regearing for 79 cj7

tatjr79

New member
I don't know what gears were stock in an amc 20, with a t-150 and 258-6. It currently has 33x12.5's on it.I want to wheel but it's also a daily driver any suggestions? :D
 

kairo

Moderator
Staff member
4.56s would be my call with that engine. Are you definately planning to regear? or are you trying to figure out what gears you have currently?
 

tatjr79

New member
definitely going to regear.4.56's won't be to low?I want to still drive it on the highway as well as use it offroad.I'm not into extreme 4x4, I like to wheel and poke around in the hills all over Nevada.I'm definitely not going to put my jeep in a spot where I'm going to bust her up.Going to put in one piece axles and a locker I got from Joe the Toe.Just put on a Mc 2100 and HEI this weekend.Probably next year going to dump the t-150 and go t-176 or t-18.(leaning towards the t-176).then i'llprobably just lower the gearing in the tranfer case to get a better crawl ratio.What about 4.11's?
 

kairo

Moderator
Staff member
Well, as far as 4.11s, here's why I say "no" I drove an 82 cj7 as a daily driver for about a year, and no offense, but I HATED that engine with a passion. Granted, I still had the 1bbl carter carb on it, but I could never coax enough out of it to comfortable spin my 33's at 60mph on the freeway. I had 3.73 gears at the time. Right now I'm spinning 33's with the 4.0 Jeep inline6, and it's adequate. Given that the 258 is a bit of an older engine, I would think 4.56 would suit it just fine.
 

Fish Sticks

New member
tatjr79 said:
Probably next year going to dump the t-150 and go t-176 or t-18.(leaning towards the t-176).then i'llprobably just lower the gearing in the tranfer case to get a better crawl ratio.What about 4.11's?

You are dead on getting rid of the T-150 (what was jeep thinking). I would hold out for a T-18 granny, sounds like you want the bolt up of a T-176, the T-18 is well worth the money and the adapter issues you will face. As for gearing behind a 3 speed. How often do you do long highway trips (noticed you are from Winnemucca)? Are 35's in your future? I would put my money on the tranny swap first, two friends have done this on CJ-5s, and both say it is their best mod. If not check and see if Randys stocks any odd size gears for your axles maybe between 4.11's and 4.56's might be a good choice.
 

tatjr79

New member
Currently I don't make any long distance trips.Every now and then I take it to work which is about 35 miles away.Most of the drivetrain is original,don't have alot of faith in almost 30 year old parts.So I've been replacing them as I go.Not really thinking of bigger tires, I like the height of the 33's but think I'm going to go a little skinnier on the width.Thought about the tranny choices alot, I really don't need the gearing of a T-18a first gear. Of course there are less issues with hooking up the T-176.This is why I'm leaning towards this.Same reason when everyone suggested doing the rebuild on my engine myself, just want to get it done with as little headache and time as possible.Also at the end of it all :disagree: :disagree: :lolrun: :lolrun: (like there is ever an end) I want to be able to drive it comfortably to where I'm going to wheel and back.( well as comfotable as a 79 cj can get :D ).
 

Fish Sticks

New member
If you want pm me and I'll have my buddy (good old Idaho boy) call you. He is an old school expert. He has built his rig on a shoe string (4 kids) budget. Dana 44's front and rear, Ford T-18, shackle reversal, outboard springs, on and on. He built his rig in stages and can offer some great advice on what worked and what didn't and how he built a $30,000 dollar plus rig on poverty with a view pay.
 

PizzaJeep

Active member
your making an axle regear sound like more than it really is.

http://www.fourwheelparts.com/4wp/assets/!!!---CHARTS---!!!/chart_gear-ratio.htm

read that chart. at 60 mph, how much of a difference is 4.11 compared to 4.56. the answer is ~315 rpm. in all reality, the difference is not going to be that drastic.

the only kind of axle regearing you should legitamately do is get back to the overall correct drive ratio from completely stock to having bigger tires. go maybe 1 or 2 ratios lower(numerically higher) to correct for the fact that your engine needs a bit more power to push the bigger tires but its honestly not going to change that drastically. if you wanna creep in lowrange better, yet maintain good gas mileage, get a lower t case ratio, then stop caring about gas mileage since your cj7 (or any legitimate trail rig) simply will not get good mileage no matter what. its a fact of life when a torquey engine is pushing 4500+ pounds, spinning a transfer case, spinning a solid axle, and cutting through air with downright horrible aerodynamics.

get the actual numbers of gear ratios of different trannys and tcases. keep as much of the normal drive ratio the same, but bring in a solid yet low tcase to give you a better 'crawl ratio'

what is your crawl ratio right now anyways?
 

Sierra Valley

Active member
In the the cj that I drive I have the t-18 w/ the dana 300 and 4.56 gears front and rear. It is perfect for everything I do. Top speed of 65-70 w/ the old leaky I 258 and it crawls great, dont even use my breaks in low gear when going down hill. The only thing is that my 4high doesnt work, which is just a project for another day.
 

tatjr79

New member
I don't know what my crawl ratio is right now( just getting started with this project).Not areodynamic? a cj ? :D :D like a brick.I'm not looking to get astounding gas mileage, that is impossible with what I want to do.All I'm trying to do is find the happy medium in wheelin and driving there.I had already decided to lower the gear ratio in the t-case to get better crawl, just needed some input on what has already been done and works, appreciate the link to the chart. all the input makes my job a whole lot easier. THANKS
 
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