4 56 vs 4 88 rock crawling cj

So I have a 78 cj 7 3 speed man. And 33 inch tires. Which gear set would be low enough. Engine is 304. I also have Dana 20 TC with tera low kit 3 to 1

Thanks guys.

 

I would suggest changing transmissions, since the first gear on a three speed is around 3 to 1. An automatic would be the best bet. You need a variety of gear ratios to go through constantly changing terrain.

 

Not exactly your answer but some JK owners who modded to V8 power do well with 4:10 to 4:56 and we're glad they avoided 5:13. JK is much heavier coupled with torquey modern V8

 

Hum. That's all I can say.

Need more feed back guys.

 

Fair enough, lets talk numbers. To calculate your total first gear final drive ratio, all the tranny, t-case, and diff ratios have to be multiplied. Your transmission, the T150 has a first gear ratio of 2.99:1, the modified t-case is 3.15:1, and the planned diff ratios are 4.56:1 or 4.88:1. So the 4:56 version has a 42.95 final drive ratio, and the 4:88 version is 45.96. Really a tiny difference. With an automatic, you can crawl as slow as you want and still drive on the highway easily assuming you have the stock rear gear ratio of 3.42:1, I believe it is. With my 4.10 rear gears, I can barely drive on the highway with 33" tires. Although I would recommend a big tranny cooler with the automatic to go with it, especially with those tires. Another option would be to just add a Ford T18 manual tranny like I did and you would have a 68.1 final first gear ratio with stock 3.42:1 rear gears. Which is barely making it into the "Rock Crawler" category. Another item that has to be added is the torque multiplication factor with a gear change, so you have to go easier on the throttle or break something.

 

Wow thanks for all the calculations but I don't have an automatic I have the T 150 3 speed
So with the 456 say and the T case modification what would be my final Drive- and is it acceptable for what I want to do and understanding that there's not that much difference between the 456 and a 488 is that correct

Thanks again. an actuality 33 is are probably closer to 32

Truth be told I just did the rear end with the 456 gears I have it out but I am thinking about turn it all apart again putting in for 488 and then 488 in the front what do you gear head experts say.

I know it's after the fact after I've already did the rear but I feel horrible that I just should have done it right the first time

 

I don't think you would even notice any difference between the two ratios. Going to anything else than that T150 will really help your crawling capability.