Center diff?

[trentsize]

I understand there is no physical center diff.

An Out of Spec video shows the beast version towing on dirt to be primarily front wheel drive with the permanent magnet being in front. This was causing tire spin until the rear motors kicked in.

My dual motor Model 3 is rear wheel favored until they spin, then the front kicks in too. I assume the AWD Cybertruck works this way too since the permanent magnet motor is in the rear?

Does CT offer any way to force the front and rear to engage full time? The Model 3 seems to keep front and rear engaged for 10-15 minutes after tire slip in snow or whatever, then goes back to rear only again.

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[mongo]

I understand there is no physical center diff.

An Out of Spec video shows the beast version towing on dirt to be primarily front wheel drive with the permanent magnet being in front. This was causing tire spin until the rear motors kicked in.

My dual motor Model 3 is rear wheel favored until they spin, then the front kicks in too. I assume the AWD Cybertruck works this way too since the permanent magnet motor is in the rear?

Does CT offer any way to force the front and rear to engage full time? The Model 3 seems to keep front and rear engaged for 10-15 minutes after tire slip in snow or whatever, then goes back to rear only again.

Yeah, AWD is primarily rear wheel drive.

The off road modes allow altering front/ rear bias, but normal traction control should at least as good as other Tesla models.

 

[trentsize]

Yeah, AWD is primarily rear wheel drive.

The off road modes allow altering front/ rear bias, but normal traction control should at least as good as other Tesla models.

For all off road modes? The manual only shows that bias slider option for Baja mode.

 

[mongo]

For all off road modes? The manual only shows that bias slider option for Baja mode.

Unsure, I know Baja has the slider, but overland may alter it also.

 

[HaulingAss]

For all off road modes? The manual only shows that bias slider option for Baja mode.

The front/rear bias slider is only available in Baja Mode. It's really only to tune the slide characteristics when driven hard through corners, not for normal off-road climbing and traction.

But my impression from having off-roaded it extensively if that the traction control has a high enough resolution and speed that it is not apparent that it is front or rear wheel drive primarily because the power transfer to wheels that are not slipping happens so instantaneously that the slipping is just as likely to happen on a front wheel as a rear wheel (even though I have the rear-biased Dual Motor).

The tightest traction control happens with the driving surface setting set to "Rock". In this mode power transfer happens at the slightest (generally unnoticeable) slip amounts. If the differentials are both in the open or unlocked mode, and you are on irregular sufaces, then you will generally have one front tire and one rear tire start slipping simultaneously. I haven't felt it apply the brake to the slipping wheels like it will do in my Performance Model 3 (after enough slippage has happened without making forward progress). Probably because the Cybertruck has locking differentials available (or perhaps the brake application is just more refined and it's not as noticable as it is in my M3P). I suspect the former though, because locking the differentials makes a night and day difference whenever traction is scarce. In sand and deep snow settings the traction control allows more slippage in general, of all wheels, and this is not always what you want (it depends upon the qualities of the snow or sand). The Rock Mode is my go-to off-road setting for climbing even steep loose slopes because it minimizes tire slippage and gravel displacement.

If I could sum up my feelings about people worrying about front or rear bias (excluding high-speed rally type driving) I would say, don't worry, it's as seamless as I've ever experienced. It's like a sure-footed mountain goat. Yes, it has open differentials until the lockers are engaged, and you will get one tire slipping on the front or back (sometimes both at the same time if it's challenging enough) when climbing steep, irregular and loose slopes, due to those open differentials, but front to rear the power is proportioned relative to how much total traction the front and rear axles are getting. It's instantaneous. In otherwords, front/rear bias becomes meaningless once there is even a minimal amount of tire slippage happening, it's no longer like a front or rear wheel drive vehicle, it's like a 4WD vehicle with the front and rear locked together and open front and rear differentials. Lock the front and rear and it feels like a 4WD with full lockers. And locking at least one differential is exactly what you want to do if getting slippage on one wheel of both axles simultaneously. It needs to be a really challenging traction situation to want to lock the front too.

For high-speed rally type driving, you have full control of front/rear bias, so no worries there. You can climb steep difficult slopes in rally mode, where you can control f/r bias, but there is no point in it. Because you cannot adjust the bias quickly enough for conditions. The bias is adjusted as needed, in real time. Rally mode is for when you want lots of tire slip on one axle or the other, which is generally exactly what you don't want when climbing challenging slopes.

 

[HaulingAss]

Unsure, I know Baja has the slider, but overland may alter it also.

Yeah, it's possible that simply entering off-road mode alters the F/R bias. But I don't think it does. More likely, the F/R bias is altered when slippage is detected, regardless of whether in Off-Road mode or not. Such automatic adjustments of bias would, by necessity, have a certain amount of "stickiness" to them. Meaning the bias could fade in/out over time depending upon how much slippage was detected. And it would make sense for this to also happen in normal road mode.

It would be interesting to know exactly what kind of strategies Tesla implemented here. All I can say is the result is pretty close to seamless.

