Can't ID this axel

[JKJeep]

I bought a '79 CJ7 two years ago. It's pieced together outta everything, it's like a Johnny Cash song. Anyway I can't figure out what these axels are. Any ideas? There was another thread about the Dana axels and none of the dif covers matched what I got. Mine was round with no indentations, looked like it might be older. Take a look and tell me what you think. The number 168 is relieved on the top of the dif. Any help would be awesome. Thanks.

 

[808CJ7]

It's an amc 20. All cj's from 76 to 86 had them. The later 86 models came with Dana 44's

 

[JKJeep]

Any idea how to remove the axel shaft? The directions in the book do not work. I gotta replace the axel seal. It says to get a puller and force it out, but my buddy busted two trying to attemp this. Any suggestions?

 

[808CJ7]

After you remove the retaining plate it should pop out. A slide hammer usually only takes one or two whacks.

 

[JKJeep]

Right on, I'll give it try. Thanks for your help.

 

[69jeepcj]

Yes, a slide hammer works. The AMC 20 axle is in my opinon a decent axle that has got a bad rap. the ring gear is slightly larger than that of a dana 44, and when upgraded with one piece axles is considered by some to be stronger than the 44. The axle tubes are known to bent when used hard, but over all for a non competitive trail riding jeep it is a good axle when one piece axles are added. stock gearig should be 3.54 or maybe 3.73,. 3.54 were in most. All the 4 cyl came with 4.10,s

 

[83-cj-7=383-stroker]

i had the amc 20 in my jeep with the one piece axles and lock right lockes added braceing and it handled my 38 swampers great axle i spit out 2 44's before i built the 20 yes its a amc 20 for sure

 

[PoliceMonkey161]

Looks like you got some really great advice from the other members. I have rebuilt and trussed out (braced up) a couple of AMC 20’s, but I’m certainly not an expert. If you really what to figure out what you have, there are a couple of simple things you can check. Since you have stated that your Jeep has been pieced together, you can’t assume it has one or the other variations of the AMC20 based on the year of the Jeep. The AMC 20 came in two general width for the Jeep CJ series, 51” wide referred to a wide track (83-86) and 46.5” wide referred to as the narrow track (76-82). Facing the differential cover to the right there is a circular shaped dimple, to the right of that is a letter or two letters. Double letters indicate a limited slip (Trac-Lok) differential and a single letter is an open diff. The letter designator identifies the ratio, but all this would only be accurate if no one upgraded the axle and gears over years. I believe Terry Mason did an article about this? Regardless there are a couple of site dedicated to the AMC 20.
You can look on the side of the ring gear and it will be stamped with series of numbers (I.e. 43X13 which would work out to 3:31 to 1). The Trac-Loc differential case will be more square shaped and you should see disk (clutch packs) next to the spider gears inside. From your photo, it looks to be an open differential.
Whether you have solid/one-piece axles or the stock shaft and hub type (you can look up online what a one piece axle will look like easier than I could explain it) the inner seal replacement is the same, however the bearings will be orientated differently depending and the removal of the outer seal is different as well. Judging by the looks of your photo, you have pretty good leak of gear oil coming from the brake drum. I would just go ahead and replace the bearings, race and both (inner and outer) seals and if I had the money (if not already equipped) go with one piece axle shafts (Superior makes a good affordable set). The great news is that this is a common repair and is fairly easy to do.
I have photos of the last re-build I did at home if you like them.

 

[JKJeep]

Great stuff guys! I'm learning a lot here. I was able to pull the axel out but I have been unable to separate the flange from the axel due to the fact that no one has a puller that will work (my book says to not use a puller that pulls on the edges because if will bend the flange?) . I'm going to take it down to a shop today and see if they can separate the two pieces. If not I was going to try to make the contraption in this YouTube video and see if that will work.

.

Truthfully I've spent more time working on the Jeep then driving it but what I've learned from it has been invaluable and I've really been enjoying myself. Thanks again for all the great info, keep it coming if you guys have anymore suggestions. I also found this article which seemed pretty straight forward for anyone looking for the same answers I was, Jeep AMC 20 Axle Tech - Jp Magazine .

 

[JKJeep]

PoliceMonkey, I got a couple questions for you. First "I would just go ahead and replace the bearings, race and both (inner and outer) seals..." What are the "race"? Sorry, total novice with a lot of this stuff. The other question is, can I just measure the hole axel housing to figure out if I have a wide or narrow track? And last but not least; that would be great if I could get those photos of the rebuild from ya. Thanks again.

PS That is a "no go" on the shop. My book says not to use it but what do you guys think about me using this puller http://www.amazon.com/gp/product/B0..._m=ATVPDKIKX0DER&pf_rd_r=0X79MZNS85K1FH0BQM2B to get it out, instead of building that contraption from the previous post?

 

[808CJ7]

Just my two cents but I wouldn't waste time and money on the two piece axles. There are some good deals online for the much stronger one piece axle shafts. Amazon. com is one of them.

 

[PoliceMonkey161]

PoliceMonkey, I got a couple questions for you. First "I would just go ahead and replace the bearings, race and both (inner and outer) seals..." What are the "race"? Sorry, total novice with a lot of this stuff. The other question is, can I just measure the hole axel housing to figure out if I have a wide or narrow track? And last but not least; that would be great if I could get those photos of the rebuild from ya. Thanks again.

