turning in 4wd

[4RNner]

I am hoping you guys can settle something for me.

I know very well to never use your part-time 4wd on dry pavement, about how you need a slippery surface etc, all of that.

Pertaining to driving off-road, on a dirt or gravel road or some other trail: Is it okay to make sharp turns while in 4hi or 4lo? Can you still do damage to any components while making a sharp turn with 4wd engaged, or are you okay?

Should I disengage 4wd if I have to make some turn and crank the steering wheel all the way?

Particularly wondering about my '16 SR5 with part-time 4wd.

Thank you! All of the past discussions I found after a search involved people making the mistake of using 4wd on dry pavement.

 

[KidVermicious]

You're safe to turn sharp in 4low on loose surfaces. You may find that you have difficulty making hairpin corners and might want to shift out of 4low or even into 2wd for that reason, but as long as the tires can shift and spin you won't cause any damage remaining in 4low.

For that matter, running 4hi and 4low on dry pavement isn't that big a deal either. You'll scrub the hell out of your tires, but the odds of breaking anything that wasn't ready to break anyway are pretty low. Rubber will almost always break traction well before you're at risk of snapping a drivetrain component.

 

[e60ral]

if you are going slow in a tight turn you'll definitely feel it bind up before you are at the point of causing damage, it will actually even bring you to a stop if you are just making a slow tight turn in 4-low. if that happens just be aware that you have driveline binding and don't give it too much throttle and you'll be fine.

 

[PWD4R]

You should be fine. The only downside is your turning radius will be a little worse but oh well. As long as you're not turning with your locker oh you're fine. Keep in mind that you have front diff so it's designed to run wheels at different speeds- front and rear tires alike.


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[e60ral]

You should be fine. The only downside is your turning radius will be a little worse but oh well. As long as you're not turning with your locker oh you're fine. Keep in mind that you have front diff so it's designed to run wheels at different speeds- front and rear tires alike.


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this is true, but you are locked front-to-rear and when turning each wheel is in its own arc so even with open front and rear diffs you will still get binding if you are turning without the ability to slip

as long as OP isn't giving it too much power he should be fine, but his '16 SR5 is part-time 4WD which means it doesn't have a center diff

 

[4RNner]

Thanks for the feedback everyone, you are all a great help!

 

[Bumbo]

So on something like a 2004 Gen 4 SR5 4x4, where you have control over locking the transfer case, would it be acceptable to drive on a wet pavement surface in 4H with the t-case unlocked?

Or is it only with the t-case locked we get these tire scrubbing issues? In my rig, both the front and rears are open differentials.

 

[KidVermicious]

So on something like a 2004 Gen 4 SR5 4x4, where you have control over locking the transfer case, would it be acceptable to drive on a wet pavement surface in 4H with the t-case unlocked?

Yes, that's why they call it full time 4WD. With your center diff unlocked, your front and rear driveshafts are free to rotate at different speeds and you can use 4WD on high traction surfaces without worrying about tire scrub or driveline binding.

 

[Bumbo]

Yes, that's why they call it full time 4WD. With your center diff unlocked, your front and rear driveshafts are free to rotate at different speeds and you can use 4WD on high traction surfaces without worrying about tire scrub or driveline binding.

You confused me again... I thought there were still differences between full time 4WD and part-time 4WD on the toyotas?

My understanding the full time 4WD like on an audi, the v8 4r full time, and others are designed to be run on high traction surfaces and cant be turned off.

Am I basically switching from 2WD to what is the equivilent of full time 4WD when going to 4 High with t-case unlocked?

I honestly dont know why I haven't just tried it, but my other truck (Silverado 1500) gets really chirpy on dry pavement and I dont think it has a t-case lock.

 

[nevada]

You confused me again... I thought there were still differences between full time 4WD and part-time 4WD on the toyotas?

My understanding the full time 4WD like on an audi, the v8 4r full time, and others are designed to be run on high traction surfaces and cant be turned off.

Am I basically switching from 2WD to what is the equivilent of full time 4WD when going to 4 High with t-case unlocked?

I honestly dont know why I haven't just tried it, but my other truck (Silverado 1500) gets really chirpy on dry pavement and I dont think it has a t-case lock.

yes.

 

[KidVermicious]

You confused me again... I thought there were still differences between full time 4WD and part-time 4WD on the toyotas?

My understanding the full time 4WD like on an audi, the v8 4r full time, and others are designed to be run on high traction surfaces and cant be turned off.

Am I basically switching from 2WD to what is the equivilent of full time 4WD when going to 4 High with t-case unlocked?

I honestly dont know why I haven't just tried it, but my other truck (Silverado 1500) gets really chirpy on dry pavement and I dont think it has a t-case lock.

Ok, so there's basically three kinds of four wheel drive. Call them part time 4WD, full time 4WD, and all wheel drive. There is no industry standard for what to call what drivetrain (forex, Audi calls their stuff 4WD but by this understanding it's more like AWD, and Europeans tend to call ALL of it 4WD), but if you break them down by functionality it looks something like this.

All wheel drive - generally based on a front wheel drive system, normally lacks a transfer case or low range. Power is distributed to all four wheels at once, sometimes intelligently. A decent all wheel drive system can do a very good impression of legit 4WD, but won't be able to keep up when it gets real. AWD is intended to allow better performance at high speeds in low traction situations (i.e., slippery roads).

Part time 4WD - this is your traditional 4WD. It has a transfer case, almost always with low range. When 4WD is selected, the front and rear driveshafts are physically linked in the transfer case and are forced to rotate at the same speed. This provides better grip than AWD in low traction situations, but can cause tire scrub and driveline binding in high traction situations. Part time 4WD is intended to allow better performance at low speeds in low traction situations (mud, deep snow, rock crawling, etc).

Full time 4WD - has a transfer case, almost always with low range. Transfer case has a differential between the front and rear driveshafts that allows them to rotate at different speeds (this is functionally identical to the differential between your axle shafts in the front and rear axle assembly). With that differential operational, you can use 4WD on a high traction surface without worrying about tire scrub. Toyota's version of full time 4WD is called "multimode", and includes an electronically actuated lock on that center differential - when the truck is in 4WD and the center diff is locked, your truck is functionally equivalent to a part-time 4WD truck, with all the benefits and drawbacks that come with part-time 4WD. With the center diff "open", or operational, the full time 4WD with ABS and traction control does a very good impression of all wheel drive, but is not quite equivalent to a dedicated AWD setup (Subaru, Audi, etc).

Clear as mud?

 

[theMayor]

As long as the center diff isn't locked, why would turning be an issue then?