|
[Home]
[General]
[Jeep]
[Land Rover]
[Reports]
[Webrings]
Why
Goody Box
Etiquette
Auto vs. Man
| |
General Odds-n-Ends
Background and why/how I started.
Tips and Tricks
- Goody Box - everyone who ventures off the pavement should have a 'Goody Box'
with stuff in it. This is my version.
- Trail Etiquette - some basic thoughts to
think about before taking your 4x4 out and thrashing it.
- Auto vs. Manual debate - some thoughts
and opinions I've collected. There is no right answer.
Some Gearing charts based
on what I had (jeep w/ AX15/NP231), what I have now (landie w/ R380/LT230).
| Crawl and final drive ratios with different
axle ratios |
|
| |
Axle |
1st |
5th |
Low |
High |
Final |
Crawl |
|
| Jeep |
3.55 |
3.83 |
0.79 |
2.72 |
1.00 |
2.8:1 |
37:1 |
|
| Jeep |
4.56 |
3.83 |
0.79 |
2.72 |
1.00 |
3.6:1 |
48:1 |
Had |
| Rover |
3.54 |
3.32 |
0.73 |
3.32 |
1.2 |
3.1:1 |
39:1 |
|
| Rover |
4.10 |
3.32 |
0.73 |
3.32 |
1.2 |
3.6:1 |
45:1 |
Got |
| Rover |
4.70 |
3.32 |
0.73 |
3.32 |
1.2 |
4.1:1 |
52:1 |
|
Some info calculated based on info from BFGoodrichTires website.
| BFG Size |
Rev/Mile |
Radius |
Diameter |
| 33x10.50 |
634 |
15.90 |
31.80 |
| 35x12.50 |
598 |
16.86 |
33.71 |
| 265x75 |
652 |
15.46 |
30.92 |
| 285x75 |
628 |
16.05 |
32.10 |
| 305x70 |
628 |
16.05 |
32.10 |
| 315x75 |
598 |
16.86 |
33.71 |
Doing the tire/gear calculation thing.
2piR in/rev * 60 min/hr
MPH = RPM * --------------------------
FinalDrive * 5280*12 in/mi
or
Rolling Radius
MPH = RPM * -------------------
FinalDrive * 168.07
Getting Rolling radius.
- Measure it
- Estimate given Outside Diameter (rolling radius will be smaller)
- Given tire revolutions/mile, getting the rolling radius:
63360 in/mile
rolling radius in = ---------------
X rev/mi * 2pi
Ex BFG 285/75R16 given as 628 rev/mi.
Rolling Radius = 63360 / 2 / 3.1415 / 628 => 16.05"
To get final drive ratio (or crawl ratio) multiply out gearing in gearbox * transfer case * diff ratio.
|