5 ms·

For context, this is a video of a traditional truck driving up the same hill: https://www.youtube.com/watch?v=ptTwpkWQY_s https://www.youtube.com/watch?v=ptTwpk

For context, this is a video of a traditional truck driving up the same hill: https://www.youtube.com/watch?v=ptTwpkWQY_s https://www.youtube.com/watch?v=ptTwpkWQY_s And here's a Range Rover going up it: https://www.youtube.com/shorts/_00ah8lG4yk https://www.youtube.com/shorts/_00ah8lG4yk It seems like the CT doesn't have the equivalent of a locking diff, and had essentially no articulation. It'll be fine for the target demo (on-road usage). Both the Lightning and the CT clearly suffer from their weight, and their optimization for on-road performance. (in the lightnings case, it even seems to be on stock tires).

giobox 3y ago
I wonder if the tri-motor CT models will be able to simulate a locked rear diff, much like the quad motor rivian models can simulate a locked diff front and rear thanks to being able to adjust torque to all four wheels individually. Only the rear axle of the CT would presumably be able to do this due to the tri-motor layout, unless they resort to the individual wheel braking like they've done on their road cars to simulate diff features. A rear only lock is still a useful offroading feature. From what I've read, it doesn't sound like the quad motor "virtual" locked diff feature on the Rivian trucks works as well as a proper locking diff - its close but still slips occasionally. If I recall correctly their cheaper dual motor models don't have the feature either. I imagine eventually the quad motor "virtual" locking diff solutions will probably get reasonably good, if Tesla decide to do a quad motor CT later.
- brucethemoose2 3y ago
  Quad motor is even better than a locking diff if all the motors are modulated right. I dunno what Rivian does, but I saw that Rimac does 1 motor per wheel, and each motor madly modulates itself during launch control to stop its wheel from slipping... Perfect, maximum torque, all the time.
  - lolbase 3y ago
    I believe that Rivian offers a quad-motor option, and a standard dual-motor with an open-diff that uses the brakes to try to compensate (similar to a typical AWD system).
  - giobox 3y ago
    There's still some slip though in all these virtual solutions - a wheel has to start slipping for the software to notice and modulation to kick in. With a real locking diff, it's physically impossible for one wheel to spin faster than the other. For sure they can likely modulate the wheel torque quickly though to get the wheels back to the same rotation speed.
    - brucethemoose2 3y ago
      In theory, the system can just monitor rotation and "lock" the wheels together with torque as a goal of the system, instead of trying to detect when the tires are slipping. As a bonus, a computer is smart enough to spin the tires at slightly different rates when turning, instead of dragging them along like a locked diff.
- SigmundA 3y ago
  I posted below but you cannot fully simulate a locker with independent motors. The quad motor Rivian is actually inferior to the dual motor for rock crawling due to this. The quad motor Rivian produces 908 lbs/ft of torque which means each motor produces 908/4 = 227 lbs/ft. It has a single speed gear ratio of 12.6:1 meaning each wheel can get a maximum of 227 * 12.6 = 2860.2 lbs/ft wheel torque. The dual motor Rivian produces 829 lbs/ft of torque which means each motor produces 829/2 = 414.5 lbs/ft. It has has a single speed gear ratio of 13.7:1 (11:1 front) in the rear meaning each rear wheel can get a maximum of 414.5 * 13.7 = 5678.65 lbs/ft wheel torque (4559.5 front) with brake locking diff. Contrast this with a Jeep Wrangler which can put out 20,000 to 30,000 lbs/ft of torque to any single wheel through its torque converter, transmission, transfer case and axle gearing which can be over 100:1 in gear ratio and single ICE. There are videos of Rivian's stalling rock crawling that are no issue for an old Jeep with weak engine due to lack of torque to the wheels. EV's will need lockers and probably at least two speed transmission to compete here, or they will need way oversized quad motors to make enough low speed torque without the gearing and lockers.
cgh 3y ago
This Nissan XTerra practically walked up it: https://www.youtube.com/watch?v=xZ8FwhUCBog https://www.youtube.com/watch?v=xZ8FwhUCBog
angled 3y ago
The RRS is on bags and has three diffs? Perhaps the CT should have used a G Wagon as a reference: https://youtube.com/shorts/4i_rxRJXaiU?si=AIOX_16-UbzyIAID https://youtube.com/shorts/4i_rxRJXaiU?si=AIOX_16-UbzyIAID
KennyBlanken 3y ago
Here's someone doing the stairs in a Suzuki Swift with no difflocks: https://www.youtube.com/watch?v=g9gaTSaTX84 https://www.youtube.com/watch?v=g9gaTSaTX84 It's fine for the buyers who will be collectors, posers and social media tools - but still worth giggling about because Musk has consistently bragged that it'll be a better truck than any other truck while also being a 'better car'...and yet it does worse than a truck designed to not really see anything more off-road than a jobsite or country dirt road because Ford can I'm guessing a P1 Touareg/Cayenne, or even a first-gen Audi Allroad wouldn't have a problem.
topspin 3y ago
Yes, it's clearly the weight; every time the tires have to climb they slip. Both EVs have this problem because they're both very heavy; the CT was just the worse of the two. The ICE trucks climb with next to no slip because their missing the extra 1500 lbs. The Tundra has a live rear axle.

