02 XLS 4x4 121K miles Tranny shutter

[svtcobratkd]

Purchased the Explorer with 67K miles on it.
My son was driving it up until a month ago.
Now, I'm the owner.
The tranny shutters a bit when downshifting going up hills, but not so much going down.
(not absolutely sure it's when it downshifts or could it be slack in the drive train??)
It currently has 121K miles on it and I do not know if the fluid has ever been replaced.
Should I take it to Ford and have it replaced??
Was wondering if it might do more harm than good.
(MORE DETAIL IN MY SECOND POST)
Thanks!!
First post! (WOOT)
Past Fords:
69 Mach 1
87 Turbo Tbird
88 Bronco II 4x4
90 Taurus Wagon
98 Taurus
96 V6 Stang
97 Cobra
98 GT vert
96 Cobra vert
99 Explorer 4x4

 

[svtcobratkd]

More Detail on the symptoms:
The shutter occurs from a stop when turning for 1 second after you start moving.
The shutter also occurs from a stop when turning going in reverse.
The shutter DOES NOT occur from a stop going straight forward.
The shutter DOES NOT occur from a stop going straight in reverse.

Maybe the shutter that I'm feeling is not the tranny??
Any thoughts or insight would be great!!

 

[shadowless127]

Sounds like its the 4wd engaging and disengaging.

 

[svtcobratkd]

It only does it turning and not going straight.
I've had 4x4's before and had one in 4x4 in a turn and ran off the snow onto the road surface and remember how that feels.
This feels like it's coming from the rear.
I'm thinking it's the LS diff.
But, would that explain the occasional shudder at higher speeds going straight? 35 or 45 MPH??
The shudder ALWAYS happens when doing a slow turn

 

[1Bad04]

The shuddering feeling you get when taking off in a turn is more than likely the rearend. Mine does this sometimes. Check out this link here: http://www.alldatadiy.com/alldata/AFI~V13178613~C38518~R0~OD~N/0/101825161/102960169/102960255/102960257/34853741/34850750/42063452/121022605

 

[Thelt]

I would get the rear diff serviced and make sure they use the right additives. Mine did this a little when I first got it but it cleared up after getting it serviced.

 

[svtcobratkd]

I did stop by the local Ford dealer and they suggested putting in a bottle of Friction Modifier. So, for $5, I thought I would give it a try! If this doesnt clear it up, I might drain & refill it also with 1 bottle of the Friction Modifier. I did get the motorcraft brand as they suggested. They said it might take 100 miles or so to tell, but I swear it feels better already!

 

[jims99]

I had a similar problem with my 99 xlt, every time i accellerate, it shutters then shifts, and sometimes there are multiple shutters, i just had the tranny rebuilt, it shifts perfectly but it shutters, is this a tranny issue or something else? thanks in advance . jim