Diffs in 4Runner

[spud72]

I am in the market for a new truck and I am almost certainly going to get a new 07 4Runner.

I thought I'd ask a question here as you all seem to be 4Runner gurus.

It seems to me that all 4runners have traction control. However, only the 2WD have a limited slip rear end. Why on Earth would that be? Is the traction control so good on the 4x4 that it isn't necessary?

I'll be driving on snow covered and icy roads and highways a lot - is the stock system well suited?

Thanks

 

[jpalaska]

OK, I'm no guru, but no one else has replied to you.
I have the V-8 Sport Edition. My truck has full time 4 wheel drive. Both the front and rear wheels have limited slip differential.
Also, you can lock the differential for "stuck in slippery" situations.

JP

 

[spud72]

OK, I'm no guru, but no one else has replied to you.
I have the V-8 Sport Edition. My truck has full time 4 wheel drive. Both the front and rear wheels have limited slip differential.
Also, you can lock the differential for "stuck in slippery" situations.

JP

Thanks for the response!

Are you sure it's a limited slip? It is great if it is, but from what I've seen in the literature it isn't. It wouldn't be the first time literature has been wrong though!

 

[teotwaki]

Thanks for the response!

Are you sure it's a limited slip? It is great if it is, but from what I've seen in the literature it isn't. It wouldn't be the first time literature has been wrong though!

Both front and rear diffs are normal open diffs. In a 4WD model there is a Torsen Type-III center diff that can be locked.

http://en.wikipedia.org/wiki/Torsen

My favorite rant is that Toyota gave the FJC a rear locking diff but not the 4Runner

 

[spud72]

So it is true then. Why on earth they would do that..?

Anyhow,

How good is the traction control system it does have on slick roads (either mud or ice). Is it more than adequate?

I am not a hardcore off roader (at least, haven't been since my days with the FJ40 with a 327) but I do like security of a good 4WD system on really crappy roads.

 

[jharris2]

So it is true then. Why on earth they would do that..?

Anyhow,

How good is the traction control system it does have on slick roads (either mud or ice). Is it more than adequate?

I am not a hardcore off roader (at least, haven't been since my days with the FJ40 with a 327) but I do like security of a good 4WD system on really crappy roads.

Do a search and you'll see what the owners think of the capabilities of the fourth generation models. You'll see that the consensus is that the 4Runner is excellent.

 

[Falls]

The front & rear diffs have something called Atrac , which acts like a limited slip/locker type axle , but they are technically open diffs. It actually works very well , but makes noise when it engages ( like anti lock brakes )

 

[Baba Booey]

While a limited-slip rear is better than an open diff, it is far from being ideal. Most limited-slip diffs that I have either experienced first-hand or seen in action provide only marginal benefits.

I would rate the 4Runner's front and rear ATRAC system as being better than a vehicle with a limited-slip rear and an open front differential.

The 4Runner's ATRAC system uses the ABS braking system to prevent the spinning wheel from receiving all of the power. In my experience, a limited-slip rear also works much better when the brake (even parking brake) is applied to help slow the spinning wheel, and so in this way there is some comparison between the two systems. However, many LSD equipped vehicles have completely open front diffs.

I give the advantage to the 4Runner's relatively aggressive ATRAC system.

Neither are as good as a true locker for maximum traction, but lockers are not always good when driving in the snow, especially on a highway. You can add a top-quality ARB locker to the 4Runner (front and rear).

 

[Tucson T4R]

I have to agree about the lockers. I have owned past 4Runners and toy pick ups with ARB lockers. I still would like to add an ARB locker someday but for 90% of wheeling or snow driving, a locker is not needed. The traction controls on the 4Runner work very well in mud and snow, just pick your line and keep the gas steady, the computers will manage the maximum traction.The system does reasonably well on rocky roads that force wheels in the air but only if you can pick a line and stay moving. If you are doing heavy rock crawling and stoping and starting at very slow speeds, a locker would be better.

 

[Falls]

This is what was described to me when trying to climb a hill in 4wd high w/center diff. locked.

My friend was outside watching and I was given it hell going up this hill ( trying to spin the tires ) I could feel the front and rear fish tailing back & forth similar to how a locking rear diff acts when taking off in snow. I could hear the Atrac kicking in with the anti lock brakes . I was told I was roosting from all 4 tires ( I could see snow flying up from both fronts ).

My friend is a 4wd nut like me ( only he drives a Chevy ) he thought I had locking diffs. in the front and the rears by how the truck was acting.

I was conducting an unofficial test on this hill. It had 12-13" of snow on it and no other tracks. It was virgin when I got to it .

I do these type of things often so I can get familiar on how my trucks 4wd system works and handles and what I can do to make it work to the best of its ability. The 4Rs 4wd system is different from any other that I've had and was very skeptical at first,but it amazing what it will go through in stock form with a decent set of tires. I feel my biggest traction problem in this situation was not how the axle/diff's work it was more so the tires. The tires I have are nice in moderate snow on the road but are not made for deep snow traction such as I was in.

 

[Thai]

Personally, i would only recommend a rear ARB locker...and i do highly recomment it if you do a lot of off-roading. I am not confident in adding a front locker to Toyota's IFS, not because it's weaker than anyone else, but because IFS in concept is not strong enough to handle the additional stress of a locker. In addition, with an ARB rear locker and ATRAC working the front, a 4runner so equipped would be pretty damn capable!