Sterling limited slip chatter

kleake

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Recently changed the fluid in my rear axle with Valvoline synthetic that supposedly has the friction modifier in it. Started noticing a chatter while towing and turning while under heavy load. Seemed to get worse so I added more friction modifier. It changed from more of a clunk clunk as I turn, to a full chatter, almost a grind while turning. Suggestions? Change fluid again and use motorcraft friction modifier?
 

Mhatlen

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It can take time for the oils to mix as well as get into the plates before smoothing out. I changed my axles oil few years back and didn’t use slip on purpose. No chatter so I pulled it off. Last truck I used it and the posi got lazy.

Is the modifier also Valvoline ? Give it a few days, if not happy still then I agree with your backup plan.

Good Luck on it.
 

kleake

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I just got back from about a 400 mile round trip. I could tell the difference within 20 miles. The modifier was a generic from Oreilys, I don't remember the brand but it's all they had. It's enough now that any load while turning and you feel it and wonder what's wrong.
 

Mhatlen

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The clutches will rub on each other every time you get the differential working. If there was no metal in the housing when you changed the oil there’s most likely nothing wrong.

The gear oils have different amount of tension or slip. I would go to a well stocked parts house and ask for a modifier compatible with the synthetic oil you used. Throw in a tube or two and see if that gets thinks slippery enough.

If you still have a chattering rear end I would pull the cover again to drain and inspect. Look at diff housing for any sign of pinion interference and metal grit .
You can jack up axle to spin each wheel as someone looks at how it sounds. May be tough since you will have to hold one to spin the other.

If that checks out I would put in factory stuff.
 

kleake

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All was good when I changed the fluid, just wanted to freshen it up and it just hasn't been smooth since. Thinking the OEM fluid may be what I need.
The clutches will rub on each other every time you get the differential working. If there was no metal in the housing when you changed the oil there’s most likely nothing wrong.

The gear oils have different amount of tension or slip. I would go to a well stocked parts house and ask for a modifier compatible with the synthetic oil you used. Throw in a tube or two and see if that gets thinks slippery enough.

If you still have a chattering rear end I would pull the cover again to drain and inspect. Look at diff housing for any sign of pinion interference and metal grit .
You can jack up axle to spin each wheel as someone looks at how it sounds. May be tough since you will have to hold one to spin the other.

If that checks out I would put in factory stuff.

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8WR_ZJ

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At the shop we have had a few issues with the limited slips and different cheap quality oils. We had used say castrol or valvoline and then used the oreilly brand friction modifier. We had a few customers come back with some of the same issues. So now if we do a limited slip we ONLY use royal purple. Royal purple must have the formula figured out no issues with limited slips since then. Only reason for royal purple is that we only buy from O'Reilly's and that was the only one they carried with the friction aide in the bottle. Limited slips are hard on oil.

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8WR_ZJ

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Only thing we use for limited slip diffs now. Been that way for about 5 or 6 years now. No complaints from clients either.

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kleake

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Drained and re-filled with just the royal purple, and all good. It still has the "thunk" as I am pulling the 5th wheel in and up-hill turn at an intersection or similar, but its MUCH better and not noticeable at all unless under heavy load in a turn. Thank you!
 

8WR_ZJ

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Drained and re-filled with just the royal purple, and all good. It still has the "thunk" as I am pulling the 5th wheel in and up-hill turn at an intersection or similar, but its MUCH better and not noticeable at all unless under heavy load in a turn. Thank you!
Awesome im glad it is not binding. How many miles since the oil swap? How many miles on the rearend

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kleake

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Awesome im glad it is not binding. How many miles since the oil swap? How many miles on the rearend

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Just over 251k on the rearend, and about 2k since the oil swap including two 3hr each way camping trips pulling the 12k 5th wheel and a 4k boat behind.
 

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