Thoughts and questions on the v6 awd setup

[stiles_s]

Newbie alert!
Hi guys, my first post here, though I've been lurking and Searching for a while... I've been driving a bunch of different cars and wagons over the years, and have owned 4 audi quattros among them. I'm trying to understand the different awd setups on the 4runners in order to help inform my purschase decision (buying one to haul my new baby around).

We know that the v6 and v8 use the same torsen 3 center diff, which is great, imo (we've had a few Audis, and they all have used Torsen (type 2, by the way. the rear-biased type3 on the 4runner is actually cooler ).

It seems that the only real difference between the AWD systems of the v6 and v8 is the ability to disconnect the front wheels (on the v6), and only drive the rears.

My question is: does anybody know where this disconnect happens? Does it really disconnect at the hubs? If Toyota wanted to maximize efficiency, wouldn't they want to take the front driveline out the equation alltogether (maybe disconnect at hubs and transfer case)?

FWIW, it really seems strange to me to allow 2wd on an AWD truck. Audi has been building torsen based quattro systems for ~15 years, and IIRC none of them have had the option of going 2wd. I can't imagine you're gaining much efficiency by doing this, especially on a truck. Please don't use the "it's a truck, so it's different" argument. Unless I'm off base here, the v8 4runner is a very similar beast from an AWD perspective to my wife's '05 Audi S4 Avant (v8, torsen AWD).

IMHO, this [funky system on the v6] sounds like a marketing ploy (this is my conspiracy theory raising its head). Other SUV manufacturers have used "full time AWD" as a high priced option. Toyota may have wanted to make the V6 appear less capable by masking its AWD system under a "switchable 4wd" stigma. Too bad, really, I think my ideal 4runner would be a SR5 with the v6 and without the 2wd-mode AWD system.

OK, all that said, how reliable are electrically controlled/locking hubs?

Thanks all,
Scott

 

[Boaz]

Just buy an SR5 and leave it in 4WD all the time if thats what you really want.

From what I understand, the V-6 is a 2WD with the abilty to lock into 4WD just like many other Trucks/SUVs have since 4x4 came about. (aka Part Time 4WD)

THe AWD on the V-8 Runners is more like your audi set up. I think the V-8 Runners are electronically controlled AWD, eg the AWD system senses a slipping tire on the front of the runner and then the AWD kicks in. Also the steering feels tighter and more 4x4 if you will on the V-6 in 4x4 than the V-8 in AWD. V-8 guys correct me if I am wrong! (*cough cough* iFORCE!!)

To be honest with you, I think the V-6 Part time 4x4 is toyotas attemp to make the 4 runner a bit more fuel efficent. Not a marketing ploy IMO.


Im sure others will chime in.. just my 2 cents bro.

Jake

 

[stiles_s]

Boaz, I read things a little differently. Based on my reading the v6's AWD/4wd setup is exactly the same as the v8's, with the exception of the ability to disconnect the front wheels (aka, go 2wd) for some bizarre reason Note that I got a hint of how this works at http://uhaweb.hartford.edu/htruong/2003_4Runner.pdf , page 12 talks about an "automatic disconnecting front differential (ADD)".

I think the reason why the steering on the v6 feels tighter is that it's carrying ~200lbs less weight over the front axle?

Somone please correct me if I'm wrong on the 4wd point above.

Another final point of trivia: It's surprising how similar the v8 4runner's AWD setup is to a modern (longitudinal-engine: a4, a6, a8) Audi's.
- both use the torsen center diff (audi is moving to a rear-biased torsen 3 next year)
- both use have "electronic limited slip" (brake the spinning wheel using the ABS system) at front a rear axles
- the key differentiator is the ability to "lock" the center diff on the 4runner; something street drivers will use pretty infrequently, IMO.

Quite an advanced AWD system for a truck -- pretty cool.

 

[Bluto]

Toyota's Automatic Disconnecting Differential (ADD) system:
http://www.off-road.com/toyota/tech/add/

Toyota uses live hubs (always engaged).

The disconnect happens in 2 locations (I think, I've never seen the V6 system):

Between the front diff and center diff.

Between the front diff and one drive shaft (driver side?).


On the 4th gen V6, it may also disconnect the other front drive shaft. Again I'm not sure.




As far as reliability, I can't give you a good answer. For Toyota, I believe the full time AWD and Torsen center diff were new in 2003. Not enough people have driven 100-200k to determine reliability. The ADD system has been around a while.

Full Time = more wear and tear?

OR

Part Time = more complex, more parts to break or fail?


I like the safety and simplicity of the full time system. I like the V8.

