Interesting Offroad Behavior of a Lightning

[SpaceEVDriver]

The nearby forest where we are has a lot of great 4x4 / jeep trails with rocky sections. No photos because (luckily) everyone was in the Lightning.

On the way up one road, there was enough cross-axle terrain that we were on three wheels multiple times. There was a lot of loose, fist-sized limestone rocks. The truck mostly did great in Normal mode with the rear differential locked and 1PD engaged. Still on the factory all-season Hankooks.

On the way down that same section, however, we experienced something unexpected. Every time we had a front wheel off the ground, it would spin... Backwards!

A couple of times it shot a bunch of rocks out in front of the truck.


That's why I said luckily everybody was inside the truck. None of my passengers are experienced spotters so I didn't ask anyone to get out and spot. They very well could have been injured by the flying rocks. The trajectory and fact that no rocks were spun up into the underbody make it clear the free wheel was spinning backwards.


I wish I had video of it.

Anyway, I'm not sure what was the cause of this, but I might need to set up a few cameras to capture this weird behavior.

 

[Mousehunter]

Kind of reminds me of what can happen if you jack up both tires on the same axle. You can spin one forward and the other might want to spin in reverse.

 

[SpaceEVDriver]

Went back to get some video. Will figure out how to upload tomorrow.

 

[Time2Roll]

I assume going down there is regenerative braking that induces a back rotation that spun the wheel as it lost traction.
Interesting observation for sure.

 

[SpaceEVDriver]

Kind of reminds me of what can happen if you jack up both tires on the same axle. You can spin one forward and the other might want to spin in reverse.

Yeah, that's an open differential. You can get that in the right conditions while driving too. This is behaving somewhat differently.

 

[SpaceEVDriver]

Okay. I created a YouTube channel and uploaded these videos (and clips from them.)

Going uphill, long video (1:18)

Going uphill, short clip (0:03)

Going downhill, long video (1:27).

Downhill clip with one example of wheelspin (0:08).

Note that Ford does offer an “offroad” mode for the Lightning. We did not have this mode engaged because it turns off 1PD and I prefer 1PD while offroading. The sun was setting when we got these videos and so we didn’t turn around and run it again with “Off-road Mode” on.

 

[Chavannigans]

I have seen this same behavior in some Rivian off-roading videos.

It seems they reverse the rotation of wheels that don’t have traction on descents.

Pretty cool IMO. More useful than simply locking up that one tire. Pretty big advantage if someone can tune it properly.

 

[SpaceEVDriver]

I have seen this same behavior in some Rivian off-roading videos.

It seems they reverse the rotation of wheels that don’t have traction on descents.

Pretty cool IMO. More useful than simply locking up that one tire. Pretty big advantage if someone can tune it properly.

I have experienced this when I hit a patch of ice too. Which surprised me but immediately made me feel great about the vehicle’s control on ice. It stopped much, much earlier than I’d expected.