Please explain Rear Wheel Drive

[TJPark01]

True, but the usefulness of a bush package is pretty questionable, except in the off-chance that your SUV gets swallowed by a sinkhole.

Which is becoming quite common in LA these days...
I read somewhere that in 2002, 30% of all new consumer use vehicles sold in the US&A were SUV's. I wonder what that number is now. I guess it's all about CUV's now, which are less worse. I'm kinda of put off by cars that try to be swiss army knives. Jack of all trades master of nothing (5 series GT,Acura ZDX,Toyota Venza, blah, blah blah). I'm starting to sound like a surly old Grandpa Simpson.

 

[jailer]

I could go on for days, but the bottom line is FWD was created for the purposes of economy and cost reduction.

I've always wondered, what amount the auto mfg's are saving per vehicle...., take Honda as a case study. Most of their vehicles are front wheel, they put out one (that I know of) rear drive, S2000,....
....THEN, most importantly for this cost issue, they put out the (has to be really expensive, IMO) SHAWD, on a significant number of cars. (not the ultra mass, however, mass prod. enough)
Now, what would Honda of saved if they put rear drive on all those SH vehicles instead?? That is completely going backward with regard to cost, when the same model cars they offer with front drive to "save cost". Check out the info on the SH system.

 

[Sayantsi]

SH-AWD is a crutch for the company to have quasi-rwd cars. Its a dry road, onroad-only awd system that keeps most power on the front wheels in most of its applications. Honda has no desire for rwd or even neutral or rwd biased awd.

 

[ilovemygenesis]

Just waiting for the front drive rear engine configuration. That should be a lot of fun.

FWD disadvantage= The drive wheels are the steering wheels. So when traction is lost, you lose drive and steering. Usually results in understeer.

FWD - Advantage - Massive weight (engine) over the drive wheels, this allows the tires to "plow" thru snow better. This is a marginal gain which is removed with correct winter tires.

RWD - Disadvantage - The drive wheels are "light" or unloaded, which results in a tendency to lose traction. This results in wheel spin in snow etc. Simple fix, 50 Lbs of salt in the trunk

Rwd - advantage - The drive wheels are dedicated , the steering wheels are dedicated. Massive power can be deployed. At the limit the platform "breaks" in a more controlled way, (understeer and oversteer are possible).
Can Provide the best steering "feel"

AWD - Disadvantage - weight. To provide drive to all wheels adds 250-400 lbs of weight. cost - upfront and long term.

AWD - advantage - Least likely platform to lose traction. Can deliver the most power to the ground.

If you care about driving dynamics, corner entry speeds, 1/4 mile times, you are likely looking at a RWD platform.

If you have more money that then Gov't , and care about the above you want a AWD performance car

If you just care about getting there, and a bus just isn't available , FWD is the way to go.

Great info, question for the group, In RWD, why if the weight of the car is predominately distributed in the rear of the car do you need to add weight to the car?

Also how does the LSD factor into the performance of each system?

 

[MattG]

Great info, question for the group, In RWD, why if the weight of the car is predominately distributed in the rear of the car do you need to add weight to the car?

Also how does the LSD factor into the performance of each system?

The weight is not typically distributed to the rear of the car in RWD cars (the engine is almost always the heaviest thing in a car). FWD cars are typically distinctly front heavy (the engine sits right on top of the drive wheels), whereas RWD cars tend to be a little more balanced (a 50/50 distribution is considered ideal), but that very balance means that the rear wheels are not being pushed down as much as they would in a FWD car. Add to this the fact that RWD lends itself to more power, and a RWD car is somewhat more likely to have more power than traction in some situations.

If the weather is going to be crappy anyway, and a person is not considering racing (where total weight might be an issue), then adding a little weight in the rear of the car can improve traction. Keep in mind, though, that this is really only likely to be needed in really nasty weather (snow, ice, mud, etc.) - a little bit of water on asphalt or concrete should pose no issues for most cars with even modestly appointed all season tires.

LSD basically prevents one wheel from getting all of the power. Imagine a car in the winter trying to head up a steep driveway. One rear wheel is over ice, the other is not. In a typical differential scenario it is possible that the wheel on the ice might just start spinning, and the car would not go anywhere. With LSD, the wheel on the ice can only spin so much before the differential locks up, and forces the other wheel to spin as well. Two wheels have a better chance of finding purchase than one.

