FWD vs RWD for snow and ice

[Autobahnschleicher]

Originally Posted by Isaac Zachary

The MR2! Back when cars were cool!

Too bad here in the USA we've been invaded by a hoard of grey marshmallows.

I've been under the impression that "snappy" characteristics are from a rather extreme bias. That's been my experience (e.g. Super Beetle).

Oh, it's the same over here.
People where actualy surprised when VAG launched their new colour "nardo grey", wich looks like clearcoated primer.
But I do have to admit mine is silver metallic, so also kind of grey.
But hey, at least it's fun and not too fuel inefficient.

In case of the MR2 the snappy characteristics, wich where especialy prominent in the early versions of the SW-20, came from the mass centralisation.
Mid engined cars have all heavy components (engine, gearbox, differential, fuel tank, driver) packed close together almost in the center of gravity.
This causes the car to have very little rotational inertia along the vertical axis, making the car very nimble.
The fomula for this is mass times radius squared, or M*R^2.
Early versions of the SW-20 had a particular rear suspension tune wich made them more agile in the hands of a capable driver, but also more dangerous in the hands of your average idiot on the road.
Toyota "neutered" the SW-20 for obvious reasons.
The later ZZW-30 however was a totaly different story.
It has the longest wheelbase of all 3 itterations while beeing the shortest car with the lowest weight.
This allowed it to be even more nimble yet stable than the SW-20.
But people disliked it because it lacked the power of the SW-20 Turbo or G-limited and its looks are a bit controversial.

[cRiPpLe_rOoStEr]

Originally Posted by Isaac Zachary

Ya, 4WD/AWD (aka, turns four wheels) is ideal for snow and ice. But the thing is it's so much more expensive right now, at least on new cars. And the older ones get worse fuel mileage with it. Plus it's another part to wear out.

Surprisingly, there were times when a Jeep CJ-5 was cheaper than a VW Beetle in Brazil, yet in the long run the operating costs favored the Beetle with nearly negligible disadvantages going through some harsh terrain. No wonder Beetle-based Jeep-type utility vehiches such as the Gurgel X-10 and X-12 were favored by corporative and governmental fleets in Brazil during the '70s. And nowadays, even though it could be quite tempting to get a Suzuki Jimny as it has a convenient size to serve for all-around commuting and 4WD for some occasional serious off-roading, I used to have fun while learning to drive off-road on front-engined FWD econoboxes when I was a teen.

Who's driving has a lot to do with what's "best". I'm assuming @JSH is a professional commercial driver, so I completely understand why he'd want a rear biased RWD vehicle. He knows how to drive one.

Maybe this also explain why some older taxi drivers have been more prone to agree with me while talking about rear-engined RWD cars. Whenever they see a modern Porsche 911, they become quite filled with nostalgia for the VW Beetle and derivatives such as the Brasília.

You got to first, not drive so fast in the first place. If the tail starts to swing out you need to make smooth changes in throttle, brake and steering. That way you don't suddenly have the tail flying out in front of you. And when it does start to slide you still have enough leeway to control it.

But take any modern day teenager (with few exceptions) and they don't know squat about how to drive slow in the snow. All these TV commercials, excuse me... Google ads, have them thinking they can drive in the snow as fast as you can on dry pavement. If the tail starts to slide then they think they can be Lightning McKing and drift like maniacs. Next thing you know they're spinning down the road or over correct and spinning down the road again. FWD helps thwart those expectations.

One time a kid passed me in a Jeep along the rim of the Black Canyon. He then lost control on the ice and flipped it right in the middle of the road and killed himself. He didn't even leave the road, not even hitting a guardrail. That probably wouldn't have happened in a FWD sedan.

Doesn't even need to go that far. Just look at those Brazilian agroboys who drive a Toyota Hilux as if it was a VW Golf, then it rolls over and the folks say on the internet a Hilux is inherently unstable.

[JSH]

Originally Posted by Isaac Zachary

Who's driving has a lot to do with what's "best". I'm assuming @JSH is a professional commercial driver, so I completely understand why he'd want a rear biased RWD vehicle. He knows how to drive one...

I am not a commercial driver. I'm a manufacturing engineer for an automaker. My profile picture is the latest vehicle we launched.

I did grow up driving RWD cars in Michigan. Snow was a regular occurrence and when I was 15 and had my learner's permit my father would take me to empty parking lots early in the morning and we would practice braking, catching slides, and steering with the throttle. Better to learn at 15 - 20 mph in a big empty parking lot than on the road. Practice enough and it become muscle memory.

I also ride motorcycles quite a bit and have taken some professional training schools and done a bit of racing. Motorcycles are RWD / rear weight bias vehicles. A lot of the throttle / braking reactions are the same even if the controls are in different places.

Originally Posted by Isaac Zachary

But take any modern day teenager (with few exceptions) and they don't know squat about how to drive slow in the snow.

