post #46 of Old 01-14-2013, 12:24 PM
BubbaK
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1983 CJ7 
 
Join Date: Jul 2012
Location: Ocean Springs, MS
Posts: 203
Colt44.

1st gear in your Auto transmission is going to be (I can't remember exactly) a little taller than that of a 4 speed manual. So you're gonna need some help from gearing there. But your final gear, 3rd, should be 1:1 just like final gear in a 4speed manual. You could do a little more research on the Forum and find out exactly what you need to do. Or you might get lucky and get another response from Keith. As he said, he had a 4speed T-4 with 3.31's and 33's.

If I were you and running 32's, I'd consider a 3.54 or 3.73 gear ratio. That way you'd have ample power/torque on take-off and still have enough top end room to comfortably run at 65 mph without revving too* high. Good luck buddy. Let us know what you decide and how it works out.

'83 CJ-7_258 I-6_T-4_D300_AMC20/D30_Bone Stock

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post #47 of Old 01-14-2013, 12:44 PM Thread Starter
Colt44
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1983 CJ7 
 
Join Date: Aug 2010
Location: Memphis, TN
Posts: 781
Quote:
Originally Posted by BubbaK View Post
Colt44.

1st gear in your Auto transmission is going to be (I can't remember exactly) a little taller than that of a 4 speed manual. So you're gonna need some help from gearing there. But your final gear, 3rd, should be 1:1 just like final gear in a 4speed manual. You could do a little more research on the Forum and find out exactly what you need to do. Or you might get lucky and get another response from Keith. As he said, he had a 4speed T-4 with 3.31's and 33's.

If I were you and running 32's, I'd consider a 3.54 or 3.73 gear ratio. That way you'd have ample power/torque on take-off and still have enough top end room to comfortably run at 65 mph without revving too* high. Good luck buddy. Let us know what you decide and how it works out.

'83 CJ-7_258 I-6_T-4_D300_AMC20/D30_Bone Stock
Thanks, BubbaK - The tires I have on there right now measure 28" and I have enough low range power for my needs and I can run smoothly at 75 on the highway. My 4.2 runs quite a bit stronger since I put the 4.0 head and MPFI on it; maybe that has something to do with it. If I had 3.73 gears on there right now it would be like a jackrabbit off the line and probably peaking out too soon on the highway.

I think I'll probably be okay with 31s; I can re-gear later if needed but I don't want to wind up with granny gears if I go to low before I know what difference the tires make.

"We are all of us in the gutter...
Some of us are looking at the stars."
~ Oscar Wilde via Chrissie Hynde
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post #48 of Old 02-23-2013, 09:28 PM
S76
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Join Date: Nov 2012
Location: Stafford Springs
Posts: 500
Guess I'm late to the party but I used this calculator to figure out what I wanted for tire size and gear ratio. There are others also.

http://www.4lo.com/4LoCalc.htm

If you always do what you've always done. You will always get what you've always got.
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