So I've searched and searched various posts. I also have a pretty good article from JP Mag that discusses the various options for crawl ratios considering your motor. The magazine article mentions that a crawl ratio lower than 100:1 with a V-8 can result in "easily shattered axles when a tires get bound up."
What you are guys running with manual trannies? I'm putting together a 350-400HP motor and wondering if I should stay at 68:1 (I'll save $$$$$) or go with a TeraLow kit and 102:1. I don't enter competitions. My previous ratio SUCKED at 22:1 (stock 74 CJ5). WOW! Your thoughts?

Unless you're doing lots of rocks, your ratio will be fine. I'm at 95:1 and it works ok.

well, a ratio in about the 80:1 would good I would think... could be easily achieved... just depends on what tranny you're going to run and what axle ratio... and also what t-case...


like for me, if i went with an sm465, np231, and 4.56s, that would put me at 80:1... if i had d60s and 5.13s, it would be up around 95:1... and if i 4:1, it would be like 113:1... just depends on waht you're doing and what you have to work with...

as low as you can get it!!!

i had a similar crawl ratio (21:1) it sucked. I basically pointed the jeep where I wanted to go, then crashed into something, then repeated the process. Right now my jeep almost has a sm420 and a dana 300 and 4.10s. It'll be at 75:1 when I'm done and I'm beginning to think I'll want it a little lower. I drove a friends who has a sm420, dana 20 and 4.10s (57:1) and it still felt like it was going at least twice as fast as I'd want it on rocks. Someday when I'm out of school I'll probably put a 4:1 kit in the transfercase. that should be very nice off road.

why are you putting together a motor with that much horsepower for rockcrawling? you'll break stuff even with a stock drivetrain with that thing.

200hp junkyard v8 with propane or tbi is all you need.

I hear that, really no need for that crazy HP. However, I'm a wild engineer and love HP and torque applications. Done too much drag racing in my life, I guess. My AMC 304 would do just fine. But I've got my 351, 393 stroker kit, and EFI setup so why not? I'll try to keep calm. Just don't get behind me when its wet.
My setup?

NP435, Dana 300, 3.73's for decent highway driving.
Runs at 65:1. I can upgrade to 4:1 TeraLow and get 102:1. Question is, should I? Maybe the smart move is to stay with stock LO @ 2.62 and then see. Those kits aren't cheap.

Your input is helping!!!!! I haven't driven anything beyond 50:1. CJ5-man, you are right. That stock ratio forces you to keep the speed. And at the time, only a rear posi made matters worse.

I'll agree with as low as you can go. Right now I'm at 54:1. Once I install my Toybox I'll be at 253:1 in T-case Low and 127:1 in T-case High. I might not use it all of the time but it's nice to know I've got when i need it, but who cares what I think.

Good luck,

HCC

I am at 349:1, and never go lower than 248:1. It all depends on your driving style and what exactly you plan on driving on with it. I used to have a cruiser , SM420, Chevy 350 @ 59:1, it was not low enough. Furthermore, If your low enogh you won't need to use your brake on the trail. Run Dog

132:1 with a built motor and 42's i love it, after this season in teh snow i will decide on the 4:1 kit for the 300 or not, if i do get it i will be at 208:1 in first gear. POW! jiMMy

Im at 140:1 and I think its low enough, Most the time Im on 2nd or even 3rd gear. 90-100:1 is the minimum Id seek for on my next rig.

SM420 - Atlas II and 4.56 gears with a 350HO (400HP), D60s and no carnage yet :rolleyes:

I have 435, 203 reduction, eb d20, 4.56 gears = 150:1. This works very well with my I6. The dual transfer cases gives me lots of flexibility for different types of terrain, where I am it is not JUST rock crawling, there's a little of everything.

When I went on the gearing hunt, it seemed to me that you should have an objective, which for me was: that your engine not stall no matter how steep you are climbing. It seemed to me that principally when going for gearing what you are trying to is make sure you don't have to do the 3-pedals-only-2-feet dance. Sure, there are plenty of other reasons, but if you can satisfy the requirement of not stalling while climbing, you will in all likelyhood meet your other objectives also. So in other words, you need enough gearing to not stall the engine on climbs - after that, any excess gearing is not as useful.

With my motor 150:1 accomplishes that. WIth a 4 cyl, maybe more would be needed, but with a V8 that runs well at idle, I would say you would need 80~100:1 and be good.

