Jacob Ochs Posted January 9, 2015 Posted January 9, 2015 I need help identifying a friends rear axle in his 84 CJ7. He said the carrier said DANA on it but It looks to me like a AMC 20. sorry for the pic this is the only one I have! Help appreciated.
Motorcharge Posted January 10, 2015 Posted January 10, 2015 Looks like a 20 to me, and would fit with the CJ, but it's hard to tell from that angle.
Jacob Ochs Posted January 10, 2015 Author Posted January 10, 2015 Looks like a 20 to me, and would fit with the CJ, but it's hard to tell from that angle.Here is another
87MJTIM Posted January 10, 2015 Posted January 10, 2015 If the diff cover looks like a WW1 helmet, then I'd say its a AMC20
PEEJ Posted January 10, 2015 Posted January 10, 2015 I had an 83 CJ7 that came with a rear Dana 20,Looked like that.Believe that's what he's got there.
cruiser54 Posted January 10, 2015 Posted January 10, 2015 If the diff cover looks like a WW1 helmet, then I'd say its a AMC20 AMC 20 cover is perfectly round.
Jacob Ochs Posted January 11, 2015 Author Posted January 11, 2015 Yup which resembles a WW1 helmet... it sure does it ended up wing a Dana 35!
Incommando Posted January 11, 2015 Posted January 11, 2015 Yup which resembles a WW1 helmet... it sure does it ended up wing a Dana 35! From crappy ( in stock CJ form) to crappier. Strange
Comanchemodder Posted January 12, 2015 Posted January 12, 2015 I am sure the helmet is stronger than the AMC 20 cover.
Eagle Posted January 12, 2015 Posted January 12, 2015 I am sure the helmet is stronger than the AMC 20 cover. And you would be wrong. The AMC Model 20 is a VERY strong axle and differential -- equal to or possibly stronger than the Dana 44. The weakness in CJs was that the outer hubs were not forged as an integral part of the axle shafts, the shafts had a tapered spline and the hubs were then bolted on. Under sufficient torque, the splines would strip and you'd be left with a free-wheeling hub. The Model 20 used in the 84-86 XJ and the 86 MJ used one-piece shafts with the hubs being an integral part of the axle. It's VERY difficult to break one of those. The biggest disadvantage is that it's physically large, which affects ground clearance. Second, there's not nearly as much aftermarket support for the AMC 20 as there is for the D44.
yxmj Posted January 12, 2015 Posted January 12, 2015 And as we all learned from this thread if the diff does fail on you........you can wear the cover as a hat :thumbsup: https://www.youtube.com/watch?v=65nNcNiwJHM
Incommando Posted January 12, 2015 Posted January 12, 2015 I am sure the helmet is stronger than the AMC 20 cover.And you would be wrong.The AMC Model 20 is a VERY strong axle and differential -- equal to or possibly stronger than the Dana 44. The weakness in CJs was that the outer hubs were not forged as an integral part of the axle shafts, the shafts had a tapered spline and the hubs were then bolted on. Under sufficient torque, the splines would strip and you'd be left with a free-wheeling hub.The Model 20 used in the 84-86 XJ and the 86 MJ used one-piece shafts with the hubs being an integral part of the axle. It's VERY difficult to break one of those. The biggest disadvantage is that it's physically large, which affects ground clearance. Second, there's not nearly as much aftermarket support for the AMC 20 as there is for the D44.I think he meant that the the helmet was stronger than the stamped *cover* not the whole assembly. I am a fan of the AMC axle. Internally the better FSJ/MJ/XJ unit was known as the model 23 to differentiate the two. Although a dandy axle they are also a little prone to both twisting and bending the tubes especially the CJ version. Although these mods help most any axle these axles may benefit from trussing or at least welding the tubes to the center section than some others. The diff internals are very strong. AMC was foolish to design a new axle with that very outdated two-piece design.
Jeepman Posted January 13, 2015 Posted January 13, 2015 Definitely Strange which makes me think its not actually a CJ or else the person that swapped it in had no clue what they were doing... I have had many of people bring me their so Called CJ only to be a YJ with a CJ front end conversion... I too am a Fan of the AMC 20 rear Axle in 2 piece form as I am not a fan of the 1 piece shafts (if you ever worked on one you'd know why) Plus the more common reason and not just the hub spinning due to too much torque but more the fact that when taken apart people over look the importance of keeping the Hub and Shaft together as what most don't know is that the hub from new has NO splines in it, the shaft splines are kind of cut into the hub when they are installed for the first time which is what keeps them together with the small alignment key... I have a Spec sheet somewhere from AMC back in the day to fix the hub spinning which was to machine the key larger then machine a second key on the opposite side, I would do this mod before ever going to 1 piece shafts... I ran my 2 CJ's with 2 piece shafts and never had Hub issues and my last CJ had a lot of HP and easily spun 35's no problem...
gogmorgo Posted January 13, 2015 Posted January 13, 2015 This is interesting. I like picking up these kinds of tidbits. I particularly like the "It works great but everyone's an idiot!" element to it. Everyone laughs at me when I pull out a paint marker to make sure I can put every piece back together in the exact same orientation, even sometimes going so far as to make sure that if I reuse bolts, they go back in the same hole they came from. Now I'm justified. :thumbsup:
PEEJ Posted January 14, 2015 Posted January 14, 2015 Jeepman you are correct.The problem is in the hub not the axle,My problems with the hubs spinning started after I removed the hubs the first time.Finally after buying a new set of axles and hubs did I discover the hubs were not splined.They actually spec. 200+ pounds of torque to install the hub onto the axle the first time.(Good breaker bar and a 6 ft. cheater pipe.)Once I replaced the setup and relized how tight the hub needed to be I no longer had any problems.I went from the 258 engine to a A.M.C. 360 out of a Javlin, running 35sRan that setup for 9 years,Pulling it and putting in a A.M.C. 401 police interceptor and running 44s with no rear end trouble.Of coarse the last set up was not used on the asphalt.
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now