Which tells us more about the sorry state of driver's training in the USA than anything else. The fact that you can get a driver's license by doing nothing more than passing a multiple choice test and a quick drive around the block is frightening.

[cRiPpLe_rOoStEr]

Originally Posted by JSH

I did grow up driving RWD cars in Michigan. Snow was a regular occurrence and when I was 15

I never drove on snow, and most of my driving had been with FWD econoboxes. Most of my RWD driving had been on trucks and SUVs, so I had my reasons to take some care I guess many folks wouldn't while driving a Beetle or a Chevette.

I also ride motorcycles quite a bit

Last time I got to ride a motorcycle was in early 2012. Now that my knees got worse, and having a dog who I would be willing to take along for rides, a tricycle is not out of question.

Which tells us more about the sorry state of driver's training in the USA than anything else.

Low quality of driver training is an issue nearly everywhere else.

[Isaac Zachary]

@cRiPpLe_rOoStEr, I've never understood totally why, from a commercial standpoint, the rear engine economy car died the way it did. It wasn't until EV's started production again that people got excited about having a front trunk/boot. People here call them "frunks." I wonder if there's any place that calls them froo... never mind.

One interesting explanation on oversteer and understeer that I found is a manual to a video game called "Gran Turismo 2."

[freebeard]

I doubt I could find a reference* but back in the day Rod & Custom magazine had an explanation that hinged on the line between the front and rear roll centers. If the line slope one way or the other you get under- or over-steer, if the line is level it's neutral.

Is that what Grand Turismo said?

*Roll Center Explained - FMI Knowledge Base

Effects of Front Roll Center Adjustment

Front roll center has most effect on on-throttle steering during mid-corner and corner exit.

LOWER front roll center

* More on-throttle steering

* Car is less responsive

* Better on smooth, high grip tracks with long fast corners

HIGHER front roll center

* Less on-throttle steering

* Car is more responsive

* Use in high grip conditions to avoid traction rolling

* Use on tracks with quick direction changes (chicanes)

Effects of Rear Roll Center Adjustment

Rear roll center affects on- and off-throttle situations in all cornering stages (entry, mid, exit)

LOWER rear roll center

* More on-throttle grip

* Less grip under braking

* Use to avoid traction rolling at corner entry (increases rear grip)

* Use under low traction conditions

* Increases traction, reduces rear tire wear

HIGHER rear roll center

* Less on-throttle steering

* Car is more responsive

* Use in high grip conditions to avoid traction rolling

[Isaac Zachary]

Originally Posted by freebeard

I doubt I could find a reference* but back in the day Rod & Custom magazine had an explanation that hinged on the line between the front and rear roll centers. If the line slope one way or the other you get under- or over-steer, if the line is level it's neutral.

Is that what Grand Turismo said?

*Roll Center Explained - FMI Knowledge Base

I haven't quiet gotten through the whole thing. But I didn't see that about suspension, although it does mention suspension's play in handling. It even mentions the disadvantages of swing axel suspension on rear engine cars over newer suspension designs on rear engine cars.

But it talks mostly about weight placement. It has a section on each drive type:
Front engine/front wheel drive "FF"
Front engine/rear wheel drive "FR"
Mid-engine/rear wheel drive "MR"
Rear engine/rear wheel drive "RR"
And Four-wheel drive, which it calls "FWD".

It also has many other sections from acceleration to breaking to corner entering and corner exiting. You know, the stuff you'd need to know to play a race simulation game.

[Piotrsko]

The VW bug was still a viable car in Mexico until recently, and CR can probably verify the recent manufacture in South America. It was killed here because it wouldn't pass emmissions and definitely won't pass in the EU. VW stopped production on the new bug because sales weren't high enough to generate a good profit. Apparently a lot if hippies are aging out of car driving.

My 72 super had IRS with dual CV joint axles SO AFAIK it shouldn't launch on odd turns because the rears canted inwards on the top.

[JSH]

Originally Posted by Isaac Zachary

@cRiPpLe_rOoStEr, I've never understood totally why, from a commercial standpoint, the rear engine economy car died the way it did.

Packaging / manufacturing cost.

It is much easier to package a liquid-cooled engine and transaxle in the front of the car. You put the radiator up front and coolant lines are short. Same with the hoses between the engine and heater core. Throttle cables are easy to route. Shifter linkages are shorter and less complicated.

As a manufacturer I can also make a sedan, coupe, wagon, and hatchback variation and not have to touch the front half of the car.

Then there is luggage / cargo room. With a rear engine car you basically just have the frunk. With a front engine car it is easy to fold down the rear seat to double the cargo room.

[Autobahnschleicher]

Well, the Smart Fortwo has some insane packaging and so do the new ForFour and Twingo.
The ForTwo drivetrain was also used in the roadster, sadly the diesel option never came in the roadster, would have been the ultimate hypermiling car...