Note that all of the precautions in the world (winter tires, weight, LSD, etc.) can only do so much before driver stupidity wins out anyway. If someone puts the hammer down in the snow, they are going to wipe out, and that holds true for FWD cars as well. The main difference is that a FWD car is basically like an underpowered RWD car that always has 150lbs of sand in the trunk.

 

[Sayantsi]

Most rwd cars have a weight distribution of around 55% front, 45% rear, or 55/45. Sports cars try for 50/50, or perfect weight balance. Ferrari states the perfect balance is actually 46/54 or so. Since there is less weight on the rear of a rwd car's drive wheels vs a fwd car with a 70/30 ratio, there's less ability to grab friction. When you want to increase traction, one method is to apply more force to the two objects, and weigh in the trunk is an easy way to do this. Another is to use thinner tires.

There are many types of LSD, but in general the idea is to force both wheels to spin equally fast when there is a traction differential. This is good for getting more traction, but comes at the expense of stability, since in a car without a LSD, one wheel will spin and the other will maintain a straight line, but if you force both to spin, neither are able to provide directional traction as they are both 100% dedicated to acceleration traction.

If you've ever tried to get up an icy drive, either one wheel spins and the car slowly if at all moves forward, or both wheels spin and the car slowly if at all moves forward, plus it slides back and forth as there's no traction whatsoever to control the car's line.

Rather than depend on an LSD or extra weight in the trunk of your car, a tire designed for cold and snow that can provide traction is a great way to ensure your car stays on the road and goes when you want it to.

Slightly OT but a fun vid - R8 out in the snow - this is an awd supercar with snow tires.
http://www.autoblog.com/2009/12/29/...hosen-chariot-for-snowy-excursions/#continued

Also apropos - snow tires ar emor important than awd:

http://www.autoblog.com/2009/12/29/proper-winter-tires-are-more-important-than-all-wheel-drive/

 

[GripperDon]

ASSUMING ALL OTHER THINGS BEING EQUAL AND FAIR (ie. weight distribution near 50/50, and the like) THEN

RWD pushes and you keep the front in front of the rear.
FWD pulls and you keep the rear behind the front.
AWD, everything pulls and pushes and you steer where youwant to go.

 

[Disaster]

When I lived in Colorado, the state dept of transportation did a study on which types of cars get into accidents during snow days. Oddly enough it was found that it was SUV's. The theory was that the extra traction from a dead stop of AWD & 4WD gave drivers a false sense of security. Apparently people forgot that 4WD doesn't help your car brake, the tires do that.
You'll be glad to read this article about winter driving in Car & Driver...
2009 Winter Tire Test - Comparison Tests

I used to work with a mechanic who had a favorite expression about 4 wheel drive. "Twice the giddy-up, no more woe."

Winter tires on a rear wheel drive will beat a 4 wheel drive car in messy conditions and get better fuel mileage.

 

[Mark_888]

Bottom line is that for people who live where it snows a fair amount, additional winter tires are often purchased for RWD cars, including many Genesis owners on this forum.

But some people are not willing to put up with the inconvenience and cost of switching tires when there are many excellent FWD cars out there. The last time I lived where it snowed a lot and I had a RWD car, one of the problems was deciding when to make the switch. Many times, no matter when the switch was made, I ended up driving with tires that were not optimal for current road conditions.

 

[TJPark01]

Bottom line is that for people who live where it snows a fair amount, additional winter tires are often purchased for RWD cars, including many Genesis owners on this forum.
But some people are not willing to put up with the inconvenience and cost of switching tires when there are many excellent FWD cars out there. The last time I lived where it snowed a lot and I had a RWD car, one of the problems was deciding when to make the switch. Many times, no matter when the switch was made, I ended up driving with tires that were not optimal for current road conditions.

I had this problem living in New Jersey. It would dump snow, by the time I got the winter shoes on, it would rain. Then the rain would freeze, and it wouldn't snow for another month. For people living in Buffalo, NY where snow is pretty consistent, not a real issue. For people in coastal N. Atlantic where snow is episodic and melts fairly quickly, it's tough to time correctly. There have also been winters where it snows everyday for a month, so it's really a crap shoot.