 

[stiles_s]

Toyota's Automatic Disconnecting Differential (ADD) system:
http://www.off-road.com/toyota/tech/add/

Toyota uses live hubs (always engaged).

The disconnect happens in 2 locations (I think, I've never seen the V6 system):

Between the front diff and center diff.

Between the front diff and one drive shaft (driver side?).


On the 4th gen V6, it may also disconnect the other front drive shaft. Again I'm not sure.

UGH, it looks like the ADD is a pneumatically/hydraulically driven sleeve that engages/disengages an axle. Given my very good experience w/the torsen based Audi AWD systems, I think I'm going to go with the "simpler" V8 setup. Plus, I like HP

Thanks!

 

[BenSD]

I have an 04 V6 4x4. I switch it into 4WD every morning because it helps when I backup a steep and often slick driveway when I park my truck at work. I work only a block from the freeway, so I have to remember to switch back to 2WD before I hop on the freeway at the end of the day. Sometimes I forget, and I sure notice the difference. In 4WD, the truck requires quite a bit more gas on the freeway. I'll usually switch to the slow lane, drop below 62MPH, switch back to 2WD, then hop back into the #1 or 2 lane.

 

[Thai]

The V6 4wd system has been around since 1999. I have not heard of a single mechanical problem with the system. It is very reliable.

 

[Hank]

Like BenSD mentioned previously, the V6 4wd in 2wd mode is noticeably more responsive w/the throttle especially at lower speeds or during acceleration. You won't really notice the difference much when cruising at highway speed. As far as improved fuel economy, I don't have the facts, but I would believe that the 4wd mode might give up .5mpg to the 2wd mode, possibly more if you have a lead foot. IMO, I like the multi-mode 4wd setup. Of course, others here have voiced their opinions (pro/con) in the past from previous posts/discussions.

 

[boston_kevin]

a friend who has been a mechanic for almost 20 years compared the 4WD system on the V6 toyota to the braking system... "How many times have you seen the brakes fail on a Toyota truck?"
I said I haven't. He said "Me either. This system will last the lifetime of the truck, so will the 4WD system."

The autodisconnect system is phenomenol and if I had to give you a weak spot, I would say that it takes a couple of seconds to engage 4WD. Aside from that, the system is the best.

Why don't you see these on luxury vehicles? The same reason you see memory seats. Convienence and on a luxury vehicle, you can charge a premium to give people convienence.

 

[stiles_s]

Like BenSD mentioned previously, the V6 4wd in 2wd mode is noticeably more responsive w/the throttle especially at lower speeds or during acceleration. You won't really notice the difference much when cruising at highway speed. As far as improved fuel economy, I don't have the facts, but I would believe that the 4wd mode might give up .5mpg to the 2wd mode, possibly more if you have a lead foot. IMO, I like the multi-mode 4wd setup. Of course, others here have voiced their opinions (pro/con) in the past from previous posts/discussions.

Thanks for everyone's feedback. This is a tough call. I'm really attracted to the V6 for a couple reasons:
- the power isn't far off from the v8
- the engine is an aluminum block, and weighs ~130lbs less than the V8 which should mean better handling (I know, it's not a sports car)
- timing chain vs belt (on the v8)

'still not sure whether I want to deal w/the IMHO unnecessary complexity of the ADD system...

thanks again.

 

[Boaz]

Like BenSD mentioned previously, the V6 4wd in 2wd mode is noticeably more responsive w/the throttle especially at lower speeds or during acceleration. You won't really notice the difference much when cruising at highway speed. As far as improved fuel economy, I don't have the facts, but I would believe that the 4wd mode might give up .5mpg to the 2wd mode, possibly more if you have a lead foot. IMO, I like the multi-mode 4wd setup. Of course, others here have voiced their opinions (pro/con) in the past from previous posts/discussions.

YOu will give up 3-5 MPG with the 4WD enganged on a V-6. THis winter I had it engaged for about 2 weeks straight and she was drinkin gas bro!

 

[Boaz]

Thanks for everyone's feedback. This is a tough call. I'm really attracted to the V6 for a couple reasons:
- the power isn't far off from the v8
- the engine is an aluminum block, and weighs ~130lbs less than the V8 which should mean better handling (I know, it's not a sports car)
- timing chain vs belt (on the v8)

'still not sure whether I want to deal w/the IMHO unnecessary complexity of the ADD system...

thanks again.

Stiles, I would encourage you to test drive both models. a good apples to apples test would be a Sport V-6 and Sport V-8.

