Transfer Case

[SLO_Scout]

I know that modern EVs, with their instant and linear “torque-curves”, do not need transfer cases per-se. I mean, the most capable EV off road rigs have direct-drive or at least direct-to-axle motors. With quad-motors and 1000lb/ft^2 of torque, transfer cases are not an option.

However, Scout will need to consider the need to flat-tow any off roader. Most EVs cannot do this without damaging the batteries and/or electronics. Please consider a way to decouple the motors from the axles/wheels. While transfer cases multiply torque at the wheels, they are also used to control wheel speed with the throttle. With no transmission, you could effectively spin the wheels at 80mph while at a standstill on sand, snow, and ice; not always a desirable characteristic.

You may also consider these benefits of a transfer case. If they are not necessary or cost effective (front and rear motors need two transfer cases), the benefits of controlling wheel speed in some conditions can be achieved by simulating gear reduction via throttle dynamics and other modifications in a driving mode.

 

[Ecca]

Please consider a way to decouple the motors from the axles/wheels.

How do you feel about classic manual locking hubs? The BOM cost would be super low and because a lot can be done in the software/electronics, it would only be for unusual edge cases.

 

[Jim Nichols]

Manual hubs at all 4 wheels for flat towing. I hope they do 2 motor solid axle front and rear. Wavetrac limited slip front and rear. What differential gear ratio would be optimal?

Wavetrac Differentials

Wavetrac limited slip torque biasing differentials.

wavetrac.net

 

[SLO_Scout]

Many dedicated trail rigs have 4 manual locking hubs in case they break an axle and need to drive home in front wheel drive. This is a good idea. Also, it is another nod to the old Scouts, with their Warn locking front hubs.

I assume that the Scout EV would be full-time 4WD. I think the hubs would be unnecessary and would remain engaged 99.9% of the time. I imagine that a circuit or relays could isolate the motors or a transmission having a neutral could alleviate the same issue. I guess SM’s fun will be in determining which way is cheapest and provides the right strength, reliability, and appeal to their market.

 

[MI Scout]

Manual hubs at all 4 wheels for flat towing. I hope they do 2 motor solid axle front and rear. Wavetrac limited slip front and rear. What differential gear ratio would be optimal?

Wavetrac Differentials

Wavetrac limited slip torque biasing differentials.

wavetrac.net

Wavetrac is the mechanical limited-slip differential I had installed on my BMW 135i back in 2011 and it still puts a smile on my face every time I drive it.

 

[Scout800a]

I actually think a 2 speed transmission would be ideal for the off road aspect of Scouts. Buuuuuut $$$ mean unless they make an offroad specific model that cost a lot more (like a Ford Raptor?) I don't see this happening for that reason.

And I would really love it if the made REAL locking differentials an option!

Current VW models (ID) have Neutral rolling mode so car can be pushed, pulled, go thru a car wash. I have no idea if the system can be left like that so car can be towed at speed. Probably going to be told to put it on a trailer. But I don't see why motor selection and some software couldn't make this a viable option on Scout.

Or maybe add a neutral position to the reduction transmission all electric vehicles have. Currently they are constant mesh and always in gear, but maybe that could be the economical option of allowing neutral for towing.

Jason

PS: And add a real Park Lock! Current models have no park lock, the car just applies the mechanical parking brake with an electrical motor.

 

[Scoobie]

Being an EV with massive torque at any motor speed, you certainly don't need a transfer case, but for off roading, it would be almost a necessity to be able to control your low speed control.
The ability to set a max (and potentially base) "crawl" speed would be a game changer! Say you set a max crawl of 10 mph, then your full throttle pedal swing would allow for very precise control of your speed UP TO 10 mph.

 

[cyure]

Being an EV with massive torque at any motor speed, you certainly don't need a transfer case, but for off roading, it would be almost a necessity to be able to control your low speed control.
The ability to set a max (and potentially base) "crawl" speed would be a game changer! Say you set a max crawl of 10 mph, then your full throttle pedal swing would allow for very precise control of your speed UP TO 10 mph.

Welcome to the community!