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[Disaster]

Bottom line is that for people who live where it snows a fair amount, additional winter tires are often purchased for RWD cars, including many Genesis owners on this forum.

But some people are not willing to put up with the inconvenience and cost of switching tires when there are many excellent FWD cars out there. The last time I lived where it snowed a lot and I had a RWD car, one of the problems was deciding when to make the switch. Many times, no matter when the switch was made, I ended up driving with tires that were not optimal for current road conditions.

The truth is, if you live where it snows, you should switch to winter rubber whether you drive rear wheel, front wheel or even rear wheel drive. The difference is dramatic. Statistics show more accidents in the winter with 4WD vehicles because the owners have too much confidence. In the words of someone I worked with. "Four Wheel Drive; Twice the giddy-up, no more woe."

 

[Mark_888]

The truth is, if you live where it snows, you should switch to winter rubber whether you drive rear wheel, front wheel or even rear wheel drive. The difference is dramatic. Statistics show more accidents in the winter with 4WD vehicles because the owners have too much confidence. In the words of someone I worked with. "Four Wheel Drive; Twice the giddy-up, no more woe."

No sir, I will respectively disagree with you. I lived in Colorado for a total of over 12 years driving both RWD and FWD cars. Very few people in Colorado who have FWD change to snow tires in the winter (unless they happen to go to the mountains on a frequent basis). I always carried light-weight "cable" chains in my trunck of my FWD cars, but never used them.

 

[Disaster]

No sir, I will respectively disagree with you. I lived in Colorado for a total of over 12 years driving both RWD and FWD cars. Very few people in Colorado who have FWD change to snow tires in the winter (unless they happen to go to the mountains on a frequent basis). I always carried light-weight "cable" chains in my trunck of my FWD cars, but never used them.

Front wheel drive doesn't have any more inherent traction than rear wheel...except for the additional weight on the front wheels of poorly weight balanced cars...and any amount it has, based on additional weight, is minuscule compared to the difference in traction between true winter tires and all season tires.

People don't drive with winter tires because of a combination of the cost and hassle and their general ignorance of the improvement in safety and performance winter tires provide.

Winter snow tires can improve traction as much as 40% on cold slick surfaces...cutting stopping distances a similar amount.

I have to admit, before I started driving with winter tires, two years ago, I too thought they were an unnecessary cost and hassle. But now I won't drive without them. By the way, I've always lived in states with snow and ice and therefore have been driving in snow for 35 years.

http://www.caranddriver.com/features/09q4/2009_winter_tire_test-comparison_tests

http://www.tirerack.com/winter/wintertesting.jsp

 

[scottdk]

I had this problem living in New Jersey. It would dump snow, by the time I got the winter shoes on, it would rain. Then the rain would freeze, and it wouldn't snow for another month. For people living in Buffalo, NY where snow is pretty consistent, not a real issue. For people in coastal N. Atlantic where snow is episodic and melts fairly quickly, it's tough to time correctly. There have also been winters where it snows everyday for a month, so it's really a crap shoot.

Keep in mind the rubber compounds in Winter tires are much differenent and give more traction in cold temps vs regular all seasons. So there is a benefit to Winter tires even if there is no snow on the roads etc.

 

[Mark_888]

Front wheel drive doesn't have any more inherent traction than rear wheel...except for the additional weight on the front wheels of poorly weight balanced cars...

That is very big "except for". As to whether FWD cars are poorly balanced, maybe they are not ideally balanced, but I never heard too many people in Denver talk about any balance problems of FWD cars. So long as they did not have switch out their tires in Winter (very few did that who had FWD cars) they were generally quite happy, especially since many of the best and most reliable family sedans on the road are FWD.

You can proselytize all you want about the added benefits of winter tires for FWD cars, but in Denver (and I am quite sure in many other cities) the average FWD car owner is not going to purchase Winter Tires for their vehicles.

 

[Disaster]

You can proselytize all you want about the added benefits of winter tires for FWD cars, but in Denver (and I am quite sure in many other cities) the average FWD car owner is not going to purchase Winter Tires for their vehicles.

..and they will drive after having a drink or two...but that doesn't make it right or smart. As long a winter tires aren't free, there will be people who claim they aren't necessary. I disagree.

