4WD confusion

[ccvortex]

Hi all, 06 4WD SR5 6cyl and I was wondering if the the 4WD setting on the dial means that it is actually in 4WD or is it waiting for wheel slippage and will then kick in 4WD like an AWD system?

I know there's a dif lock that locks it in 4WD, so I was curious if we could just leave it in 4WD High all winter? It's basically my wife's car now and I'd like to know she had good grip while driving.

Thx all,
Mike

 

[BlackWorksInc]

It's a real 4WD vehicle, if it's in 4Hi or 4lo the transfer case is engaged and you're powering all 4 wheels.

 

[madeinhb]

If you flip the switch to 4hi - it works as AWD. I keep mine in 4hi all winter. Locking the differential will make it act like a true 4wheel drove.

 

[BOFFROAD]

If you flip the switch to 4hi - it works as AWD. I keep mine in 4hi all winter. Locking the differential will make it act like a true 4wheel drove.

Agree

 

[ccvortex]

Awesome, thanks all, I'll just leave it in 4hi for her then once the snow starts.

 

[foxtrot]

I would believe blackworksinc over anyone else on here considering he is a Toyota service tec. If I'm in 4hi on pavement, there is resistance in the steering which means it is engaged doesn't it?

 

[M1911]

I would believe blackworksinc over anyone else on here considering he is a Toyota service tec. If I'm in 4hi on pavement, there is resistance in the steering which means it is engaged doesn't it?

As long as you haven't locked the center diff, then you can drive in 4hi on pavement forever. There won't be any binding in turns, because unlike a part-time system, the Torsen center diff allows the front and rear driveshafts to turn at different speeds.

Only lock the center diff if you are off pavement, on snow, or you are on pavement but you just don't turn.

 

[BlackWorksInc]

If you flip the switch to 4hi - it works as AWD. I keep mine in 4hi all winter. Locking the differential will make it act like a true 4wheel drove.

Yes and no, I just want to clarify this point because it is often confused on this forum with newer members (not picking on you, it's just something that does pop up from time to time.)

The 4th Gen 4Runner in particular is a 4WD vehicle, it comes in two flavors of 4WD. Part-Time 4WD which means you can switch between 2WD, 4Hi, and 4Lo (all V6 4WD units are equipped with Part-Time 4WD,) the other option is All-Time 4WD (all V8 4WD units are equipped with this.) The biggest difference between the two is the that Full-Time 4WD does not have a 2WD option. It basically means that the V8's are always in 4Hi (the V6 will drive exactly the same as the V8 in 4Hi and it is perfectly okay to use it in daily driving as many members do.)

The main distinction I want to make here is mainly between AWD & 4WD (they do drive similar, but they are two completely different systems.)

All-Wheel Drive means that there is only a single stage transfer gearset (basically all it is is a secondary differential that shifts some power to the other axle as well.) An AWD vehicle is typically either FWD or RWD biased with some power distributed to the second axle; the "transfer case" is little more than a very small gearset attached to the end of the transaxle or transmission.

A 4WD vehicle has at minimum a 2 stage Transfer Case (often chain driven) that allows you to further change the gearing of the vehicle when in 4WD. This means that your final drive ratio is modified by selecting what transfer case position you want, (i.e. in 4Lo your gearing is so low in a 4th gen you cannot really go about about 30~35mph)

This is something that an AWD vehicle does not have the capability to do, not to mention the system is not as robust/stout enough to handle the type of low speed torque required to do some off-roading (which is why you have a 4Lo gearset to begin.)

Additionally all North American (basically all US model) 4th Gens come with a T3 Torsen Center Differential that allows torque distribution without binding up the 4WD system. This basically means that the vehicle can be driven in 4Hi on the road with minimal to no impact on driving characteristics (where as say a Jeep or other Domestic vehicle with a Part-Time 4WD system will bind and skip in turns when trying to drive on-road.)

 

[madeinhb]

Well yes - but most people don't understand it to that depth. Was easier to just compare it to AWD.

