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What Do You Consider To Be A Respectable Crawl Ratio?

you know we could argue this and I don't know what to say. I've heard of a mog with something like 1000:1 crawl ratio. The things we look at and say you need wheelspin for, he didn't. He could just go to a "waterfall"(I'm sure many of you understand I mean a stream like area not a shear 90 plus degree waterfall), and crawl right up what everyone else had no chance of getting traction on and had to winch or try and momentum up.
 
Unimogs have 1000:1 in first but they have like 9,000 gears so you can just keep shifting if you need wheel spin. /forums/images/graemlins/thumb.gif
 
IIRC, the lowest gears you can get in a Mog with a crawler box added on is 39x:1 and its a 7 speed trans with no high/low in the tcase, so ultimately its about the same number of speeds as a 465 equipped truck (4 speeds in the trans X 2 in the tcase = 8 speeds).
 
22.40784 and 36" Swampers /forums/images/graemlins/peace.gif /forums/images/graemlins/peace.gif /forums/images/graemlins/peace.gif

350/205/4.56
 
For all you automatic guys, you have to add in the torque converter. Most TC have a ratio of 2:1, but if you are lucky enough to have a dual stator, like some of the 4L80E came with, you can factor in 3.5:1.
 
x 2 for the converter eh

autos with 2.73 gears in the dif sure dont launch like a 4 speed car with 5.13s
the x2 number seems a bit far fetched but if the 'rule of thumb' makes a difference to an auto guy bench racing it is fine by me

seems odd to get all exited about a crawl ratio number that does not incorperate the biggest gear, the tire
 
you realize once a torque converter stalls up, or locks that 2:1 is gone don't you? Its basically before stall that the slippage occurs. On a launch in a race car you stall up the torque converter and get rid of that slippage before you ever launch.
 
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you realize once a torque converter stalls up, or locks that 2:1 is gone don't you? Its basically before stall that the slippage occurs. On a launch in a race car you stall up the torque converter and get rid of that slippage before you ever launch.

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Don't waste your time, they'll never understand.

In theory both a torque converter and a clutch provide indefinite ratios if you want to be technical. You can be sitting there in gear, not moving at all with an auto. Does that mean your crawl ratio at that moment is infinity:1? You're not moving forward, but you're in gear....

With my 4 speed, I can not only vary the speed at which my transmission engages, but the torque that is transferred by slipping the clutch. I look at this as a major advantage to a manual.

The reason the auto guys want to factor in an additional 2:1 is that extreme slow speed stuff WILL take place before they ever get to the torque converter stall speed if it is a stock torque converter. Thats why autos have overheating issues on the rocks if not cooled sufficiently.
 
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A big factor that trusty brings to light is engine torque, his diesel has plenty of low end torque and can idle pretty slow and stay running so it's easy to get by with a bit higher crawl ratio.

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The diesel is a near perfect crawler motor IMO...just not as glamorous as a BBC or healthy SBC. I think if I still had my 350 I'd be looking for deeper gearing in the rocks, but with the 6.2 it'll either crawl or spin the tires slowly looking for traction at idle. Most of the more technical stuff I did in Moab I did with both my feet flat on the floor...all I did was steer.

Nobody has brought up compression braking yet.

MJ, I have often thought of how to fairly compare crawl ratio's including tire size as a factor. I think Stephen came up with a comparo that seemed good. Crawl should be close to tire circumference for good performance. 39" tire = 122.5" circumference...122.5:1 crawl with 39" tires works good /forums/images/graemlins/grin.gif)

I just do the math and figure out how fast the truck will travel at idle. I can pull my truck down to just under 1 mph (504 rpm)

Rene
 
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With my 4 speed, I can not only vary the speed at which my transmission engages, but the torque that is transferred by slipping the clutch. I look at this as a major advantage to a manual.