 

[Mark_888]

..and they will drive after having a drink or two...but that doesn't make it right or smart. As long a winter tires aren't free, there will be people who claim they aren't necessary. I disagree.

I guess that we just have to agree to disagree.

However, when you start saying that something isn't "right" and comparing it to DUI, I think you are crossing over the line.

 

[Disaster]

I guess that we just have to agree to disagree.

However, when you start saying that something isn't "right" and comparing it to DUI, I think you are crossing over the line.

Yes, it is obvious that we disagree. Perhaps you've really researched the difference in abilities of winter tires vs. all season performance and made your decision based on that...but perhaps not. I was in the latter camp for years.

I am sort of "evangelized" toward winter tires. Let me explain my history.

I grew up and drove in Northern PA, where we got quite a bit of lake effect snow from Erie. It wasn't unusual to have 2 foot of snow on the ground. There were a lot of 4 wheel drive vehicles...but also good old American rear wheel drive. Occasionally, we'd have a set of studded "snow" tires fit to one of our cars...but the performance wasn't that great compared to decent all seasons. You just got a feel for how a car slipped around and drove accordingly...much slower. It was never as safe as driving in the summer. When front wheel drive came along I definitely was "evangelized" to it...and Audi's "It is better to pull a car, than push it" commercials. Front wheel drive did seem to get stuck less...and was less likely to spin out.

Cut to a couple years ago. My son is going to a dental appointment. Fresh icy snow is falling. I tell him, "Drive slow, the roads are freezing up." 15 minutes later I get a call from his cell phone. He has put my front wheel drive, stability/traction controlled Volvo S60 into the wall. He was going around a wide sweeping bridge when it started to drift. Not sure how he reacted but the final result was, car meets concrete barrier...concrete barrier wins.

Yes, it was his fault for going to fast, however during the retelling of the story to my brother he asked if I had winter tires on the car. I told him how I had expensive all seasons on it and they were less than two years old. He told me that there was a revolution in winter tire technology started by Bridgestone with their Blizzak tires and that there was no comparison between the performance of these new tires vs. even the best all seasons. He also tells me that these tires outperform studded tires and chains. It is a special material technology that keeps the tires compliant and grippy in the coldest weather.

I decided to do a little research on my own and found lots of info that suggested winter tires were not only much better, but so much better that it was almost stupid not to use them (see my above links.)

We had leased cars for years, and that made separate winter tires even more costly (because we'd be throwing away good tires unless we leased a vehicle that took the exact same tire size each time.) However, I decided to get off the lease merry go round and bought a car, a 5 year old Acura TL. Time to really check out those winter tires.

Picked up a set of Blizzaks, for the Acura, because those were the tires my brother had recommended. When the first snows hit I was out there...trying to see if I could see a real difference. At first I wasn't sure. Then, I had to take my son back to college after Christmas break (yes, the same one that wrecked my S60...and we had to drive right by the same spot.) A couple hours before we are to leave the snow starts...and it really comes down. By the time we hit the road there is already almost of foot on the ground and it isn't letting up. I see cars off the road everywhere...spun into trees, nose down in the ditch...tangled together at intersections...it is a mess. But we just go. Sure, it isn't as nice as driving in the dry, but the tires bite in and we are able to drive 30-35 miles per hour where everyone else is moving at 10 or 15. We are passing big SUV's on the freeway. You can actually hear the tires throwing huge amounts of snow out from under them...whirring loudly as they clean their path. On the way home I have to get around a pick up truck that is stuck on a hill by the college.

I can't help but wonder if my son might not have had that accident if I had a set of winter tires on the Volvo. Just avoiding that one accident would have paid for the tires...not to mention what could have happened...I shudder to think that. Plus, now I've got son number 2 driving. He drives a Toyota Avalon, in the winter we shod it with General Altimax Artics. So far, so good...no cell phone calls. When we bought our Genny the first thing I did was hit the Tirerack website and ordered a set of winter tires for it.

So, yeah, I'm sold...and do feel it is irresponsible to drive in the snow with anything less....just like drinking and driving. Maybe some people have to "hit bottom", like an alcoholic, before they realize that all seasons are unsafe for winter driving. I feel lucky to have gotten by with just an injury free accident.

