R1T climbing steep grade - video posted by RJ

[BillArnett]

Another good point. What we're seeing is a STOCK R1T. Most wranglers you see off-road have so much customization and aftermarket parts that they basically paid twice (or more) for their Jeep.

Yeah. But I doubt it will be possible to modify a Rivian much. Heck, there isn't even room for bigger tires and a lift is out of the question. So we'll have to live with it stock. And it seems that Rivian has chosen the off-road vs street compromises mostly in favor of the later. Not what I would have chosen.

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[Trandall]

My biggest issue with all the videos we have seen at lower speed, in low grip situations, is maintaining wheel speed synchronization ( like a locked center diff and locked front and rear axles gives you) which is essential for keeping momentum. When a fully locked 4x4 lifts tires in the air, the engine rpm stays the same and the weight of the vehicle and the power shifts to the tire with grip. Hopefully we see more programming fixing this, at the current time it looks like a Land Rover lr4 hopping up a hill (quite decent off-road but not much articulation and brake/computer based lockers that cannot maintain momentum like a fully locked 4x4 can.

As was stated previously though, this isn’t marketed as a rock crawler, less jeep rubicon and more as a luxury exploring vehicle like a Range Rover and Lexus.

I think everyone will agree that rock crawling is a niche that Rivian isn't targeting. I'm not an off-road enthusiast but I can't resist chiming in; Isn't maintaining momentum sort-of substitute for torque? I'm thinking this would be much less important if a Jeep had 850ft.*lbs. of instant torque. My point is that a Jeep drivetrain and Rivian drivetrain are drastically different and I would expect very different strategies to traverse loose, steep, and uneven terrain.

 

[CommodoreAmiga]

Yeah. But I doubt it will be possible to modify a Rivian much. Heck, there isn't even room for bigger tires and a lift is out of the question. So we'll have to live with it stock. And it seems that Rivian has chosen the off-road vs street compromises mostly in favor of the later. Not what I would have chosen.

Why do you think a lift is out of the question? I assume we’ll see a lift (even if it’s just a 2-3” one).

There’s already been Interest from at least one off-road accessory manufacturer to make new bumpers.

 

[BillArnett]

Why do you think a lift is out of the question? I assume we’ll see a lift (even if it’s just a 2-3” one).

There’s already been Interest from at least one off-road accessory manufacturer to make new bumpers.

A lift for independent suspension is hard, especially with Rivian’s limited articulation. I suppose it’s possible. I hope you’re right!

and that’s very good news about bumpers. With luck they will be able to improve the approach and departure angles and make room for a winch.

 

[CommodoreAmiga]

A lift for independent suspension is hard, especially with Rivian’s limited articulation. I suppose it’s possible. I hope you’re right!

MOST pickup trucks are independent suspension in the front. ALL half-ton trucks made in the last 20 years are independent front suspension. There are lift kits available for every model and every model year.

The Honda Ridgeline even has independent suspension at all four corners and there are small lifts available for them, even.

 

[skyote]

Warning, longwinded response. TLDR - I have faith in Rivian's traction capabilities due to the architecture. Folks, this should be far superior to traditional, mechanical differentials and brake-powered traction control.

Detailed thoughts:

Rivian's 4 independent motor architecture should be better than traditional lockers. The point of lockers is to ensure that both tires receive power from the drivetrain in hopes that at least one of them will have adequate traction; open or limited slip differentials will send power to the wheel that doesn't have traction.

Rivian should provide optimal traction very quickly. Don't take wheel spin (on the rocks or in the air) as an issue with their system, you can spin tires with lockers too. Also, when the tires spin in the air, it looks to me like Rivian cuts power to the wheels without traction, which stop spinning once they land again, so this looks to me just like momentum from previously applied power. Cutting power to spinning wheels could prevent digging into mud or sand, but sometimes you need some spin to maintain limited traction & continue forward momentum.

I can see the potential for various off road drive modes where varying degrees of power requested (skinny pedal) ratio to allowable wheel spin are applied.

 

[skyote]

Also, regarding lifts...

It will likely be extremely difficult to do any sort of suspension lift, so I think that's out of the question for these vehicles. However, it might be possible to do some sort of 1-2" body lift that might be able to clear up to 37s.

Ability to do a body lift will depend on how everything attaches to the frame/chassis, and adapting cooling airflow to the same.

