When/How to use 4x4?

I just purchase at '17 Tacoma and have a question about how to use the 4 wheel drive system.

In all of my previous trucks, I had a 4x4 auto mode. In the winter time, I'd always keep the truck in this mode and never really paid attention to when it actually used 4 wheel drive and when it didn't. The Tacoma does not have an auto setting.

When should I be using 4 hi? I'm interested in how to properly use it in snow. Is it safe to just turn it on while driving down the road? Should the road be snow packed first? Just some snow/ice? Should it only be used to get moving if I'm stuck? Used on the express way?

Drop some knowledge on me!

 

Use it when you feel you need traction. On snow pack roads I use it, when I am stuck I use it. You can turn it on while driving (except 4lo) and you can use it on the interstates and such, though I personally do not exceed 55mph in it. there may be a speed restriction in the manual but if road conditions are bad enough I need 4wd then I don't need to be going fast. There is no solution for ice except chains and studs but 4wd may make it easier for you to control the slide if you are familiar with driving in 4wd.

I usually do a road test on snow. Do my rear wheels spin under normal accel, do I slide when I hit the brake? If yes to any, 4wd is on.

 

Just use common sense...yes you can engage and disengage 4 high while your moving. If the road surface is slippery enough for your rear tires to spin when they otherwise wouldn't then it's probably an OK time to use 4WD.

 

Is there any risk of damage to the truck if a certain speed is breached or if the road is too dry and 4x4 isn't really needed?

 

Yes!

 

4wd on drive pavement is ok under normal driving conditions. However it will bind and jerk if you turn the wheel all the way over like if you were parking.

This has always been an old test to confirm functioning 4wd, turn the wheel all the way over and slightly hit the gas (one of many). As far as top speed in 4wd, I can't answer.

 

I mean no...if you don't care to read your owners manual then why should I care

 

What? Stop giving out terrible advice man

 

Yes, if you make sharp turns on 4x4 and there is enough traction, you will most likely break your transfer case/transmission.

 

I belive the truck wont shift into 4wd if youre going above a certain speed anyway

 

Its not terrible. Normal driving conditions you are turning the wheel only a few degrees, this doesnt really affect wheel turn rates.
Though I agree that testing your 4wd by turning the wheel all the way over is not the best advice, its worked for decades with no problems, even did it on my test drive.

I personally never drive on dry pavement in 4wd, no reason to especially with how easy it is to turn 4wd on and off.

 

If all else fails, you can read the manual.

 

You shouldn't engage 4H going over 62MPH

 

4x4 auto in most vehicles is activated when traction control senses abs rings are moving at irregular rates of speed in relation to each other. Basically, if a wheel fails to find traction it either accelerates or decelerates in a fashion not consistent with the other wheels and it engages 4x4. This system is really great for folks who may not recognize when they don't have traction. The Toyota system is more simple, depends on driver discretion to activate, and works very well with the electronic traction aids. Just remember the phrase "when in doubt, whip it out".

What many people don't realize is that 4x4 is very useful for maintaining traction even off throttle or braking. Because all four wheels are transferring resistance to the roadway from the dead load on the drivetrain, you are less likely to break loose than if only the rear wheels transferred the resistance while the front wheels coasted. I have seen people accelerate, let off the gas, and then the back end comes around from the dead load of the driveline. An auto 4x4 system in this scenario will be in 2wd, lose traction, and engage ABS instead of 4x4. Again the part time 4x4 on the Tacoma would just be in 4x4 and not do this. The whole vehicle might slide a bit, but you can usually power out of it.

I'd read the owners manual on engagement speeds, but in my mind if you are in conditions that are bad and you're above 30mph in 2wd, you've already pushed the safety envelope. I'd ease off, let people behind you be annoyed, and engage it at a slower speed.

Again, when in doubt, whip it out. I find that I can get around town even in snow up to 4-5 inches without 4x4, but its not prudent to wait until you find slippage. My test is done on an empty side road between my house and the main road. I get up to about 20mph and hit the brakes hard. If I have ANY slipping, I go into 4x4. Go light on the gas, light on the braking, increase reactionary gap distances, and stop about 15 feet back from someone at a stoplight, so that if a car seems to be approaching my tail end too fast or braking late I can idle forward as they get close. Being from Minnesota, I can say that move has saved me several bumpers.

If there is dry pavement do not go into 4x4. Binding is bad. If you're in snow and getting a little binding, just don't make sharp turns or do more "multi-point" parking.

Last note is that if its raining, or starts snowing but the snow on the road isn't sticking, you can be in 2wd, but the first sign of any persisting accumulation you're better off in 4x4. You can be in 4x4 on wet roads especially if it looks like it might freeze, as it will slip enough if you turn sharp to prevent most binding. The new tacoma will put up the ambient temperature on the dash and even give you a "snowflake" if the temps are low enough to freeze. Overpasses and bridges can freeze up in temps as high as 38 if there is enough wind chill so an abundance of caution over those can save lives.

Keep speeds down and remember that if you use 4x4 a LOT you need to increase your front differential fluid change intervals. You can also use heavy snow as an opportunity to get in the prescribed monthly 4x4 lo and diff lock usage if you have an OR model.

 

Fundamental question....How is the Tacoma 4x4 different than an 4x4 full time system? (say like one found in a Jeep?)

 

http://www.tacomahq.com/4546/toyota-tacoma-4-wheel-drive-explained/

Maybe this will help you.

Using my Jeep as an example an 88YJ, it uses full time 4wd so the drive shaft is always spinning. It has fulltime detroit lockers which means under power the differential is always locked, even in 2wd. Tacomas are part-time 4wd, open difs and LSD and electronic lockers (if you have this option). On My Jeep the wheels turn together all the time under same power forever which causes wheel rub and tire squeals when turning on pavement. On the Tacoma with open difs and LSD your wheels can still turn at different rates making it easier to drive on pavement as well as in snow.

 

This is tough to perfectly cover because there are so many different ways to cook a goose.

EDIT: A better, more concise explanation was posted three posts down from mine by David K.

 

LOL What?

 

Full time 4WD (AWD) has a third differential that permits different drive shaft rotation speeds (front vs. back). This allows 4WD on dry pavement. The power split is usually 40/60 or less between front and rear.

Part time 4WD (Tacoma) does not have a third diff. The front and back driveshafts are locked together for a true 50/50 power split (best for off roading) but must be used off any dry pavement so there can be slippage during turns, since the front and rear rotate at different speeds, in a turn.

 

I think what he means is that if you're turning, the wheels on the outside radius of the turn are required to make more revolutions than the wheels on the inside of the turn. This is where the binding comes from as the inner wheels when locked to the outer wheels build up torque and eventually break loose in order to make the same number of revolutions the outer wheels made.

The mud thing I don't get.