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I agree. that is the entire reason I went with the 4-speed instead of another slush-box. Most people think of a clutch as an on/off device. IT IS NOT. I MUCH prefer a 4-speed in snow and ice situations for the mere fact that you CAN limit the amount of power going to the wheels without bogging the engine. A clutch really is a variable-torque transfer device when used correctly, although doing this to the extreme will limit the life of the clutch. It just takes a little more skill and concentration to wheel with than a slush box. The entire standard vs auto tranny topic is a beaten horse so I will not sit here and say that an auto isn't just as capable, if not more, than a standard. In truck that either tow or wheel, I like manuals. In my go-fast truck, I like autos...

/forums/images/graemlins/usaflag.gif /forums/images/graemlins/usaflag.gif /forums/images/graemlins/usaflag.gif
 
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x 2 for the converter eh

autos with 2.73 gears in the dif sure dont launch like a 4 speed car with 5.13s
the x2 number seems a bit far fetched but if the 'rule of thumb' makes a difference to an auto guy bench racing it is fine by me

seems odd to get all exited about a crawl ratio number that does not incorperate the biggest gear, the tire

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That's not a very good comparison......you would need to compare a 4-speed car with 5.13's to an auto car with 5.13's. In general, the 1st gear of an automatic is a lot higher than the first gear of a manual, so the torque converter multiplication if just making up for the overall 1st gear ratio and not other factors like the axle gears.

Back to the original question, the "best" crawl ratio just depends on the terrain you are driving. In the midwest to east coast region you really don't need a super-low crawl ratio since most of the difficult obstacles require wheelspin.

I currently am running an auto and 34:1 with 38" tires. There has been maybe one or two times in 5 years of trailriding where a lower gear would have been "nice to have", but not really required. Of course I also am running a diesel which should help out. I am planning on eventually swapping the 4.10 axle gears for 5.13's which will net almost 43:1 CR which should be more than enough for anything around here. I have some friends running TH400's and 205's and even with 4.88 axle gears (24:1 CR) they could really use a lower gear.

I also regularly wheel with Jeep guys that have Atlas t-cases or 4:1 kits. Honestly these vehicles don't wheel any better than normal low range vehicles that are otherwise similarly equipped....at least on the trails around here. If you went out west to hardcore rocks trails than I'm sure it would make a difference.

In my opinion, a lot of people who either have super low ranges, or say you have to have it to wheel, really don't need it......
 
wow, very interetsing post!

my 1st gear crawl is 50:1 or 2.4" to 1 (1.5mph @650rpm)
my 2nd gear crawl is 31:1 or 3.8" to 1 (2.4mph @650rpm)

i wheel in second. i wheeled all of land between the lakes in 2nd. i pull stuck people out in second.... i have never done rocks, and i do all this at idle. a diesel makes alot more torque at 650rpm than a gasser, my peak torque is at 1400rpm (some say 1600)

what RPM and gear do you guys run with the 4 to 1 kits???? 1500rpm with 4:1 low, 5.13 r&p, 6.4 first and 38's puts you almost at the same SPEED as me at idle in first. is 1500 considered too high a rpm?
 
To answer someone's question from above, I'm pretty happy with my 62:1 crawl with the 42's. I have good control, the tranny stays cool, I have good compression braking and reasonable throttle response in low. Overall it's useful and durable.

A lot of this comes down to technique, working the clutch properly is essential to wheeling a manual trans no matter what gears you have, though I know with really low gears, the clutch becomes more on/off than variable just because you don't need to slip it to control speed.
With an auto, I see a lot of people driving with one foot and making it look way harder than it should be. Keeping the motion smooth requires some brake pressure so working the gas and brake together is key. This is also a way to make a higher geared truck look like it's geared lower. At TTC, the stall speed in the converter was a bit high so I was on the brakes the whole time to keep the speed down and keep the motion smooth. I mention this because some of you have seen the video and can correlate what I'm talking about with what it looked like.
With a bit tighter torque converter I don't ride the brake as much, this is just an example of another variable.