giobox 3y ago

I wonder if the tri-motor CT models will be able to simulate a locked rear diff, much like the quad motor rivian models can simulate a locked diff front and rear thanks to being able to adjust torque to all four wheels individually. Only the rear axle of the CT would presumably be able to do this due to the tri-motor layout, unless they resort to the individual wheel braking like they've done on their road cars to simulate diff features. A rear only lock is still a useful offroading feature. From what I've read, it doesn't sound like the quad motor "virtual" locked diff feature on the Rivian trucks works as well as a proper locking diff - its close but still slips occasionally. If I recall correctly their cheaper dual motor models don't have the feature either. I imagine eventually the quad motor "virtual" locking diff solutions will probably get reasonably good, if Tesla decide to do a quad motor CT later.

brucethemoose2 3y ago
Quad motor is even better than a locking diff if all the motors are modulated right. I dunno what Rivian does, but I saw that Rimac does 1 motor per wheel, and each motor madly modulates itself during launch control to stop its wheel from slipping... Perfect, maximum torque, all the time.
- lolbase 3y ago
  I believe that Rivian offers a quad-motor option, and a standard dual-motor with an open-diff that uses the brakes to try to compensate (similar to a typical AWD system).
- giobox 3y ago
  There's still some slip though in all these virtual solutions - a wheel has to start slipping for the software to notice and modulation to kick in. With a real locking diff, it's physically impossible for one wheel to spin faster than the other. For sure they can likely modulate the wheel torque quickly though to get the wheels back to the same rotation speed.
  - brucethemoose2 3y ago
    In theory, the system can just monitor rotation and "lock" the wheels together with torque as a goal of the system, instead of trying to detect when the tires are slipping. As a bonus, a computer is smart enough to spin the tires at slightly different rates when turning, instead of dragging them along like a locked diff.
SigmundA 3y ago
I posted below but you cannot fully simulate a locker with independent motors. The quad motor Rivian is actually inferior to the dual motor for rock crawling due to this. The quad motor Rivian produces 908 lbs/ft of torque which means each motor produces 908/4 = 227 lbs/ft. It has a single speed gear ratio of 12.6:1 meaning each wheel can get a maximum of 227 * 12.6 = 2860.2 lbs/ft wheel torque. The dual motor Rivian produces 829 lbs/ft of torque which means each motor produces 829/2 = 414.5 lbs/ft. It has has a single speed gear ratio of 13.7:1 (11:1 front) in the rear meaning each rear wheel can get a maximum of 414.5 * 13.7 = 5678.65 lbs/ft wheel torque (4559.5 front) with brake locking diff. Contrast this with a Jeep Wrangler which can put out 20,000 to 30,000 lbs/ft of torque to any single wheel through its torque converter, transmission, transfer case and axle gearing which can be over 100:1 in gear ratio and single ICE. There are videos of Rivian's stalling rock crawling that are no issue for an old Jeep with weak engine due to lack of torque to the wheels. EV's will need lockers and probably at least two speed transmission to compete here, or they will need way oversized quad motors to make enough low speed torque without the gearing and lockers.

cgh 3y ago

This Nissan XTerra practically walked up it: https://www.youtube.com/watch?v=xZ8FwhUCBog https://www.youtube.com/watch?v=xZ8FwhUCBog

angled 3y ago

The RRS is on bags and has three diffs? Perhaps the CT should have used a G Wagon as a reference: https://youtube.com/shorts/4i_rxRJXaiU?si=AIOX_16-UbzyIAID https://youtube.com/shorts/4i_rxRJXaiU?si=AIOX_16-UbzyIAID

KennyBlanken 3y ago

Here's someone doing the stairs in a Suzuki Swift with no difflocks: https://www.youtube.com/watch?v=g9gaTSaTX84 https://www.youtube.com/watch?v=g9gaTSaTX84 It's fine for the buyers who will be collectors, posers and social media tools - but still worth giggling about because Musk has consistently bragged that it'll be a better truck than any other truck while also being a 'better car'...and yet it does worse than a truck designed to not really see anything more off-road than a jobsite or country dirt road because Ford can I'm guessing a P1 Touareg/Cayenne, or even a first-gen Audi Allroad wouldn't have a problem.

topspin 3y ago

Yes, it's clearly the weight; every time the tires have to climb they slip. Both EVs have this problem because they're both very heavy; the CT was just the worse of the two. The ICE trucks climb with next to no slip because their missing the extra 1500 lbs. The Tundra has a live rear axle.