Rear-wheel-drive cars are back and we have EVs to thank • Hacker News Board

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

#101

Post by akira2501 » Fri, Apr 21, 2023, 12:32 AM UTC

skeeter2020 wrote: post #55

frosted-flakes wrote: post #51

Earlier quoted context omitted.

This is obvious to anyone who's changed the brakes on their car. Front brakes are massive compared to the rear.

Or used any vehicle with independent front/rear braking like a motorcycle or bike. The rear is for fine tuning while the front is for actually stopping.

They're both for stopping. It's why they're biased to have more power in the front than the rear. You can take advantage of this with the rear to "tune" in some situations, or to maintain stability at low speeds, but it should also be fully used when braking.

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

#102

Post by amluto » Fri, Apr 21, 2023, 12:36 AM UTC

robocat wrote: post #88

kenhwang wrote: post #47

Earlier quoted context omitted.

"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 co…

Rear wheel regenerative braking (with a decent traction control system, which is table stakes) is fairly effective, but the down side is reduced life span of the rear wheels.

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

#103

Post by cblum » Fri, Apr 21, 2023, 12:37 AM UTC

ars wrote: post #98

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 2019 Norway had around 1/4 the fatality rate of the US. (In deaths/distance.) But in 2000 it had a slightly higher rate than the US. The road tests did not change, rather Norway changed how its roads are engineered (due to an initiative called Vision Zero!). So I doesn't seem like the more difficult testing actually helps much. (BTW If you want to lookup numbers be aware most sites quote death/population instead w…

> So I doesn't seem like the more difficult testing actually helps much.

Brazil has a higher rate than the US, but you wouldn’t be able to tell based on the testing there. Mine was:

- Backup parking

- Parallel parking

- Drive around the city with an examiner for a few minutes

Any mistakes in the first two and you’re disqualified. You have to get them right the first time with no corrections (or at least that was the case back in 2007 or so).

For the driving part, you can make two small mistakes. Any critical mistakes immediately disqualify you.

In comparison, in my WA test when I moved here I botched parallel parking 3 times until I got it right. Then I indavertently speeded and also didn’t fully stop at a stop sign (either of which would’ve been a disqualifying mistake in Brazil IIRC). Still got my license.

Nevertheless, I find it MUCH safer to drive in the US (WA in particular, the only place where I’ve ever seen folks consistently driving at or below the speed limit). Brazilian drivers are crazy aggressive and in a lot of places traffic rules are treated as mere suggestions.

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

#104

Post by jasonwatkinspdx » Fri, Apr 21, 2023, 12:38 AM UTC

Dalewyn wrote: post #90

jasonwatkinspdx wrote: post #85

Earlier quoted context omitted.

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.

I'm in Oregon as well and my understanding is if you have an existing valid license you can skip, but that's different if you've never had one or yours is expired. I had to do a driving test in my mid 20s because I lived car free downtown for a number of years and when my license expired just got an id card as replacement out of laziness.

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

#105

Post by jerrysievert » Fri, Apr 21, 2023, 12:44 AM UTC

jcadam wrote: post #99

jerrysievert wrote: post #79

Earlier quoted context omitted.

FWD don't have more control under slippery conditions if your front tires break free. RWD + traction control is pretty amazing. of course, it doesn't help too much in ice if you're running on summer sports tires, but that's an entirely different problem.

I keep meaning to get me a set of studded tires for the winter. Next winter, for sure :)

if you can, please use non-studded winter tires. they are much better to the roads, and typically have very good winter traction (just change them out for summer).

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

#106

Post by vvanders » Fri, Apr 21, 2023, 12:56 AM UTC

> Moreover, modern traction control systems are just plain good. This isn't something exclusive to electric cars—even gas-powered vehicles have achieved decent torque vectoring by modulating brakes independently at each wheel, but modern EVs take it up a notch by performing thousands of software-based every second.

While this is not wrong it's also missing the fact that EVs use AC VFD motors that don't need to have a closed loop response under traction loss due to the fact that the AC field will slow down the wheel of it tries to over speed just by nature of how the mechanism works. This helps keep the wheels in the static friction region where traction is highest. In trains this and other factors[1] contribute to a 2x increase in traction over DC motors. With an ICE you have all sorts of momentum in the flywheel and drivetrain that are trying to runaway until the system/driver reacts and compensates.

[1] http://www.republiclocomotive.com/ac-traction-vs-dc-traction...

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

#107

Post by ars » Fri, Apr 21, 2023, 12:57 AM UTC

0_____0 wrote: post #100

ars wrote: post #98

Earlier quoted context omitted.

In 2019 Norway had around 1/4 the fatality rate of the US. (In deaths/distance.) But in 2000 it had a slightly higher rate than the US. The road tests did not change, rather Norway changed how its roads are engineered (due to an initiative called Vision Zero!). So I doesn't seem like the more difficult testing actually helps much. (BTW If you want to lookup numbers be aware most sites quote death/population instead w…

I'm not sure we can draw much of a conclusion from the accident data, since as you point out, there are confounding variables.

If anything it points to US drivers being even better than Norway since they can drive without such initiatives.

Perhaps that why Norway has such a hard test - they need it!

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

#108

Post by throwawaaarrgh » Fri, Apr 21, 2023, 1:17 AM UTC

I live in a rural mountainous area. FWD cars have a huge advantage over anything RWD: traction going up hill. Nothings funnier than watching delivery trucks going up a giant hill backwards because it's the only way they can maintain traction.

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

#109

Post by ghostpepper » Fri, Apr 21, 2023, 1:25 AM UTC

zemvpferreira wrote: post #87

ethbr0 wrote: post #62

Earlier quoted context omitted.

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.

It doesn't sound to me like it was intentional

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

#110

Post by inkyoto » Fri, Apr 21, 2023, 1:36 AM UTC

kube-system wrote: post #21

yamtaddle wrote: post #17

Earlier quoted context omitted.

FF = Front-wheel drive FR = Rear-wheel drive For anyone else who couldn't puzzle out WTF those meant, I'll save you looking it up.

The first letter refers to the location of the engine. The second letter refers to the drive wheels. FF = front engine, front wheel drive FR = front engine, rear wheel drive RR = rear engine, rear wheel drive MR = mid engine, rear wheel drive

There are also (rare nowadays and are mostly available in higher end / performance cars but used to be more frequent in late 80's and 90's):

FF 4WS

FR 4WS

4WS is for «four wheel steering» (the emphasis is on «steering», not «driving») where – depending on the travelling speed – the rear pair of wheels turns either in the direction opposite to the front wheels (≤ 20 kmh) or in the same direction (≥ 20 kmh). The former makes the parking easier and reduces a turnaround circle. The latter makes the car look moving sideways when going around a bend or disappearing from its lane and emerging in the neighbouring lane during the lane change. 4WS also handles a bit differently on slippery roads around the bends.