4 WHEEL DRIVE ENGAGEMENT

Hello. I have a 2020 TRD, with the lever 4-wheel drive engagement. My prior 4-wheel drive vehicle as a JEEP COMMANDER with ALL WHEEL DRIVE. I want to understand something about this system. I drive along I-5 south from OREGON, to MOUNT SHASTA CALIFORNIA then onto STATE HWY 89, then onto STATE HWY 44 to SUSANVILLE. Then SUSANVILLE to CARSON CITY. I will be driving, during winter/snow. The road is plowed, but sometimes it has patches of dryness when the sun hits it and melts the snow. So, what all happens when the 4-wheel drive is engaged? Do I just stay in 2-wheel drive, until and if the road gets really bad, and let the system work? I don't drive like a madman. I would just like to get a better understanding of how this system works. TY for your time.

 

4WD can be used if going back and forth from slippery to dry as long as you don’t stay in 4WD for an extended time on dry pavement

 

Once there is ice/snow you can slow down to 50 mph (I forget the exact number but 50 or lower works) and shift into 4 wheel drive high. You don't need to stop or put it in neutral either (which you do need to do if you are going into 4 low). I'd leave it there until you are back on non-slippery roads. I don't think it's a problem to go back and forth between 2wd and 4 high if you hit intermittent snow/ice patches.

 

I drive in snow a bunch and only use 4x4 when approaching an intersection or taking off, as they can sometimes be icee. I wouldn’t drive down the highway in 4 wheel drive, but that’s me. I think of 4 wheel as getting me out of jams, not using it to get me in jams. If you can do 50 plus, is 4wheel drive helping?

 

It was a rude awakening for me too. Coming from AWD vehicle to a Part-Time 4WD. (Didn't understand the system)
Not really useful for driving through snowstorm at highway speeds unfortunately.

 

If you can go highway speed, you shouldn't be in 4wd.. if you NEED 4wd... You should slow down...

 

Huh??

I absolutely love 4wd over AWD driving through snowstorm at highway speeds because regardless how much I give gas / coasting (zero gas) I have equal engine power. I can drive on 4H without any speed limit. Only thing I need to remember is not to take tight turns when the road is dry.

Other than highway driving even at going uphill on unclean driveway I love how smooth the 4wd system is vs AWD been reactive sending more power after slip and then cutting power to the wheels that are spinning end up with more mess.

 

IMO if you are at highway speeds eg 55 / 65 / 70mph flowing with other traffic on winter time when the roads are wet & snow'ish please use 4wd. Do not risk yourself and others on the road driving in 2wd.


Edit-
I think people are confused about the speed limit to change from 2wd to 4wd. That is the speed limit to change not a speed limit you can drive in 4H.

 

Just so impractical switching btw 2WD and 4WD. Remember the stormy highway would suddenly be bone dry without warning (because it was just cleared) and immediately drive into sloshy ice/black ice without warning or time to flip btw gears. To turn into a icy curvy bridge.

With AWD and good tires.. you don't have to do anything. Just keep flying through storms with peace of mind.

 

Make sense. If you don't like to drive part time 4wd next best thing is full-time 4wd, why my wife has Limited. If you don't need 4wd vehicle and drive slowly and carefully AWD is a good choice. But remember if you don't apply enough gas on AWD vehicle for the viscous clutch to engage or electro-magnetic clutch to engage you are in 2wd.

For me in the mountain states we know on the shade side of the mountain after a snowstorm there will be snow & ice so we switch to 4wd if I'm not in 4wd already. But normally in highways when there is signs of snow on the side of the road even though the high traffic area is dry I'm in 4H on curvy mountain roads.

edit -

If I'm "flying through storms" 4wd is far more peaceful for me knowing I have engine control all the time vs AWD mostly 2wd unless you give adequate gas to power all wheels and still the power is variable depending how much gas you give. Unless you have AWD system like Sti where you use the center diff control to lock it. Then same theory apply as part-time 4wd.

 

For those that have an ORP, how is the engagement “feel” at the lever? Is it smooth? Notchy? Rough? I’ve heard some describe it as buttery smooth, which mine isn’t necessarily, but curious as to everyone’s experience. Again, this is referring to the shift lever and not the knob.

 

With my experience it is not smooth as shifting a stock manual transmission shifter. But things are much easier when you let off the gas and shift to 4H little faster with your hand position like shifting to 2nd gear (not dead straight like 4th gear).

 

The lever being an actual mechanical device, the feel of the shifting action will vary, based on how it’s shifted.

(Edit: in reference to part time 4wd) It’s a synchroed transfer case, as far as I understand, which allows it to shift on the fly. However, that doesnt mean you can shift with abandon.

When shifting the transfer case, there cant be a speed difference between the front wheels and the rear wheels. As long as you are at a steady state speed going straight, a butter smooth shift will result. I also tend to lift throttle to unload the drivetrain right as Im shifting (which results in an effortless feeling shift)

However, there can be times where you just decide to shift at the wrong time…like while you are slightly turning, or if stopped with a slight steering angle, or noticeable suspension articulation, for example. In those situations the shift will feel like trying to stir cold chunky-style peanut butter. You’ll have to force it in, which just feels wrong and horrible lol. Because you’re fighting the tension in the way gears are meshed, it might not move enough to completely engage the gears, which triggers ADD actuation, which completes the 4wd actuation process.

This is one of the reasons I never wait to need 4wd before selecting it. If you’re stuck, you might struggle getting the tension between all 4 wheels to be equal on the drivetrain, which would interfere with the shift and 4wd engagement. It’s just like the planning needed driving a manual transmission car…never wait till you “need” a particular gear to shift…anticipate it and have the gear selected by the time you are going to make use it.

