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Rear-wheel-drive cars are back and we have EVs to thank

thedrive.com

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Re: Rear-wheel-drive cars are back and we have EVs to thank

#81

Post by kolinko »

m463 wrote: post #64
mrinterweb wrote: post #59

Rear-wheel-drive vehicles have traction problems on slick roads. Losing traction on your front wheels is terrifying. I've had this happen before as I have had the opposite fishtailing with front-wheel-drive. Losing rear-wheel traction is something that can be compensated, but I don't think you can do much when you lose front-wheel traction.

I would think that front wheel drive would impair steering in tricky situations, while rear wheel drive would separate steering from drive and be better (with computerized help)

It's the opposite. If you lose back wheel traction in an FWD car, you "just" point your wheels in the right direction and accelerate - the front wheels will have both steering and power, so they will "drag" the car out of a slip.

With RWD you need more training for these situations, and it's more difficult to save a car.

With front wheels slipping it's also easier with FWD.

In either case, it's good to go for training lessons to learn how to deal with situations like these. Without practice your first instincts will most likely be wrong ;)

Re: Rear-wheel-drive cars are back and we have EVs to thank

#82

Post by lukevp »

0_____0 wrote: post #75
jasonwatkinspdx wrote: post #73

Earlier quoted context omitted.

No matter the powertrain layout if you lose traction on the front, ie understeer, you need to create a weight shift forward to restore traction. I've done a couple rally instructional clinics, and one of the introductory drills they spent a fair bit of time on was just a giant circle of cones set up on dirt. You go around it faster and faster until the car breaks free into a slide, then you learn how to control and m…

In Norway, this is basic driver education. The drivers' license there requires "slippery road" training, which involves a more basic version of what you're describing.

In the land of the free, you can drive with a parent at 15 and get a license at 16 with zero required classes or real world driving test, with just your parent’s signature, a 70% pass rate on a written test and $25. That’s how I got my license in TX at least.

I think this is a bad thing, fwiw. The standards of driver safety training here are incredibly low.

Re: Rear-wheel-drive cars are back and we have EVs to thank

#83

Post by [deleted] »

gnicholas wrote: post #53
lowbloodsugar wrote: post #45

Earlier quoted context omitted.

The front brakes do most of the work. It is not the case, as you assume, that both front and rear contribute equally to braking. If you didn't use the front brakes, or even if you tried to have them apply the same force, the rear wheels would absolutely skid. If you want an extreme visual example, check out stunt cyclists who brake so hard the rear wheel comes off the ground. Pretty easy to see that the rear wheel is…

Bingo. When I was a kid, I once flipped my bike because I was only braking with the front. I learned not to do that, but to an extreme — I then braked almost always with just the back. It wasn't until I got older and faster that I realized that braking just in the back is not as effective, since the braking action makes your nose dive and puts more weight over your front tire. I now brake with both sides, but always…

[deleted]

Re: Rear-wheel-drive cars are back and we have EVs to thank

#84

Post by B1FF_PSUVM »

dumbfounder wrote: post #60
Kon-Peki wrote: post #27

One of the big negatives to sportiness in FWD cars has always been torque steer. But that is due to unequal-length driveshafts, not strictly the FWD-ness. A FWD EV shouldn't suffer from torque steer. I do welcome RWD EVs, but let's not get carried away. Honda has demonstrated again and again that FWD vehicles are capable of very high track performance.

Very high performance != Fun. They are different. They say Miatas are fun to drive, and they are cheap, and therefore popular to race. But they are definitely not fast cars. I have never driven one, but I have always favored RWD cars, and never driven a FWD car that is anywhere near as fun. But that said, I haven't driven everything.

> != Fun

You know what's not fun? Reading about a RWD car that slid into a roadside tree, killing the mother and child who had no training in drifting, like 99% of drivers.

RWD cars, even with modern ESP etc, should simply not be sold to untrained drivers.

Re: Rear-wheel-drive cars are back and we have EVs to thank

#85

Post by jasonwatkinspdx »

lukevp wrote: post #82
0_____0 wrote: post #75

Earlier quoted context omitted.

In Norway, this is basic driver education. The drivers' license there requires "slippery road" training, which involves a more basic version of what you're describing.

In the land of the free, you can drive with a parent at 15 and get a license at 16 with zero required classes or real world driving test, with just your parent’s signature, a 70% pass rate on a written test and $25. That’s how I got my license in TX at least. I think this is a bad thing, fwiw. The standards of driver safety training here are incredibly low.

It varies by state, but most of them require either a driving exam or a piece of paper from a drivers education class. Texas is something of an exception in it's general lassie faire posture.

Re: Rear-wheel-drive cars are back and we have EVs to thank

#86

Post by yellowapple »

m463 wrote: post #69
yellowapple wrote: post #34

Earlier quoted context omitted.

> Snow tires makes more of a difference than being FWD or RWD in heavy conditions is the real truth here. A FWD with snow tires or chains will almost certainly have better snow/ice handling than a RWD with snow tires or chains, by the simple virtue of the drive axle being steerable. If you've played Kerbal Space Program or a similar spaceflight simulator + rocket designer, then the reasoning here should be pretty int…

> by the simple virtue of the drive axle being steerable. Is that a virtue? it makes steering tougher. The actual virtue is the weight of the motor over the front wheels (coefficient of friction * basically weight above tires)

> Is that a virtue? it makes steering tougher.

