Outer Limits 4x4 Board

Thanx champ

Brent at Trail Tough said it best:
http://php.trailtough.com/viewtopic.php?t=3
While doing transfer case gears is probably the biggest bang for the buck and a quick-fix, it is definitely a lousy way to try and create a reliable, trouble-free drivetrain. So think about this for a minute...you put on larger tires, so your pinion now becomes TWICE as hard to turn putting TWICE as much stress on the u-joints, transfer case mounts and the transfer case itself, as well as the brackets on the side of the frame that holds the transfer case in place. It leads to problem chasing such as having to use unnecessary large and heavy driveshafts, having the bolts pull out of the transfer case on the long arm side, having the mounting boss break off of the transfer case or having the short arm side bracket start to tear off of the frame rail. It is because you have given your transfer case up to 3 times as much power by putting in lower gears and now the transfer case wants to do flip-flops in its mount. Many people consider only the POWER issue of this equation as opposed to considering the STRESS LOADING situation as well. You need to change the ring and pinion gears also - relative to your tire size - which will make the driveshaft easy to turn again, taking all of the strain off of these parts - just like it was made from the factory when the smaller tires were on it. It is a mistake to do all of your gear reduction at one point. Especially that far up the mechanical chain. Do yourself a favor....reduce the ratio at the ring and pinions relative to the size tire you want to run, then select the transfer case gears that will best meet your 4-wheeling needs. By going this route, you will have a well thought out and trouble-free drivetrain, working well within the parameters of strain that the parts can and will reliably handle.

Vagabond wrote:Brent at Trail Tough said it best:
http://php.trailtough.com/viewtopic.php?t=3
While doing transfer case gears is probably the biggest bang for the buck ............................................................................ etc.

X2
Now that seems like good sense to me.
Until now couldn't think of an answer, this one will do

I chose diff gearing for purely financial reasons (1.0 litre zook diff can use LJ r&p at less than $100 each.)
4:9 diffs from 4:1 added to the 12% lower 1.o litre t-case works well enuff. (more would be nice of course)

well said vagabond.

There is merit in what Brent from TT said, but seriously, who wants to shell out the extra $ to regear their diffs after they just dropped $1k - 1.5k on transfer gears.

And as you go to shorter ratio diffs to correct for taller tyres, your pinion gets smaller & smaller. That's fine if you are running hilux diffs which will be physically larger, but on zook diffs it's a step backwards IMO.

the transfer case teeth are a lot smaller and thats why i've seen many broken in cardboard boxes and owners out of pocket 1k,and no warranty backup.

I read the Trail Tough spiel some time ago and while it does make sense,.. there is a bit of a flaw in the plan, which is that with the high range drop in the sierra transfer, this does the tyre offset.

Lets say you want to run a 33. this is 6" or just over a 20% increase. do offset this with diffs, you would need a 4.6 diff gear. Cool - that's off the shelf for a vitara.

Now, to fix low range.... the minimum you would need would be 4:1, but these days most people are going 6:1. A 6:1 In any case, you'll be looking at an 18-24% drop in high range, so now you are 20% beyond stock on the highway, which means you're revving way too high- like over 4k.

Like I said, I understand Brent's point, but to dig into both diffs and the transfer and actually loose functionality to do it doesn't make any sense.

That said, I think that beyond a 33" tyre, there is a need to do both diffs and transfer.

Steve.

PS the failures I have seen of Rockhoppers cannot be put down to tooth size. They typically appear to be quality control issues, which is why some people's seem to take masses of abuse and others fail easily.

mmmmheyy