20/30 gearing, locker, etc

jeepmanjr

jeepmanjr

New member
Before you beat me up - looked, searched this site and didn't find a good answer. Or maybe it was the Coors Lite...I don't know...

Anyway, here's the project ('84 cj7):

AMC20: 272's, Lockrite, cool anti-wrap/truss
Dana 30: 272's, open
Motor: 4.2 (Chevy 4.3 TBI, electronic ignition)
Trans: TF727
TC: Stock Dana 300
Tires: 12.50x35

The local shop says I can't go larger than 4.10s in an AMC20. The local shop says I can't use my (brand spankin' new) AMC Lockrite with 4.10s.

I know I need new carriers for both axles, no need to go there.

Questions:

1. Opinions on gearing (70% pavement - 30% off road)

2. How big can I go in an AMC20/Dana 30 axle (gear ratio)?

3. Can I use my current Lockrite with bigger gears?

Keep in mind that the Jeep is near a complete body-off go-through. Changing axles would mean changing other expensive components as well - including my brand new driveshafts, disc brake conversion and SOA stuff.

Thanks fellas....
 

Pick up the Four Wheelers bible by Jim Allen. Great book!.

I would toss the 20 for a Dana 44. Look for a 86CJ7 rear end or a Scout.
I would put in 4:10's or 4:56's . Look at the chart for Loc right see it there is a case cut off. I think the case on a 44 is 2:73's to 3:54's
and the other is 3:73's and down 4:10, 4:56.
 
Thanks for the reply. Well, 40's, 60's even Rockwell toploaders would be cool. But like I said, it's set up with an AMC 20 and Dana 30. I don't want to change axles at this stage in the game. After some homework it appears that the information given me may be bogus. I just thought someone here might know something about the 20's and possibly provide some insight. Thanks....
 

I'm no expert with axles but here's my take on it. I have the same axles as you do with 35X14.5x 15's. From what i've gathered from the members here that knows a lot about them, keep the 20's and 30's. i'm re gearing mine sometime with either a 4.10 or 4.56's . I'm leaning towards the 4.10's since i do a lot of highway driving to and from work and offroading on the weekends out in the ranch. I have a friend with a CJ5 that has the AMC 20 on the rear with 4.10's and a lockrite from 4WD hardware and is very pleased with it. the only thing he's broken so far is the Moser one piece axle on the driver side, but i think that was his own stupidity. Anyways, i just thought i'd share that with you if it helps.
 
Thanks for the reply Steel! I'm definitely keeping these axles, at least for a while. Mine will also spend quite a bit of time on the pavement, so probably 4.10's for mine as well. Still haven't determined whether or not my Lockright will work with a bigger carrier. Their site shows one application for all AMC 20's, but the local shop says it can't be used with a larger carrier. I emailed Richmond Gear and have yet to get a response from them. Desert rat in Phoenix, AZ quoted me $1300 to do the job - parts 'n all.
 
Rubiconrich said:
I would toss the 20 for a Dana 44. Look for a 86CJ7 rear end or a Scout.
Click to expand...

Why the heck would you down grade?

I don't get it. If you get the 3.08 on up carrier, you should be able to put 4.88's in there. I would go with 4.10's since you don't have overdrive. The lockrite should be fine.
 

Thanks Collin! I have the AMC 20 set up real nice with 1-piece axles (floaters soon), custom truss, disc brakes, anti-wrap...too far along to change axles now. I, too, was thinking 4.10's.

Appreciate the input. Maybe I'll post a pic so ya'll can see my humble work.
 
I have 4.56s in my CJ5 with about 33" of tire. I find that once you are in top gear going about 40 mph it feels like you need to shift again but there I nothing left to shift to. I've been thinking about adding a Teralow 4:1 to my Scout Dana 300 (assuming they still make them) and put some taller gears in the pumpkins for better streetablity.

