[Zook_Fan]

I know there are a million and one different threads about gearing but most of them are of the "if I fit 31's and 6.5's is my car going to be awesome" persuasion, this one is not that.

Looking forward to a new (kinda) Sierra project and trying to organise parts for when I have the time to get it done early next year. Basically I'm not 100% sure on the gearing combination to go with. I have ran the following combinations:

4.16 transfer, 3.7 diffs and 31" tyres. Okay in sand, not much good for anything else.
6.5 transfer, 3.9 diffs and 29" tyres. Great in rock, too low to be practical for anything else
6.5 transfer, 3.9 diffs and 31" tyres. Still good on rock, little bit better for general use. Didn't really like high range and still felt 1st low was far too low for my liking.

So moving forward to this build I will be running a Vit floater in the rear, have ordered the axles from Dean and trying to source the laser cut bits from Gwagensteve. I have two full sets of 4.3 diff gears so I plan to run these in the diffs. The tyre size will range, I'd like to run 33's as the social offroad tyre, 35's as the competition offroad tyre and maybe the occasional 31's if I'm trying to blend in a bit better around town. Obviously it will be a compromise to run any of these if it's geared okay for the others aswell.

I've attached a spreadsheet that shows all the gearing combinations available with aftermarket sierra transfer gears and common vitara ratio's (4.3, 4.6 and 5.12). I don't want to be geared too deeply, I didn't like the 6.5/31 combo and don't want to go down to that again so it is in red at the top of the table. Blue at the very top is stock. Green is 4.16, Orange 4.9 and Purple for 6.5.

For now the car is running a G16a with Sierra 5 speed box. I'd love to go to a G16b and AW4 so will temporarily compromise gearing if something suits the later combination better than the current set up.

So the question is, what is the ideal crawl ratio and revs at 100kph for each size tyre? Which transfer gears would you be better? I am leaning towards 4.9's but the 4237rpm at 100kph seems excessive in 5th for 31's. The 4.16's also seem close 4092rpm at 100kph for 31's and 3624rpm at 100kph for 35's which looks to be a good split.

[Gwagensteve]

Sorry about the floater stuff- I do have some. Look for a pm soon.

[Zook_Fan]

You're right Steve, like I said I'm only gathering stuff for early next year so there is no rush.

[pezz]

4.9 with 4.3 is my plan for 33s

[neofitou]

If you put the gear ratios for the AW4 into your spreadsheet, it works much betterer.
1st 2nd 3rd 4th 5th
2.800 1.530 1.000 0.750 0.750

[Gwagensteve]

I thought aw-4's had an ever wider spread than that- 2.95 to 0.73 or 0.69

That overdrive is super tall- only way to make short diff gears work IMHO.

Steve.

[neofitou]

It might be different for Vitaras. that's the wikipedia entry for jeeps aw4

principal is the same though, tall 4th is good.

[Zook_Fan]

Which transfer gearing works better neo? 4.9's as Pezz is going for?

I do much like the sound of the aw-4 over drive being so high. That would make for a much better in low but that puts revs at 100kph stupidly low for all but 6.5 and 5.12's which I now realise is why you guys run that combo.

It is an auto though so going through gears on road with 4.9's would be managable for a while before another gearing swap is done. Obviously the more expensive option.

[jdk81]

I've looked at this a lot, and always reassessing.

I really disliked deep xfer gears with the manual
3.7 diffs, 7.2 xfer.
Gears most often used, Low 2nd with 33s, low 3rd-2nd with 31s.
Besides dicking around climbing shit in low 1st for the sake of it, it was annoying having so few usable gears.
Low 4th and 5th whined like crazy.
low 1st was 98:1, low 2nd 52:1, low 3rd 38:1
Even descents low 1st was a little too low, and if you needed throttle input to correct the line, it didnt do very much.
Low 2nd was preferred on greasy/pebbly descents where I could quickly tap/pulse the brakes to slow down, and open up the throttle to change lines etc easily.

What im building currently, so much theoretical love for the aw4
4.16, with 4.875 diffs and aw4
with torque conv slip is 126:1
Without torque conv 57.3
High range 3500rpm at 100km/h with 33s, 3300ish at 100km/h with 35s.
g16b (baleno and vits with aw4) are around 3100 rpm at 100km/h


I dont like the idea of the auto driving through the brakes in low range.
Relying on torque converter when needed seems like a good compromise to me.
The aw4 offers so much versatility.
The downside is weight and heat management.