Quad motor vs locking diff

[White Shadow]

LOL. You have oscillated from "you are all wrong, quad motors are better that a locking diff" to "they are not even as good as a brake based AWD"? I am having having trouble keeping up with ya man, you are switching sides too fast.

Hey, I admit 'tho, I am old & slow these days.

Yes, I agree. My R1T is _not_ as good on simple obstacles as an inexpensive brake-based AWD vehicle is. You say "they can easily fix this".

Well, that would be nice. Here is to hoping.

You're a disaster....you really are a complete disaster. I don't know why I'm wasting my tire with you, but I'll say this---if you're going to quote me, then actually quote me. Don't put words in my mouth. I didn't even suggest what you're claiming I said. Not even close.

Let's recap---my whole argument here is that it is entirely possible to have a quad motor set up work exactly as well as a fully locked 4wd system. Has Rivian accomplished that? No, they have not. Does that mean it can't be done? No, it does not. My comment about Rivian not even having their vehicles set up to be as good as a traction based AWD/4wd system is my opinion after watching Kyle's video. Like I said, there's no good reason to see power not being transferred from the wheels that slip, to the wheels that grip (to steal Subaru's line) as Rivian is currently set up (with the current software) and is evident is Kyle's video. That said, this part is VERY easily fixable with software alone. Is that not obvious?

Sponsored

 

[White Shadow]

@R.I.P. load up a factory optioned jeep gladiator without aftermarket alterations to 7000lbs, put similar tires on compared to the T, then run both through the same situations. Film it, and put it on youtube. This is the only way you'll be able to stand on your soapbox and not be questioned by people.
.

Sadly, in current state, I think any Rivian would pale in comparison to the Jeep with it's true lockers in the situation you have described. However, it takes nothing more than to update the software in order to make the vehicle transfer power from side to side or front to rear, or even corner to corner. The real question should be this---why didn't Rivian set up these vehicles to do that in the first place? Watching Kyle's video, Rivian is currently set up like a 4wd with nothing but open differentials, which is crazy for a vehicle that doesn't even have differentials. To be fair, it's not really apparent if Rivian does put some level of power where it can benefit, but the R1T just sat like a dead duck, spinning one front tire and one rear tire while the other two tires got absolutely no power. At least that's the way it looked in the video. And if that's the case the question is why set up a quad motor vehicle to act like a 4wd vehicle with open differentials? Makes no sense to me at all.

 

[SoCal Rob]

Well, unlike Kyle I am not a yubtub guy lol. That is why I posted his vid. What I have experienced is on full display in his vid. Note how the vehicle "hangs" on the off camber test, with only two wheels spinning. Note the un-controlled spin of some wheels on the rock climb, causing dicey slides. It is all there, I just posted it for anybody that was interested, along with my similar experience.

As for being questioned, there ended up being a lot of people that don't even own one saying "nuhuh". Weird, and childish really. I drive one, have experienced the same things Kyle demonstrated in his video, and shared my experience. If somehow this offended people, I just don't know what to do with that.

Imagine if someone took a chainsaw, didn’t start it, and began bashing the bar and chain end against a tree. After a while they’ll declare an axe victorious at cutting down trees. I understand why they’ll be sincere in their judgement, but that isn’t the same as taking one person familiar with cutting trees with chainsaws and another person familiar with cutting trees with axes and judging the outcomes when both tools are used optimally.

My take on this video is that Kyle didn’t always do the best job with vehicle setup for the conditions.

I haven’t driven a Rivian off road but we’ve taken our LR3 off road a lot and many times through stuff like Kyle encountered in his video. Of course there is no guarantee that Rivian’s Rock Crawl behaves like Land Rover’s Rock Crawl but rock crawl is what we use when going over rock or rocky surfaces at a very slow pace. I don’t know exactly how Land Rover makes this mode work so much better for this type of terrain, but it makes a dramatic difference. I don’t know why Rivian allows a wheel or two to remain motionless in other (non rock crawl) modes, but I don’t think it’s because the motors cannot generate enough force to turn them. It seems like the programming in those modes doesn’t permit them to send enough power to the corners with traction.

I just found it really odd that after that demo in All Terrain, at 11:06 in the video Kyle talks about the main challenge and he says, “Typically what we do is we get the vehicles in the most off-roady settings for this…” and then he continues on to say that he’s changing to Rock Crawl, highest suspension, and ride in stiff. If he’s determined that those are the most off-roady then why not use them in the earlier test?

I think a lot of people assume that the way they are used to driving their traditional 4x4 with solid axles, steel springs, and 3 locking diffs directly translates to driving a modern 4x4 without those things when it doesn’t. When they try using the new tool in the same old way and it yields poor results on a modern 4x4, they think it means the modern vehicle is worse. What it really means is that they haven’t changed their way of driving to take advantage of the tech.

