Actual Off-Road Testing: climbing & descending (@ Hollister Hill RSVA - 10/23/23)

[Crimson_Fate]

TFL had some interesting pictures of the CT about 3 minutes in.




They have never been fans of the CT but It does loook like the upper A arm is bent on the driver side. The viseos posted in this forum do have some loud bangs, it may be the same car.

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[Bill837]

No. A helical limited slip differential makes it up this.
A locked rear end won’t chatter or what is sometimes called bark the tires.

I’m seeing the same issue the rivian and the hummer exibit. I’m no coder and certainly no digital driveline tech but in thousands of miles of offroading I fully understand the limitations of being without a fixed traction device.
While this merely just makes the truck look and sound awkward climbing, an off camber situation or worse a muddy hillclimb is going to be tough for this truck as it stands

Consider this constructive criticism in hopes the tesla lurkers here pay attention

I was really speaking to your point about lockers being common in 1/2 ton pickups. I can see LSDs being common, but I don't really think lockers are, but maybe I'm wrong.

 

[Crissa]

Here’s a Rover basically half asleep going up it

You'll notice their line of attack is different. Not to mention the shorter wheelbase.

They have never been fans of the CT but It does loook like the upper A arm is bent on the driver side. The viseos posted in this forum do have some loud bangs, it may be the same car.

It's probably someone closing or opening a truck in the parking lot that the film is from.

-Crissa

 

[Trekboy]

Rear lockers are exceedingly common on half ton trucks even 2wd ones. One wet boat ramp is enough to warrant having them.

I’m not being a hater but that obstacle is a test of approach angles and a little bit on the break over side. Its not insignificant that it make it but any vehicle with sufficient clearance and a locked or good limited slip differential makes it calmly.

Cybertruck BETTER have a way to lock the axles. Elon should know this.

 

[cvalue13]

TFL had some interesting pictures of the CT about 3 minutes in.




They have never been fans of the CT but It does loook like the upper A arm is bent on the driver side. The viseos posted in this forum do have some loud bangs, it may be the same car.

interesting…

here’s a pic from one of the units that did the Baja (peninsula, not race)

unbent for compare

 

[TacoTuesday]

Stretch, the old jeep, from the OP did this climb with no effort, haha.

Last video in IG post

 

[EVSport7]

Rear lockers are exceedingly common on half ton trucks even 2wd ones. One wet boat ramp is enough to warrant having them.

I’m not being a hater but that obstacle is a test of approach angles and a little bit on the break over side. Its not insignificant that it make it but any vehicle with sufficient clearance and a locked or good limited slip differential makes it calmly.

I understand that Rivian and everyone else want to let the computer "figure it out", but if you're in a tough spot I just would rather have some form of an e-locker.

 

[JBee]

TFL had some interesting pictures of the CT about 3 minutes in.




They have never been fans of the CT but It does loook like the upper A arm is bent on the driver side. The viseos posted in this forum do have some loud bangs, it may be the same car.

That looks like a structural failure for sure.

Now if it would of been an exoskeleton that would of never happened, I'm sure of it, because Tesla engineers are God level at structural design.

Honestly to me that looks like the upper suspension arm plate thickness was too heavily weight optimized, and they ended up compromising structural integrity of the pressed part.

I also don't think it is an intentional point of failure for heavy impacts, normally they have progressive rubber stops for that.

 

[JBee]

The inherent difference between mechanical locker and traction control is that a locker is instantaneous torque on the wheel with the most traction, and traction control is a delayed torque, after brake intervention with the wheel with least traction.

The suspension setup also seems way to stiff and doesn't comply and articulate with the undulations of the road well. Some of this can be adjusted by using the airbag suspension, but if they do not have a way to disengage of reduce the impact of the torsion sway bar it will still want to hang on the high parts and dangle the opposite wheel. Wheel articulation is critical in keeping as many wheels as possible on the ground with traction.

Now with a locker this would simply mean the compressed wheel has more traction and it would use that to drive further. In a traction control setup, this will mean the dangling wheel has no traction and would spin, and the traction control would see this, reduce throttle and activate the brake to stop it from spinning, which in turn puts torque onto the compressed wheel with traction, and moves the vehicle forwards.

This delay produces intermittent loss of traction on all the drive wheels which impedes forward propulsion, as power is constantly being reshuffled between the drive wheels that have traction, and energy is lost through the use of brakes, which also causes heat and wear.

The difference is quite large, in that a locker needs far less power to achieve the same amount of forward momentum, and as such would consume far less battery to achieve the same task.

The combination of having a non-articulating suspension, limited by the sway arms and airspring settings, and not having lockers makes this simple hill a chore for the CT.

This is also why the Range Rover just idles up there with apparently no traction loss. Because it's wheel articulation is excellent, and at a minimum it has a rear locker/LSD.

For an off-road EV, a mechanical locker is a efficiency device, because no dive inertia is lost through traction control interference which has to be compensated for by more individual wheel acceleration, and no brake interventions cause energy to be converted into heat instead, along with brake wear.

So although traction control is an easy add on to any vehicle with ABS by just adding code, it is in no way a replacement for a locker type system.

You can see this in the following video which shows the traction only version in low range at 0:50 and the locker version going up the same hill with the same car at 5:20.



The only way to achieve the same as a locker with a EV, and in fact it would likely be even better, is by using a individual motor per wheel setup like the QM Rivian. That way you can not only "lock' the drive wheels in synchronization with each other, but also torque vector, in that it would also be "locked" to the steering angle and would make sure each wheel is spinning at the exact speed required to turn, being faster on the outside and slower in the inside of the corner. This is like tank turn, but limited to the steering angle of the wheels.

