4wd on dry pavement

i really appreciate the thorough response. It is a 9 year old truck that I just bought this past Feb with 73k miles; there’s no telling how the truck was ridden in that time span by the original owner. I do know he was military and had to leave it sitting for long periods while he was away on tour. I had it checked out before I bought it, and it came out fine from the inspection. But, things break, I get that.
There’s no vibration when I’m driving it now (just the clicks); but, I’m going to take it in and get it checked out by a local mechanic that I trust.
Thank you very much!

 

When you go back to 2WD do it in motion... for a smooth transition with no clunk noise after giving it a bit of gas take your foot off the pedal so there's no load on the drive train then make the switch. Best to engage your 4WD on low traction surfaces (dirt/gravel/snow, etc.)

 

Forget the transfer case. What matters is the type of oil you use.

 

Can i ask very stupid basic questions for my knowledge here? I assume so, so here i go, sorry if any of this should be logic but I like to understand why things need to be certain ways. I got my truck back in February and i only turned it on 4 times, 3 times for the 10 miles (which i see i was making a mistake doing it on pavement) and 1 time last week when it snowed and roads were slick because the towns did not expect the snow so they had no provision of salting/plowing/clearing. I want to make sure i am doing the absolute best for the truck.

1) Why does AWD, specifically, 4H need to be turned on only in non-pavement surfaces?
2) Why can you only use this on non-pavement surfaces? What is happening physically?
3) Is there a proper sequence of turning it on? (Ex: driving while turning it on, etc)
4) I assume 4L has more strict provisions on turning on and using? (to date, i have never had it turned on)
5) What can i do if i cannot find a gravel/non-pavement surface to do my monthly 10 miles?
6) What is the best way to utilize it in the rain/ice/snow?
7) Since turning becomes very limited, anytime we are meant to take sharp turns (assuming using during rain/ice/snow), do we turn it off?
8) What about in reverse?

I should point out i just noticed this thread is in 2nd gen and my questions are for my 3rd gen, i assume they both have similar systems and procedures? If not, can someone please direct the way for me to post this correctly?

Thank you!

 

AWD and 4wd are 2 different things, an AWD vehicle allows for the front and rear driveshafts to rotate at different speeds when making turns either via a center differential or through a modulated clutch pack. A 4wd vehicle locks the front and rear druveshafts together when it is in 4wd so when making turns on a hard surface there is alot of stress put on the driveline because of everything being locked together.
Driving in a straight line in 4wd on pavement isn't gona hurt anything, even gradual turns while not ideal aren't going to hurt. You just don't want to be going around corners or turning in a parking lot in 4wd though.

4Lo is mainly for offroad use where you want to keep a slow speed but have high torque available.

That being said I have no experience driving in ice and snow as we might get it once every 5-10 years here, @Bishop84 probably could tell you more about using it in ice and snow as he's up in Canada.

 

We have a few easy rules up here.

Feel unsafe? 4x4, don’t worry about the consequences, drive it and get home. Any speed, I drive 4x4 for entire months. My truck has winters and weight but it will kick out with acceleration if I’m not in 4x4.

Can’t see the road? 4x4. Easy choice.

The big problem is highway driving when theres good traction, but it’s not as bad as everyone makes it out to be.

 

1. Our trucks don't have AWD, our only choices are 2WD (RWD) and 4WD (4HI and 4LO). 4WD engages both the front and rear drive shafts, but doesn't allow them to turn at different rates. On level terrain with good traction, the axles rotate at different rates when you turn, because the front and rear tires travel different distances. Forcing them to move in unison with 4WD causes bindup, where the drivetrain has to force one or more tires to skid across the pavement to make up the difference. Just like engaging a locker will cause tires to skid on one side of an axle... 4WD is like having a locker between the front and rear axles. It reduces your turn radius, one or more tires skid when you turn, and this causes unnecessary wear and tear on all the whole drivetrain. Unnecessary because if you have that much traction, then you'd be fine with 2WD.

