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Cake day: November 6th, 2023

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  • There is an answer and it’s the one I already gave. There are always edge cases and exceptions because there are an absurd number of variations and vehicles types. By and large I already gave the deciding definition, and it is in what I linked as well as many others places.

    Edmunds - “Traditional 4WD systems have a two-speed transfer case with high- and low-range modes that can be selected by the driver, either with an electronic switch or a mechanical lever.”

    CARMAX - “Key to how a 4x4 works is a piece of equipment called a transfer case. This connects the vehicle’s front and rear wheels, splitting the engine’s power evenly between them and making both axles turn at the same speed.”

    And the article didn’t list the rules because it was wrong about everything. The rules are listed by the National Park Sevice. “A four wheel drive vehicle is defined as a sport utility vehicle (SUV) or truck with at least 15-inch tire rims and at least eight inches of clearance from the lowest point of the frame, body, suspension, or differential to the ground. Four wheel drive vehicles have a transfer case between the front and rear axles that locks the front and rear drive shafts together when four wheel drive is engaged. All wheel drive (AWD) vehicles do not meet this definition.”

    So again, repeating yourself doesn’t make you more right. It does however increasingly make you look like an ignorant ass that has no desire to actually learn anything.




  • So there are a few things that make a transfer case and most 4WD systems generally better for off-road. The biggest two are gearing and how durable/robust the systems are.

    The ability to change the final drive gives incredibly low gearing to 4WD vehicles. This provides increased torque for traversing obstacles and better low speed control.

    In the durability front, that is largely due to design considerations. AWD vehicles are typically designed for on road use, so the engineers built them with that in mind. This means lighter and weaker drive shafts, weaker steering racks, less robust suspension, and generally lighter duty pieces throughout the entire system. 4WD vehicles usually designed with heavier duty used in mind (even if the majority of people won’t use them that way). This means the entire drive train is built stronger and more capable of abuse.

    This is a huge generalization though. You could build a purpose built AWD off road vehicle with low gearing, and locking differentials if you wanted. And there are plenty of 4WD vehicles that wouldn’t survive even moderately difficult trails. So the NPS probably made the rule because generally 4WD is more capable for that use case, and it would be difficult to make an all exhaustive list of what vehicles or components would give you the capability to navigate the trail.


  • Generally if there is a question of AWD vs 4WD, the only thing you need to look for as an ability to shift to 4 low. It changes the final drive ratio so all of your gearing is dramatically lower. It’s a capability that requires having a transfer case. Though I’m sure there are some weird exceptions out there of 4WD vehicles that don’t have 4 low, it’s a pretty simple rule of thumb to decide which side a vehicle falls on.

    It’s possible to have an AWD vehicle that has a clutch or some other way to disengage two of the drive wheels. So you can have a selectable RWD or AWD. This is different than how a transfer case works though, and does not allow a change in final drive ratio.


  • Almost nothing in this article is accurate. AWD vs 4WD has nothing to do with locking front and rear differentials. It is that one has a transfer case, and the other does not. Most 4WD vehicles have open front and rear differentials.

    The National Park Service doesn’t require locking differentials, so I’m not sure where this person got that idea from. They do however require that they have a transfer case, which the Cybertruck and Rivian do not. So despite the author claiming those would be 4WD, they are not. And do not qualify by the definition used by the NPS.

    I think they are correct that there may be a need to update the rules since EVs have no need for a transfer case since there is no mechanical connection between the front and rear axles typically. It’s terrible to try and make that argument with all of your other information incorrect however.