about 3,000 or 4,000 miles and the clunk went away. My '93 XJ has developed a clunk and I'm starting to suspect the same issue.

 

[Unclewolverine]

Don't know about not adding it but mine developed one because the spiders were wore out. Put a new kit in, worked perfectly.

 

[maxbraketorque]

Friction modifiers are only (sometimes) needed for clutch type limited slip diffs. Is that what you have in your XJ?

 

[Ken M]

I assume it's a clutch type; it's the original factory diff.

 

[RCP Phx]

The only thing that would cause is additional slipping and a possible chirp/squeal.

 

[maxbraketorque]

I assume it's a clutch type; it's the original factory diff.

Nearly all XJs have an open diff from the factory. Only a few had a factory clutch type limited slip rear. Supposedly, its possible to verify if its open or limited by the tag on the diff.

 

[Unclewolverine]

Mine still has the tag, but much like the other identification tag they can easily be displaced. Easiest way to identify it is jack it up and see how the wheels spin. But if your clutches are shot it will act like an open diff.

 

[Saudade]

You can pull the diff cover off and look, or you can lookup the build number stamped on the axle.

https://www.therangerstation.com/tech_library/identify_a_dana_axle.shtml

My '88 still has the tags.

The site linked above lists it as

605389 JEEP 35 Rear 1988 1/2-89 XJ Utility, Trailer Tow

 

[lawsoncl]

Not using limited slip friction modifier causes the clutches to wear faster and sometimes "stick" which kinda sounds like a clunk.

Even if he had a D35 with limited slip, the clutches would likely be long worn out by now. Plenty of other causes for a clunk, including needing to grease the driveshaft splines by the xfer case, bad ujoints, etc.

 

[tjmotter]

Not using limited slip friction modifier causes the clutches to wear faster and sometimes "stick" which kinda sounds like a clunk.

Even if he had a D35 with limited slip, the clutches would likely be long worn out by now. Plenty of other causes for a clunk, including needing to grease the driveshaft splines by the xfer case, bad ujoints, etc.

I always take mine to a dealer for diff work or do it myself. I once had a lube shop convince me that their replacement fluid "has all the proper additives for your specific differential" so I let them drain/refill. Almost immediately I started to get a groan from the rear during any turn. I went to the dealer, bought a bottle of the proper modifier, added it in the parking lot and the groan immediately went away.


HTH

 

[Unclewolverine]

Mine had a weird clunk when accelerating away from mailboxes since I got it. The limited slip was completely worn out and didn't work. I put a clutch kit in it, the clunk went away and has worked flawlessly since. BTW, the kit is a major pain to install!

 

[denverd1]

I find it hard to believe that LSD from 28 years ago is still limiting slip, no matter what fluid goes in it.

plenty of other more reliable options