AWD or "full-time 4WD" can transmit torque to both axles, but still lets them turn independently (like an open or limited-slip differential within an axle). So AWD is suitable for driving on dry pavement. The downside is that with open-gear AWD, if you wind up with just one wheel off the ground (or on ice), you can still get stuck, with that one wheel spinning uselessly. So many AWD systems also include some degree of "lock" or "limited slip" behavior, usually automatic but sometimes by manual selection, affecting the linkage in the transfer case or the differentials, or applying brakes at the free-spinning wheels, to help you get unstuck. AWD is more common on passenger cars and crossovers (e.g., subarus) and is great for driving in snow or other situations where all four wheels are on the ground and have similar traction. Some trucks and SUVs also offer AWD transfer cases, where you can choose between AWD, 4HI, and 4LO. But again, our trucks don't offer AWD, so our only suitable configuration for dry pavement is 2WD/RWD.

Before you conclude that AWD is universally better than true 4WD or "part-time 4WD" which is what our trucks have, true 4x4 vehicles have low-range gearing and beefier drivetrains which are entirely more capable off road, and are better for climbing over boulders and ditches, and steep climbs and descents. The downside is that you can't use 4x4 on pavement, and you have to shift the transfer case to the appropriate configuration yourself.

2. I hope the above explanation answers this question as well, if not, I'm sure you can find articles or videos with a web search.

3. I'm not sure about proper, but here's what I do: To switch from 2WD to 4WD (4HI), I slow to below maybe 10 MPH, or if I'm stopped, I leave the transmission in drive, then move the selector. Some amount of motion/torque helps ease the engagement of gears, but don't shift while you're accelerating briskly, and especially not when the tires are spinning wildly. When disengaging, if the drivetrain is bound up, you'll hear a loud clunk. This is normal. But you can avoid or reduce it by shifting back to 2WD before reaching pavement.

4. Yes, to shift to/from 4LO, from/to 4HI, you should be at a complete stop with the transmission in neutral. Note that this is different than what I wrote for switching from 2WD to 4HI. So to go from 2WD to 4LO (or back) there are two different shift sequences.

5. If Catholic: Three rosaries. Otherwise, don't sweat it.

6. In general, don't use 4WD unless you need it, especially on snowy or icy roads. In most cases, you can drive in 2WD all the time, then switch to 4WD if you get stuck or feel like you're about to get stuck. Again, don't shift while spinning the tires.

Driving in 4WD on light snow or icy roads can be dangerous, because when you turn, the bindup will force one tire to start skidding, and this might be enough to send you out of control in an otherwise controllable turn. On the other hand, in very deep snow, you might need 4x4 all the time, and the risk of getting stuck outweighs the risk of entering a skid. Sand is quite different, and gives similar levels of traction whether you're skidding or not, so you can usually drive faster and with better directional control in 4x4 all the time. Rain is just rain, and if you feel the need to use 4WD in rain, then you need new tires.

However, there are some situations where driving in 4WD is better, even if you don't necessarily need it for traction. For example, if you're driving on sandy or muddy trails... you should use 4WD proactively to minimize spinning your tires. Spinning tires chews up the trails and causes deep ruts, and makes it harder for future vehicles to pass. Another example: certain obstacles require momentum in addition to 4WD traction or lockers, so you need to have them engaged before you lose momentum at the obstacle. The worst is soft sand, mud, or snow, where spinning your tires will dig holes in the ground, making it even harder to get unstuck. Or for a third example: when descending extremely steep slopes, 4LO engine braking can help you maintain directional control, whereas mashing the brakes could cause you to slip sideways and roll over.

However, if you're driving on paved public roads, your best bet is leaving it in 2WD, and engaging 4WD only to get unstuck.

7. You are correct that turning radius is reduced in 2WD. The correct choice for tight turns depends on available traction. Sometimes it makes sense to switch to 2WD to negotiate a tight turn within otherwise 4x4 terrain, but in general, if you don't need 4WD traction for a turn, then you should already be in 2WD.

8. I can't think of any differences for reverse.

No worries about the 2nd gen vs. 3rd gen issue. Pretty sure they have very similar drivetrains. Yours also has a computer system ("ATRAC?") that can help limit wheel spin by applying brakes to individual wheels, which should further reduce the situations in which you'll ever need 4WD or the rear locker. Mine has manual lockers and no traction control, which is overall a great setup, but it's up to me to push the correct buttons and levers to get it unstuck.



