I have a 2004 6.0 4X4 SC with the limited slip axle option. The other day I stopped in my driveway to pick up my mail. My drive has a slight incline. I was in 2 wheel drive and my right rear tire was on some ice and started spinning when I tried to drive up to the garage. Is this the way the factory limited slip axle works? If so, then can this be corrected so it works like the old positracks and lockers?

Thanks

 

Yes this is the way it works. Limited slip allows the other tire to engage when you start loosing traction. Unfortunately Ford's LS, at least on the Super Duty is weak, works great in the Crown Vic. There is another thread in here somewhere that explains how changing the gear oil and adding less friction modifier to it can help lock the rear up better. The only other thing you can do is to buy an aftermarket locker or limited slip system. There are alot of knowlegable guys here on the best ones out there to look for and I'm sure one of them will be along shortly to offer some help.

 

johnnysF350 has it right.

If you would like the LS to engage more, then a gear oil change is needed. Make sure to fill with the recommended 75w140 full synthetic gear oil. Then add just 2oz of the friction modifier. Drive around an open area (ie: parking lot) in a figure S pattern. Listen for rear chatter from the LS. Continue to increase the friction modifier by 2oz until the chatter goes away. Usually 4oz is a good amount.


biz

 

How much gear oil does the rear axle require?
Thanks again.

 

3.3 Liters or 6.9 pints (75W-140 Synthetic)

 

And...........it's expensive!