Not in my experience it doesn't. In icy or otherwise low-friction conditions, the steerable wheels being powered makes correcting for understeer and oversteer much easier than if they're unpowered - specifically because, per above, you can readily accelerate in directions other than forward/reverse, allowing you to orient the car even when sliding out. You can't rely on the tires' lateral friction to help you steer; a tire at an angle on ice will just slide with the rest of the car, and needs to be spinning to apply any force on said car other than forward.

The catch, though, is that you have to be willing to accelerate at the very moment your brain would otherwise panic and tell your feet to hit the brakes. Hitting the brakes will make things considerably worse by stopping the spin on your tires (especially the fronts, which are the very tires for which spinning is absolutely essential for steering control).

(In snow, this is a little bit less severe; the deeper the snow, the more pushback on the sides of the steering tires when at an angle, which helps a little bit with steering - but not nearly as much as on a dry road, thus still necessitating being able to accelerate with those tires)

> The actual virtue is the weight of the motor over the front wheels (coefficient of friction * basically weight above tires)

This also helps, but not nearly as much as the front wheels being able to accelerate in the direction they're pointed.

Re: Rear-wheel-drive cars are back and we have EVs to thank

#87

Post by zemvpferreira »

ethbr0 wrote: post #62
dumbfounder wrote: post #60

Earlier quoted context omitted.

Very high performance != Fun. They are different. They say Miatas are fun to drive, and they are cheap, and therefore popular to race. But they are definitely not fast cars. I have never driven one, but I have always favored RWD cars, and never driven a FWD car that is anywhere near as fun. But that said, I haven't driven everything.

I came in a little hot trying to catch a yellow light on a left hand turn (US) and powerslid a Miata perfectly across 4 lanes... my second month of owning one and driving stick. That's the day I fell in love with 50/50 weight distribution, rear wheel drive, and low and light weight.

Please don't drive recklessly on public roads. Take it to a track if you want to go 'hot'. You'll have more fun and not put others in danger.

Re: Rear-wheel-drive cars are back and we have EVs to thank

#88

Post by robocat »

kenhwang wrote: post #47
Kirby64 wrote: post #44

Earlier quoted context omitted.

How does FWD vs RWD matter for energy recapture in regen breaking? As long as you're not losing traction on your rear wheels during breaking, there's no difference in terms of energy captured in FWD vs RWD.

"As long as you're not losing traction on your rear wheels" is the key part. The more you brake, the more weight shifts forward, which results in less traction available to use to recapture. People vastly overestimate how much traction is available at the rear during braking, and running out of traction at the rear typically results in the car spinning (especially in an EV with low rotational inertia with most of the…

Rear-wheel energy recapture is surely fine so long as you are braking normally. Similar to driving a rear wheel drive car and just using engine braking.

Yes, when braking strongly rear wheels alone certainly don’t have enough traction: signs of strong front wheel braking are the nose of the car starts to dip and your passengers are complaining! Similar issue with slippery surfaces and no ABS (regenerative traction control)?

I would be interested to see some real-world figures of how often rear-wheel-only regenerative braking hits limits and wastes power.

In addition, are there limits to the amount of power regenerative braking can push into the batteries? I presume that even on front-wheel regenerative braking, when heavy braking occurs the front calliper is engaged and energy is lost. The theoretical difference between front and rear regeneration might not matter in practice?

Disclaimer: I don’t know much about this, and I suspect you are technically correct, but my guess is that it doesn’t matter in reality, and other constraints/costs/benefits matter more for deciding on front vs rear wheel drive.

Re: Rear-wheel-drive cars are back and we have EVs to thank

#89

Post by alephxyz »

skeeter2020 wrote: post #56
gnicholas wrote: post #53

Earlier quoted context omitted.

Bingo. When I was a kid, I once flipped my bike because I was only braking with the front. I learned not to do that, but to an extreme — I then braked almost always with just the back. It wasn't until I got older and faster that I realized that braking just in the back is not as effective, since the braking action makes your nose dive and puts more weight over your front tire. I now brake with both sides, but always…

My commuter bike only has a front brake. You can shift body position to make it pretty much impossible to go OTB. Meanwhile my DJ bike only has a rear brake, which at best "strongly suggests" you slow down.

Ironically the law pretty much everywhere in north America mandates that bikes have at least a rear brake.

Re: Rear-wheel-drive cars are back and we have EVs to thank

#90

Post by Dalewyn »

jasonwatkinspdx wrote: post #85
lukevp wrote: post #82

Earlier quoted context omitted.

In the land of the free, you can drive with a parent at 15 and get a license at 16 with zero required classes or real world driving test, with just your parent’s signature, a 70% pass rate on a written test and $25. That’s how I got my license in TX at least. I think this is a bad thing, fwiw. The standards of driver safety training here are incredibly low.

It varies by state, but most of them require either a driving exam or a piece of paper from a drivers education class. Texas is something of an exception in it's general lassie faire posture.

Naw, it's not the exception.

Got my license in California, instructor skipped the freeway part of the drive test which is mandatory.

Moved to Oregon, new licensees require both a written and a drive test but the DMV skipped them both because I already had an out-of-state (California) license.

Driver licenses are literally stupid easy to get here in the US.

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