I have a 2001 Ford SuperCrew 5.4L, and the 9.75 LS rear axle... i had a bering go out about 30,000 miles ago and i had to replace it and the clutch packs in the LS because they were chattering so bad.... Now the rear diff is chattering again when i go around corners... has anybod else had this problem? is it common with the ford 9.75 axles cause i have the 8.8 in my 99 and never had any trouble with it... whats the cause and solution to the chattering? any help would be great thanks

 

Mine would chatter while turning during long drives. Took it in to the dealership and they added friction modifyer (for LS diffs). The Service Manager told me Ford doesn't add enough modifyer at the factory. Haven't had any problems since. You can find the friction modifyer at most parts stores.

Hope that helps!

 

Auto Zone sells a 7 ounce tube for $5. just squirt it in on top of the lube and it will start mixing. might siphon out a little lube prior to adding the LS fluid.

 

My differential chatters sometimes when I turn on wet pavement, when one wheel loses traction. Doesn't do it on dry pavement.
I am changing the fluid tomorrow and will add Ford's Friction Modifier.

 

Are all friction modifiers the same---is Fords better?, I have always read that if you are using full synthetic oil that you dont need a modifier--is this true??

 

FORD does not make friction modifier, they buy it frome someone, so i would not worry about getting the "ford" brand. synthetics are supposed to be used in the rear axles, and the addative should be added to it. FORD recommmends synthetic in all the truck rear alxes these days. I have used the 75w90 instead of the 75w-140, but any synthetic brand, with the extra addative is the way to go.

 

It has friction modifier in it...its deffintly a LS problem but its most likely a failure...any body having these troubles?

 

I really need some help with this....Does anybody have anything similar happening, or ideas why it keeps chattering after being replaced and the appropriate fluids are involved.

 

i would add another bottle of the frictin modifier and see what happens. i have seen that fix this before. it might have had minimal amouont fill last time. worth a try.