[badonkadonk]

[christover1]

diff ratio check rear;
with one wheel off ground.
spin tail shaft by hand till tyre does one rotation,
count tailshaft rotations. (chalk marks can help)
eg 4 turns of t shaft for 1 tyre rotation = 4:1
More than one tyre rotation gives more accuracy.
repeat for front if you suspect a diffrent ratio
Stock WT is 3:7

t-case ratio check
In high or low gear, whichever you testing
with free wheels un locked,
spin jack shaft and count turns of tail shaft

[christover1]

Sounds like you have a 1.o transfer case fitted

[Gwagensteve]

Nope, 5.12's in the diffs. Transfer is standard.

I've just played with my gearing calculator and with 31.5" tyres (a fair guess for 7.50's) stock WT transfer and 5.12 diffs I get 3969rpm at 100 km/h

I can't get close to that figure with any other gearing combination.

Crawl ratio based on that is 41:1. As you have noticed, that's not really enough for comfortable control.

Here's the problem though. Upgrade your transfer gearing, and regardless of the ratio you choose, your highway revs go up to at least 4360rpm @ 100km/h, due to the greater high range reduction of reduction transfer gears. This is normally a good thing, but it's not helpful when you already have 5.12's.

Really, the ideal setup for you would be maybe 4.1 diffs and 4.9 transfer gears - that gives the same cruise RPM you have now but 74:1 low range. That's a difficult to find option though (4.1's are rare, or if you get Jimny gears, made of cheese.)

The next best option are stock WT (3.7) or stock NT(3.9) diff gears and 6.4 transfer gears. with 3.9's, cruise revs drop to stock - 3550 rpm, but crawl ratio goes to 92:1.

Next best would be Vitara 3 speed auto diff gears - 4.6, and 4.1 transfer gears. These take road revs to 3900, hight than is ideal - and crawl ratio is 68:1

I don't have any other workable options, and I can't see a solution that can keep your highway revs and use your 5.12's unless you go up to giant tyres. (34"+)

Steve.

[badonkadonk]

Mexicans helping Mexicans- thanks lads!

Steve, going by the calculators available online, 5.12 was the nearest I had also come up with based on the tyres, rpms & a relatively educated guess at the transfer gears however I was hesitant to take it as gospel as it didn't make a lot of sense to me as to why it was a standard case yet running 5.12s in the diffs. As you're aware it was an unfinished project car when it came into my possession so retrospectively it makes some sense I suppose given the track bar mounts on the diff etc.

As you've pointed out the big problem is going to be finding a sensible solution that allows me to retain its highway rpms whilst gaining a functional gear reduction at the t'case when she's offroad. Much for me to consider now. Rather than mash my brain over it at the moment I think I might leave it till we're chewing the fat. As mentioned back at the last Vic Zook meeting 6.4s & 3.9s were what I was hoping to run given the setup's versatility, however since you confirming that 5.12s were the likely diff ratios it throws a a bit of a spanner in my crown wheel as it means a swap out at both the diffs & t'case, & be damned if I'm going to run 34s! Shit-damn-fuck!

Franks & beans for the help!

[shakes]

36's and gears - you know you wanna.

What price do 5.12's sell for vs 3.9's? be someone somewhere that will do a swap.

Yell out if you need a hand. Have tools, will travel.

[dono1]

I have a pair of 3.9's I would swap but its just a tad too far away!

[badonkadonk]

shakes wrote:

36's and gears - you know you wanna.

What price do 5.12's sell for vs 3.9's? be someone somewhere that will do a swap.

Yell out if you need a hand. Have tools, will travel.

Bwahaha, thanks Sim. An extra set of hands might come in handy! You can roll around the corner & I'll keep you fed & beered.