Outer Limits 4x4 Board

Firstly I have no idea how to use a gear calculator so any help will be appreciated.
I want to pit a vitara 3spd auto in my Sierra, but if I remember correctly with my current gearing the engine rpm at 100 klmh would be around 4100 which I felt was a bit high

I run g16a (carby motor)
3.9 diff gears
31" tyres
and 4.16 transfer gears

My question is if I run 3.7 diffs what will my rpm at 100klmh be and how will it affect my crawl ratio?

Cheers

I get 4072rpm @ 100 for your setup (if your tyres are exactly 31" - unlikely) so your calculations are correct.

With 3.7 diff gears you'll run 3863rpm @ 100.

Crawl ratio will be 39:1 with 3.7's in the diffs, 41.2:1 with 3.9's.

Steve.

I get 4072rpm @ 100 for your setup (if your tyres are exactly 31" - unlikely) so your calculations are correct.

With 3.7 diff gears you'll run 3863rpm @ 100.

Crawl ratio will be 39:1 with 3.7's in the diffs, 41.2:1 with 3.9's.

We have a car in the club with exactly that setup (3.7 diffs, 4:1 case, G16A) and the owner runs 7.50 16's on road and 35" Krawlers off road. It's a little tall geared on the Krawlers off road but the gearing is perfect on road with them.

Steve.

That doesn't seem to bad and being auto it should
slip some what am I correct?
I don't do alot of highway driving but when I do I'd like it to be somewhat sustainable as I sometimes travel for up to 2 hours

Cheers

That doesn't seem to bad and being auto it should
slip some what am I correct?
I don't do alot of highway driving but when I do I'd like it to be somewhat sustainable as I sometimes travel for up to 2 hours

Cheers

whats my crawl??
6.5s transfer
4.88 diff
37" tyre
3 speed auto

thanks

11_evl wrote:whats my crawl??
6.5s transfer
4.88 diff
37" tyre
3 speed auto

thanks

1st gear=2.4
transfer=6.5
diff=4.88
crawl ratio=76.12