You have to keep in mind that there will be plenty of times when you need wheelspeed. Of course you can always shift up to get it, but when you run a single transfer case with really steep gears, you might not be able to find just the right gear - I had to play considerably with all my shifters to find the right combination of gears that would let me get the wheel spin I sometimes need without stalling or bogging, and I found it changed (for the better) when I went to 4.56 fgrom 4.88. With my I6 that "wheel spin without bogging" is a narrow range, with a V8 it would be easier, but point is if you gear too low you might not be able to find the right gears for other situations.

If I were you, I'd run it at 68:1 for a little while. Run the trails you normally run, then decide wether you need lower gearing or not. I do think that 102:1 with your built V8 would be about right though. I have like 132:1 with a 220hp 4.3, and think its perfect.

A lower ratio may take you longer to get from the trailer to the Show-N-Shine area.

I am at about 75 to 1 with a 4 liter. This works good for me. I have only come accross one place I would like to go slower and that is in the box :flipoff2: Just cause the motor will die frequently in there. I would say with that amount of HP go with what you have now and see if you need to upgrade.
JOe

I run 210:1 with a 5-speed manual and dual transfer cases (20 forward speeds is PLENTY of choices!). There's no such thing as too low -- but there is such a thing as too few choices.... I've seen that with 4-speed granny trannies hooked straight to crawler-geared cases.

IMHO, spend the bucks on a crawler box -- don't just gear down what you have. The flexibility really pays off.b

Randii

my old heep was 102:1 with a V-8 and 38's. it was slow enough for most obastacles. if your in the rocks, lower is better. you may never use it, but its there if you ever want it. i dont like 4:1 kits, cause you dont have the option of 2:1 if you need wheelspeed. just my .02 :D

I've got a 4.0 with an AX15, AtlasII, and 4.56 axles for a 74.5:1 crawl ratio. It's not low enough for the trails I run. Somewhere around 110:1 is what I'd like.


Jes

Well, it first gear, I am at 130 to 1...way to low for normal trail usage..but nice when trying hard stuff. However, my 2nd gear puts me at 70 to 1...which is what I use for most obsticals...I usually motor down the trail in 3rd or 4th.


Drivetrain: Chevy 305 (On deathbed:( ) SM456 / 4.3 Atlas running 38's

I personally think that something around 100 to1 with a v-8 should be fine...

I run a 360/420/300/4.27s and I am 80:1 Its low enough but I want lower.

I had no problems this weekend that wasnt driver related. I think I stalled it twice all weekend and that was because I was being a dork.

Great info! Thanks. Looks like I'll stay at 62:1 then move up to 4:1 kit if I feel the need.
Are you guys breaking stuff at 100:1 with anything smaller than D60s? I'm gonna run a D44 up front with CTM and alloys. Worried about carnage.

I thik that depends on:

Tire Size
Right Foot Size

my thoughts are that the $ would be better spent on lockers.
the more torque you make the less crawl ratio you will need. also what type of wheeling do you do? tight slick trails? rock? sand? the local mall parking lot?

it all factors in....

Originally posted by T1H5_TA3
my thoughts are that the $ would be better spent on lockers.
the more torque you make the less crawl ratio you will need.

Have you ever been rock crawling? its not about torque, its about going VERY VERY SLOW!!! lockers won't do any good if your still spinning all 4 wheels, which he'll do with a 24:1 ratio.

All this talk about the crawl ratios, and it is important, but I got a question: What size tire are you running? The crawl ratio may still be 68:1, but depending on the tire size, you may want to go deeper.
Remember, the ratio that worls for a 35 may not work for a 40.

if you finished reading, it asks what kind of wheeling he does. not every person on this board is a hard core rock crawler. i agree yes, the lower the crawl ratio is the slower you are able to go. you will probably notice that super deep crawl ratios are kinda a fad, just like super flexy suspension. im not saying that ether is bad, but there is a law of diminishing returns, in otherwords, a little bit might make a huge diferance, but down the road you can make huge changes and only see a little gain.

short and sweet, crawl ratio depends on what type of wheeling you do, as well as how much power is needed to do it.

Originally posted by JeepinIan
All this talk about the crawl ratios, and it is important, but I got a question: What size tire are you running? The crawl ratio may still be 68:1, but depending on the tire size, you may want to go deeper.
Remember, the ratio that worls for a 35 may not work for a 40.

THANK YOU - I didn't have to type it....