 

[Mark_888]

I can't help but wonder if my son might not have had that accident if I had a set of winter tires on the Volvo. Just avoiding that one accident would have paid for the tires...not to mention what could have happened...I shudder to think that. Plus, now I've got son number 2 driving. He drives a Toyota Avalon, in the winter we shod it with General Altimax Artics. So far, so good...no cell phone calls. When we bought our Genny the first thing I did was hit the Tirerack website and ordered a set of winter tires for it.

So, yeah, I'm sold...and do feel it is irresponsible to drive in the snow with anything less....just like drinking and driving. Maybe you some people have to "hit bottom", like an alcoholic. I feel lucky to have gotten by with just an injury free accident.

Probably he would have had the accident anyway. Even if there is improved traction with snow tires, you son probably would have driven faster thinking he was safe. Sort of for the same reasons that 4-wheel drive SUV's have higher than average accident rate in winter conditions that regular cars, because their drivers have a false sense of security and drive faster.

You mentioned the Genesis. Most people know that a RWD car needs snow tires in snow/ice, or not driven in winter conditions (which is OK for people who have more than one car). The overwhelming majority of people with FWD cars do not purchase (and will not purchase) snow tires and get satisfactory results.

So your statements are your own personal opinion, which are contrary to the public at large (except for tire dealers).

 

[Disaster]

You mentioned the Genesis. Most people know that a RWD car needs snow tires in snow/ice, or not driven in winter conditions (which is OK for people who have more than one car). The overwhelming majority of people with FWD cars do not purchase (and will not purchase) snow tires and get satisfactory results.

So your statements are your own personal opinion, which are contrary to the public at large (except for tire dealers).

Once again, we disagree. I think the public is just ignorant or complacent...or a combination. A majority does not make things right. In Europe, winter tire sales are many times what they are in the U.S. Same with Canada (of course they get more snow.) Also, recently Canada made winter tires mandatory because they understand the improvement they make.

The bottom line is you will always have much better stopping and turning capability with winter tires than with all season. This is true not just on snow and ice...but when temperatures fall below freezing where the softer compound of winter tires start outperforming the stiffer compounds used in all season tires. You will be safer and others on the road will be safer around you.

Your tires are the only thing that holds that 3000 lb vehicle on the road and keeps it pointed in the correct direction. Take time to read the Car and Driver article. They suggest, and I agree, it makes more sense to buy winter tires than to invest in 4 wheel drive. Watch the Tirerack test. It takes almost twice as much braking distance for the car with all seasons to stop on ice. Besides being safer (ie. better control and stopping with winter tires vs. all seasons and 4 wheel drive) the cost is less...initially (compared to the 4 wheel drive system) and over the lifetime of the car from the gas savings (We got 28mpg from a FWD Volvo vs. 21mpg for a AWD.) As far as front wheel drive is concerned, while it affords a small advantage over rear wheel because of the added weight on the wheels, it is still not going to stop any faster than a rear wheel drive car.

I also disagree that rear wheel drive is inherently more dangerous than front wheel drive even with the same tires. It is more a factor of the cars set up...weight distribution, alignment and power and driver experience. Generally, rear wheel drive cars are set up with more "aggressive" alignment (as opposed to mucho understeer), have more power and less weight on the drive tires. If those things were more equal, rear wheel drive would do just as well...in fact, it offers more capabilities because of it's throttle controlled oversteer capability. However, for the typical driver, who doesn't have slippery driving experience, the front wheel drive tends to be more manageable. If they get into a understeer slide, just releasing the throttle will often save them. Of course, I've also seen inexperienced drivers steer further when the understeer happens and plow right off the road...or the wheels "catch" and oversteer in the other direction and often go into a spin.

