Axle Swap/Upgrade

[jbentley]

OK, so I recently had a post about a jerry rig solution to an axle problem...

Short version:
Factory AMC 20 NT got replaced with a WT, tires rubbed fenders, so a poor man's lift solution was created.....

Bottom line, I'm going to need to ditch the WT and put a proper length Axle in place, which leaves me three options:
A. Return to factory AMC 20 NT
B. Upgrade the axle, say a Dana 44 (though the AMC 20 is said to be equivical), but if I'm swapping out the axle, why not put in something more common/modern? Maybe swipe one from another vehicle with disc brakes perhaps, the skies the limit....
C. Upgrade the axle with a newer unit that has a trackbar for better stability and towing. See, I really like this idea here, because my 82 doesn't have a trac-bar and I think that would a be a snappy feature, not to mention safer...

So, I know nadda of axles or swaps... I don't want to break the bank on this project, $200-$300 tops, I don't want to alter Drive shafts.... I can make shock perches or brackets and weld 'em on if required, but I just don't know what'll work on these things. The last thing I want to do is run out, get a new axle and find that it's too long, narrow, the differential doesn't line up with the drive shaft, you know, those kind of gotchas that make you feel like you just dropped the pry bar on your crotch...

Maybe sticking with a factory NT is best given the budget, but I don't want to do it and find out later that I could have put in an 84 rear axle with trac-bar for the same $$ and had a rig with more modern features.

[addicted]

If you can weld up shock tabs and stuff then making track bar mount shouldn't be heard either. Find a NT that's the same ratio as yours and swap it in. If it doesn't have a track bar mount make one, you'll have to make one for the frame side anyway.

[jbentley]

Nice! So I don't have to have a newer axle then eh? Just snag an existing trac-bar from a new FSJ with the AMC 20 and build my own axle/frame mounts?

Sweet!

BTW, to my knowledge, the gear ration hasn't been touched, so if the cover differential bell stamp isn't lying, the "circled A" character means it is a 3.34, so that should be easy enough to matching NT. Now, I just need to find one 'round Dallas/Lewisville.

[addicted]

Are you talking about the piece of tin between two of the cover bolts? If you are then that should be the gear ratio. The best way to tell is to pull the cover off and find the ratio stamped into the edge of the ring gear or count the teeth on the gears. I should also point out that you want one from '80-'91. The majority of them from the mid 70's to '79 will have an offset to the pass side for the Qtrac case they used.

[derf]

Originally Posted by jbentley

Nice! So I don't have to have a newer axle then eh? Just snag an existing trac-bar from a new FSJ with the AMC 20 and build my own axle/frame mounts?

Sweet!

BTW, to my knowledge, the gear ration hasn't been touched, so if the cover differential bell stamp isn't lying, the "circled A" character means it is a 3.34, so that should be easy enough to matching NT. Now, I just need to find one 'round Dallas/Lewisville.

Back when I lived in DFW I remember finding a few FSJs in junk yards around the mid cities area. I grabbed a few parts out of one that still had it's axles probably 10 years ago. It's probably been crushed by now. But I'm sure if you call around you can find something. If push came to shove and you can't find an axle with 3.31 gears, just find an 80's wag and grab both axles so you have matching ratios. They'll probably be 2.73 gears. Grab the speedo gear out of the t-case while you're at it so your speedo reads right.

[joe]

I have no clue what a circled A means. All 1980-91 Wags and Chero's only had two factory options. Standard were 2.73's and the optional towing pack included 3.31's.
The 80-mid86 years used an AMC 20 rear axle. Late 86-91 used D44's I agree AMC20 or D44 similar in strength. The ratio code on an AMC20 axle is stamped into the flat boss next to the dowel hole on the pass side of the differential. "D" = 2.73, "B" = 3.31 On a D44 the ratio is on a tag between two cover bolts. No letter code just the tooth count. 2.73's would show a number like 41 15 I would go with either flavor NT axle so long as the ratio is the same and it's from an 80 or later with the centered differential. Price varies with location but around here you could find either axle for $150. So doing a stock 80-91axle swap is well within your $300 budget

[Tad]

If you can't find a 80-91 NT rear with 3.31's then grab the cheapest NT you can find.
I have 3.31's for D44 and AMC20 (complete, pulled w/carriers) I'd send over for the price of shipping. They are dirty and dusty from sitting but quite useable.
You would need install kits, I have not priced those in a long time so you'd have to figure that into the equation.

[78J-10]

If you up for a little fabbing. You could go with a ford 8.8 31 spline axles and 98+ had disk brakes. come in 3.31 to 4.10 gear raitos with LSDs

I have on in my 95 YJ and i beat the snot out of it with no issues.

[addicted]

Originally Posted by 78J-10

If you up for a little fabbing. You could go with a ford 8.8 31 spline axles and 98+ had disk brakes. come in 3.31 to 4.10 gear raitos with LSDs

I have on in my 95 YJ and i beat the snot out of it with no issues.

He'll need to do some serious work to that axle to make it work. The bearing ends will need to be replaced with 9" big bearing ends and have custom shafts made for the 5.5" bolt pattern. The stock flanges aren't big enough for anything bigger than the 4.5" pattern.

[78J-10]

Why you you have to replace the bearing with 9" ones? Aftermarket shafts with 5.5 bolt pattern can be had for a decent price and there stronger. I have friends with 8.8 behind V8s and run 38s on 5.13 gears and its on stock shafts and bearings.

[jeeping1974]

If you still have the stock NT axle, just swap that back in. The ring gear is a little larger than the D44. Only thing you need to watch for are the axle tubes spinning in the diff. Easy fix is to weld the tubes to the diff housing. Same bolt pattern, no drive shaft mods needed and no welding required.

If you want disc brakes, do some research on what you need for calipers and rotors and get some weld on brackets.

As for a track bar, all it does is keep the axle from moving side to side (which your leaf springs can do). If you'll be tow with it, install a sway bar and links in the rear.

[addicted]

Originally Posted by 78J-10

Why you you have to replace the bearing with 9" ones? Aftermarket shafts with 5.5 bolt pattern can be had for a decent price and there stronger. I have friends with 8.8 behind V8s and run 38s on 5.13 gears and its on stock shafts and bearings.

I called or visited several shops in my area that do axle work/custom off-road fab and they all told me that a 5.5" bolt pattern weather it's 5 or 6 lug will require a custom shaft and different bearing end. One shop even called 3 axle suppliers in front of me and was told the same by all 3. Currie and Yukon were 2 of them the other was either Moser or Superior.

[jbentley]

Thanks all!

I'm really excited about this project.. It doesn't seem nearly as daunting as before now. I appreciate all the great input.

[bshoke]

I use www.car-part.com to hunt down some parts, I usually use the distance search, and follow up call to the yard to make sure they still have the part. Never used it for rear ends though.