Limited Slip Chatter

[Bill Ellis]

There have been some postings here of late that regard chatter noise while making turns from a stop; or slow, tight turns. Here is what I found on a Lincoln site about the LS diff.



Chatter on Corners



Chatter on corners is a condition where the whole rear end vibrates when the vehicle is turning. The vibration is plainly felt and heard. In conventional axles, extra differential thrust washers cause a condition of partial lockup that creates this chatter. Chatter noise on Traction-Lok axles can usually be traced to erratic movement between adjacent clutch plates and can be corrected with a lubricant change that includes Ford Friction Modifier F3TZ-19B546-MA or equivalent meeting Ford Specification WSP-M2C196-A.





This is most common when it's cold so we don't ever here about it in the warmer months. My 04 has done this since it was new. Although it seems to happen more frequently. I'm taking it in for a check, but I suspect they will just add some friction modifier and let me tell them if it solved the issue. It probably will.

 

[Michael Cacioppo]

Posi-traction, Limited Slip, Traction Lok, and such named rears require a friction modifier in their rear end fluid. The additive is only a few bucks and only a few ounces. Buy a bottle, pour it in and see if it solves your problem. it only takes a few minutes and save you a trip to the dealer. This additive can be gotten in auto parts stores.

 

[Mark Grumpy]

I've been experiencing the same thing - just started (or I just noticed it) about a month back.



MikeC, anyone, assuming the factory fluid either has a modifier in it or it is added when built, does it wear out? Is this why some of us are just noticing the noise/vibration now?



grump

 

[Hal S]

Yeah, but be sure to drive a few tight figure eights to get the stuff worked in.

And did anyone mention the odor? Whew, that stuff stinks!

 

[Michael Cacioppo]

Grumpy, I really don't know the total chemistry of the additive, but I know that perfectly working rears require it to remove the chatter that occurs later in life. So my assumption is that it must somehow become non effective. I've not seen an assembly plant but it may be possible to put too little or non at all, at the factory. That would give problems to some Tracs and not others. This is purely speculation on my part.

 

[Mark Grumpy]

Thanks Mike - seems reasonable that it, like other greases/fluids would break down over time and use. Will look in the book later but anyone know the recommended service time for diff off top of their head??



grump

 

[Bill Ellis]

According to the Ford maintenance guide, diff is filled with syn lube should be changed at 150,000 miles. Heat is the primary cause of lube breakdown and under normal driving, diff just doesn't get that hot. In terms of oil temp it only gets warm.

 

[Yardsale]

In the afternoon. (Sorry - couldn't resist.)



I have this (front and rear), and the transmission and transfer, done every 50,000 miles, just because.

 

[Gavin Allan]

My wife's Liberty needs the rear end lube drained and refilled with new additive about every 20,000 miles. I use Mobil 1 80w140 synthetic and have tried a couple of different brands of additive, but they still seem to break down and the chattering starts again.



Is it the additive breaking down?



I have wondered if I can just drain out a little gear lube and just add more additivie, but it seems that doing so would dilute the gear lube.



any more advice or information? This is aggrivating to have to do this for a "lubed for life" unit.

 

[Bill Ellis]

The Liberty uses a Dana Trac-Lok diff while the ST uses a Ford Traction-Lok diff. Both are clutch-pack designs and look very much alike.

 

[Todd Z]

The issue is with synthetic oil only, The regular oil has the additive in it, No need for the bottle. BUT with all ford rears that use the synthetic, you MUST add the additive. You can get a bottle from a local auto store, BUT the ford stuff is about $8.00 a bottle and worth it !!!!



IF you have a NON slip Rear you can use the synthetic with out the additive, But if any type of posi unit or limited slip you must use the additive..

Even if i use regular oil in a rear I still add the bottle even though it says it is in there already. $8.00 is a cheep insurance policy!!!!



AND put the additive in first to insure you get it all in there...

Todd Z