6 ms·

It's gotta be a typo. Front wheel drive gives you the opposite of a lot of space in the wheel wells.

_yb2s 4y ago
I agree this must be a typo! The demo car in the video (BMW i3) is a rear wheel drive car. Given that, this whole thing doesn't make any sense to me as a supposed advance. RWD cars have always had tighter turning raidii. Many of them actually have a stop to keep you from turning the wheel 90 degrees such that the tires push instead of roll. I remember adjusting an early 70s Volvo so the front wheel could turn almost 90 degrees just as an experiment, and doing this adjustment was trivial.
- twawaaay 4y ago
  Well, FWD cars will always have a potential for tighter turning radius. RWD car is essentially pushing on a wheel that is almost perpendicular -- not very helpful, a lot of force needed to start the car rolling, potential to damage the wheel. As you get closer to 90 degrees the force needed becomes higher than available traction and the entire thing stops steering at all. FWD can be thought as "pulling" the car by the front of it, the wheels can be in any position as long as we know how to transfer power.
  - ryukoposting 4y ago
    Sure, it's true that "FWD cars will always have a potential for tighter turning radius." In practice, that's not the case for conventional front-engine layouts. Most RWD cars mount their engines longitudinally, so the transmission sticks out the back of the engine. This means there isn't a whole lot of "stuff" sticking out to the left and right of the engine. That means more room for wheel articulation. One problem with FWD is space. Since the engine is usually mounted transversely, the transmission has to go under/beside the engine, taking up space that would otherwise be usable for larger suspension components / wheel articulation. The other problem with FWD is, as you mention, power transfer. It would be extremely difficult to design a shaft that could transfer power to a wheel that articulates up to 80 degrees. Keep in mind that such a shaft must snake its way through suspension components, too. If I understand it properly, the demo is using torque-vectoring-by-brake during turns (basically braking the inside drive wheel). Most modern cars can do this, it's just not typically necessary for low-speed turns. I suspect that the BMW i3 was featured in the video for a lot of reasons: 1) It's RWD, which leaves room for extreme wheel articulation. 2) It's electric, so there's less stuff up front in the first place. 3) The i3's tires are super skinny, meaning less resistance on those super tight turns. 4) The i3's short wheelbase means the outside rear wheel doesn't scrub too badly during tight turns.
    - anonair 4y ago
      Also RWS present in the video helps to make rear wheels push the front wheels in more obtuse angle (sorry, not my first language)
  - Thorrez 4y ago
    Yeah, from my experience driving bumper cars, they seem to be front wheel drive and have a near 180 degree turning radius. You go in reverse by turning really far.
  - throw1234651234 4y ago
    I was getting ready to tell you how wrong you are, but you make a good point - if the wheels are turned all the way and the car is RWD, the rear wheels will just put a bunch of pressure on the front wheels without the car turning, if it's not already in motion. Of course, the other posters are right about there being way more space up front in RWD. Btw, you can achieve the maneuver at 1:20 on FWD by dropping the clutch with the front wheels turned all the way even in conventional range. This slides the car into position at extreme angles. Of course, I don't recommend it due to the wear and tear on the tires, suspension, components, clutch, and the possibility that you don't actually slip the tires and back up into the car behind you, but it is doable, especially in rain / snow.
- nabilhat 4y ago
  Not only that, but the headline's gone off the path quite a way. While the I3's front wheels are not driven by an axle, they do rotate on a stub axle, which I guess is technically an axle. It's really just a short metal stick (an accurately manufactured one) that locates the center of the wheel bearings. They're also using the stock steering knuckle, which is the part that actually turns. What they've invented is moving the tie rod connection closer to the stock center of rotation with hacked-up bolt-on bits. That's beer engineer level stuff.

I agree this must be a typo! The demo car in the video (BMW i3) is a rear wheel drive car. Given that, this whole thing doesn't make any sense to me as a supposed advance. RWD cars have always had tighter turning raidii. Many of them actually have a stop to keep you from turning the wheel 90 degrees such that the tires push instead of roll. I remember adjusting an early 70s Volvo so the front wheel could turn almost 90 degrees just as an experiment, and doing this adjustment was trivial.

twawaaay 4y ago
Well, FWD cars will always have a potential for tighter turning radius. RWD car is essentially pushing on a wheel that is almost perpendicular -- not very helpful, a lot of force needed to start the car rolling, potential to damage the wheel. As you get closer to 90 degrees the force needed becomes higher than available traction and the entire thing stops steering at all. FWD can be thought as "pulling" the car by the front of it, the wheels can be in any position as long as we know how to transfer power.
- ryukoposting 4y ago
  Sure, it's true that "FWD cars will always have a potential for tighter turning radius." In practice, that's not the case for conventional front-engine layouts. Most RWD cars mount their engines longitudinally, so the transmission sticks out the back of the engine. This means there isn't a whole lot of "stuff" sticking out to the left and right of the engine. That means more room for wheel articulation. One problem with FWD is space. Since the engine is usually mounted transversely, the transmission has to go under/beside the engine, taking up space that would otherwise be usable for larger suspension components / wheel articulation. The other problem with FWD is, as you mention, power transfer. It would be extremely difficult to design a shaft that could transfer power to a wheel that articulates up to 80 degrees. Keep in mind that such a shaft must snake its way through suspension components, too. If I understand it properly, the demo is using torque-vectoring-by-brake during turns (basically braking the inside drive wheel). Most modern cars can do this, it's just not typically necessary for low-speed turns. I suspect that the BMW i3 was featured in the video for a lot of reasons: 1) It's RWD, which leaves room for extreme wheel articulation. 2) It's electric, so there's less stuff up front in the first place. 3) The i3's tires are super skinny, meaning less resistance on those super tight turns. 4) The i3's short wheelbase means the outside rear wheel doesn't scrub too badly during tight turns.
  - anonair 4y ago
    Also RWS present in the video helps to make rear wheels push the front wheels in more obtuse angle (sorry, not my first language)
- Thorrez 4y ago
  Yeah, from my experience driving bumper cars, they seem to be front wheel drive and have a near 180 degree turning radius. You go in reverse by turning really far.
- throw1234651234 4y ago
  I was getting ready to tell you how wrong you are, but you make a good point - if the wheels are turned all the way and the car is RWD, the rear wheels will just put a bunch of pressure on the front wheels without the car turning, if it's not already in motion. Of course, the other posters are right about there being way more space up front in RWD. Btw, you can achieve the maneuver at 1:20 on FWD by dropping the clutch with the front wheels turned all the way even in conventional range. This slides the car into position at extreme angles. Of course, I don't recommend it due to the wear and tear on the tires, suspension, components, clutch, and the possibility that you don't actually slip the tires and back up into the car behind you, but it is doable, especially in rain / snow.
nabilhat 4y ago
Not only that, but the headline's gone off the path quite a way. While the I3's front wheels are not driven by an axle, they do rotate on a stub axle, which I guess is technically an axle. It's really just a short metal stick (an accurately manufactured one) that locates the center of the wheel bearings. They're also using the stock steering knuckle, which is the part that actually turns. What they've invented is moving the tie rod connection closer to the stock center of rotation with hacked-up bolt-on bits. That's beer engineer level stuff.