 

[Logan]

I actually brought this up in another thread. But, I'll just say that public opinion doesn't currently seem to agree with the idea.

The short version, is I think this is 100% valid.

EV's do have the same torque from any RPM, which means they can get away with having 1 speed. And, there was a bone stock Rivian R1S that did a 13 mile section of the Rubicon.

HOWEVER, they used something like 85% of the battery, on 13 miles, because while the motors had the torque to get over the obstacles, the amount of electrical current drawn from the battery for those big steep/tough moves on the trail, REALLY hammered their battery life.

There are a few multi-speed transmissions in EV's, but they are rare. The Porsche Taycan and its Audi twin both have 2 speed transmissions (to help with acceleration). Mercedes has an EV with a 2 speed transmission.

Why Mercedes Is Putting Transmissions in Its EVs—Starting With the CLA

The CLA's two-speed gearbox adds cost, but Mercedes told The Drive that the investment is worth it, especially at highway speeds.

www.thedrive.com

The Tesla Model S and X actually have different gear ratios in the front and rear axles for the AWD versions. So, only "1 speed", but they use different axles primarily at different speeds, to sort of get the same effect as 2 speeds.

And finally, Jeep just got a patent on a 3 speed transmission, where they talk about exactly what I mentioned above.

https://www.motor1.com/news/762882/stellantis-three-speed-ev-gearbox-patent/

Also, when you look at the designs of the transmissions, they're very different from what most people are thinking (which, I mean, I get it, why deal with more complexity, potential reliability issues and cost if you don't have to).

Anyway, I really don't think we'll see it in the Scout.

But, I think its entirely possible that in 10-15 years, multi-speed EV transmissions or "transfer cases" could be common. With their larger torque curves, I don't think we'll ever see 10 speed EV transmissions like we have on normal combustion vehicles, but, I think there are enough compelling arguments for at least 2-3 gears that we might see it happen.

 

[Scoobie]

I get what you're saying ... I drive a model 3 currently. I was using quotation marks around transfer case because I think it can be as simple as a software script .... Dial in the max speed at something very low (like 5 or 10 mph) and that would give a finesse in the gogo pedal.
I also wheel a 95 YJ wrangler and changing t-cases to an even lower ratio that what came stock made an IMMENSE difference! Moving smoothly but even slower made EVERYTHING easier!
Now I was unaware about the Rivian on the Rubicon and TOTALLY unaware about the battery loss.... So that may change things, but I can still hope!
Thanks for the heads up, I just put my deposit down like a month ago and just found this community..... Hope you become more active and feed as many ideas as I can while they still seem to have at least the appearance of openness to new and outside ideas!

Cheers!

 

[Time2Roll]

If there is a ordering box for optional manual locking hubs on both axles.... I will be taking that option.
+1 for optional geared limited slip differentials front and rear.

 

[J Alynn]

Being an EV with massive torque at any motor speed, you certainly don't need a transfer case, but for off roading, it would be almost a necessity to be able to control your low speed control.
The ability to set a max (and potentially base) "crawl" speed would be a game changer! Say you set a max crawl of 10 mph, then your full throttle pedal swing would allow for very precise control of your speed UP TO 10 mph.

Welcome aboard the SM forum. Hope you enjoy every minute(s). We always offer suggestions like checking out the search button as it will help you find just about any info you may be looking for. Tons of great info and reasonable speculation over the past 2-1/2.

 

[dreamweaver]

I get what you're saying ... I drive a model 3 currently. I was using quotation marks around transfer case because I think it can be as simple as a software script .... Dial in the max speed at something very low (like 5 or 10 mph) and that would give a finesse in the gogo pedal.
I also wheel a 95 YJ wrangler and changing t-cases to an even lower ratio that what came stock made an IMMENSE difference! Moving smoothly but even slower made EVERYTHING easier!
Now I was unaware about the Rivian on the Rubicon and TOTALLY unaware about the battery loss.... So that may change things, but I can still hope!
Thanks for the heads up, I just put my deposit down like a month ago and just found this community..... Hope you become more active and feed as many ideas as I can while they still seem to have at least the appearance of openness to new and outside ideas!

Cheers!

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