JolietJEEP'84 Posted March 11, 2019 Share Posted March 11, 2019 Okay so I traveled a couple hrs for what I THOUGHT was an AMC20 w/ 4:10 gears from an XJ. Turned out axel has 6 studs, was actually from a FSJ Grand Wagoneer. Since I made the trip and I got the axel dirt cheap I decided to keep it. My question: is it worth it or even possible to make this rear axel work on an MJ? What would be involved and easiest way to accomplish? Or am I better off selling and finding a MJ or XJ specific axel. Thanks in advance! Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 11, 2019 Share Posted March 11, 2019 Measure the WMS to WMS distance please. Link to comment Share on other sites More sharing options...
JolietJEEP'84 Posted March 12, 2019 Author Share Posted March 12, 2019 4 hours ago, Jeep Driver said: Measure the WMS to WMS distance please. 57.5" Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 12, 2019 Share Posted March 12, 2019 I'd move on, you are 2.5 inches short. Link to comment Share on other sites More sharing options...
JolietJEEP'84 Posted March 12, 2019 Author Share Posted March 12, 2019 I see that now. Good call. Thanks! Link to comment Share on other sites More sharing options...
gogmorgo Posted March 12, 2019 Share Posted March 12, 2019 2.5" could be made up with adapters to get you back to 5x4.5 lug pattern, but whether it's worth doing, I dunno. I don't think the XJ ever got the AMC 20. Link to comment Share on other sites More sharing options...
JolietJEEP'84 Posted March 12, 2019 Author Share Posted March 12, 2019 Not a bad thought on the adaptors... 29 minutes ago, gogmorgo said: 2.5" could be made up with adapters to get you back to 5x4.5 lug pattern, but whether it's worth doing, I dunno. I don't think the XJ ever got the AMC 20. Link to comment Share on other sites More sharing options...
DirtyComanche Posted March 12, 2019 Share Posted March 12, 2019 It's not worth it. Wrong width, wrong bolt pattern, thick adapters aren't cheap and cause other problems, the axle itself is obsolete and parts are more expensive and less available, and it's got drum brakes. I'd look at more modern axles. The Libby 8.25 seems like a deal. Link to comment Share on other sites More sharing options...
Eagle Posted March 13, 2019 Share Posted March 13, 2019 22 hours ago, gogmorgo said: I don't think the XJ ever got the AMC 20. Factory optional heavy-duty axle, 1984-1986. Link to comment Share on other sites More sharing options...
90MJ Posted March 14, 2019 Share Posted March 14, 2019 AMC 20 parts are far from obsolete. There is a ton of support for them (CJs,FSJs,AMC cars,etc). The ring gear is just a hair shy of 9" (8 7/8 IIRC) and overall they were not bad axles despite having a bad rep by people who abused them beyond their design. They DO have a tendency to bend tubes under hardcore abuse which can be remedied with either a truss, by sleeving, or both. Unless you are running at King of the Hammers it would probably be fine and will handle the power of a stock v8. Also being from a FSJ it SHOULD have 11x2 drum brakes. I ran my 67 FSJ for over a decade on 35s with 11x2 drum brakes both front and rear. If adjusted correctly a drum brake is a good setup that works well. Sure, discs stop better generally, but if drum brakes can stop a semi truck I am sure proportionally they'll stop your truck. The AMC 20 and Spicer 53 are the two most bashed FSJ axles by people. The internet is your friend. The parts and upgrades are out there. If it is a LSD version even better. If it was cheap enough and it were me, I would get the spacer/adapters, sleeve it, and enjoy having a cheap full size jeep axle under my MJ. If you don't want it and are in the northeast I will happily take that off your hands Link to comment Share on other sites More sharing options...
JolietJEEP'84 Posted March 14, 2019 Author Share Posted March 14, 2019 LSD version? Link to comment Share on other sites More sharing options...
Jeep Driver Posted March 14, 2019 Share Posted March 14, 2019 Just now, JC4XJ2MJ said: LSD version? Limited slip. Link to comment Share on other sites More sharing options...
90MJ Posted March 14, 2019 Share Posted March 14, 2019 Limited slip. Is it an open carrier or does it have a factory trac-lok? Link to comment Share on other sites More sharing options...
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