> Switching to a 1 ton helical transfer case (I'm not sure on the low but
3.15
> to 1 comes to mind) or the suffix A (2.88 to 1) are I believe the only
> options at this time in North america.
First off let me say that I have the suffix 'B' gears in the shop but
haven't finished installing them yet. So when I get around to it there
should be a noticeable difference off road. I was thinking about something
lower though. For Toyota's you can get as much as 4.7:1 in a single t-case,
the new J++p is 4:1, even the early Broncos now have 4.89:1 for the D20!
How come nobody has gotten to work on the LR?!?!
As for the 1 ton helical box, I would need to run seriously large tires
to make that work on the road which would negate any difference off road.
3.27:1 is great in low range but there's more to it than that. What a
person really wants is the proper 'spread' of ratios. The LR boxes are all
kind of screwy because none of them have a 1:1 high range. What would
really be more useful in many cases is a ratio of the high to low ranges.
For example:
Helical 3.27/1.53 = 2.14
Suffix A-B 2.88/1.148 = 2.51
Suffix C-on 2.35/1.148 = 2.05
LT230 3.32/1.113 = 2.98
We already know how fast we want to go on the road so that's somewhat
fixed, so the difference between high and low has to be greater. The
obvious choice of LR boxes mathematically is the Suffix C/LT230. The R380
would be nice for the highway gearing, but a Series box has a slightly
better first gear.
Now comes the debate about how low is too low. What's the answer?
There isn't one definitive solution. If you wanted to restart an accent on
a steep and muddy slope there are some agricultural Unimogs that are
unmatched at around 500:1. For most uses though it's so slow you can't tell
if you are moving or not. Other times it's not good enough because the
traction simply isn't there. In low range now I never use 4th and hardly
ever 3rd, because I might as well be in high. Logically there seems to be a
good argument to say the best arrangement would be to have the low range low
enough to be a continuation (numerically) down from 1st in high range, i.e.
when 1st high isn't low enough the next step is 4th low. Having the early
t-case and later transmission is closer but still not there. Since 1st high
is about 16:1, I think 4th low should be about 20:1, 3rd 30:1, 2nd 45:1 and
finally 68:1.
There have been many, many more knowledgeable off-roaders than I who
have sort of picked 80:1 as the magic number. Much lower than that and it's
useless in all but the most extreme cases. But to get this all to work out
(assuming SIII gearbox and 4.7 R&P) I would need a low range of about 4.25.
The other option is simply to use a granny gear transmission. Boom, low
gearing without changing the t-case. These gearboxes make me wonder how
much I really need that nice, tightly and evenly spaced gearing I'm used to.
Oh, heck, why not dream of the granny NV4500 with the LT230?
100:1 off road and 100 kph at a mere 2688 RPM!!! (Theoretically)
Sorry about the really long, disorganized post. I was just sort of
daydreaming and happened to write it down instead of letting it float away.
For those that slogged through the whole thing and got nothing out of it,
sorry. If I had the inclination to rewrite the whole message it would be
much more clear and logical... but I don't. ;-)
Kirk
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