 

[ccvortex]

OK, just to confirm, I can leave the 4wd setting in 4Hi on my 2006 SR5 24/7, and it will kick on the "awd" when it senses tires are losing grip, correct?

 

[m85476585]

OK, just to confirm, I can leave the 4wd setting in 4Hi on my 2006 SR5 24/7, and it will kick on the "awd" when it senses tires are losing grip, correct?

Yes, you can leave it in 4Hi all the time. There is a limited slip center differential, so it mechanically/automatically distributes power, which is faster than electronic systems on some vehicles that have to sense slipping first. It also has electronic control in case there is too much slipping for the LSD to correct, in which case it will pulse the brakes to the slipping wheel(s) to help send power to the ones with traction. It works well, and it's similar to the AWD found in high end cars such as some Audi Quattros.

 

[M1911]

OK, just to confirm, I can leave the 4wd setting in 4Hi on my 2006 SR5 24/7,

Yes.

and it will kick on the "awd" when it senses tires are losing grip, correct?

No. It doesn't "kick on the AWD when it senses tires are losing grip." Instead, it is always sending power to both axles, all the time.

Cheap (and crappy) all-wheel-drive systems only send power to other axle once your primary drive axle has already started to slip. The 4Runner system is far better -- when in 4WD (high or low, center diff locked or unlocked), it is always sending power to both axles all the time. It doesn't wait until the rear axle has started to slip before sending power to the front.

 

[Range]

So is there really a need for a rear locking diff on the 4th Gen V8?

 

[BlackWorksInc]

So is there really a need for a rear locking diff on the 4th Gen V8?

Yes and no for a 4WD. The ATRAC system works pretty well, but it is not a replacement for a locker, but most people do fine without it unless they are doing more technical off-roading. For 2WD, it is a bit better as you're hampered off-road by a lack of front driven axle, so the lockable rear helps get out of sticky situations (and momentum.)

 

[Range]

So the need is dictated by the severity of the terrain. I've been contemplating adding the ARB to mine (2004 V8). Great info once again BW.

 

[M1911]

So is there really a need for a rear locking diff on the 4th Gen V8?

The center diff controls the distribution of torque from front to rear, but not side to side. Once you lock the center diff, both the front and rear driveshafts turn at the same speed.

However, you still have open diffs in the front and rear axles. The traction control system tries to transfer torque side to side. But if you have a front and rear wheel with no traction, I'm not sure how successful it will be.

IMO, a locking rear diff would still be an advantage in difficult terrain. ARB makes one.

 

[m85476585]

The traction control system tries to transfer torque side to side. But if you have a front and rear wheel with no traction, I'm not sure how successful it will be.

IMO, a locking rear diff would still be an advantage in difficult terrain. ARB makes one.

Traction Control or ATRAC works surprisingly well for transferring power from side to side if one front and one rear wheel have low traction. I have not used it with two wheels in the air, but I think there it a video out there where someone shows that it works in that case.

 

[M1911]

Traction Control or ATRAC works surprisingly well for transferring power from side to side if one front and one rear wheel have low traction. I have not used it with two wheels in the air, but I think there it a video out there where someone shows that it works in that case.

It's not that great in my '03. Perhaps it has gotten better in later years.

If I was going to do significant offroading in my '03, I'd put in an ARB rear diff. I take mine out on the beach, but that is not very challenging.

 

[Lolrax]

OK, just to confirm, I can leave the 4wd setting in 4Hi on my 2006 SR5 24/7, and it will kick on the "awd" when it senses tires are losing grip, correct?

No, it doesn't kick on the AWD. It is sending power to all 4 wheels all of the time but the differential is open so you can drive around however you want. Systems that kick on the AWD almost always kick it on way too late for it to be useful.

I leave mine on from basically October-April here in Canada.

 

[ccvortex]

No, it doesn't kick on the AWD. It is sending power to all 4 wheels all of the time but the differential is open so you can drive around however you want. Systems that kick on the AWD almost always kick it on way too late for it to be useful.

I leave mine on from basically October-April here in Canada.

Perfect, thanks.