Had the truck about 2 months. When turning from stopped I get some shudder. It just started. Add some friction modifier? When it is time to fix it do you just rebuild it? Replace with a full case like a detroit or trutrac? Can you reuse the LSD carrier and add a lunchbox locker?
Negative on the lunch box. Ford uses a clutch pack with springs. Carrier is different. Try a Ford brand friction modifier as suggested.
As a note I had a similar feel in a Ford LSD just before the whole mess went south. High milage carrier and the carrier bearings went.
Pop the cover, check for side load slop and pinion slop. If it's all good New oil and friction modifier. Skip the synthetic in my opinion.
My 03 expedition this exactly this. Changed fluid with full synthetic (expensive I know lol) and no more noise and the lsd works as it should problem free for 2months now. 230k miles too. So its worth a shot
Shudder turns into more of a jerk. Like a full carrier Detroit locking in. Usually manifested more in turns. Put off to long it goes into this anytime a load is on it. This is just before ka-boom. Mine went through this sequence years ago when I didn't know any better. By the time I asked my father about it the vehicle nearly didn't make it to the shop.
I don't know what was worse. Me not knowing any better or my father being a service manager limping the thing in to get it repaired. I'm sure the folks working for him ragged him hard about his kids killing their vehicles.
Side load and diferential speed is what drives the clutches or cones in a Ford/Auburn LSD. It simply tries to catch the slower side up via friction and clutches. This is why you can make buildable ones better through stiffer springs. Side to side slop from carrier bearing wear causes all the right priciples to act weird. In real bad situations this is all bypassed because the gear movement is so bad your now loading up the pinion.
In all cases beyond LSD shutter you should start getting some rear end roar or noise under a load or coasting. One usually points to carrier bearings, the other pinion.
