Electronic brake activated limited slip vs lockers

[wfo9]

Thought this was an interesting demonstration of lockers vs something like ATRAC. It's not exactly the same, but it matches what I have observed many times on trails.

The two trucks here are very different.
- A stock chevrolet colorado zr2 with lockers and stock 31" duratracks and 128" wheelbase running IFS.
- A jeep JK sport with 7k in suspension and tires including 35" tires (but without lockers). The jeep does have a brake activated limited slip similar to ATRAC. And a short 95" wheelbase with a the obvious solid front axle.

Notice how the jeep lunges and struggles while the zr2 just walks up the same loose spot.

Don't want to start a controversy....but it matches what I have mostly observed in the real world. You still make it with ATRAC on something like this..., but with less grace and a bit more potential for damage IMHO.

Anyway, though it was worth sharing. The interesting part is at the 8:00 mark (the player should start it there). The zr2 is pretty impressive overall out of the box.
<iframe width="560" height="315" src="https://www.youtube.com/embed/PN8PQkhTFyc?start=480" frameborder="0" allowfullscreen></iframe>

 

[SS_Syndicate]

My experience has been that the JK Jeep's "brake lock" requires pretty low wheel speed to work well if at all.... I haven't used the A-track much so I can't really comment on that or the ZR2 as I don't know enough about them, but there are a lot of other factors in play here, and I think the wheelbase was the ZR2's major advantage. The Jeep has to deal with a lot all at once, where the longer truck only had one axle dealing with the spot at a time.

 

[nb rob]

Toyota's Atrac is much more responsive than any other anti lock brake limited slip I've ever seen. I used to think they were all garbage until I experienced the 4runner's Atrac

 

[SS_Syndicate]

Toyota's Atrac is much more responsive than any other anti lock brake limited slip I've ever seen. I used to think they were all garbage until I experienced the 4runner's Atrac

Interesting.... I agree but my turning point was our KL Cherokee. It is always carrying a tire and there is not a bit of detectable hesitation when doing it. I call it wheeling with voodoo and snake-oil. The biggest weakness to the KL Cherokee is the low clearance. Even with a lift and 31s we are still just under 12" down the belly. This is fine if you can get a tire on the big stiff, but it's trouble when it comes time to straddle something.

 

[wfo9]

Toyota's Atrac is much more responsive than any other anti lock brake limited slip I've ever seen. I used to think they were all garbage until I experienced the 4runner's Atrac

I've wheeled with many jeeps with it and compared the behavior with ATRAC a few times. They don't seem all that different to me. ATRAC may have a slight edge.. It's a pretty simple concept once the sensors are in place. The bigger your tires are.. the less effective it is... for obvious reasons.

I think it was not as good on the early JKs and is much better now.

There are also multiple versions of ATRAC. The early GX version is complete garbage. Also, not so hot on the early FJ that I have.

 

[(none)]

Its a tool and like any tool, it's all about how you use it.

I had 2 jks, both 2doors, 6-speeds and rubicons. I enjoyed seeing how far the electronics could get it and was highly impressed. Maybe it has different programming on the manuals though. i could get get it flexed out with 2 wheels off the ground, clutch out in first gear, just spinning. As soon as i'd start to feed it gas, the brakes would start applying on the 2 spinning and off it'd go.

I've messed around with toyota MTS and atrac. I've pretty much come to the conclusion the MTS isn't worth it. Just hit the atrac button and rock on. The atrac does seem to do fairly well too. There is no substitute for lockers though, as we all know. I can say that (i was in the nasty mess of the appilachian toyota roundup last weekend) atrac did an admirable job of making up for the lack of a locking front diff when needed.

 

[borfoo3]

All else being equal:

ATRAC (or any electronic brake based traction aid, whatever its called) may help get you out of a sticky situation.



Lockers won't get you there to begin with.



In the real world, that fraction of time in power loss / slip for any electronic aid kicking in can make all the difference.