 

[Almex1]

Boy oh boy did you upset the apple cart, RIP. What I read was a description of a specific problem inherent in the quad motor design.

What other people heard was an attack on their very souls. White shadow came out swinging like you had insulted his momma. If it was such a simple software solution, why haven't they implemented it? RIP has simply, succinctly, and accurately explained why a differential, without software, can be superior in low traction scenarios to a quad motor setup.

He has been on the same surfaces in his fully locked vehicle,and his quad motor, and talked about the results. Why oh why would anyone feel like they need to flame him or resort to personal attacks? Dude just made an observation.

White shadow, you must be real fun at parties. I mean, what did he do to you to get you so riled up?

 

[Inkedsphynx]

Boy oh boy did you upset the apple cart, RIP. What I read was a description of a specific problem inherent in the quad motor design.

What other people heard was an attack on their very souls. White shadow came out swinging like you had insulted his momma. If it was such a simple software solution, why haven't they implemented it? RIP has simply, succinctly, and accurately explained why a differential, without software, can be superior in low traction scenarios to a quad motor setup.

He has been on the same surfaces in his fully locked vehicle,and his quad motor, and talked about the results. Why oh why would anyone feel like they need to flame him or resort to personal attacks? Dude just made an observation.

White shadow, you must be real fun at parties. I mean, what did he do to you to get you so riled up?

To be fair, White Shadow asserted a point and the OP then responded while not actually addressing the point White Shadow has been making. I get pretty pissy when people come at me after having clearly not read or understood what I was saying as well.

But also, let's avoid the hypocrisy and not personally insult people while complaining they've personally insulted people.

 

[R.I.P.]

In this update Kyle makes a couple of great points.

1. Recent updates have helped a lot.
2. Yes, a locking diff would be better.

I agree with both.

The thing that horrified me in this vid was 22"s off-road. Shall we get into a raging argument over that now?

This is a pretty lite 4x4 trail with conditions that the R1T likes; hard ground and good traction.

Biggest point? Everybody is having fun playing with their toys. Headed out today to do the same.... Cheers.

 

[kurtlikevonnegut]

This pissing match discussion is very reminiscent of when someone hyperbolically says the truck drives "like a sports car" and 47 people come out of the woodwork to mention that "ackshually it doesn't handle anything like my 911 GT2 OR my Lotus thank you very much."

The simple fact that you can have people arguing about whether or not it's a Sports Car, and whether or not it's a Serious Offroader amplifies the unique space that the S and the T occupy. The quad motors are what allow both conversations to happen simultaneously and you would never see that with solid axles and locking differentials. This is by design and I'm going to go out on a limb and say that the vast majority of owners and prospective buyers of a Rivian are pleased with the tradeoff.

 

[racekarl]

To be fair, White Shadow asserted a point and the OP then responded while not actually addressing the point White Shadow has been making.

And to be fair, WhiteShadow did the same thing to R.I.P. At this point they are just talking past each other...

 

[Almex1]

I mean, he came out of the gates with a real attitude like he was personally insulted. I found his demeanor off putting and a bit petty, so I said he's not fun at parties. I guess it's an insult, but it more gets to the core of WHY would someone get so upset? He said he could build a quad EV in his garage that would mimic locking diffs, ridiculous. Can rivian come out with some software to help? Almost assuredly! But RIP simply compared quad motors to differentials here, nothing more. He did not claim to be able to build a superior rivian in his garage.

And yes, he invited you out to ride on the off road park to demonstrate ideas he already laid out that were ignored

 

[Inkedsphynx]

Ignoring the 'which is better' and focusing on the 'how could an R1 emulate physical lockers performance' my thought is this:

I think it's reasonable to assume that the system is both aware of and able to limit the RPM of the electric motors at each wheel. I believe it's also reasonable for the system to know how those RPMs translate to RPM of the tires, and thus 'speed'. I believe Rivian has the power to limit RPMs at the motor, as not being able to do so would be terrible for safety and longevity of the motors. I'm not sure if the speed limiter accomplishes this by capping motor rpm, but I do believe the speed limiter is proof that Rivian can modulate the RPM of the motors.

If all of that is true, is it then not reasonable to assume Rivian could release an ultra-rock-crawl mode that allows you to specifically set the max rotation of the motors, no matter how hard you mash the pedal, and assure that the same amount of RPM is going to each wheel, with full torque. Would this not, for all intents and purposes, simulate what physical lockers are doing without any need for feedback on traction from the underlying surface?

Edit: This is a legit question. That all makes sense to me, but I'm not a physicist or a mechanical/electrical engineer.

