[Gwagensteve]

Yay - finally got this posted.

So I've been thinking about Sierra gearing, and something occurred to be the other day.

My Defender has a 3.269 low range, and compared with high range (1.211) it feels really low.
We have a member in the club who runs a TJ Wrangler. It has a 2.7:1 low range and it seems to crawl quite well with 4.56 diffs and 35's. It's manual.
My Gwagen only had a 2:1 low range and it felt quite low. (4.88 diffs)
Rubicon Wranglers with a 4:1 transfer (and 4.1 diffs) are criticised for having too much reduction

How come Sierras need 4.1 or lower transfer gears?

It occurred to be that the "real" reduction (as in the step between high and low) isn't as big as it looks because high range has quite a deep reduction.

So the apparent reduction in a Sierra is as follows:

2.21 divided by 1.409 = 1.56 - so in stock Sierra, low range is only 1.56 times lower than high range.
4.1 divided by 1.58 = 2.59 - so with 4:1 transfer gears, the apparent low range is 2.59 times lower than high.
Even 6.5's are effectively 3.9:1

So my defender with 3.27:1 low range and 1.2 high, has 2.72:1 apparent low range, lower than a Sierra with 4:1 gears.

Kind of interesting I reckon.

[Gwagensteve]

Bump - was finally able to get this up.

[VitNick]

Different way of thinking, and actually makes sense. Similar with my motorbike, 4th is nice an usable, but anything less than 100km'h 5th is a dog. And going from 5th to 4th is like smashing the car into low range at speed. The actual difference is a fair bit between the two, and the rest of the gears are super close together. But those two gears feel so massively different .

Also starting to worry me with the gears about to go in the Vit, going from 1.8 (or there about's from memory) to 4:1 is going from almost no apparent low range to nearly 3:1 apparent. Along withe 5.12's in the diffs and only 30's this could get interesting.

Always love the tech Steve, and always learn something or understand a concept better , hopefully I'll have some useful tech eventually to share

[Gwagensteve]

I can confirm that 31's and 4:1 low range in a Vitara feels really quite low - And the numbers bear that out - they would feel equivalent to a Sierra with 31's and 6.5's.

Steve.

[VitNick]

So should be even lower then with only 30's , hmm hills are going to be great (mostly grippy rock).

[Gwagensteve]

It'll be great on rock.

[pezz]

i ran 6.5 with 3.9 diffs on 30's
first gear wasnt really needed, but is was great fun, sand was a high range affair

i also ran 4.88 diffs in a tj with 33's and then 35s. that was a great setup.. both on and off road

i now run 4.9 tcase with 3.9 diffs on 33s, of road its good unless its super technical, i think the increased wheel speed due to under gearing helps me drive more things. due to momentum.
ideally i will go to 4.3 or 4.6 diffs as hiway sucks and a bit lower gearing would be nice for those super technical bits, but i think a auto and efi motor will happen first

[alien]

I often feel that my 5.14 tcase gears arent quite low enough in low range when climbing things in low range. High range though the gearing is fine... but i'd rather keep the 5.14s in favour of 6.5's given mines a DD.

[SierraDan]

Agreed. 5.14's aren't good enough.

[Marko_SJ]

alien wrote:

I often feel that my 5.14 tcase gears arent quite low enough in low range when climbing things in low range. High range though the gearing is fine... but i'd rather keep the 5.14s in favour of 6.5's given mines a DD.

I guess you have a 1.6, but my 1.3 loves 6.5s on 30s and they are fine for dailying.

Unless you are worried about the reliability of the gears themselves?

[alien]

Yeah i think the motor makes the difference.. I had a 1.6 before going to 31s so never got to see a difference the motor made on the gearing as such.

the 5.14s are brilliant on the road, just offroad now and then i'd like to have another 1 gear lower so i don't have to ride the clutch, but its not often enough that i want to change ratios.

[MrRocky]

My lwb on 31"s with 4.1 diffs and 6:5's absolutly sucked balls on hwy 3rd gear into a wind and thats been 2-3 in that state ive had.
Also had 1.6 8v with 3.7 diffs and 6:5s on 33"s that was down to 80 on the hwy into the breeze.

Gearing can only multiply the torque so much before you actually need some ponies

[MrRocky]

Iam currently running 5:14's for the first time and they are very nice onroad but i find the 6:5's better in every possible scenario for me offroad in sand/rock and mud

[whincup]

MrRocky wrote:

My lwb on 31"s with 4.1 diffs and 6:5's absolutly sucked balls on hwy 3rd gear into a wind and thats been 2-3 in that state ive had.

wow. i've had it lucky. mine held 100 on flat ground fairly easy, 80 in 4th into a strong headwind... 4.1 diffs & 4.16 transfer on 31s. i had a good aftermarket carby though.

[SierraDan]

I've had:
4.16 and 3.7
4.16 and 3.9
5.14 and 3.9
6.5 and 3.7
All on 31's twin locked with a 1.3 carb, 6.5's has been the best out of the lot but sand was better on 5.14's.

[MrRocky]

I found with 6:5's in sand i can hold 5th low up anything and gets me virtually anywhere but the bloody 5:14's got me reaching right where i dont want to be.
Quick changes with reductions always seems to end badly i much prefer to pick a gear and stick with it

[SierraDan]

I had the 3.9's. Might have brought them into a sweeter spot?