amc 20 2 piece axle shaft questions -
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Unread 11-09-2013, 06:35 PM   #1
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1982 CJ7 
Join Date: Mar 2009
Location: Winslow, Arizona
Posts: 122
amc 20 2 piece axle shaft questions

been doing some reading:
and a few other threads...
ended up with a few questions...

what exactly are the shims do? or i guess i should ask what happens if you either don't use them or use to many? mine had none...

also the little dust shield that goes on after the outer seal, is it really needed? mine dont have them...

on the one piece axle's i pulled out there was some weird spacer between the inner seal and bearing... needed? or on the 2 piece is it just inner seal, then bearing?

and on a random note, the four bolts that hold the backing plate and everything together, what is the bottom one(fifth one) for? everyone elses is empty and mine had a bolt in it lol.

if i can think of anything else i will definately ask and as always thanks in advance

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Unread 11-09-2013, 08:05 PM   #2
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1978 CJ7 
Join Date: Jun 2011
Location: Scottdale, Pa
Posts: 4,766
The shims set the end play in the axle. Basically how tight they go against the bearing. Too tight, and bad things happen when the bearings get warm and expand. Too loose, and different bad things will happen. The shims are only used on one side (driver's side if I remember correctly.
As far as yours not having them. The axles may have the proper end play without any shims, or they were simple left out. Only way to know for sure is with a dial indicator.

I don't use the outer dust shield on mine anymore. They always seemed to just pack full of dirt and rust away anyhow. They will however keep oil from leaking onto the brake shoes if the seal leaks.
Which leads to your other question......
The very bottom hole (fifth hole as you called it)should be left open, for oil to run out of in case of a leak. The outer dust seal (tho one I don't run) will funnel it out of the hole.(supposedly).

The weird spacer on the one piece axles does the same thing as the shims do on the two piece axles. It sets the pressure on the bearings. The spacer needs to be ground down (if needed) to a certain size to achieve this.
78 CJ7.. 258.. TH400/Dana18.. SOA/stock YJ springs.. 35" General Grabbers.. Waggy 44s.. 4.88 gears...Spartan/Lockright...Fiberglass front to rear
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