Further to this, a disconnect-able sway bar also is beneficial off-road, but is required to stop the vehicle from leaning out of a corner on-road. There are a few options for this as well. My old 2001 Discovery already had this, in that when they were owned by BMW, they added an active hydraulic actuator to the sway bar that would lean the vehicle into the corner. This also leaned the body against a side slope whilst crossing sideways along a hill. But being cross linked, also meant that the wheel articulation (that is the front wheels leaning one way and the rear leaning the opposite way) was excellent and not impeded by the active sway bar in any way.

The alternative version is to have a passive system, that like the locally developed Kinetic system was used in Toyota production vehicles with KDSS in Landcruiser, can do so by simply cross linking a hydraulic actuator on either sway bar. This takes advantage of the fact that on-road a vehicle leans out of the corner, compressing the two outside wheels equally in the same direction, and opposite to the two inside wheels, which in turn is met with the full resistance of the actuator and heavy sway bar.

Conversely, off-road, wheel articulation is such that the front suspension is opposite to the rear, meaning that the cross link of the actuator line wo opposite corners allows full wheel articulation without the sway bar trying to resist it.



So given the above, I'd rate the CT as an "average" off-roader in it's current configuration from what we have seen so far.

I am obviously hopeful they will sort some of these issues out with further testing, optimizations and iterations, but I doubt that active hydraulic brake actuation and modulation is able to achieve the levels of torque distribution offered by a solid mechanical connection or single motor per wheel torque vectoring.

 

[Setok]

Cybertruck BETTER have a way to lock the axles. Elon should know this.

It’s very likely there won’t be lockers, with Tesla relying on traction control and/or multiple motors. Like Rivian.

It’s nice to see the Cybertruck do some real off-roading at last. We can see the size somewhat hinders it compared to the smaller off-roaders, but that goes for all American sized pickups. The wheel squeal indeed can be an indication of the limitation of even having multiple motors, versus locks. We have seen that with Rivian too. People don’t understand that even with multiple motors, wheels will need to slip before the computer can figure out how to adjust torque. That’s just reality. Whereas a lock will prevent a wheel with less traction from slipping compared to one that has traction. This matters less on rock or concrete but can matter a lot on mud or snow.

The wheel articulation did seem stiff but may be helped if they can dial in the software. It’s not true to say you can’t have decent on road manners with big articulation. The old stiff axle Defenders have massive articulation for an off the shelf vehicle, and are still OK on road. Probably easier with a stiff axle and coil springs. The air suspension versions, I believe, react by deflating suspension on one side while inflating the other. Thus simulating a stiff axle. I would assume the Cybertruck could do this, unless some patent prevents it.

I’m not saying the Cybertruck won’t be decent offroad. It’s always a compromise. But people frothing about how it will be the greatest ever are maybe not seeing the full picture.

 

[WHIZZARD OF OZ]

Free-range Cybertrucks

After the 'Al Capone' weekend 'SHOOT', be sure to look out in the fields for 'Cows With Guns' ( Dana C. Lyons )

"We will run free with the Buffalo, or die"

 

[Crissa]

My spouse peered over at this and asked, 'who would know best about locking axles being useful' then she said 'military!' then she ran off to figure out what vehicles the military uses that have locking axles...

'Marines on beaches and multi-axle trucks,' she came back with. 'That is all I can find.'

The only reason you use locking axles is because you don't care about cornering, you only want to scrabble forward or backwards. There's no reason a truck with motor per wheel cannot simulate it.

Besides, experience with the vehicle and track overcomes alot of slip. Knowing where to put your tires is just, the most important thing.

Having a locking differential won't stop you from spinning your tires if you put them in the wrong spots with the wrong torque.

-Crissa

 

[Ehninger1212]

Here’s a Rover basically half asleep going up it

Land rovers just kinda rule.. I have an 05 LR3 that really just dominates its class of vehicle off road. I bought it thinking I'm might sacrifice some off road worthiness for some comfort. Boy was i wrong haha.

That being said, the Cybertruck is clearly wider, longer and probably 2k-3klbs heavier.

 

[cvalue13]

The wheel articulation did seem stiff but may be helped if they can dial in the software.

The suspension setup also seems way to stiff and doesn't comply and articulate with the undulations of the road well.

faik, Land Rover really the only ones to figure out adjustable air suspension for off-road articulation

took them several decades to dial in

that cheat-sheet in hand, I’ll be surprised if Tesla doesn’t get it dialed in quickly

 

[JBee]

My spouse peered over at this and asked, 'who would know best about locking axles being useful' then she said 'military!' then she ran off to figure out what vehicles the military uses that have locking axles...

'Marines on beaches and multi-axle trucks,' she came back with. 'That is all I can find.'

The only reason you use locking axles is because you don't care about cornering, you only want to scrabble forward or backwards. There's no reason a truck with motor per wheel cannot simulate it.

Besides, experience with the vehicle and track overcomes alot of slip. Knowing where to put your tires is just, the most important thing.

Having a locking differential won't stop you from spinning your tires if you put them in the wrong spots with the wrong torque.

-Crissa

Hey Crissa.

Not sure if you read my post above about lockers and suspension articulation?
Get back to me once you have, there's more to it.

You are right that a "motor per wheel" can "simulate" a differential lock, like with a quad motor Rivian or CT, but the point is that "traction control" can not simulate nor compete with a mechanical lock, as I have written in detail about above. Same goes with the lack of appropriate sway bar.

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