A-TRAC Plus 3 Torsen Diffs

[lmlenzen]

I'm curious as to why the 4th gen 4Runners only have one Torsen diff for the center. Trust me I fully understand how A-TRAC works, I have utilized A-TRAC off-road numerous times, and I will attest to how well it works.

It seems as though if the 4Runner had a Torsen diff in the front and rear in addition to A-TRAC it would reduce the required braking effort and would make the transition from loss of traction to redirecting power a little smoother. Having a mechanical transfer of power at the source instead of braking a spinning wheel to force a transfer of power just seems to make more sense to me.

My best guess for the reasoning why we only have 1 Torsen diff would be for pricing reasons but that is only my guess.

Let me say again before I get hammered with posts that I do think the A-TRAC system is one of the best and wouldn't trade my current 4Runner for anything. As an engineer I am always thinking of possible improvements. Thoughts?

 

[CJ3Flyr]

I'm curious as to why the 4th gen 4Runners only have one Torsen diff for the center. Trust me I fully understand how A-TRAC works, I have utilized A-TRAC off-road numerous times, and I will attest to how well it works.

It seems as though if the 4Runner had a Torsen diff in the front and rear in addition to A-TRAC it would reduce the required braking effort and would make the transition from loss of traction to redirecting power a little smoother. Having a mechanical transfer of power at the source instead of braking a spinning wheel to force a transfer of power just seems to make more sense to me.

My best guess for the reasoning why we only have 1 Torsen diff would be for pricing reasons but that is only my guess.

Let me say again before I get hammered with posts that I do think the A-TRAC system is one of the best and wouldn't trade my current 4Runner for anything. As an engineer I am always thinking of possible improvements. Thoughts?

I agree.


Mercedes has a Torsen axle in conjunction with thier version of ATRAC. As a former Nissan Titan owner I used to frequent a couple of Titan forums. Early Titans blow the rear differential easiliy. Some of the guys replaced the weak stock unit with a Trutrac (torsen). It seemed universal amongst the people who did it, the Trutrac rocks. :bigok: The Titan has it's own version of ATRAC (it doesn't work nearly as well as the T4R; don't know if it was programming, weak brakes or massive torque that caused it to suck). The off-road guys and the hot-rod street guys had nothing but good things to say about the combo of ALBS (Nissan ATRAC) and a Torsen diff.

There's only 2 downsides I see: 1)$$$$$$$, 2)The V6 guys would have to disable thier axle disconnect that helps with efficiency when operating in 2wd. Probably not that big of a deal.


Do it:bouncy: Do it:bouncy: Do it:bouncy:....

:cheers:

 

[techno]

The 2WD 4Runners have the LSD in the rear, and I think the central american 4WD 4Runners have the rear LSD.

 

[808BMW]

Cost most likely. Why spend millions for a truly good working ATRAC system, only to spend more money to help the problem ATRAC is supposed to solve.

If I could have it my way, I'd have a LSD up front, factory electric locker in the rear (yes I know it's weak compared to aftermarket, it's still a free locker and toyota puts it on everything else) and the torsen transfer case with ATRAC added in

 

[Mike07SE]

I've been asking and saying this since I've got my 4Runner and joined this forum. I want to put a TruTrac to start with in the rear of my Runner to lessen the effects of wheelspin and ATRAC intervention. I know I'm a bit of a lead-footed person, but it amazes me how easily the rear wheels break traction when accelerating and turning, and before you know it, it feels like you've dropped an anchor as ATRAC starts doing it's thing.

 

[Thai]

Let me get this out of the way...the only way up from ATRAC is a true mechanical locker (e.g. ARB). LSD will NOT be an improvement over ATRAC under most circumstances, including off-roading.

The 2wd 4runner (in the USA) does NOT have LSD. It has what Toyota calls, "Auto LSD," which is just a marketing term for traction control on the rear axle. The only Toyota that has a true LSD is the Tacoma Sport.

Torsen LSD (truetrac) has it's limitations...and this is why i actually prefer ATRAC over LSD for off-roading. For example, if one wheel is on ice and the other on dry pavement, then you are stuck. Torsen LSD only works if there is some resistance on the slipping tire. This is why i recommend locking the Torsen center diff on the 4runner while off-roading. You turn OFF VSC but you also equalize traction between front and rear axle. If both your front (or rear) tires are on ice/mud/sand, then you are stuck unless you lock the center diff.

If you guys want to upgrade your off-road capability, then i would go for a locker. Adding LSD will not improve much, if at all.

Remember also, that when you're on-road and slipping, part of the problem is VSC (stability control) intervention along with traction control. VSC is responsible for most of the dethrottling. Therefore, adding a Torsen LSD may interfere with VSC activation. I don't know how other manufacturers get around having VSC and a rear LSD. My old BMW M3 had mechanical LSD along with stability control and i never could get an answer on how they interact during normal or aggressive driving.

IMHO, the perfect setup for a 4runner is what the FJ has...ATRAC + rear locker. The ATRAC on the FJ is super aggressive (more so than 4runner). Personally, i do not trust a locker with IFS...so ATRAC is just fine in the front.

 

[CJ3Flyr]

1)Let me get this out of the way...the only way up from ATRAC is a true mechanical locker (e.g. ARB). LSD will NOT be an improvement over ATRAC under most circumstances, including off-roading.

2)Torsen LSD (truetrac) has its limitations...and this is why i actually prefer ATRAC over LSD for off-roading. For example, if one wheel is on ice and the other on dry pavement, then you are stuck. Torsen LSD only works if there is some resistance on the slipping tire....

If you guys want to upgrade your off-road capability, then i would go for a locker. Adding LSD will not improve much, if at all.

3)Remember also, that when you're on-road and slipping, part of the problem is VSC (stability control) intervention along with traction control. VSC is responsible for most of the dethrottling. Therefore, adding a Torsen LSD may interfere with VSC activation. I don't know how other manufacturers get around having VSC and a rear LSD....

The way I have interpreted this discussion it's about a Torsen to supplement ATRAC not replace it. I agree with all of your comment if the question was ATRAC OR Torsen.

1) :nono:I disagree. The ATRAC is severely hampered when the rotors are wet or the gas pedal is stomped hard. Furthermore the larger the tire diameter the less effective the ATRAC can be. It has to be that way.


2) Even a wet or 'over-powered' brake will provide enough resistance to get the Torsen doing its thing. :yesyes:


3) I wondered about this myself



I'm standing by for my:whipping2:behead:


Hahaha:biggrin2:

:cheers:

 

[Thai]

Yeah, ATRAC has it's limitations in terms of brake wear, system heat, etc...however, you're not gaining much (if at all) with a Torsen LSD. The only real upgrade is a locker from ATRAC. This is why you do not see many (if at all) off-roaders who add Torsen LSD to their ATRAC-like system. It's just not worth it for the price. I would rather spend a little bit more and get ARB locker with air compressor. For one, the ARB unit supposedly strengthens the rear diff and is a bullet-proof locker. The air compressor is just cool because you can air up your tires easily and use air tools (e.g. to take off tires).

Again, i am not sure how VSC would interact with a Torsen LSD in the rear (or front).