 

[SentinelOne]

There is slippery surface mode under dynamics - I believe this uses both Front and Rear motors equally for good traction and to avoid the slip on the PMM axle before triggering the non PMM axle. Could be wrong but I believe that's there for more confidence / less bs in snow, etc.

 

[mongo]

Yeah, it's possible that simply entering off-road mode alters the F/R bias. But I don't think it does. More likely, the F/R bias is altered when slippage is detected, regardless of whether in Off-Road mode or not. Such automatic adjustments of bias would, by necessity, have a certain amount of "stickiness" to them. Meaning the bias could fade in/out over time depending upon how much slippage was detected. And it would make sense for this to also happen in normal road mode.

It would be interesting to know exactly what kind of strategies Tesla implemented here. All I can say is the result is pretty close to seamless.

The way I read this, off-road is less efficient because it does use both motors:

TO MAXIMIZE YOUR EFFICIENCY:
• USE BAJA MODE AND MOVE TORQUE TO BIAS TO THE PERMANENT MAGNET MOTOR.
(FOR DUAL MOTOR ALL-WHEEL DRIVE THIS IS THE REAR, FOR TRI-MOTOR CYBERBEAST
THIS IS THE FRONT).

 

[trentsize]

There is slippery surface mode under dynamics - I believe this uses both Front and Rear motors equally for good traction and to avoid the slip on the PMM axle before triggering the non PMM axle. Could be wrong but I believe that's there for more confidence / less bs in snow, etc.

I forgot that was a feature, thanks! Wish my M3 had that lol

“Your vehicle can distribute traction evenly across all tires to provide more traction and stability during slippery conditions, such as rain, snow, or ice. To enable, go to Controls > Dynamics > Slippery Surface.”

I ask because we often pull on to fast highways (55-70mph) that are ice covered. The M3 can get a bit squirrelly before the front end activates.

 

[SentinelOne]

I forgot that was a feature, thanks! Wish my M3 had that lol

“Your vehicle can distribute traction evenly across all tires to provide more traction and stability during slippery conditions, such as rain, snow, or ice. To enable, go to Controls > Dynamics > Slippery Surface.”

I ask because we often pull on to fast highways (55-70mph) that are ice covered. The M3 can get a bit squirrelly before the front end activates.

Yes, hopefully they back port this to all teslas....should be easy to add...gonna make the cyber truck fun in the snow!!!!

 

[HaulingAss]

I forgot that was a feature, thanks! Wish my M3 had that lol

“Your vehicle can distribute traction evenly across all tires to provide more traction and stability during slippery conditions, such as rain, snow, or ice. To enable, go to Controls > Dynamics > Slippery Surface.”

I ask because we often pull on to fast highways (55-70mph) that are ice covered. The M3 can get a bit squirrelly before the front end activates.

My Model 3 Performance has surprising acceleration on snow and ice, I would say the rear end feels "loose" before I would call it "squirrelly". I say it like this because it's not like the rear end ever threatens to get away from you under hard acceleration on snow/ice, it just rockets forward with surprising urgency, even if it allows the rear end to feel a little loose.

I have to put it in Track Mode to get anything close to what I would call squirrelly and, even then, the rear end can swing wide to one side but then the traction controls still kick in and hold the yaw angle steady, preventing the rear from going more than 25 degrees or so off line. It feels like the hand of God descends from the sky and gently holds the rear quarter panel from sliding onto the outside shoulder of the road, no matter how much additional power I dial in with the throttle. In normal (non-Track Mode), it does the same thing except it only allows a much smaller yaw angle, and it's a little less apparent that the hand of God is there helping you hold the line since the yaw angle is so much reduced (it feels more like it's just limiting power to prevent excessive yaw).

I think what you are describing, when you are turning onto a fast, icy highway, is not any built-in delay before it transfers power to the front, it's that the very act of accelerating and turning onto the highway overwhelms the traction on the front tires (due to the steering angle required) and thus the power to the front wheels doesn't really kick in much until the steering wheel is straightened out. That could create quite a delay in power transfer. In a straight line on ice I feel power to the front wheels applied instantaneously, as soon as I floor it. I get slightly faster acceleration if I roll on the throttle in a manner more in line with the amount of traction available. I also feel the traction controls are tuned to allow more rear wheel spin (than front wheel spin), probably so the vehicle can remain better controlled.

I doubt there is much difference between the tuning of the AWD and Performance versions (when in regular driving modes). Do you use dedicated winter tires on your AWD Model 3? They make the car a blast to drive on snow and ice in rally mode. I have a dead end mountain highway to play on with literally zero other traffic at certain times of the day/week. The only real threat is losing it and leaving the road/impacting a snow bank. Because there's no cell service either! So I always bring water, good hiking boots and warm clothing in case I need to hike 10 or 15 miles out.

While I have driven the Cybertruck through a lot of deep, sloppy, treacherous spring snowpack requiring high ground clearance, I haven't had the opportunity to drive it on snowy or icy roads yet, in rally mode. I can tell it's going to be awesome, assuming I can find some good winter tires for it before the cold weather arrives.