 

[skyote]

My biggest issue with all the videos we have seen at lower speed, in low grip situations, is maintaining wheel speed synchronization ( like a locked center diff and locked front and rear axles gives you) which is essential for keeping momentum. When a fully locked 4x4 lifts tires in the air, the engine rpm stays the same and the weight of the vehicle and the power shifts to the tire with grip.

A "virtual locker" would be super simple to do, but what they're trying to do is actually better. Virtual rear locker would be fun for drifting in low traction scenarios, but not as helpful in situations where you're actually trying to optimize traction.

 

[MReda]

Warning, longwinded response. TLDR - I have faith in Rivian's traction capabilities due to the architecture. Folks, this should be far superior to traditional, mechanical differentials and brake-powered traction control.

Detailed thoughts:

Rivian's 4 independent motor architecture should be better than traditional lockers. The point of lockers is to ensure that both tires receive power from the drivetrain in hopes that at least one of them will have adequate traction; open or limited slip differentials will send power to the wheel that doesn't have traction.

Rivian should provide optimal traction very quickly. Don't take wheel spin (on the rocks or in the air) as an issue with their system, you can spin tires with lockers too. Also, when the tires spin in the air, it looks to me like Rivian cuts power to the wheels without traction, which stop spinning once they land again, so this looks to me just like momentum from previously applied power. Cutting power to spinning wheels could prevent digging into mud or sand, but sometimes you need some spin to maintain limited traction & continue forward momentum.

I can see the potential for various off road drive modes where varying degrees of power requested (skinny pedal) ratio to allowable wheel spin are applied.

There is no doubt in my mind that this is correct. I've owned (and driven in low traction conditions) four wheel drive vehicles with lockers, open diffs, and a variety of limited slip diffs (clutch, torsen, viscous, etc). Four motors with independent control has the capability to take all of the best features of any mechanical system and apply it as needed. No mechanical system has the ability to provide as precise control or better traction in any given condition.

We could debate whether Rivian has the data to 100% optimize the drivetrain in a variety of conditions, but given the test footage we've seen over the last couple years, I'm guessing they're close. And honestly, since driving in snow and ice can be one of the lowest traction surfaces out there, if I wasn't confident in their software, I probably wouldn't buy one.

 

[kanundrum]

 

[Eager2own]

Would’ve loved to see how each of those wheel sizes fared out there.
Looks like they’re running some comparative testing.

 

[electruck]

Seems RJ is trying to be more active on social these days.

 

[Gshenderson]

MOST pickup trucks are independent suspension in the front. ALL half-ton trucks made in the last 20 years are independent front suspension. There are lift kits available for every model and every model year.

The Honda Ridgeline even has independent suspension at all four corners and there are small lifts available for them, even.

I think the independent electric motors at each wheel may limit the amount of lift and articulation possible. Based on renderings I’ve seen of the chassis with motors and wheels mounted, it appears that the drive shafts from the motor to the wheel hub will be pretty short. This shorter distance means that for each inch of lift or articulation, you are having a more significant change in the angle of the drive shaft. This shaft angle is often the limiting factor in how much you can lift a truck, due to gear binding, without also modifying the drive components. It may not be impossible, but likely less straightforward than traditional truck design.

 

[electruck]

Based on renderings I’ve seen of the chassis with motors and wheels mounted, it appears that the drive shafts from the motor to the wheel hub will be pretty short.

Quite the opposite, actually. The half shafts are actually longer than with a conventional ICE drivetrain. The reason for this is the output shafts of the motors face each other, ie toward the center of the vehicle. Each motor's reduction gear is as physically close to the other along the centerline of the vehicle as they can possibly be and are quite a bit more compact than the differential housing found in a typical ICE drivetrain.

 

[CommodoreAmiga]

I think the independent electric motors at each wheel may limit the amount of lift and articulation possible. Based on renderings I’ve seen of the chassis with motors and wheels mounted, it appears that the drive shafts from the motor to the wheel hub will be pretty short. This shorter distance means that for each inch of lift or articulation, you are having a more significant change in the angle of the drive shaft. This shaft angle is often the limiting factor in how much you can lift a truck, due to gear binding, without also modifying the drive components. It may not be impossible, but likely less straightforward than traditional truck design.

In conventional ICE pickups, it's common to "drop" the front axle assembly down to keep an acceptable half-shaft angle. It may be similarly possible to add a spacer or subframe to the electric motors.

GM has shown the Hummer EV to have telescopic half-shafts to address their large amount of adjustable suspension height.

The problems are solvable -- and in many cases the solutions already exist.