I don't have a locking differential, but when I turn off the traction control and make a full-throttle start my truck lays down two equal strips of rubber.
Splain dat.

 

You don't have a e-locker but you have posi track so when there is slippage it will kick in ie spinning your tires

 

Reminds me of the movie "My cousin vinny "

 

Uh, did you say two yutes?

 

Not trying to hijack your thread but since its about open-limited slip rear ends here goes.

When I first purchased my F150 i was trying ti find out what kind of rear end was in it. Open or limited slip. From what I could find since I had the FX4 package i had a open diff since I had the option to lock it by pulling out on the 4 wheel drive ****. Is this correct? If I turn off traction control and punch it Ill leave two marks as well with the e-lock turned off.


BKVic

 

What's a yute?

I'm sorry judge, two yoouuthhhsss.

Great movie.

 

Our trucks have open diffs or e-lock as an option.
With an open diff, if both rear wheels are on an equal traction surface, both tires will spin at the same rate, and laying two nice black stripes.

I'm not sure for Ford, but I think they also do it, on my BMW, even if the traction control is disabled, there is another function that remains ON and acts as a locking diff. It will stop the spinning wheel on the same axle. It still lets you do donuts if you want, but will still activate the brake on the spinning wheel of the same axle to simulate a locking axle.
Hard on brake pads, and not as effective as a real mechanical LS or locker diff, but it get the job done.

 

So you are telling me I have a limited slip, but not a locking differential? I haven't seen any mention of such in any Ford literature. I would think Ford would be touting the limited slip if it were standard.

 

Sorry if I was not clear.
No, you don't have a limited slip diff.
It is either 'open' or 'e-lock' if ordered as an option.

What I was saying, is an open diff, if both wheels are on the same surface, each wheel will receive 50% of the torque and spin equally.

If one wheel has less traction, due to bad road surface, or the suspension twisting under high torque, then the wheel with less traction will start spinning, and not the other one. That's the way an open diff works, it will send it's torque to the wheel with the less resistance.

 

No limited slip or positive traction differentials in 2015+ F-150s. The only option is a electronic locking differential. I've found that the traction control will act like a E-LSD and lay two strips of rubber during wheel spin.

To test this theory in my 2.7, I did a boost launch at 2K RPMs. Massive wheel spin and two nice strips of rubber laid down. I've found my 2.7 with 3.31s launches best around 1500 RPMs.