TommyJeep's got an awesome crawl ratio calculator that will give you the numbers we're used to seeing...

But also in a different light - in Forward Movement Feet Per Second @ 750 RPM

This will show you how fast (or slow ;) ) you crawl at any given ratio AND you can change the tire size to see how it affects your rate of movement.

http://www.tommyjeep.com/apps/ratio/index.htm

Originally posted by CJ5-man

lockers won't do any good if your still spinning all 4 wheels,

:rolleyes: yha, i spun all 4 at the same time alot before i was locked up:rolleyes:

Originally posted by T1H5_TA3


:rolleyes: yha, i spun all 4 at the same time alot before i was locked up:rolleyes:

Zamboni driver? :flipoff2:

With a half a motor (if that), a normal (non-granny) five-speed, and 44's, I'm running 170:1. Works good for most stuff, a little lower might be nice, but not nice enough to where I'm interested in spending money on making it lower. With 35's, I'd be fine around 140:1, and 40's, around 155:1 would be plenty, IMHO. If I was building something competition specific (I might be doing exactly that soon) I think I'd run around 60 or 80 to 1, in first-gear low, with an automatic and 37's. Or if it was a five-speed, I'd want it around 150:1 with (as Randii noted) lots of close-ratio choices for the next upshift.

got to love being able to run 2-3 times less ratio with an auto.. but lets not get that war started again.. lol

Originally posted by T1H5_TA3


:rolleyes: yha, i spun all 4 at the same time alot before i was locked up:rolleyes:

thats not what I said. let me dumb it down a notch for you. if you lock the axles and still have a bad crawl ratio you'll just spin all 4 tires instead of the previous 2.

sure, over exageration, but it happens a lot on slick stuff like we have out here.

another vote for "as low as you can go"!!

i am goin the KLUNE-V route, that'll bring me up to 271:1
:D

I'll be running 36". 38" at the most. But I'm 95% sure about the 36" considering my front HP D44.
Yes, I've been rock crawling. It is all relative though. I haven't been out to the Moab or the West at all. However, I've done some of best stuff in Virginia and West Virginia. And my 74 stock CJ5 ratio SUCKED big time for it. Anything super steep was sketchy b/c you never knew if you'd make it up or not...a big risk for rolling with my wheelbase.
I know I don't need all that power. Just that I've built motors for drag and autocross cars for most my life. I'm actually tuning it down some. My foot can be relaxed when it needs to be.

Slam a drag motor in it and forget about the crawl ratio. With all that power and wheel speed you'll be able to "skip" across the tops of the rocks the rest of us have to crawl over. Yeah you're right, I'll shut up now.

ZZZZZZIP,

HCC

Well as kinda mentioned before Tire size Greatly changes the crawl ratio needed.
here is an example: @1000 rpm with 100:1 crawl ratio this is how fast each of the following tires would go

33"=.98125 mph
35"=1.0407 mph
37"=1.1001 mph
40"=1.1839 mph
44"=1.308 mph

I personally belive 1mph is an optimum crawl ratio...

I am at 55:1 and I am no where near low enough with a stock 5.0 HO/NP435/NP205 and 4.10s I got a buddie who's got 400 hp and the same crawl ratio and to me i seem to crawl better cuz his torque don't kick in until over 1k so he's got wheel spin when I don't and if you got a hefty cam in there you will need a higher crawl ratio.

i am going with 146:1 with dual marlins. 2.8 auto trans first gear, 4.7 and 2.28 in the cases, and 4.88 r&p. i can leave the 2.28 case in high or run a different tranny gear to get anything less than full crawl. this is with 210HP 3.4L.

Originally posted by randii
I run 210:1 with a 5-speed manual and dual transfer cases (20 forward speeds is PLENTY of choices!). There's no such thing as too low -- but there is such a thing as too few choices.... I've seen that with 4-speed granny trannies hooked straight to crawler-geared cases.

IMHO, spend the bucks on a crawler box -- don't just gear down what you have. The flexibility really pays off.b

Randii
Very true. I went from 44:1 to 190:1 with dual cases, and a 4.0 gearset in the rear case. The gear choices are great! Granted I only have a 120 HP 4 cyl. so it's a differant ball game for us folks IMO Do I need that much gearing? Probably not. Is it nice to have there? Hell yes! Would I run dual stock cases instead? NOPE! I run with just the the rear case (85:1) most often, but it's nice to have the options there.