Different types of 4WD

[Thorin]

Here's a two-part series (is that still a series, if there's only two parts?) where they show the difference between 4WD with open differentials, 4WD with open differentials and electronic traction control (what most SUVs have these days), and 4WD with locking differentials:

http://www.youtube.com/watch?v=C2wkW05Pc6c
http://www.youtube.com/watch?v=YNFacsKnswM

It's about 15 minutes altogether, but the guy does a good job of showing the differences between how the systems handle more extreme conditions.  Note that for on-road driving, you actually want the open differentials as they allow your vehicle to turn easier and better.

Kinda cool that the locking differentials are locked via air compression, which means you end up with an air compressor in your car that you can also use to inflate tires when they're low.

[Thorin]

And this is the absolute best-ever explanation of how a differential works!

http://www.youtube.com/watch?v=K4JhruinbWc

Takes almost 2 minutes to really get started, and the complete video's over 9 minutes long.  Still, if you have the time, you'll definitely learn something!

[Melbosa]

Good finds Thorin.  Why were you looking it up?

As for myself, my '93 4Runner has the 4WD with Locking Diff, and yes my turning isn't that great in 4WD on the road, but neither is it hugely impacted.  Also my compressor whines in the real deep cold, and was a known issue until after '96 (my '92 stick had it, as well as this '93 auto).  It still works fine, just whines, and is a bit confusing when you first hear it - hard time explaining that when I sold my '92 - had to find some articles from Mags my Mechanic has from '91 talking about it.

A nice history of the 4Runner is here: //[url="http://www.toyoland.com/trucks/4runner.html/"]http://www.toyoland.com/trucks/4runner.html/[URL]

Something to note though that depending on the part of the world, and the country, the Toyota models and options differ, such as Europe and Asia see models we never did in North America.  Even in Canada we saw a different set of cars or options compared to the US.  Sometimes a blend, sometimes because of laws, or sometimes just because of ties we had to overseas the US didn't or vice-versa.

As an example, the history above lists optional anti-lock breaks in '94, but I can tell you my '92 and my current '93 have the option on them.  My '93 has leather seats, and sun roof, which are listed as a '94 option again in this article (although the wording they use could be interpreted as it was available before but limited).

[Lazybones]

Anyone who has driven an older 4WD with locking differential enough in the winter can probably tell you how difficult it can make turning and sometimes even slowing down in VERY icy conditions. On the other hand as a simple system it is great at getting you going and avoiding getting stuck when your wheels are on different traction surfaces. Hence why if you had an older locking system you didn't leave it engaged unless you needed it.

Traction control is probably the best compromise for normal driving, it really improves even two-wheel drive performance in terms of traction.

[Thorin]

I just happened to search for something that had a link to something else that had a link to YouTube that had the second ARB video in it's top 4 suggestions.  Can't remember what I started searching for, but it had nothing to do with cars.

Melbosa, you had air-powered locking diffs?  Those are only available as aftermarket components as far as I know.  Most locking diffs, especially back in the 90s and earlier, were simple mechanical devices.  For instance, the Eaton G80, like what is in my Suburban's rear diff.  And most locking diffs were made to engage automatically, whereas these ARB air-powered locking differentials are completely manually engaged and disengaged.

Lazy, I agree that traction control works awesome for on-road applications.  Locking diffs really aren't very useful in on-road situations except when trying to get going in a straight line (such as starting on ice at a light, or pulling a trailer with a boat on it out of the water).  Which is why I like these air lockers so much - you can control when they're engaged.  As for mixing traction control with these lockers, it's no problem; if the locker's engaged the wheels spin at the same speed, so the traction control system doesn't sense any wheel slip.

Limited-slip differentials like the Torsen system on Subarus, Audis, and Hummer H1s (real Hummers) work very well in on-road situations as well.  But once those tires are off the ground, LSD just doesn't work.  Well, unless you follow the instructions in the Hummer manual, which says to lightly apply the brake so the wheel in the air can't spin.

And that's what these videos are showing - once you're in a true offroad situation, with wheels at opposite corners off the ground, locking diffs make a huge difference.

<sigh>  Maybe someday I'll have the money to really go 4x4ing.

[Melbosa]

Melbosa, you had air-powered locking diffs?  Those are only available as aftermarket components as far as I know.  Most locking diffs, especially back in the 90s and earlier, were simple mechanical devices.

Sorry brain locked there.

Not an air compressor for the diffs... my hydraulic "compressor" for my power steering does.  Was reading about these for another reason yesterday, and meant to put in my "hydraulics" where I said compressor.  Then I wanted to say that "I wonder if the air compressors have similar issues in the cold?" but I missed that line completely.

I should have waited I guess before clicking the post button.

Good to see people still read my posts