 

[the long way downunder]

you may get flamed for insinuating that Rivian is "behind" lol.

Hopefully not here. But yes, there are Rivian zealots who refuse to discuss "emperor may have garments unbefitting."

I made the mistake of posting something like "Rivian touchscreen is really annoying sometimes."

I think I'm -2000 karma now … : )

 

[R.I.P.]

Ignoring the 'which is better' and focusing on the 'how could an R1 emulate physical lockers performance' my thought is this:

I think it's reasonable to assume that the system is both aware of and able to limit the RPM of the electric motors at each wheel. I believe it's also reasonable for the system to know how those RPMs translate to RPM of the tires, and thus 'speed'. I believe Rivian has the power to limit RPMs at the motor, as not being able to do so would be terrible for safety and longevity of the motors. I'm not sure if the speed limiter accomplishes this by capping motor rpm, but I do believe the speed limiter is proof that Rivian can modulate the RPM of the motors.

If all of that is true, is it then not reasonable to assume Rivian could release an ultra-rock-crawl mode that allows you to specifically set the max rotation of the motors, no matter how hard you mash the pedal, and assure that the same amount of RPM is going to each wheel, with full torque. Would this not, for all intents and purposes, simulate what physical lockers are doing without any need for feedback on traction from the underlying surface?

Edit: This is a legit question. That all makes sense to me, but I'm not a physicist or a mechanical/electrical engineer.

Good thought process, and I believe that the process is valid. Again, it is the "long way" around a problem that has a much simpler solution, so I may not give it the credence some would like me to.

All that said, it is the vehicles' inability to mimic an _open_ differential that I find is it's biggest handicap. Refer to example test #2 way up the thread. One poster's solution was "well that is ridiculous, I just don't go on off camber surfaces. Um, OK, but that is not practical where I live:

Some would say "wow, I am glad that is not my $100k Rivian over that bank". In fact, I have way over $100k in that Jeep, so it is not the money thing I am grateful for. No, I am grateful that was my 2000lb Jeep there, not my 7000lb R1T with traction control issues.

I weirdly got grief for inviting people out to play with us, instead of manipulating a keyboard into wild, unsubstantiated claims. Come on, come show me what I am doing wrong. I am literally going out today, because getting into situations like this is what I do for fun; and I am retired having fun.

With that, I really am headed out now... we will see how much hate is waiting for me when I get back lol.

 

[MadMac]

Is it time to bring up CarPlay in this thread? (Asking for a friend)

 

[SoCal Rob]

Ignoring the 'which is better' and focusing on the 'how could an R1 emulate physical lockers performance' my thought is this:

I think it's reasonable to assume that the system is both aware of and able to limit the RPM of the electric motors at each wheel. I believe it's also reasonable for the system to know how those RPMs translate to RPM of the tires, and thus 'speed'. I believe Rivian has the power to limit RPMs at the motor, as not being able to do so would be terrible for safety and longevity of the motors. I'm not sure if the limiter accomplishes this by capping motor rpm, but I do believe the speed limiter is proof that Rivian can modulate the RPM of the motors.

If all of that is true, is it then not reasonable to assume Rivian could release an ultra-rock-crawl mode that allows you to specifically set the max rotation of the motors, no matter how hard you mash the pedal, and assure that the same amount of RPM is going to each wheel, with full torque. Would this not, for all intents and purposes, simulate what physical lockers are doing without any need for feedback on traction from the underlying surface?

Edit: This is a legit question. That all makes sense to me, but I'm not a physicist or a mechanical/electrical engineer.

At the risk of getting off-topic in this... debate (I think debate is a more positive way of saying pissing match) I think that a lot of the emotion here is a result of communication style. I tend to communicate like you did in this post by using words like reasonable, believe, not sure, if, and by asking questions rather than making proclamations. When people come into a discussion with words like never, always, impossible, and other absolutes in a topic which is not resolved but being debated it can cause friction.

I grew up in an area where the motto may as well have been, "That's the way it's always been and that's the way it's always going to be." which never suited me. That line of thinking doesn't lead to improvement and I like to make things better.

I can't speak for others, but when I encounter naysayers my reaction is a mix of ¯\_(ツ)_/¯ and and new ideas because it seems preposterous that people could think that improvement is impossible when there have been so, SO many times in history that the naysayers end up being disproven by progress. My perception is that the naysayers seem to react with and absolute statements because someone, somewhere is questioning the status quo which they know to be immutable.

 

[moosehead]

Soooo, there seem to be a few references in this debate to a classic locking diff setup “knowing” which wheel has traction vs which does not.

How does it know?

I’d really like to know.

Sponsored