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Tgrif11

AMC 20 shimming issue

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Hello all:

    my wife wants to relieve her glory days, so we are now the proud owners of a 1983 CJ-7.  I found a lot of issues with the AMC rear end. It had a leak on the drives side that was spilling diff fluid everywhere. While I was attempting to figure out what was going on I found that most of the parts were totally crap so I ditched almost everything from the axles out and bought new parts (axles are the correct length). Now that I have inserted the new axils I am finding that my endplay is .090 with no shims installed, and I am confused as how to proceed.  attached are photos of the left and right side.  Any advice would be greatly appreciated!

Thanks in advance, Tim.

IMG_20170906_155330.jpg

IMG_20170906_155221.jpg

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Tgrif11...Welcome to the forum community and thanks for participating!  We have covered your AMC Model 20 axle issue from a variety of angles, with lots of details and even PDF illustrations.  You'll discover footnote concerns that need address.  

Begin with a review of these references and discussions.  Pay attention to the hub/axle nut torque concerns, a commonly overlooked item when you get past the end play and shimming issue.  The parts orientation is crucial:

 

 

 

 

 

 

 

Let us know how this goes...If you have further questions after reviewing the topics and discussions, please share...

Moses

 

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Thank you for the reply:

 I had already read most of these and found that most of the issues relate to the bearing sticking too far out on the passenger side. My issue is the opposite, my bearing race rides .176 inside of the face the axle tube.  If I set it flush on the passenger side the race on the drivers side sits inside the axle housing.  I was in under the impression that the passenger side bearing race should be flush with the face of the housing, and be retained in place by the backing plate.  If it is allowed to be recessed into the housing than all is well, if it must sit flush than I have no idea what is wrong.  I have cross checked all my part numbers and compared axles and all measure correctly.

Right side.jpg

Left side.jpg

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Tgrif11...Sorry you're have this kind of issue.  Neither bearing cup should set this far into the housing tubing at either side, as this would create extreme axle shaft end play, nearly 3/8ths of an inch!

Since the control factor is the length of the axle shafts, and presuming that you have a length match here with the original shafts or their lengths, the other issue discussed has been the slotted spacer block at the center pin of the differential.  In the interest of viewing these parts in relationship, here is a PDF of all pieces in an AMC Model 20 axle for your Jeep CJ-7.  The only additional items you need to place in correct parts orientation are the brake backing plates.  They are part of the "stack thickness":

1981-86 Jeep CJ AMC Rear Axle Parts Schematics.pdf

Let me know where this leads and ask any additional questions that come up.  If the space block ends are badly worn or damaged, or if the block is missing, the axle shafts and bearing cups would fit too far into the axle housing, which would create excessive end play.  You can inspect the block at the center cavity of an open differential;  a bit more difficult if you have factory Trac-Lok (Dana/Spicer limited slip differential).  

Also note that the axle shaft lengths differ between open and Trac-Lok differential types, and there are narrow and wide-track axle housing widths with different axle shaft lengths as well.

Moses

  

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