Interesting Find: Comments on Color Development & R1's are not actually Full Time All Wheel Drive

Autolycus

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FWIW, in the video in the OP, the Rivian engineer's (?) exact words were, "The rears have an electronic disconnect, so they can be disconnected from the axles."
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DucRider

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FWIW, in the video in the OP, the Rivian engineer's (?) exact words were, "The rears have an electronic disconnect, so they can be disconnected from the axles."
Yes, and at that time they also were stating that it would have the electrochromic roof and powered tailgate as seen on the prototype.

Did it make it to production versions? It will be interesting to find out.
 

ajdelange

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Ok…you should already know that there is no material way to increase efficiency with PM motors as you’ve highlighted in other posts without disengagement of the drivetrain.
Don't think I ever said that because there is. The motor is most efficient at one combination of torque and speed just as is the case with an ICE engine except that it is radically less dramatic. Thus to increase efficiency you do the same thing you do in an ICE engine: shift gears according to speed range. You don't here do this is a single transmission coupled to the wheels. You do it by having two sets of wheels each set connected to its own transmission with the forward set having a different gearing ratio than the rear set. To maximize efficiency you then use whichever wheel set gives you the better efficiency and turn the other off. Except that I don't believe that either set will be completely off.

MT has flat out communicated that the truck goes into front wheel drive only. So what is the logical conclusion?
That MT doesn't know what they are talking about.


FWIW, in the video in the OP, the Rivian engineer's (?) exact words were, "The rears have an electronic disconnect, so they can be disconnected from the axles."
Since we are in the same part of the country how about a friendly wager for a drink if we ever cross paths.
We won't know the truth until someone tears down the motor assembly but if you still want to propose the wager given Autolycus's post I'll take it. One way or the other it would be my pleasure to buy beer for a fellow Rivian nut.
 

Autolycus

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We could probably get into lots of fun semantic debates about what an "electronic disconnect" could mean. I agree that ultimately the only way this debate will likely be settled is when someone's got a drivetrain in hand and breaks it down. Although maybe they'll be more open about components and functionality once the trucks are in customer's hands? I doubt they'll be giving schematics to us anyway.
 

azbill

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On the Mach E forums a guy instrumented the front and rear motors using Torque Pro and an OBD II dongle. Ford basically turns off the front motor (zero torque) when above 22mph, unless the car is accelerating. So going down the highway it is running in RWD mode.
 

SeaGeo

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This has been kicked around here fairly recently. I don't think there will be a 2WD mode in which 2 of the motors are totally disabled. I think that for any given speed, grade and wind there will be a particular ratio of power delivered to the front motors to the power delivered by the rear motors that will be the most efficient. I believe the car will calculate that and set the power ratio accordingly. This might even be real time adaptive - the same idea as used in maximum power point tracking in solar converters.
Just watched a first drive of the EV6 by OOS, and Kyle mentioned a nugget that I didn't know of about that. The AWD version of that will also declutch the front motor. So we now have the Taycan and EV6 doing that to extend range. There must be something there that the manufacturers are seeing.
 

SeaGeo

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On the Mach E forums a guy instrumented the front and rear motors using Torque Pro and an OBD II dongle. Ford basically turns off the front motor (zero torque) when above 22mph, unless the car is accelerating. So going down the highway it is running in RWD mode.
Interesting. Good thinking by him.
 

Autolycus

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Just watched a first drive of the EV6 by OOS, and Kyle mentioned a nugget that I didn't know of about that. The AWD version of that will also declutch the front motor. So we now have the Taycan and EV6 doing that to extend range. There must be something there that the manufacturers are seeing.
Yep, it’s mentioned in Hyundai’s press information announcing the E-GMP platform. There’s a transmission built into the front engine stack. It’s extremely simple since it’s literally just 2 gears with 2 states—engaged and not engaged—but it’s technically a transmission all the same.

Here’s the release, and you can see renderings of the front and rear engines. Pretty clear difference between them because of the transmission.


https://www.hyundai.com/worldwide/en/company/newsroom/-0000016584
 
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