crawl ratio

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[HEYzipupyourfly]

after build I'll be 112.1 assuming I run 42" tires.
right now I am 51.1 but witht the doubler I'll have options in between

pfft my drivetrain package is 115:1 at first gear and 62:1 second gear. i got you beat by 3 crawl points on this one john haha

[bobnoxious]

Stick shifts work well around here at 100-125:1. Automatics don't really need more than 50-75:1...especially if you can't manually select a higher gear, or have uber-brakes (they don't like to stop with lots of gear ratio).

Also depends on your engine. My Sami is at 124:1, and can use more...it has a twin cam 1.3 with a stock flywheel, so there is NO idle torque, but it revs to 7K. A good running 4.0 (and anything bigger) will stay running at idle at 100:1, and still give something resembling wheel speed when required.

Gear the transfer case for off road, and the diffs for on road.

[jps4jeep]

having wheeled with you, yes we all know your rev limiter is 7 grand... we hear it repeatedly

[Twisty]

Bob, does that number (for autos) take into account for the torque converter?  Or is the 60:1 before the torque converter slip?

[rich]

When multiplying for a auto crawl ratio it is
1st gear x t-case x axle ratio x 2 (torque converter)

[Mitch]

Some one do mine!

4.0L
AW4
NP231
4.88 gears
35" tires

[mika401]

50-75 for an auto would be without the torque converter multiplication.
I'm at 44:1 and its barely adequate.  With the 5.13's I'll be at 55:1 which would be perfect.  Got other things on the priority list for the moment

[mika401]

4.0L
AW4
NP231
4.88 gears
35" tires

2.8x2.73x4.88 = 37:1

[Mitch]

4.0L
AW4
NP231
4.88 gears
35" tires

2.8x2.73x4.88 = 37:1

Thanks for that. Can you explain, and is that good or bad?

[mika401]

Mitch it aint bad for general purpose wheeling.
If you were planning on getting into the serious rock crawling (involving body damage & potential rolls) I would go to 45:1 or higher, which would probably mean a 4:1 Rub1 T-Case giving you 56:1 which would be perfect!

[Mitch]

Thanks duuuuuude!

[Posimoto]

Mitch, that's the same crawl ratio as my stock geared flattie 37.1

[rich]

What about the torque converter ?

[jason m]

When multiplying for a auto crawl ratio it is
1st gear x t-case x axle ratio x 2 (torque converter)

Yes the T/C nearly double's your gear on gear ratio. Lock-up on the T/C is important to, if its low of a stall and locks early it wont allow much for slip, so you wont get the needed high launch from the trans or slip for crawling. If its to high then it will slip and you will be using more gas to move forward before it locks and when it does you have a higher RPM.

Thats a breif decription of how some one told me. I run a 3.06 first, a 2.73 case and 4.10 at the axle's, so my gear on gear is 36-1, add my stock 2500ish rpm T/C and it puts me around 50ish to one. Thats OK but I could be a lot better and the last thing to factor is tire size. I have 39's and its a harder strain on the 4.10's to push them.
Is it ideal , no but it works pretty good in New England were theres muddy trails. Put me in dry rocks and I'm really using that T/C and my brake's to make more crawl ratio.

Jason.

[mika401]

Figure I'd calculate my flaty for the heck of it.
7.05 x 2.0 x 4.27 = 60:1