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post #1 of (permalink) Old 12-12-2001, 09:18 AM Thread Starter
 
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75:1 low enough?

so i was using one of those gear calculators and with 4.10's id come up with about a 75:1 final drive ratio with 36's in low. this would get me about 2200 rpm @ 60 mph in regualr driving mode. any lower and my gas miliage goes strait to hell. so do yall think 4.10 will be low enough offroad? what does everyone else get for final drive ratio.

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post #2 of (permalink) Old 12-12-2001, 09:34 AM
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Re: 75:1 low enough?

That isnt bad. The holy number is 100:1 for crawlers, but most people can get by with less than that. I'm currently running at 86:1 and plan to be over 100:1 when I'm done with the axle swaps.


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post #3 of (permalink) Old 12-12-2001, 09:52 AM
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Re: 75:1 low enough?

crawl ratio is dependent on what type of wheeling you do, if you are playing in the rocks then real low is good, but if you are into mud it is not as much of an issue. 75:1 sounds about perfect to me. Unless you are into rocks.

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post #4 of (permalink) Old 12-12-2001, 12:55 PM
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Re: 75:1 low enough?

My opinion, 75:1 is about as good as you really need short of , well short doing things that no streetable rig should be doing. I've known guys with all the way to 24x:1 and found that 98% of the time, anything more than 75-100:1 is wasted. AS far as the 4.10s, probably be fine on the street up to 33s or 35s with an automatic, maybe even 35s with a manual if you're beyond hot rodding around town, and at 2200 rpm on the highway you should get decent mpg. If you have dana/dana for axels you might go 4.27 as a compromise between the 4.10 and 4.56s. They're adequate for my CJ 5 with a t18 and 35s (crawl at 71:1)

post #5 of (permalink) Old 12-12-2001, 01:02 PM
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Re: 75:1 low enough?

That should be plenty unless you're into serious rock crawling. Sounds about right for a highway use too. My Heep is at 84:1, but I only use that for big rocks, etc. More often, I'm in 2nd low (43:1) or 1st high (32:1) for the tough trails. I have seen no need to have lower gears than I have now with a 454 and 38's.

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post #6 of (permalink) Old 12-12-2001, 02:36 PM
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Re: 75:1 low enough?

My opinion, 75:1 is about as good as you really need short of , well short doing things that no streetable rig should be doing. I've known guys with all the way to 24x:1 and found that 98% of the time, anything more than 75-100:1 is wasted. AS far as the 4.10s, probably be fine on the street up to 33s or 35s with an automatic, maybe even 35s with a manual if you're beyond hot rodding around town, and at 2200 rpm on the highway you should get decent mpg. If you have dana/dana for axels you might go 4.27 as a compromise between the 4.10 and 4.56s. They're adequate for my CJ 5 with a t18 and 35s (crawl at 71:1)

post #7 of (permalink) Old 12-12-2001, 03:50 PM
 
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Re: 75:1 low enough?

Hey, your profile says you live in the south, i'm thinking that's south east which is most mud or mud covered rocks so that should be more than enough, 50:1 is probably better suited to that type of wheeling though 4.56's might be better for the high way and would lower your crawl ratio a little if you want it even lower (extreme rocks).

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post #8 of (permalink) Old 12-12-2001, 04:06 PM
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Re: 75:1 low enough?

Guys what would the cralw ratio be on my best buds TJ be. I know he has stock t case, 5 speed, and 4.88 gears. Also what woudl his rpms be at 60mph???

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post #9 of (permalink) Old 12-12-2001, 04:21 PM
 
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Re: 75:1 low enough?

75:1 is a good crawl ratio, especialy with an automatic, for all but the toughest of rock trails. I have ran the hammers with a 70:1 ratio, and 33" and 35" tires, and it was doable but a lot of clutching. At about 100:1 you can take your foot off the clutch much of the time and concentarte on driving.
If you arent driving regularly on Extreme rock trails I wouldnt worry to much about going lower.
I run at about 135:1 and use the lowest gears all day long in the rocks, but I barely grab anything lower than 3rd gear low, on trails.

Jeff
89 YJ
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