DON'T SAY THAT!

 

What model/year Yota do you have? The AWD/4WD or just the 4WD system? There are different specs and requirements for each drive-train. The reason 4WD hi or AWD is better in the rain is because your front wheels are pulling instead of only your rear tires pushing. There is a notice difference between 2WD and AWD in the rain-at all speeds.

As far as spinning in the rain- what kind of tires did you have? I don't have a 5-speed but I do have a S/C and revos and have to absolutely punch the gas to cut loose in the rain. I have ridden on BFG A/Ts in the rain and they are to slick on wet pavement.

 

Can you expand on that? That alone does not explain why it is actually better, that is just stating that 4 wheels drive, while in 4 wheel drive mode.

 

"...because your front wheels are pulling instead of only your rear tires pushing"

sounds about as simple an explanation as you can get to me. It kinda sounds like you've got a burr in your bonnet about this one.

 

What's wrong with being inquisitive?

I'm sure we are all mature adults here, and this is a democratic forum, so we do not get 'pissed' when something we say is legitimately questioned. And that is exactly what I'm doing, I honestly do not understand the mechanics behind this concept of 'surefootedness'.

That is an incomplete thought, though. Do the rear wheels have not enough traction to retain the momentum at 60mph? Can anyone even tell while at 60mph if 1 wheels keeps up that momentum or all 4? Can anyone break the rear wheels at 60mph? Or do the rear wheels constantly lose traction completely so that front wheels have to 'pull' to correct?

Maybe I'm endangering my life and the lives of my passengers as a result of not driving in 4x4 while on the highway. If there is a simple explanation, why can't anybody put inquisitive minds at rest?

 

AWD and 4wd are not the same;AWD controls all 4 wheels independently and will pull power from the wheel(s) that are slipping even if you stay on the throttle while with 4wd the wheels will continue to spin with the throttle applied,it's the driver that has to control the slippage. AWD is superior on slick/sandy surfaces for control.

I've driven my truck in 4hi and then my mom's '99 back2back using the AWD mode in about 8 inches of snow and the AWD has much more stability especially going from soft snow to hard packed surfaces and then into standing water/slush. If I ever get an auto 4Runner it will be one with the AWD option.

 

Yes, I'm sure most are aware of that, but for all intensive purposes in this discussion let's just use the simplified term 4WD for any variation of where front wheels drive, and RWD where only the rear wheels drive.

 

Sorry;I misread something.

 

It's alright; everyone is welcome to add. I guess we can also restate what is being discussed: a vehicle going high-way speed (45+ mph) in rain, or otherwise in slick conditions. Speed and behavior does exceed those conditions to become dangerous, i.e. accelerating excessively, going fast enough to hydroplane, etc...

Some claim that using 4WD mode in these conditions improves traction, or in other words decreases the risk of losing control.

All I'm curious about is a real world example of where 4WD would aid responsible driving to avoid loss of control, and the mechanics behind it.

 

I am not a engineer nor do I play one on TV. I have no scientific data but my maniac driving style has put all to the test. The AWD/4WD system is much more stable in heavy rain and water than 2WD. If you have driven a front wheel drive car in the rain/through puddles- they are much more stable than rear wheel drive cars. It justs makes sense that 4 wheels (although 4WD hi is one rear and one front tire- correct?) performing together are superior to 2 wheels "pushing" through water. Next time it rains and the streets puddle up- test it out and see what you think. If you can drive 60-70 mph on the interstate- then it's not raining hard but if you're on a two-lane backroad and raining like a bi*ch- I would try 4WD/AWD.

This is a real world test. Fall 1999. One of the Hurricanes that actually hit NC was headed at Charleston and they evacuated the city on Tuesday. The storm was expected to hit Wednesday night. Catorgory 2/3 nothing life-threatening but after Hugo- no thanks. Traffic was crap on Tuesday so I was leaving Wednesday morning. My Bonneville was acting up and died about 100 yards from the harbor on James Island. Couldn't leave it so I called my Dad and he drove down and we fixed it. Something with the battery cable. Always something. We were headed back up I-26 and I was in the lead. Heavy rain and 30-40 MPH gusts. I-26 is beat-up pretty bad b/c of the "big-rigs" that are constantly on the road and have left "tracks" in the right lane where water holds during a rain storm. I went through deep water- felt a little hydo-planing but made it through at about 55-60. My Dad was in a new Explorer and he left the road in my rear-view mirror. Rear wheel drive on a narrow SUV. He hit a massive pine tree backwards, lucky to say the least. The ride was destroyed but he had a cut on his hand and that's it. The next week he bought a MB ML320. AWD and a tank. Crappy tires, rear wheel drive is asking for trouble in the rain. Sorry about the novel.

 

During cornering under power, FWD will tend to understeer, RWD tend to oversteer and 4WD tends to be neutral. I won't pretend to understand the explanations but if you internet search on the term oversteer understeer you will find many discussions about this.

For example:
http://www.toymods.org.au/fwd_rwd_awd.html

 

Make sure before you tow in 4WD that your front diff gears are properly broken-in. Sometimes it takes a while to get a couple hundred miles on those front gears. Here is a break-in write-up that recommends 500 miles before towing http://www.precisiongear.com/pgtech_breakin.htm

 

Quote:Have you ever lost traction when it was raining outside?