PS That is a "no go" on the shop. My book says not to use it but what do you guys think about me using this puller Amazon.com: OEM 25919 Long 2/3 Jaw Gear Puller: Home Improvement to get it out, instead of building that contraption from the previous post?

Yes, you would measure between the brake backing plates or if the axles are moved from flange to flange. Eitherway the measurements will be closer to one or the other. The "race" is the cup that the cage style bearing will fit into, normally a brand new bearing will be sold as a set with the race and the race will appear to be attached to the bearing (they will come apart after installation or more likely the removal of the axle from the housing).

I would be inclined to go with 808CJ7 recommendation of the one piece axle shafts. Consider that the factory two style are the weakest link of the rear and they are infamous for stripping where the hub/axle join (even more so after dis-assembley and re-assembley). You may find yourself spending more money in the long run replacing the factory axles..... Plus, who wants to do a job twice? But everyones budget is different.

I will glady send some photos later.

 

[PoliceMonkey161]

That is a three jaw puller that you have found, it will likely work but I would soak the splines at the axle and hub generiously with PB Blaster a day before. A harmonic balancer puller will work as well........ Check at Harbor Frieght Tools for either tool if have one close by.

 

[PoliceMonkey161]

Alright, so I thought I had more photo's. But these will do,unfortunately they are of an AMC20 being upgraded to one piece axles during a complete rebuild and only show the stock set up being pulled out. And just in case you decide to upgrade, a couple of photo's of the wrong way to press on bearings (those are from a repair I did after a so called "Professional Shop" did an axles swap).

As you can see, the old shafts come out after removing the drum brake hardware and you take off the four axle flange bolts located under the hub. I normal just flip the drum over and install it upside down with the lugs tighten just a few turns, it will work just like a slide hammer to get the axle lose from the differential. Take note of what side and how many shims come off the orginal set up if you just repair the stock axle shafts, you will be reusing them.

Before you replace the seals and bearings, you will need to clean out the axle flange to remove the old grease, residue, etc. I like to run a green scouring pad around the inside. Next you will put a light coating of RTV around the edge of the inner seal and gently seat it with your fingers.Then use a bearing race/seal tool to seat the seal fully (just couple of light taps making sure its square inside the tube). Without one piece axles you will not have the silver spacer.

This photo is just FYI if you go with the upgraded axle route, the bearing and race should extend greater than .020" but not more.060". If its greater, you need to add shims to the face of the axle flange.

Regardless of the set up you go with, the next step is press the bearing on the axle shaft. On the stock AMC 20 axle the cone shape of the bearing faces the brake drum (remember that the race will be seated on top of the cage with the new bearing, so look close). If you don't have a hydraulic press equipped for this, your local garage should be able to do it. However, I have seen some clever ways of getting the bearing on the stock axle since it only has to move a little on the open end of the axle (on a one piece axle it must go on the splined end and slide down towards the flange, this will require a press). Do not try to use a hammer! With the one piece axle shaft upgrade, there are some additional steps before pressing on the bearing like putting the dust shield on,the outer seal and the brake backing platein place prior to pressing the bearing. Additionally, you'll have a thick metalring pressed on last as a retainer. Not to worry, all the one piece kits I have seen include crystal clear instructions.

In the photos below you will see a botched up job. The bearing and retainer were not fully pressed on and this pretty much ruined the bearing, spacer and inner seal.

Good Luck and holler if you have additional questions. Keep in mind this is just a short run down of things........

 

[JKJeep]

Hey thanks for uploading all of that. Great looking axel to boot. Unfortunately I'll have to stick with the old two piece axel just because of finances but if I ever have to tear down this thing again, I'm buying the one piece for sure.

Couple questions for ya. One I didn't have any shims on mine when I pulled it apart. Two, my brake backing plate is bent out in the center, like someone tried to do this before and attached the puller without taking out the bolts that hold the dust cover to the axel housing. I'm kinda thinking that this is the reason that the thing is leaking. Do I need a shim there and do I need to hammer that backing plate back to flat to get it to stop leaking? The old seals actually look good, I am of course going to replace them.

BTW, do I need to grease the bearings before I put them back in or is the gear oil enough? Just wondering because of the inner seal, it almost seems unnecessary?

 

[PoliceMonkey161]

Not all of the axles had shims, it depended on the tolerance standards during the initial production.

I have had a bent backing plate before and just used a mallet to get it straight again. A replacement plate will be challenging to find and costly. Try to straighten it first.

Yes, you will certainly need to repack the bearing with grease after you clean the old grease and gear oil out of it. Gear oil is not a suitable lube for bearings, it will cause them to burn up. FYI, normally the leaking gear oil will push out your grease, so inspect your bearings closely!

 

[PoliceMonkey161]

Sorry, met to say that " NOT ALL AXLES had shims"

 

[69jeepcj]

Get some bearing grease at your local auto store. Greasing bearings is a bear, you have to pack the grease so it go,s inside the bearings, just dont wipe grease onto them. I would spend about 5 mins on each bearing packing them.