 

[Northof49]

a friend who has been a mechanic for almost 20 years compared the 4WD system on the V6 toyota to the braking system... "How many times have you seen the brakes fail on a Toyota truck?"
I said I haven't. He said "Me either. This system will last the lifetime of the truck, so will the 4WD system."

That's really what it comes down to....we're not talking about a Jeep here with some mickey-mouse part-time/full-time 4wd system.

So far in all of the lengthly V6/V8 debates that have gone into immense detail on every point of difference between the 2, no one can produce any solid evidence that one will outlast the other. If I had to make a bet, I'd say chances are high both will outlive the useful life of the truck itself.

 

[Koz]

YOu will give up 3-5 MPG with the 4WD enganged on a V-6. THis winter I had it engaged for about 2 weeks straight and she was drinkin gas bro!

I don't think so, your talking about a 35% increase in efficiency. It's probably less then .5 mpg.

Koz

 

[Boaz]

I don't think so, your talking about a 35% increase in efficiency. It's probably less then .5 mpg.

Koz

From my experience the 4WD engaged made a big difference in my MPG. My case might be extreme, but it will at least drop more than .5 MPG. Now I guess you can factor in that I was driving in snow, letting the 4R warm up in the morning doing doughnuts .... etc

Everytime I engage that 4wd for any long amount of time, the fuel comsuption goes up.

I would be willing to bet that a AWD v-6 would get worse MPG than the V-8.

 

[stiles_s]

I would be willing to bet that a AWD v-6 would get worse MPG than the V-8.

How could that be? The v6 is more efficient, the truck weighs approx 200lbs less (than the v8), and the AWD system in the two is "the same" when it's in 4-wheel Hi. they both are using the same torsen center diff...

 

[Boaz]

If the V-6 was left in 4wd all the time, the engine would be working harder than the V-8. As in it takes more fuel to push the v-6 because it has less torque.

Do you see what im getting at?
V-6= Less torque to turn 4wd system = more fuel

V-8= Less throttle to turn 4wd system because it has more torque/ HP(2005). Which could equal a lower fuel comsuption
in the end.

Im sure this is true with towing as well.
Say 2 4runners are hooked to identical trailers to tow. YOur going to have your foot in the v-6 to stay at highway speeds and go up hills etc... the V-8 with more low end torque will pull up hills easier and with less throttle and will be easier to get up to hwy speeds.

Im just saying this could happen.. I have no data to back it up.
Im just down for a good discussion



And if you check my V-6 MPG poll in my sig, the V-6 isnt much better on gas than the V-8.

 

[Koz]

If the V-6 was left in 4wd all the time, the engine would be working harder than the V-8. As in it takes more fuel to push the v-6 because it has less torque.

Do you see what im getting at?
V-6= Less torque to turn 4wd system = more fuel

V-8= Less throttle to turn 4wd system because it has more torque/ HP(2005). Which could equal a lower fuel comsuption
in the end.

Im sure this is true with towing as well.
Say 2 4runners are hooked to identical trailers to tow. YOur going to have your foot in the v-6 to stay at highway speeds and go up hills etc... the V-8 with more low end torque will pull up hills easier and with less throttle and will be easier to get up to hwy speeds.

Im just saying this could happen.. I have no data to back it up.
Im just down for a good discussion

And if you check my V-6 MPG poll in my sig, the V-6 isnt much better on gas than the V-8.

I agree that under a load (trailer) the V8 could get better mileage, but not without the load. It has been proven that the V6 gets better gas mileage, but not much.

Now if you were comparing a 2wd V6 (Not having the weight of 4wd) runner with a 4wd V8, you will maybe see 3 mpg better.

Koz

 

[Boaz]

I agree that under a load (trailer) the V8 could get better mileage, but not without the load. It has been proven that the V6 gets better gas mileage, but not much.

Now if you were comparing a 2wd V6 (Not having the weight of 4wd) runner with a 4wd V8, you will maybe see 3 mpg better.

Koz

So I'm not crazy???!!!


Maybe my heavy foot made my MPG drop this winter. I dunno... I wish the 4 runner got better mpg, but I know its not terrible for a vehicle its size.

I will be collecting some data this winter in 4wd. Just to see if there is that big of a differecne.. I will be back!!!!!!

 

[boston_kevin]

I would be willing to bet that a AWD v-6 would get worse MPG than the V-8.

I would be willing to take that bet...

Treating each vehicle equally (warm up times, speed, distances travelled, etc), the V6 will definitely be better on gas than the V8 (it's at least 200 lbs lighter).

Personally I haven't noticed much difference between 4wd and 2wd... Maybe 1 MPG tops, but even that is difficult to say it was due to the 4WD being engaged.