Well yes I have I was driving responsibly, however there was no weight in the bed of my 97 4x4 Taco. Getting onto an on ramp at 55mph, my overdrive kicked in and my taco went into an instant hydro-plane spin. 5 or 6 360 degree rotations later, my trucke slammed into a grass bank. I looked out the passenger window, and all I could see was grass. The taco was sitting on it's side and slowly fell back on 4 wheels. When I got out to assess the damage, there was grass embedded into the top of the door! My truck was sitting in about 2 foot deep water and I thought for certain I was stuck. Locked the hubs, yanked the transfer into 4 hi, and crawled out of that scary situation. My toyota took care of me that day. I thank it every day from here on out. I watched two big-rigs fly by and miss me by a mere couple foot, the thought of this is creeping me out so I better cut it short.

anyways, the tacoma is great. I got a trashed front 1/4 panel and huge dent in the bed but structurally is is fantastic! I've put 30,000 miles on it since then and it runs like a dream still. I LOVE my TACOMA.

 

but it sure is fun pulling all of the lowered f-150's out of the snow banks. i never saw so many lowered full size trucks until i moved to the denver area!

 

Here's a Google search that comes up with multiple articles saying that you should not.

Click Here

 

More articles about the handling characteristics of 4WD vs FWD vs RWD:
http://www.rallycars.com/Cars/4wd_turbo_cars1.html
http://autozine.kyul.net/technical_s...handling_5.htm
http://www.snowtire.info/References/...ll_or_Both.pdf

 

My 2c. As I see some urls pointing to other people's opinions. Again lots of people will have lots of opinions on this one.

First as mentioned in some post AWD or permanent 4WD is very different to plain old 4WD as on Tacomas older 4Runners. The reason is as said the AWD has a center differential in the transfer case, and the normal 4WD only has a direct connection meaning power goes 50/50 front and back. SO driving in a straight line is no problem with either, but the issues come in when you start turning. SImilar to your inner and outer wheels turning at different speeds in a croner, so does your front and rear axles. The job of an differential is basically to even out the speed difference by applying more torque to the wheel or axle going the furthest/fastest.

Now in normal 4WD you lock the front and rear axles at the same speed always, which means when going around a croner you will get the sensation (actually what happens) that your front wheels are being pushed into an understeer as they loose traction as they always take the longer route around a corner but is now being forced by the rear to take the same route, so the rear pushes (it needs less wheel rotations for the turn). Now at speed on a wet/ low grip road it can be very dangerous if you need to do an emergeny turn, as your front wheels will loose traction and your ability to steer. AWD or permanent 4WD with a center diff does not have this problem. I'm not even talking about wear issues and binding here just safety.

Next, if your tires does not have enough traction on a road surface to accelarate moderately without spinning in RWD only, you seriously need to think if you want to drive at any speed on this road surface, as you will have little braking or steering ability at speed. In short very dangerous!!! Fun when doing trails at low speed, big trouble at highway speeds.

As to the FWD vs RWD argument I will just say lots of very smart engineers ahave been working on this for many years, and there is reason why all sport/race cars, even real sport sedans are either RWD or AWD and why all/most economy cars are FWD.

Again my opinion with explanation of why I think what I think.

Hope this helps 4RUNR

 

This is it exactly. When both drive axles are receiving power, steering, and directional control for that matter, tend to be more neutral. You can "feel" it. If you aren't willing to test this out for yourself, and don't have any personal experience to bring to the table with this, it's almost impossible to describe any other way.

There's a damn good reason the Audi Racing Team campaigns AWD cars. Late in the races, when there's oil, antifreeze burnt rubber and other crap all over the track, they simply are able to out-drive their opponents. In fact, the first year they fielded these cars, they were deemed an unfair advantage. All wheels being driven = more traction and directional control, period.

Peace.
G

 

DO not agree with such an absolute statement as you made. It greatly depends on the configuration of the vechile. Mid engine and rear engine vehicle have far better directional control, and they are RWD. F1 is a good example, or should we take a NSX. The question of AWD, RWD FWD depends greatly on the setup and configuration of the vehicle. The reason of late they add AWD to supercars is just to get the power down in a straight line. Many suspension and race gurus do not agree with power on the front wheels in high speed situations as it reduces the traction of the tires for steering.

Rally is a whole different world as there is never enough traction, so the ability of the front wheels to "pull" the vehicle in the aimed direction is important. I specifically chose aim as that is what it felt like to me when I did it a litle bit (steer would not be an accurate description), I didn't have enough "you know what" to go really fast. SO had to do a bit of track racing with little FWDs, racing takes BOSS (if you know what it means) I lacked that level of skill and loved life too much maybe. But even here (low traction) you have different setups, look at Baja.

So my point is there is no superior method, as there is a time and a place where each will work better.

 

Keeping traction in the rain is easy. Slow down, go easy on the throttle. I never have a problem in 4X2 on wet roads. If you're getting sideways all the time in wet weather then it's simply driver error. Hard to put it any other way. Slow down and get there safe, drive like you do on dry pavement and live with the risks.

Unless you are driving on very curvy roads, driving in 4X4 isn't a serious problem. The idea that it will somehow bind up or seriously damage the drive train is a false assumption and bad information. Fact is, my owners manual says I should drive the rig around in 4X4 about 30 miles per month.

Towing in 4X4 is another matter. I wouldn't do it for any distance, especially if driving on curvy roads. If you can't get traction towing on wet roads you're towing too much for the conditions. Buy a real truck for that or fill the bed with sand bags.

Toyo Master