FSJ AMC 20 strength

[rstickley]

Is the AMC 20 from a FSJ stronger than the CJ version and is it worth building? I am getting the front Dana 44 from a 79 Cherokee Chief ( wide track) and the guy said he will throw in a 20 if I want it. Just don't know anything about them.

 

[AK-RWC]

They've got bigger tubes and 1-piece shafts, so yes, they are stronger. The only "weak" point they still retain is the relatively small amount of engagement between the tubes and the cast diff housing itself, but it's not that bad. Guys build FSJs and keep the stock axles all the time.

Depending on the t-case though, you still won't want the axle. The Quadratrac cases from FSJs of that era have an offset rear diff.

 

[Randyzzz]

I’m not a fan. They have a 27 spline axle (IIRC) and not many options others than stock alloy replacements. My 5.3 with an automatic had an easy time twisting shafts with 35” tires and 4.56 gears.

 

[Chamba]

I wish I'd taken a pic of my Corporate 20 sitting next to my new Dana 60 on the garage floor before I installed it. The perspective it gave would be great here.

The 20 really looks more like a car axle. I think with the stock 4 or 6 cylinder and open diffs it is only just adequate. Any extra power, traction devices or silly wheeling and I'd steer well clear.

 

[Randyzzz]

I wish I'd taken a pic of my Corporate 20 sitting next to my new Dana 60 on the garage floor before I installed it. The perspective it gave would be great here.

The 20 really looks more like a car axle. I think with the stock 4 or 6 cylinder and open diffs it is only just adequate. Any extra power, traction devices or silly wheeling and I'd steer well clear.

Something that’s about the same width, bolt pattern, and already has disc brakes is the Isuzu Rodeo D44 rear. Lots of upgrades possible there.

 

[OGRES]

Something that’s about the same width, bolt pattern, and already has disc brakes is the Isuzu Rodeo D44 rear. Lots of upgrades possible there.

Yup, the previous owner of my last Scrambler put one of those in. It was nice. The only thing he didn't do was weld on tabs for shocks...I never did add rear shocks while I owned it. It rode surprisingly well without them.

 

[jpnmaine]

Never looked into the rodeo rear. Thought I heard about some idiosyncrasies (6 lug?) that made it not worth it. All hearsay.

 

[sdsupilot]

The rodeo is a fine option, just make sure to do plenty of research. They come in 3 different widths based on year. The +98s are likely too wide and also are considered a modified 44. They have some quirks with carrier selection and bearings. They have been used enough that most vendors are familiar with proper setup.

 

[rstickley]

Well darn! Thanks for all the input. Guess it's back to square 1.

 

[Randyzzz]

I think the biggest difference is the Rodeo rear uses a metric flange for the driveshaft, and metric wheel studs. Easy work- around a for both. But- a bonus is they mostly came with 4:10 gearing. Some 4 cyls had even lower gears!

I think it’s the 1st gen Rodeos that you’re looking for.

 

[Ron84cj]

My understanding of the rodeo axles is the 93- 95 are 58 inches, the 96-97 are 60.5 inches, and the 98+ are 63 inches. If you want the width don't be afraid of the 98+ axle. Most of the info you will find online is very outdated on this. It is basically just an HD Dana 44 that is found in the non Rubicon Wrangler JK. This axle came out years before the JK which is why all the confusion. They didn't know what it was. You use Non Rubicon jk gears and wheel bearings and a carrier or locker from an old school Dana 44 3.73 down REGARDLESS of what ratio you are actually running. They use thick cut gears which is the reason for the 3.73 down carrier. The axle shafts are much beefier than the old 44. Plus the axle tubes themselves are 3 1/8" in diameter! I picked up 2 last year for $75 each. They are a great upgrade.