 

[HaulingAss]

Yes, hopefully they back port this to all teslas....should be easy to add...gonna make the cyber truck fun in the snow!!!!

Judging just from my limited experience using the slippery surface feature, a setting that is not even available in the off-road modes, I can say confidently that this is not a feature people will use when they want to "play" on slippery surfaces. That would be, somewhat ironically, Baja Mode. And there will be a number of Cybertrucks lost/damaged due to people using Baja Mode to reduce the traction controls on snow and ice by people who think they are better drivers than they actually are. ?

 

[SentinelOne]

Judging just from my limited experience using the slippery surface feature, a setting that is not even available in the off-road modes, I can say confidently that this is not a feature people will use when they want to "play" on slippery surfaces. That would be, somewhat ironically, Baja Mode. And there will be a number of Cybertrucks lost/damaged due to people using Baja Mode to reduce the traction controls on snow and ice by people who think they are better drivers than they actually are. ?

you nailed it - I did mean for fun - aka puts the power down so can confidently move without fear of 100% rear bias and min traction....diff different definition of fun.....I know my limits and it's not to use drift settings in the snow - save that for wide open off-road conditions.

 

[trentsize]

My Model 3 Performance has surprising acceleration on snow and ice, I would say the rear end feels "loose" before I would call it "squirrelly". I say it like this because it's not like the rear end ever threatens to get away from you under hard acceleration on snow/ice, it just rockets forward with surprising urgency, even if it allows the rear end to feel a little loose.

I have to put it in Track Mode to get anything close to what I would call squirrelly and, even then, the rear end can swing wide to one side but then the traction controls still kick in and hold the yaw angle steady, preventing the rear from going more than 25 degrees or so off line. It feels like the hand of God descends from the sky and gently holds the rear quarter panel from sliding onto the outside shoulder of the road, no matter how much additional power I dial in with the throttle. In normal (non-Track Mode), it does the same thing except it only allows a much smaller yaw angle, and it's a little less apparent that the hand of God is there helping you hold the line since the yaw angle is so much reduced (it feels more like it's just limiting power to prevent excessive yaw).

I think what you are describing, when you are turning onto a fast, icy highway, is not any built-in delay before it transfers power to the front, it's that the very act of accelerating and turning onto the highway overwhelms the traction on the front tires (due to the steering angle required) and thus the power to the front wheels doesn't really kick in much until the steering wheel is straightened out. That could create quite a delay in power transfer. In a straight line on ice I feel power to the front wheels applied instantaneously, as soon as I floor it. I get slightly faster acceleration if I roll on the throttle in a manner more in line with the amount of traction available. I also feel the traction controls are tuned to allow more rear wheel spin (than front wheel spin), probably so the vehicle can remain better controlled.

I doubt there is much difference between the tuning of the AWD and Performance versions (when in regular driving modes). Do you use dedicated winter tires on your AWD Model 3? They make the car a blast to drive on snow and ice in rally mode. I have a dead end mountain highway to play on with literally zero other traffic at certain times of the day/week. The only real threat is losing it and leaving the road/impacting a snow bank. Because there's no cell service either! So I always bring water, good hiking boots and warm clothing in case I need to hike 10 or 15 miles out.

While I have driven the Cybertruck through a lot of deep, sloppy, treacherous spring snowpack requiring high ground clearance, I haven't had the opportunity to drive it on snowy or icy roads yet, in rally mode. I can tell it's going to be awesome, assuming I can find some good winter tires for it before the cold weather arrives.

Thanks for the detailed reply!

I do use snow tires (Blizzak WS90) and on snow it is exactly as you described. It just GOES with a limited angle like you said. I don’t have any of the track mode settings to play with, only “slip start” that I’ve tried. There’s probably some fear still that the car is going to go sideways on the faster icy highway, and it’s not exactly a place to push it and see what happens. It also took some time to get used to the rear end feeling loose on full regen braking on ice.

 

[HaulingAss]

The way I read this, off-road is less efficient because it does use both motors:

TO MAXIMIZE YOUR EFFICIENCY:
• USE BAJA MODE AND MOVE TORQUE TO BIAS TO THE PERMANENT MAGNET MOTOR.
(FOR DUAL MOTOR ALL-WHEEL DRIVE THIS IS THE REAR, FOR TRI-MOTOR CYBERBEAST
THIS IS THE FRONT).

That's interesting. I presume this instruction to maximize efficiency is in the off-road section? Or lifted from the off-road manual Tesla published recently?

If so, it does seem to imply the baseline F/R power bias in automatically moved closer to 50/50 in Overland Mode. But my point remains, if low traction is actually coming into play, via wheel slippage (while not in Baja Mode), the F/R bias is probably adjusted (based on wheel slippage) such that the instantaneous traction controls don't need to be activated as frequently. Baja Mode probably turns off those automatic adjustments to F/R bias in order to provide a consistent driving experience when Baja Mode is selected.

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