Diff Spacer Shavn', One Piece Axle Kit

[JackD]

Hey Guys, doing the Moser upgrade and need to kind of poll the people who have done this. I have already taken .080 off the spacer and by my calculations, I have another .130 to go to hit my target sweet spot .050. This seems like an awful lot of shaving down to me. You can take too much but ya can't put it back.. What has been your experience with this? Thanks..

 

[Belizean]

It's been over 25 years since mine were installed and I don't remember having to shave a spacer off hand.

 

[Patrick]

Is this the AMC20 one piece axle shaft conversion? There shouldn’t be a need to grind material off if you remove the infamous thrust block. I did this conversion many years ago also. But I could be wrong.

 

[JackD]

yes it is, the instructions from Moser say .020-.080 of bearing sticking out from the flange is acceptable....I got .185 after shaving off .080...and I have the spacer and race bottomed out and setting where they are supposed to be.. This spacer and bearing sit in the end of the tube...has nothing to do with the thrust block which is definitely coming out before the axles go in..

 

[Patrick]

I stand corrected. Sorry I couldn’t help you here.

 

[Scout1067]

I did the Moser conversion on mine (258 w/AMC20) last year and IIRC I ended up shaving .040 off my drivers side and none off the passenger. Once I got the spacer right and thrust block out it went together sweet as pie. The only rough part about reassembly was reattaching the brake lines to my drums, they were a pain to get the threads lined up without cross-threading.

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[JackD]

Well, after cleaning, sanding, rubber mallet hammering and various other methods of trying to get the bearing clearance correct....I finally got it to .030 off the flange...I'm happy with the way it's setting in the tube..axle spins freely with no binding. The other side is gonna be much easier now that I figured out the tricks..I'm hoping the driver's side goes together with no problems..The machine shop kinda depleted the grease that I packed in the bearing....anyone know the best way to pack a bearing that's installed on an axle shaft? I'm thinking grease gun needle maybe?

 

[Scout1067]

Driver's side is what will bind up if you haven't already pulled out the thrust block

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[JackD]

Scout, I already pulled it out..This CJ is gonna be fairly new when I finish it...seems like every time I fix something, I find something that needs to be repaired...The plus side is that the differential looks really good inside, the axle bearings were just about to out...43 years of tired...but they still had some grease!

 

[Patrick]

Gentlemen, please educate me here. I’d like to know why there is still a need to grind down components with the absence of the thrust block. Is it done to get the right bearing preload? Axial end play adjustment? If this is the case, the instructions cannot tell you how much material to remove. You’d have to figure that out yourself.

Another question, does this upgrade allow the shaft bearings to be lubricated with the oil in the axle housing? Thank you!

 

[JackD]

With the Moser one piece, that's exactly why you have to shave the spacer, to get proper axle end play and bearing preload. Shave off too much, the bearing will wobble in the race, loose and wear out early, Shave off too little and the backing plate will press too hard on the bearing, run hot, too tight and burn up. On the Moser one piece, the taper of the bearing faces the Diff and presses in to the race that is seated on the spacer. The stock AMC 2 piece, the bearing taper faces the backing plate and presses into the race against the seal and backing plate. Exactly Backwards from the Moser one piece setup....The thrust block is the spacer for the axles on the two piece AMC20. So..... the thrust block is a spacer in the Diff, that sets axle end play and preload in the stock two piece AMC20 and some have shims on the end of the tube also...

Moser one piece, the spacer is in the end of the axle tube...so you remove the thrust block from the diff so there is zero interference with the axle ends.. a better and stronger system, all the way around but the clearance on the bearing to backing plate has to be right for things to work as advertised...and you are correct, there is no set number of how much you need to shave off your spacer....you have to seat it, measure, pull back out, shave....repeat until you get the proper clearance. All axle tube ends are not created equal..lol

Some guys have gotten away with leaving the thrust block in and had no problems, some guys have left the thrust block in and had all kinds of problems...pretty much left to luck at that point but I have no luck so my thrust block came out, which for the most part is recommended by one piece axle manufacturers I believe...

Hope you can make sense out of that...The axle bearings are packed with grease, that is how they are lubricated, the axle tube has seals that separates the gear oil from the axle bearings.......inner seal, close to the carrier and outer seal that sets next to the spacer in the end of the axle tube..

 

[Patrick]

JackD, it all makes sense. And you made it very clear why the thrust block has to go: Moser reversed the bearing tapers where bearing preload and end play is adjusted differently. Thanks for taking time.

 

[JackD]

Yep, you got it Patrick! It is kind of a PITA to get the adjustment correct on the Moser kit but you can tell just by looking at the one piece axle setup that it is a much better/stronger system. Just makes sense to have the bearing taper facing into the axle tube instead of facing to the outside of the axle tube..

 

[Patrick]

One more question, JackD. Was the pressed in locking collar eliminated?

 

[JackD]

There is a metal bearing retaining ring that presses on to the axle with the bearing...I am assuming that this is what you are asking? It sets up against the bearing and keeps it from moving on the axle...The press fit for the bearing and retainer was taxing the machine shop press so the likelihood of the bearing ever moving is nil...but the retainer is there if it ever does!

 

[Patrick]

So there is a machined groove for a retaining ring. Moser knows what they are doing. Thanks again, man.

 

[JackD]

Well it appears that .080 off the passenger side spacer and nothing off the driver's side spacer appears to be the solution to my new Moser axle installation...everything is working great...seems weird to me that it worked out that way but it's working fine..

 

[Belizean]

Great. How did you take off the.080 ?

 

[JackD]

Had the machine shop shave it...

 

[Belizean]

Thanks that was my thoughts.