When I was in Colorado off-roading I felt the EDL working, climbing some obstacles I'd get some wheel spin, then the truck would just climb up whatever obstacle I pointed it at.

So with the nice weather we've had, I did a test last night. Plus I've been thinking about True-trac diffs again.

Jacked up the truck and put one side of the rear axle on a jackstand, and the other side on the ground. Disabled the AdvanceTrac (traction and stability control). Made sure it was in 2WD, and put it in gear. I was mostly level ground, and the ground was wet cement (My driveway)

At idle nothing happened. The wheel in the air spun, and my truck went nowhere. At light throttle application I could hear the ABS starting to cycle, and the truck pulled forward slightly, but not enough to come off of the jackstand. If I let off the throttle, the ABS stopped cycling. The more I pressed the throttle, the more the ABS cycled, and the greater the torque transfer to the other side. It was controllable enough that I inched the truck forward until the jackstand was angled, but the truck hadn't fallen off. Then I put it in reverse, and inched back the other way until I was back where I started.

It seemed to need quite alot of wheel speed difference before it actuated. So that's a negative. But then again with an open differential and one wheel completely in the air the truck pushed froward.

This is all with a completely open differential on a 2012 F150.
I may not ever need a newer differential. Snow driving would be more stable with a Truetrac, but I have no interest in anything with greater lockup than that.

Just something I thought was interesting and wanted to share.

Next test would be to do the same thing on a hill. Too bad I didn't think of it at the time, I could've put some ramps in front of the front wheels.

 

This sounds like a recipe for disaster if the truck jumps off the jackstand and takes off.

Here is a better demonstration.

http://www.youtube.com/watch?v=3on27AINjaM

http://www.youtube.com/watch?v=zrdcC7WyvG8

 

Uhm, no. I was using a helluva lot less throttle than that guy. Around 1200-1500 rpm with no load. And there was nothing in front of me.

That guy has both wheels still on the ground. I wanted to do a test with one wheel in the air. That was the entire point.

 

If it is using the ABS, it is an electronic limited slip.

If it were an electronic locker, you would have driven right off that jackstand.

Once a wheel is off the ground, limited slip is of limited use.

 

I don't understand, can you do it again but video it?


its not electronic locking diff. its applying the brake to the side that is obviously not getting traction to force the other wheel to turn. physically its the same things as a traction lock diff but the brake pad and disc become the clutch and steel.

 

I've done this test, and the one-wheel-spin-control (eLSD) didn't "transfer" enough power to the wheel with traction to move me up the hill. I was articulated, meaning one wheel had lots of traction, and the other wheel had almost zero. The wheel with no load (almost hanging) just spun.

I then had to turn on my electric locker to move anywhere.

I find the 1wsc is great for level ground, where each rear tire is on a similar surface, with equal/flat pressure on the suspension.

FYI - the 1wsc control also works on the front axle when in 4x4.

 

Wow...just wow.

 

Like others said, you are seeing the 1 wheel spin control(Simulated LSD) in action. You have to manually activate the ELD if equiped.

If you do not have the ELD, adding a True Trac Front and Rear, combined with the 1 wheel spin control, will transfer more torque to contact wheel in your setup.Think of the Park Brake or Pulse Break trick Jeep drivers use with out Lockers on rocks. Except, yours will be automatic thanks to the TSC on your truck.

 

Question(s): Why is a LSD ineffective when one wheel is off the ground? Is it because the torque bias overwhelms the coupling? Are some LSDs better than others in this regard?

 

The one tire was probably jacked up 1", on the axle housing. If he drove forward too far, the jack stand would just tip forward, and he'd be back on all 4 wheels. He was in the truck, applying light throttle. I don't see this as dangerous, or risky.