Also, regarding AWD or part time 4wd for snow driving. It kinda sounds like people expect that AWD will allow for aggressive driving in bad weather. That really sounds like really bad, really unsafe way of thinking about things. I’d rather not look for ways to preserve high energy levels in situations where me or anybody around me is more prone to crashing.

AWD has a big element of marketing behind it. Very few know how to take advantage of the improved acceleration awd brings in poor traction situations. And there are very few day-to-day situations when gassing the throttle is what saves you in a high speed turn.

No thanks, leave that for the WRXs and Evos on the racetrack.

Either 4wd or AWD will help you avoid getting stuck… but thinking you’ll take advantage of it to justify high speed driving sounds “youthful” (to put it nicely lol).

 

I found over the past few winters, that if there's just a couple inches of packed icy snow on the roads, my AWD 07 Volvo XC70 was superior in those types of conditions, especially when running snow tires. However, if it's deeper, or unplowed, the 4Runner is superior. The nice thing about all-wheel drive vehicles is that they're idiot proof, you just drive. The act and principle of shifting between 2WD and 4H is a lot for some people. It's a shame these don't have a more versatile transfer case like the 3rd gen's had, that allowed you to drive in 4H on the pavement because the center diff lock was separate. The fact that you could get that in a '90s Toyota (or an '80s Cherokee) makes it kind of inexplicable why they don't offer that now.

For blizzard conditions, I prefer the 4R as well. Last winter we went to New Hampshire and drove black in a blizzard before the plows had hit the road. There was probably about 6" of unplowed snow on the highway, and in 4H at 40 mph, the 4R was extremely sure-footed. I do like that the front and rear wheels are both turning at the same rate, and there's no waiting for the rear wheels to kick in when the computer tells them too.

The thing that people need to remember is that while 4WD may make you GO better, it does nothing to help you STOP better. There's also only so much traction to go around between breaking, steering, and accelerating, so one must choose wisely.

Every winter I see plenty of people with 4WD or AWD cars spun off into the highway median because they were not driving intelligently.

 

So, did all 4th gen 4runners have center differentials? I thought they did but I don't remember so good lol. I do recall being initially being mildly disappointed that my 5th gen was so old school with it’s non-differentialed transfer case. I mean, I eventually got over it, but remember it being something I had to get over. Lol

 

I think there's a video from o'niel rally school (can't remember the name exactly) showing how 4wd help stopping and turning on snow and ice not lockup wheels since there is engine power.

 

The ones with full time 4wd had a center diff. I believe all of the V8's came with full time 4wd, and maybe the Limited, as well.

I think it was some of the 3rd gens that had the "multi-mode" 4WD system, where you could select 4HI with an open center diff, or locked center diff. But, they could also be driven in 2hi.

 

https://youtu.be/EMnT1gCYjP8

 

I was not talking about the speed for going from 4wd to 2wd etc.. it's more about, if the conditions are bad enough that you NEED to be in 4wd... You should probably go little slower than highway speed.. 4wd won't make you stop faster if you need to stop in bad weather.

 

Whoa, I never considered how 4wd CAN actually improve braking. But there are some good explanations of how the mechanics of 4wd can help with threshold braking.

Then I realized only part time 4wd, (without a center differential), is really capable of benefiting from the effect being explained in the video.

So basically, by physically connecting all 4 wheels together through 4wd, engine forces would keep the driving force on every tire equal, making threshold braking more forgiving…as a tire approahes the limit of traction, it cant really lock up as long as other tires are turning. Hmmmm, and this only applies to part time 4wd.


ok I feel better about my part time system lol.

Actually, this would only really work if the engine is solidly locked to the drivetrain. So automatics are out ? But it WOULD work in 4low because the transmission keeps engine/driveline locked together until like 0.4mph.

Ok, maybe the lesson here is that during torrential snowstorms, the safest vehicle to use on busy downhill interstates is actually 4runner in 4LO!

 

Not a bad video but the gentleman should probably cut back on the Mountain Dew before filming.

 

The Limited comes with a center differential lock. When engaged, the dynamics of the drive train are just like part-time 4WD. So it can benefit too.

Not exactly. Wherever there is an open differential you have the opportunity for a wheel to lock up. To physically connect the wheels and keep the driving force on each wheel equal as you describe would require front and rear locking diffs (in the case of part-time 4WD) or front, rear, and center locking diffs (in the case of full-time 4WD).

You can still feel good about your part-time system. It’s excellent.

The slip in the automatic transmission is insignificant for the purpose of this discussion I think.

 

On the street, 2wd until you need 4wd and leave it in 4wd it's slippery enough.

 

After awhile, engaging and disengaging 4wd will become second nature. Having had the manual lever in my Tacoma and now the dial in my SR5 4Runner, I think the manual lever offers more instantaneous control when road conditions are varied.

 

Does anyone know for certain about highest speed in 4HI? I thought you could not exceed 55MPH in 4HI. Is that not the case? (I am not talking about speed to shift into 4HI)

 

Hi just glanced at my owners manual and didn’t find an upper limit.

 

Thank you. I read the manual when I got the vehicle and thought there was nothing about it as well, but at the dealer on pickup was told to keep it under 55 when in 4HI. This thread made me remember that. Wasn't sure what was fact and what was misinformation.

 

Nope, there's no max speed stated for 4H.
There's only 2 max speeds posted for part time 4wd systems to change from 2H to 4H.
If I'm not mistaken for Limited it says to shift from H4F to H4L at any speed.

 

Outstanding. Thank you. I can't believe how many people were given this same bad info prior. Glad to get clarification. Thanks!

 

That’s what it says. You can lock the differential at any speed.