Quote:
Originally Posted by Iron Chef
The 4Runner is my first 4x4. I'm just trying to wrap my head around the various modes of 4x4, across the various models of the 4Runner.
From my research, as I understand it, the V6's 4Hi mode is EXACTLY the same as the always-on 4Hi of my V8. (Let me know if I'm off on that, or if there's any caveats).
I still have a question then, on what this 4Hi mode actually does, in terms of delivering effective power to each wheel, and comparing 4Hi + Center diff unlocked, vs 4Hi + Center diff locked.
With center diff unlocked, it seems to me that we still have open front & rear diffs, and power will still always go the wheel with the least traction. - So even if just one wheel is completely off the ground, it will get 100% of the power (to spin uselessly), and no power will be delivered to any of the other 3 wheels.
- Is that an accurate assessment?
- Is this is true, then what's the point of 4Hi with center diff unlocked?
With center diff locked, we get a 50/50 split of power to the front and rear axels. So if one wheel is off the ground, there's still 50% power at the other axel.
My last question is - when I'm driving on gravel or dirt roads, should I just lock the center diff right away? Is there any reason or benefit to NOT locking the center diff if I'm on a loose surface? |
You actually seem to have a pretty good grip of this. The Torsen center diff has a bias ratio, I think 4:1. So, if a wheel starts to slip, 4x the power can be sent to the opposite axle. However, when a wheel is in the air spinning, it effectively has 0 power (oversimplification) so 4 x 0 is still 0. ATRAC however is your friend, because it gives that spinning wheel some small amount of grip, which in turn allows the LSD to work its magic.
4Hi with center unlock is great for driving on roads with ice, or other variable grip situations. It will keep more grip longer than 2WD, but you can still turn. On trails, the advantage of center unlocked is corners. Sometimes, in tight turns on trails, you can end up with the front and rear wheels fighting eachother. This can increase your turning radius, which in some places is more a limiting factor than grip.
This is why the center lock/unlock is so handy. You can lock it when you need it, and leave it undone when you don't. That said, I end up driving with it locked mostly off road because it disables VSC. There is a mod to give "VSC off" its own switch, but I have not done that yet.