As far as a Lockright in a CJ, at least a CJ5, I would not do that again. On the road your jeep will have very bad manners and will hop, skip, jump, and clank at will. If you want to turn while driving down the road you will need to let off the gas, turn, the gas or your jeep will plow a head in a straight line. These are all manageable but not for the faint of hart.
 
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Saddle Tramp said:
As far as a Lockright in a CJ, at least a CJ5, I would not do that again.
Click to expand...

A few years ago I had an M38A1 body on a CJ5 frame, SOA, etc, etc. I built my own full-floaters for the rear offset Dana 44. It had a Lockright in it - worked great off-road. But like you mentioned, it did have some bad on-road manners. It would pull to one side on acceleration and while turning it was so loud and clanky that it would attract attention. Had guys doing a double take like I was dropping parts or something! But other than that I really didn't have a problem with it. Easy to install, no setup...and they're fairly inexpensive. Kind of a trade-off I guess. I've contemplated putting one in the front as well.

you guys think $1300 is a decent price for a re-gear?
 
I agree with jeepmanjr on keping his axles. Jeepmanjr considering your mods changing the 20 to a D44 is al lateral move when considering all the pros and cons. On a 20 axle the 2.73 used it's own carrier (the only ratio to do this) 3.31-5.13 ratios use the same carrier. The 4.56 is the lowest common ratio between a 20 and a D30, the 5.13 was not offered in a D30. So you will need another carrier for your new gears and your lockrite should work just fine. IMO I have no issue running a locker in front as you can always lock only one hub for 4x4 street driving. The price is just a little high but you are in AZ so I have no idea what your market is like, just that at one time there were a lot of bad quality coming out of some of the bigger 4x4 shops down there.
 
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Thanks Ggg! You're right about some of the shops down here. The local shop is a Good Year dealer and does a good portion of the fleet repairs for the agency I work for. He wants $1800 for the job! He's also the one saying my locker won't work and can't go bigger than 4.10's. I was Phoenix the other day and got a quote from Desert Rat. If anyone has any recommendations I really would appreciate it. I live near Blythe, CA on the Arizona side of the Colorado River. So Phoenix, Yuma, Laka Havasu City, Palm Springs....let me know.

BTW, I finally got a reply from Richmond Gear:

"The locker will work with the 3 series carrier. We offer 3.54, 3.73, 4.10 and 4.56 for the AMC 20. All these ratios fit the 3.08 and up carrier."


 

A quick pic of the 20 in my '84 CJ7...
 

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Saddle Tramp said:
Uh, I just want to know how you keep the underside of your jeep that clean? Living in the rain/snow zone I guess the whole idea of a pretty undercarriage is just a foreign concept.
Click to expand...

It hasn't left the garage yet! :D

I bought the Jeep from my brother, brought it home and discovered there was literally nothing salvageable. Did a complete body-off, bumper to bumper. Spent more money than any sane man should. Still not complete, got some fuel injection/electronic ignition bugs to work out and a few other do-dads.

Here's another quick pic I snapped. Not a good one - my garage is air conditioned and I didn't want to open the door! ;)
 

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jeepmanjr said:
It hasn't left the garage yet! :D

I bought the Jeep from my brother, brought it home and discovered there was literally nothing salvageable. Did a complete body-off, bumper to bumper. Spent more money than any sane man should. Still not complete, got some fuel injection/electronic ignition bugs to work out and a few other do-dads.

Here's another quick pic I snapped. Not a good one - my garage is air conditioned and I didn't want to open the door! ;)
Click to expand...

Looks good!

Air conditioned garage? What's that? (LOL) It was raining here this morning, in fact we have rain forecast for Labor Day weekend. All kidding aside, we do get some heat during the summer.
 

Was a brisk 107 degrees here today. Lightning and thunder from 0300 to 0500 and little bit of rain. Funny...anything under 65 degrees and we're looking for a sweater!!

Thanks for the comments... And again, any input on a good axle/gear shop in my area would be very much appreciated.
 
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