Edit: In response to @Bishop84's comments, perhaps I was being overly cautious in recommending against 4x4 in snow. I have driven in a lot of snow, but not as much as anybody from Canada. I've found that my trucks steer less predictably on light snow, plowed roads, or light ice, when in 4WD vs. 2WD. I've unexpectedly slid off the road a few times on curves or in turns in 4x4. I'm not actually sure if it's because of drivetrain bind-up initiating a slide, or just because 4x4 traction led me to drive too fast for the conditions. Either way I try to stick to 2WD in the snow, except when I really need 4x4 traction to get going. Once again I'm not Canadian, so I'd listen to the other guy there.

 

Thank you very much @Bishop84 and @mk5. This clears up a lot. I guess everything is case by case scenario which i will surely learn as i this winter comes.

 

Could be the U-joint on the steering intermediate shaft going bad.

 

@mk5 -- that's probably the best response I've seen on TW, kudos.

 

@mk5 For sure a good write up.

And that there is pretty solid advice in adverse/winter weather, and remember, getting somewhere slowly/late is always better than not getting there at all.

 

UPDATE: good news (at least i identified the clicking sound)!
So, I rolled down the window as suggested and did not hear a clicking sound outside the vehicle while making a sharp turn; the sound was definitely coming from my steering wheel.
I pinpointed the position of the steering wheel when it was making the sound, and took a peek from the side.
I found a small white piece of plastic that had somehow come ajar from within the steering wheel, and it was rubbing up against the steering column. (See pic). It obviously had nothing to do with me making a sharp turn on pavement while in 4WD. I have no clue what could’ve caused this piece to come ajar, and I don’t know what purpose it serves; but, for now, everything seems to be working fine. I may still get the 4WD system inspected since it did act funny on the pavement; but, hopefully, I’m out of the clear for now. I will look up an explosion of the steering wheel and see if I can identify this mystery piece of plastic. My guess it secured some wiring.
What a relief…an early Christmas present!

 

On the hunt for dirt roads here in Hampton, Va... 10 miles seems excessive to me. I only bought the 4x4 in case we decide to move up north we're it will definitely come in hand.

 

You are probably Fine

The loud clunk was just the front end disengaging and is normal

Driving on hard road in 4wd AND MAKING LOTS OF TURNS at high speed will kill your front end

The front end does not slip
It is locked.

The inside wheel in a turn is traveling less distance than the outside wheel

This causes the front end to bind up because the wheels are trying to rotate the same, but cant.

Your little 1/4mile drive probably did zero damage

 

Using the 4x4 for 10 miles monthly is excessive...

 

Maybe, maybe not. The owners manual says to use 4wd 10 miles a month. Hard to argue with the OM. But I agree that number and frequency is probably somewhat arbitrary. Maybe 5 miles a month is good enough or maybe 10 or 15 miles every other month is good. Who knows? No one here knows for sure. It’s either a “I think” or “I guess”. But we “know” you won’t go wrong following the OM.

 

The FWD system is not a delicate flower, you would know right away if you have it engaged it will try to take the steering wheel out of you hand if you turn too hard one direction our the other. Just backup with the wheels straight shift out and go about your business. It is not going to self destruct even if you drive a hundred miles in 4WD.

 

EXACTLY! these posts always make me laugh. Everyone thinks their trucks are so delicate. You should be able to put your truck in 4wd and do figure 8's in dry parking lots for hours and not have problems. Just imagine the unbalanced loads and binding that happens during serious offroading (See Moab)

If you break your truck by turning on 4wd then it was already broken or very nearly so.

 

Both my son-in-laws state otherwise and they are Mechanic's. I believe Toyota is only throwing a high number to cover their ass.

 

What is important is to "exercise" the 4WD mechanism(s): regularly. Turn the dial every so often to every selection position and back: underway or just sitting still in the driveway. It's the actuators and the moving the linkages that you want to keep happy. When I do this, the loudest "clunks" come on the very first actuation(s): H2 to H4 and H4 and L4 from anywhere. Much less noise and drama on the second-switch "exercise" of any flavor. If I run in H4 on a flat straight-away (rain or snow) for 3-5 miles and switch it back to H2", it's like butter: quiet, smooth, minimum noise or drama: It's telling me it's happy. I have all kinds of dry pavement, flat straight-always in my area where I can put it in H4 for a few miles. I do it. Then I get to the spring/summer fishing spots in Maine and I run it on the fire-roads in H4 all day. The truck rewards me with quiet, no-strain, no complaint shifts.

Good truck



Good Dog