Anybody have any idea what's going on? 2010 F150 Supercrew, LSD. Never tows.

The clutch pack first went at 90,582 km /56,613 miles, replaced under warranty
It went out again at 113,000 km/ 70,625, replaced at my cost
Now at 148,000 km/ 92,500 and today it started shuddering and howling on turns again!!!! I really don't want to fork out ANOTHER $1300 for this issue.

Is this just shoddy work from the dealership? Any ideas?

Thanks

 

What is your definition of goes out? Most people never know when they wear out as they just one wheel more easily. Usually when they grab and chatter in turns they are working too well. That is why they sell the LSD additive. the additive makes the fluid more slippery so the clutches are not so grabby. To test a LSD I believe you jack up one wheel and turn it with a torque wrench. it should hold to a certain lb ft rating. I would throw it out and install a TruTrac all gear LSD if it was my dime. No more clutches...

 

howling could be a bearing/race issue from a poor install

 

My mistake, they are working too well, grabbing and chattering. The second time it did that I had them add more friction modifier, and it worked for a week, and then it was back again, they told me the clutch pack had to be replaced. Thanks for the info on the TruTrac, I'll call around to some 4x4 places on Monday.

 

It only howls going around tight corners. Would a bearing/race issue be all the time, or just on corners?

 

You can try a fluid change to Mobil 1 try it but leave it a smidgen low. Then add friction modifier as needed starting with one bottle until it is quiet? I prefer the GM friction modifier, I think it is cheaper as well. The Mobil 1 synthetic may be a little slicker than Motorcraft.

I would start with adding a bottle of GM friction modifier to your truck. On a full diff you can jack up one side and the fluid will run down the axle tube giving you room to add.

I put two bottles of the GM modifier in one posi and it one wheeled from then on

 

Well, I'll try the cheap fix first and see if it works. . adding the friction modifier and going from there.

 

theres 5 bearings/races in the axle assembly.

The pinion bearing is most likely to cause noise when loaded with power vs unloading. (power and coast)

two differential bearings and two axle bearings (on the axle ends) can cause noise when loaded with lateral movement, or weight, or both.



Also if you're refilling or adding to the axle, its easier to take out the wheel speed sensor, it gives you a larger opening to pour into than the fill hole. Plus its a vertical drop instead of sideways filling. Just remember to leave the fill plug off when filling from the wheel speed sensor hole.

 

I had the whole chattering grabbing issue awhile back on my newly rebuilt GM 12 bolt. Used the Ford friction modifier first. Had such a chattering and grabbing I was sure something was broken, installed wrong or just plain defective. New clutch pak had been soaking for days in gear lube prior to install too. Drained and refilled using the GM additive, same problem. Finally drained it and refilled it with the Royal Purple gear lube and it is now so unbelievably smooth now that I can't believe it! I was ready to tear down the rear end again and redo the new clutch pak I had installed. Seems odd you are having that issue though.

 

My update at this point is that the chattering went away by itself as I was on my way to go buy a bottle of friction modifier. I have never had it go away on it's own before, usually it just gets worse and worse. I'm going to keep my "eye" on it and see what happens, if it starts again I'll add a bottle and go from there.