[JuniorJoel]

Hey guys,

I know this is proberly anoying. I did search but couldnt find what i wanted. Simply I have a 2000 Jimny that i have 30's and a sierra transfer case and ORA conversion kit already in. I am wanting gears as i need lower for the rock crawling driving i do.

Would

-4.16:1
or
-4.9:1
or
-5.14:1

be better?

I plan on running no bigger tires but am tired of riding the clutch and want to finally do my gearing once and for all as the clutch can no longer handle my driving terrain.

Thanks,
Joel

[tanshi]

how much bigger tyres are you planning on running.

im assuming manual vs auto?

[JuniorJoel]

no bigger tires. Just 30's. And yeah the car is a manual.

[tanshi]

4.1s will give you a 71:1 crawl ratio which will be plenty. you'll be able to use 1st 2nd and possibly 3rd in different off road situations. top speed in first low of about 25km/h

unfortunalty this will give you 4290 rpm at 100km/h in 5th gear. it will be ok but lots of people dont like driving around like that

[JuniorJoel]

when you say 4.1's do you mean the 4.9's or the 4.16's? also you seem to have the maths down so if i were to go 4.9's instead of 4.1's do you know what my revs would be at 100kmph

[tanshi]

4.1s = 4.16

with 4.9s your gonna have 4400 at 100 in 5th

[tanshi]

this is based around you having 3.9 diffs which i think is accurate. if you have the 4.09 diffs then obviously its going to be lower geared again.

[Bruce]

tanshi wrote:

top speed in first low of about 25km/h

Gee I would not even get close to 25km/h in 5th

[tanshi]

in 4th brucie you should be doing 4000 at 25kmh

[Bruce]

Ya think? Not to worry. Have to try it next time we are camping.

[JuniorJoel]

So if i use the 4.9's i will have to get used to the highway revs but its probably worth it for the extra low range. 115% as opose to the 84% from the 4.1's

[tanshi]

no, in my opinion its not worth it.

115 : 1 on 30s will be pointlessly low.

if i was building it i would go for the 4.16:1 gears

[JuniorJoel]

Oh okay, so you think that it would be too low to be usable? dont mind me being blunt but how come? i have never driven a geared car so mind my ignorance haha

[tanshi]

gearing that low in first will end up in wheel spin and stuff all else.

i have 113:1 in my lj50 but im running 33s and alot of the time i find 1st is too low to be useful.

around 70-80 to 1 will be heaps

[JuniorJoel]

Cool. thanks for your help Tanshi

[sideways]

Tanshi, I'm pretty sure you're calculating for a VVT ratio gear box and 3.909s, this would have the Sierra ratio box and (I think) 4.1s?

3800rpm @ 100km/h with 30s, 4.11 diffs and 4.16s. 62.44:1 crawl.

3900 @ 100 with 4.9s, 73.082 crawl.

4000 @ 100 with 5.14s, 77.150 crawl.

For comparison, assuming you've got a 1.3l transfer, right now you'll be doing 3380 at 100 with a 34.042 crawl. A 1l case would have the same high range as the 4.16s with a 37.689 crawl.

Stock tyres and gearing is 3650 @ 100 and 32.169 crawl.

[tanshi]

fair enough, i just used the ratios i could find.

was pretty sure the diffs were 3.9s

if you wanna be spoon fed
some times you wont like whats on the spoon

[JuniorJoel]

So does that mean I could theoretically run 5.14's? I'm just trying to work out what gears I should be buying as I have never had the opportunity to drive a geared jimny or sierra and don't wan to waste my money basically. Thanks all for your help.

[madmacca]

http://www.grimmjeeper.com/gears.html

play with this gear calculator , the drop down options have some zook bits (g,box and transfers )