I have been on the trail with a truck with a 465/205/4.56 combo with 35's and it wasn't enough for big boulders. We were in 21 Road and there were several times that he was against a big rock and just couldn't get on the rock with any kind of control.

Check the link to the crawl ratio post someone else posted, a lot of this has been covered and there's some good info in there on converting your crawl ratio to inches traveled per revolution of the motor. I still think this is a useful comparison number.
 
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<font color="red"> Don't waste your time, they'll never understand. </font>

In theory both a torque converter and a clutch provide indefinite ratios if you want to be technical. You can be sitting there in gear, not moving at all with an auto. Does that mean your crawl ratio at that moment is infinity:1? You're not moving forward, but you're in gear....

With my 4 speed, I can not only vary the speed at which my transmission engages, but the torque that is transferred by slipping the clutch. I look at this as a major advantage to a manual.

The reason the auto guys want to factor in an additional 2:1 is that extreme slow speed stuff WILL take place before they ever get to the torque converter stall speed if it is a stock torque converter. Thats why autos have overheating issues on the rocks if not cooled sufficiently.

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Man your right, we auto guys are just to stupid to get it.
mad34.gif
I sure wish I had your insight.
Here is where I am at if you dont figure in the converter:
700r4 @ 3.06
KluneV @ 2.8
Atlass @ 3.8
RearDiff @ 5.13
This equals a 167.02 : 01

OK, now if you figure the converter in it is what , 334:01
Either way it is NASTY LOW. Either way it goes, just ask BALOO when I CRAWLED his ledge in Katemcy. Everyone else has to POWER up it I just crawl it. Very rarely do I have to power up anything.

I crawl legdes that others just either roll over on, or just pound on. The lines I tend to take are what you would call , uhhhhhh, strange, and my crawl ration is what gets my 6500lb rig up and over. It gives ultimate control and lets me take a thining mans line. I can come up to a vertical wall and damn near idle up it.

The comment was also made that without the doubler the auto sucks, well again I say what a tidbit of mental genious. I can't figure out how I ever wheeled before without my Klune. (doubler) It is all in how you wheel, where you wheel. A standard may be better for you, but not for all.
 
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That's not a very good comparison......you would need to compare a 4-speed car with 5.13's to an auto car with 5.13's. In general, the 1st gear of an automatic is a lot higher than the first gear of a manual, so the torque converter multiplication if just making up for the overall 1st gear ratio and not other factors like the axle gears.
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drag 4 speeds are pretty close to the first gear ratio of racing automatics, stick ~3:1, auto ~2.80
but the auto gets a super loose convertor

years ago I was trying to get my truck to float on the top of some deep snow
at idle I got it to crawl along for quite a ways
as soon as I touched the throttle or hit a drift that spun the tires it was like falling into a 3" hole
this is the application that Benies 4x4 shop in Iceland started making 203 based doublers for
 
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A standard may be better for you, but not for all.

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To be honest, I don't really think the 4 speed is, "Better" for me. Sometimes it is. Sometimes it's not. It's just one of the tradeoffs we make.

As I've said before, I'm not anti-automatic. If I could afford a doubler I honstly cannot tell you if I'd cross to the dark side. I probably would, although a doubler with a 4 speed would rock.

One of the biggest reasons I have a 465 is that it offers nearly twice as much low range as my 700R4/NP 208 did. I didn't really feel that the torque converter offered this 2:1 you guys speak of, either.

300:1, no matter what you've got (auto or manual) is crazy. I imagine that if you're into severe low speed stuff, that woudl be really cool.

Another thing most of us need to realize is that all these crawler boxes are really going to tax our axles. DBlazer has managed to break a 14 bolt axle shaft!!

I'll admit it. I've thought about going back to an auto a lot of times. I don't think I'll ever do it, but I've definitely thought about it.
 
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