IMHO, winter tires should be mandatory as well as real accident avoidance driver's training. After the accident I sent my boys to the MidOhio defensive driving school...something else I should have done before the accident. The statistics for accidental auto deaths and injuries is staggering in this country...far more than planes or guns...or half the other silly stuff the press gets worked up about. This is especially true with young adults. In fact, it is the highest cause of deaths for young people. Anything that makes driving safer should not be ignored.

http://injurylaw.reganfirm.com/2006...ccidents-leading-cause-of-death-for-ages-434/

"Among Americans ages 4-34, motor vehicle crashes on public highways are the most common cause of death, according to the National Highway Traffic Safety Administration. "

http://www.edgarsnyder.com/car-accident/resources/statistics.html

"National Car Accident Statistics
There are more than six million car accidents each year in the United States.
A person dies in a car accident every 12 minutes and each year car crashes kill 40,000 people.
The leading cause of death for individuals between 2 and 34 years old is motor vehicle crashes.
Someone is injured by a car crash every 14 seconds and about two million of the people injured in car accidents each year suffer permanent injuries.
Over 25% of all drivers were involved in an auto accident in a five-year period.
Excessive speed is the second most common cause of deadly auto accidents, which accounts for about 30% of fatal accidents.
Car crashes cost each American more than $1,000 a year; $164.2 billion is the total cost each year across the United States.
Car accidents are the leading cause of death for kids between 2 and 14; About 2,000 children die each year from injuries caused by car accidents.
Each year, almost 250,000 children are injured in car crashes, meaning nearly 700 kids are harmed every day.
Car accidents are the leading cause of acquired disability nationwide.
2008 Car Accident Statistics
In 2008, the number of overall traffic fatalities reached a record low since 1961, and that number continued to decrease in the first few months of 2009.
The number of car crash deaths in 2008, 37,261, dropped 9.7% from the number of deaths in 2007; this is the largest annual reduction since 1982.
The 2008 passenger car occupant fatalities have decreased for the sixth year in a row, accounting for 25,351 deaths. This is the lowest number since 1975 when the NHTSA began collecting fatality crash data.
Motor vehicle traffic crashes injured about 2.35 million people in 2008, which is the lowest number the NHTSA has seen since it began collecting injury data in 1988.
In 2008, there were a total of over 5.8 million car crashes, 1,630,000 causing injury, 4,146,000 resulting in property-damage only, and 34,017 ending in death.
There were 15,983 urban crash fatalities in 2008, decreasing 11% from 2007.
Car accident deaths in rural crashes totaled 20,905, a 10% decrease from 2007.
2007 Car Crash Statistics
41,059 people were killed in car accidents in 2007, an almost 4% decrease from 42,708 people in 2006.
The highest number of deaths from car accidents occured in July and the fewest in February.
17,725 fatalities occured over the weekend and 23,237 during the weekday in 2007.
In 2007, the highest number of fatalities, 6,796, occured in the 25-34 age range while the lowest number, 470, occured in the 5-9 range.
13,040 deaths in were linked to speeding.
In 2007, 8,657 deaths occured in intersections.
About 23,482 deadly crashes involved a single vehicle while 17,577 involved multiple vehicles in 2007.
Instances where the vehicle in a crash veered off the road led to 24,147 fatalities in 2007.
Non-fatal car accidents totaled 5,987,000 in 2007.
In 2007, individuals were injured in about 1,711,000 accidents, while around 4,275,000 crashes only caused property damage.
Car accidents disabled 270,000 people in 2007."

Some additional winter vs. all season tire articles, videos and tests.

From Canada
http://www.bchighway.com/myvehicle/allseasonsnowtires.html

http://www.consumersearch.com/snow-tires/all-season-or-snow-tires

Tirerack test on snow
[ame="http://www.youtube.com/watch?v=JGfvyPtYR0Y"]YouTube- Tire Rack Tire Test - All-Season vs. Winter Tires[/ame]

Discount tire stopping distance comparison.
http://www.discounttire.com/dtcs/winterAllSeason.dos

Edmunds winter tire testing with Honda Civic.
http://www.insideline.com/features/tire-test-all-season-vs-snow-vs-summer.html

Ontario gov. info.
http://www.mto.gov.on.ca/english/safety/topics/wintertires.shtml
Stopping distances at 50 km/h*

Test conditions
- 20° C with 3 to 5 cm of compacted snow and ice on asphalt surface.
Vehicles equipped with automatic transmission and anti-lock brakes.
Tests in 4-wheel drive vehicle conducted in all-wheel drive mode.
*Fournier L., Comparative Evaluation of Performance of All-Season tires and Winter tires, Ministry of Transportation, Quebec, 2002.