"Friction Modifier" For Rear Diff
#31
06-11-2011, 06:40 PM
#33
06-12-2011, 01:06 PM
Thank you glc!! i dont believe it is either, i found the right XL-3 on another site for 4.09 a bottle and it is a little different then what i saw on ebay. they also have the motorcraft 75W-140 synthetic for 14.89 a bottle. seemed like a good price to me. would you recommend 1 or 2 bottles of the FM?
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#34
06-22-2011, 11:38 PM
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I`m also having the same issues ...shudder or vibration on take off, more going up inclines, and turns.. The Ford people said about my `05 FX4 SC ...5.4 3v Auto...that the differential needs "clutch packs"...and is not covered on my warrantry...considered like your brake pads...they get me every time .... Has any one ever heard of this term before? "clutch packs" ...and how much $ are we talking?
good luck ,
Hankster
good luck ,
Hankster
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#35
06-22-2011, 11:45 PM
I`m also having the same issues ...shudder or vibration on take off, more going up inclines, and turns.. The Ford people said about my `05 FX4 SC ...5.4 3v Auto...that the differential needs "clutch packs"...and is not covered on my warrantry...considered like your brake pads...they get me every time .... Has any one ever heard of this term before? "clutch packs" ...and how much $ are we talking?
good luck ,
Hankster
good luck ,
Hankster
Mine was shuddering at about 28000 miles. I tilted the axle up on the side that has the fill plug, dumped in the two bottles of friction modifier, drove a couple of figure 8's and no more shuddering!
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#36
06-23-2011, 08:47 PM
I`m also having the same issues ...shudder or vibration on take off, more going up inclines, and turns.. The Ford people said about my `05 FX4 SC ...5.4 3v Auto...that the differential needs "clutch packs"...and is not covered on my warrantry...considered like your brake pads...they get me every time .... Has any one ever heard of this term before? "clutch packs" ...and how much $ are we talking?
good luck ,
Hankster
good luck ,
Hankster
#37
06-24-2011, 08:20 AM
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#38
06-24-2011, 09:23 AM
#39
06-24-2011, 09:28 AM
#40
06-25-2011, 09:27 PM
#41
04-21-2016, 12:31 PM
Rear shudder
Did using the fluid work?
My new to me '06 FX4 appears to have the dreaded "rear differential shudder". It only happens from a standing start when making turns and at this point it's not that bad but I want to catch it before it gets worse. I'm willing to bet the dealer that sold the truck to me didn't really know this was an issue as they put new rubber on the rear 2 tires for me and from what I've read that can be a catalyst to this starting.
I'm going to do a fluid change on the rear diff which spurred a couple of quetions based on the rearch I've done on the forum.
First question is what fluid do I use for the change? I've read varying suggestions with some saying Royal Purple synth to regular Ford issued fluid and I've also seen a couple fluid rates recommended.
Also, one of the purposes of the fluid change is to add the "friction modifier". Is there a specific name / brand / Ford part number for this. If I'm going to do this I want to make sure I do it right. Hopefully this will solve the issue without tearing into clutch packs etc. Thanks in advance.
I'm going to do a fluid change on the rear diff which spurred a couple of quetions based on the rearch I've done on the forum.
First question is what fluid do I use for the change? I've read varying suggestions with some saying Royal Purple synth to regular Ford issued fluid and I've also seen a couple fluid rates recommended.
Also, one of the purposes of the fluid change is to add the "friction modifier". Is there a specific name / brand / Ford part number for this. If I'm going to do this I want to make sure I do it right. Hopefully this will solve the issue without tearing into clutch packs etc. Thanks in advance.
#42
04-22-2016, 04:40 PM
If you have to add even more friction modifier to get the shudder to dissapear, you have bad clutches. It's a common issue in the newer ford ls. If it works, go for it. But don't expect the limited action to work as it did before. The modifier actually makes the clutches grab less. On an older ls, it was only required on the first fluid fill. From what I've read, an eaton (detroit) ls is the only way to avoid this problem again if you run larger tires or drive the truck hard all the time. It's really not that hard to rebuild yours if you have the tools and an evening to devote to it.
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